viper.go

// Copyright © 2014 Steve Francia <spf@spf13.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

// Viper is an application configuration system.
// It believes that applications can be configured a variety of ways
// via flags, ENVIRONMENT variables, configuration files retrieved
// from the file system, or a remote key/value store.

// Each item takes precedence over the item below it:

// overrides
// flag
// env
// config
// key/value store
// default

package viper

import (
    "bytes"
    "encoding/csv"
    "encoding/json"
    "errors"
    "fmt"
    "io"
    "log"
    "os"
    "path/filepath"
    "reflect"
    "strings"
    "sync"
    "time"

    "github.com/fsnotify/fsnotify"
    "github.com/hashicorp/hcl"
    "github.com/hashicorp/hcl/hcl/printer"
    "github.com/magiconair/properties"
    "github.com/mitchellh/mapstructure"
    "github.com/pelletier/go-toml"
    "github.com/spf13/afero"
    "github.com/spf13/cast"
    jww "github.com/spf13/jwalterweatherman"
    "github.com/spf13/pflag"
    "github.com/subosito/gotenv"
    "gopkg.in/ini.v1"
    "gopkg.in/yaml.v2"
)

// ConfigMarshalError happens when failing to marshal the configuration.
type ConfigMarshalError struct {
    err error
}

// Error returns the formatted configuration error.
func (e ConfigMarshalError) Error() string {
    return fmt.Sprintf("While marshaling config: %s", e.err.Error())
}

var v *Viper

type RemoteResponse struct {
    Value []byte
    Error error
}

func init() {
    v = New()
}

type remoteConfigFactory interface {
    Get(rp RemoteProvider) (io.Reader, error)
    Watch(rp RemoteProvider) (io.Reader, error)
    WatchChannel(rp RemoteProvider) (<-chan *RemoteResponse, chan bool)
}

// RemoteConfig is optional, see the remote package
var RemoteConfig remoteConfigFactory

// UnsupportedConfigError denotes encountering an unsupported
// configuration filetype.
type UnsupportedConfigError string

// Error returns the formatted configuration error.
func (str UnsupportedConfigError) Error() string {
    return fmt.Sprintf("Unsupported Config Type %q", string(str))
}

// UnsupportedRemoteProviderError denotes encountering an unsupported remote
// provider. Currently only etcd and Consul are supported.
type UnsupportedRemoteProviderError string

// Error returns the formatted remote provider error.
func (str UnsupportedRemoteProviderError) Error() string {
    return fmt.Sprintf("Unsupported Remote Provider Type %q", string(str))
}

// RemoteConfigError denotes encountering an error while trying to
// pull the configuration from the remote provider.
type RemoteConfigError string

// Error returns the formatted remote provider error
func (rce RemoteConfigError) Error() string {
    return fmt.Sprintf("Remote Configurations Error: %s", string(rce))
}

// ConfigFileNotFoundError denotes failing to find configuration file.
type ConfigFileNotFoundError struct {
    name, locations string
}

// Error returns the formatted configuration error.
func (fnfe ConfigFileNotFoundError) Error() string {
    return fmt.Sprintf("Config File %q Not Found in %q", fnfe.name, fnfe.locations)
}

// ConfigFileAlreadyExistsError denotes failure to write new configuration file.
type ConfigFileAlreadyExistsError string

// Error returns the formatted error when configuration already exists.
func (faee ConfigFileAlreadyExistsError) Error() string {
    return fmt.Sprintf("Config File %q Already Exists", string(faee))
}

// A DecoderConfigOption can be passed to viper.Unmarshal to configure
// mapstructure.DecoderConfig options
type DecoderConfigOption func(*mapstructure.DecoderConfig)

// DecodeHook returns a DecoderConfigOption which overrides the default
// DecoderConfig.DecodeHook value, the default is:
//
//  mapstructure.ComposeDecodeHookFunc(
//		mapstructure.StringToTimeDurationHookFunc(),
//		mapstructure.StringToSliceHookFunc(","),
//	)
func DecodeHook(hook mapstructure.DecodeHookFunc) DecoderConfigOption {
    return func(c *mapstructure.DecoderConfig) {
        c.DecodeHook = hook
    }
}

// Viper is a prioritized configuration registry. It
// maintains a set of configuration sources, fetches
// values to populate those, and provides them according
// to the source's priority.
// The priority of the sources is the following:
// 1. overrides
// 2. flags
// 3. env. variables
// 4. config file
// 5. key/value store
// 6. defaults
//
// For example, if values from the following sources were loaded:
//
//  Defaults : {
//  	"secret": "",
//  	"user": "default",
//  	"endpoint": "https://localhost"
//  }
//  Config : {
//  	"user": "root"
//  	"secret": "defaultsecret"
//  }
//  Env : {
//  	"secret": "somesecretkey"
//  }
//
// The resulting config will have the following values:
//
//	{
//		"secret": "somesecretkey",
//		"user": "root",
//		"endpoint": "https://localhost"
//	}
type Viper struct {
    // Delimiter that separates a list of keys
    // used to access a nested value in one go
    keyDelim string

    // A set of paths to look for the config file in
    configPaths []string

    // The filesystem to read config from.
    fs afero.Fs

    // A set of remote providers to search for the configuration
    remoteProviders []*defaultRemoteProvider

    // Name of file to look for inside the path
    configName        string
    configFile        string
    configType        string
    configPermissions os.FileMode
    envPrefix         string

    automaticEnvApplied bool
    envKeyReplacer      StringReplacer
    allowEmptyEnv       bool

    config         map[string]interface{}
    override       map[string]interface{}
    defaults       map[string]interface{}
    kvstore        map[string]interface{}
    pflags         map[string]FlagValue
    env            map[string]string
    aliases        map[string]string
    typeByDefValue bool

    // Store read properties on the object so that we can write back in order with comments.
    // This will only be used if the configuration read is a properties file.
    properties *properties.Properties

    onConfigChange func(fsnotify.Event)

    quitList []chan bool
}

// New returns an initialized Viper instance.
func New() *Viper {
    v := new(Viper)
    v.keyDelim = "."
    v.configName = "config"
    v.configPermissions = os.FileMode(0644)
    v.fs = afero.NewOsFs()
    v.config = make(map[string]interface{})
    v.override = make(map[string]interface{})
    v.defaults = make(map[string]interface{})
    v.kvstore = make(map[string]interface{})
    v.pflags = make(map[string]FlagValue)
    v.env = make(map[string]string)
    v.aliases = make(map[string]string)
    v.typeByDefValue = false
    v.quitList = make([]chan bool, 0)

    return v
}

// Option configures Viper using the functional options paradigm popularized by Rob Pike and Dave Cheney.
// If you're unfamiliar with this style,
// see https://commandcenter.blogspot.com/2014/01/self-referential-functions-and-design.html and
// https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis.
type Option interface {
    apply(v *Viper)
}

type optionFunc func(v *Viper)

func (fn optionFunc) apply(v *Viper) {
    fn(v)
}

// KeyDelimiter sets the delimiter used for determining key parts.
// By default it's value is ".".
func KeyDelimiter(d string) Option {
    return optionFunc(func(v *Viper) {
        v.keyDelim = d
    })
}

// StringReplacer applies a set of replacements to a string.
type StringReplacer interface {
    // Replace returns a copy of s with all replacements performed.
    Replace(s string) string
}

// EnvKeyReplacer sets a replacer used for mapping environment variables to internal keys.
func EnvKeyReplacer(r StringReplacer) Option {
    return optionFunc(func(v *Viper) {
        v.envKeyReplacer = r
    })
}

// NewWithOptions creates a new Viper instance.
func NewWithOptions(opts ...Option) *Viper {
    v := New()

    for _, opt := range opts {
        opt.apply(v)
    }

    return v
}

// Reset is intended for testing, will reset all to default settings.
// In the public interface for the viper package so applications
// can use it in their testing as well.
func Reset() {
    v = New()
    SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "dotenv", "env", "ini"}
    SupportedRemoteProviders = []string{"etcd", "consul", "firestore"}
}

type defaultRemoteProvider struct {
    provider      string
    endpoint      string
    path          string
    secretKeyring string
}

func (rp defaultRemoteProvider) Provider() string {
    return rp.provider
}

func (rp defaultRemoteProvider) Endpoint() string {
    return rp.endpoint
}

func (rp defaultRemoteProvider) Path() string {
    return rp.path
}

func (rp defaultRemoteProvider) SecretKeyring() string {
    return rp.secretKeyring
}

// RemoteProvider stores the configuration necessary
// to connect to a remote key/value store.
// Optional secretKeyring to unencrypt encrypted values
// can be provided.
type RemoteProvider interface {
    Provider() string
    Endpoint() string
    Path() string
    SecretKeyring() string
}

// SupportedExts are universally supported extensions.
var SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "dotenv", "env", "ini"}

// SupportedRemoteProviders are universally supported remote providers.
var SupportedRemoteProviders = []string{"etcd", "consul", "firestore"}

func OnConfigChange(run func(in fsnotify.Event)) { v.OnConfigChange(run) }
func (v *Viper) OnConfigChange(run func(in fsnotify.Event)) {
    v.onConfigChange = run
}

func WatchConfig() { v.WatchConfig() }

func (v *Viper) WatchConfig() {
    initWG := sync.WaitGroup{}
    initWG.Add(1)
    go func() {
        watcher, err := fsnotify.NewWatcher()
        if err != nil {
            log.Fatal(err)
        }
        defer watcher.Close()
        // we have to watch the entire directory to pick up renames/atomic saves in a cross-platform way
        filename, err := v.getConfigFile()
        if err != nil {
            log.Printf("error: %v\n", err)
            initWG.Done()
            return
        }

        configFile := filepath.Clean(filename)
        configDir, _ := filepath.Split(configFile)
        realConfigFile, _ := filepath.EvalSymlinks(filename)

        eventsWG := sync.WaitGroup{}
        eventsWG.Add(1)
        go func() {
            for {
                select {
                case event, ok := <-watcher.Events:
                    if !ok { // 'Events' channel is closed
                        eventsWG.Done()
                        return
                    }
                    currentConfigFile, _ := filepath.EvalSymlinks(filename)
                    // we only care about the config file with the following cases:
                    // 1 - if the config file was modified or created
                    // 2 - if the real path to the config file changed (eg: k8s ConfigMap replacement)
                    const writeOrCreateMask = fsnotify.Write | fsnotify.Create
                    if (filepath.Clean(event.Name) == configFile &&
                        event.Op&writeOrCreateMask != 0) ||
                        (currentConfigFile != "" && currentConfigFile != realConfigFile) {
                        realConfigFile = currentConfigFile
                        err := v.ReadInConfig()
                        if err != nil {
                            log.Printf("error reading config file: %v\n", err)
                        }
                        if v.onConfigChange != nil {
                            v.onConfigChange(event)
                        }
                    } else if filepath.Clean(event.Name) == configFile &&
                        event.Op&fsnotify.Remove&fsnotify.Remove != 0 {
                        eventsWG.Done()
                        return
                    }

                case err, ok := <-watcher.Errors:
                    if ok { // 'Errors' channel is not closed
                        log.Printf("watcher error: %v\n", err)
                    }
                    eventsWG.Done()
                    return
                }
            }
        }()
        watcher.Add(configDir)
        initWG.Done()   // done initializing the watch in this go routine, so the parent routine can move on...
        eventsWG.Wait() // now, wait for event loop to end in this go-routine...
    }()
    initWG.Wait() // make sure that the go routine above fully ended before returning
}

// SetConfigFile explicitly defines the path, name and extension of the config file.
// Viper will use this and not check any of the config paths.
func SetConfigFile(in string) { v.SetConfigFile(in) }
func (v *Viper) SetConfigFile(in string) {
    if in != "" {
        v.configFile = in
    }
}

// SetEnvPrefix defines a prefix that ENVIRONMENT variables will use.
// E.g. if your prefix is "spf", the env registry will look for env
// variables that start with "SPF_".
func SetEnvPrefix(in string) { v.SetEnvPrefix(in) }
func (v *Viper) SetEnvPrefix(in string) {
    if in != "" {
        v.envPrefix = in
    }
}

func (v *Viper) mergeWithEnvPrefix(in string) string {
    if v.envPrefix != "" {
        return strings.ToUpper(v.envPrefix + "_" + in)
    }

    return strings.ToUpper(in)
}

// AllowEmptyEnv tells Viper to consider set,
// but empty environment variables as valid values instead of falling back.
// For backward compatibility reasons this is false by default.
func AllowEmptyEnv(allowEmptyEnv bool) { v.AllowEmptyEnv(allowEmptyEnv) }
func (v *Viper) AllowEmptyEnv(allowEmptyEnv bool) {
    v.allowEmptyEnv = allowEmptyEnv
}

// TODO: should getEnv logic be moved into find(). Can generalize the use of
// rewriting keys many things, Ex: Get('someKey') -> some_key
// (camel case to snake case for JSON keys perhaps)

// getEnv is a wrapper around os.Getenv which replaces characters in the original
// key. This allows env vars which have different keys than the config object
// keys.
func (v *Viper) getEnv(key string) (string, bool) {
    if v.envKeyReplacer != nil {
        key = v.envKeyReplacer.Replace(key)
    }

    val, ok := os.LookupEnv(key)

    return val, ok && (v.allowEmptyEnv || val != "")
}

// ConfigFileUsed returns the file used to populate the config registry.
func ConfigFileUsed() string            { return v.ConfigFileUsed() }
func (v *Viper) ConfigFileUsed() string { return v.configFile }

// AddConfigPath adds a path for Viper to search for the config file in.
// Can be called multiple times to define multiple search paths.
func AddConfigPath(in string) { v.AddConfigPath(in) }
func (v *Viper) AddConfigPath(in string) {
    if in != "" {
        absin := absPathify(in)
        jww.INFO.Println("adding", absin, "to paths to search")
        if !stringInSlice(absin, v.configPaths) {
            v.configPaths = append(v.configPaths, absin)
        }
    }
}

// AddRemoteProvider adds a remote configuration source.
// Remote Providers are searched in the order they are added.
// provider is a string value: "etcd", "consul" or "firestore" are currently supported.
// endpoint is the url.  etcd requires http://ip:port  consul requires ip:port
// path is the path in the k/v store to retrieve configuration
// To retrieve a config file called myapp.json from /configs/myapp.json
// you should set path to /configs and set config name (SetConfigName()) to
// "myapp"
func AddRemoteProvider(provider, endpoint, path string) error {
    return v.AddRemoteProvider(provider, endpoint, path)
}
func (v *Viper) AddRemoteProvider(provider, endpoint, path string) error {
    if !stringInSlice(provider, SupportedRemoteProviders) {
        return UnsupportedRemoteProviderError(provider)
    }
    if provider != "" && endpoint != "" {
        jww.INFO.Printf("adding %s:%s to remote provider list", provider, endpoint)
        rp := &defaultRemoteProvider{
            endpoint: endpoint,
            provider: provider,
            path:     path,
        }
        if !v.providerPathExists(rp) {
            v.remoteProviders = append(v.remoteProviders, rp)
        }
    }
    return nil
}

// AddSecureRemoteProvider adds a remote configuration source.
// Secure Remote Providers are searched in the order they are added.
// provider is a string value: "etcd", "consul" or "firestore" are currently supported.
// endpoint is the url.  etcd requires http://ip:port  consul requires ip:port
// secretkeyring is the filepath to your openpgp secret keyring.  e.g. /etc/secrets/myring.gpg
// path is the path in the k/v store to retrieve configuration
// To retrieve a config file called myapp.json from /configs/myapp.json
// you should set path to /configs and set config name (SetConfigName()) to
// "myapp"
// Secure Remote Providers are implemented with github.com/bketelsen/crypt
func AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error {
    return v.AddSecureRemoteProvider(provider, endpoint, path, secretkeyring)
}

func (v *Viper) AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error {
    if !stringInSlice(provider, SupportedRemoteProviders) {
        return UnsupportedRemoteProviderError(provider)
    }
    if provider != "" && endpoint != "" {
        jww.INFO.Printf("adding %s:%s to remote provider list", provider, endpoint)
        rp := &defaultRemoteProvider{
            endpoint:      endpoint,
            provider:      provider,
            path:          path,
            secretKeyring: secretkeyring,
        }
        if !v.providerPathExists(rp) {
            v.remoteProviders = append(v.remoteProviders, rp)
        }
    }
    return nil
}

func (v *Viper) providerPathExists(p *defaultRemoteProvider) bool {
    for _, y := range v.remoteProviders {
        if reflect.DeepEqual(y, p) {
            return true
        }
    }
    return false
}

// searchMap recursively searches for a value for path in source map.
// Returns nil if not found.
// Note: This assumes that the path entries and map keys are lower cased.
func (v *Viper) searchMap(source map[string]interface{}, path []string) interface{} {
    if len(path) == 0 {
        return source
    }

    next, ok := source[path[0]]
    if ok {
        // Fast path
        if len(path) == 1 {
            return next
        }

        // Nested case
        switch next.(type) {
        case map[interface{}]interface{}:
            return v.searchMap(cast.ToStringMap(next), path[1:])
        case map[string]interface{}:
            // Type assertion is safe here since it is only reached
            // if the type of `next` is the same as the type being asserted
            return v.searchMap(next.(map[string]interface{}), path[1:])
        default:
            // got a value but nested key expected, return "nil" for not found
            return nil
        }
    }
    return nil
}

// searchMapWithPathPrefixes recursively searches for a value for path in source map.
//
// While searchMap() considers each path element as a single map key, this
// function searches for, and prioritizes, merged path elements.
// e.g., if in the source, "foo" is defined with a sub-key "bar", and "foo.bar"
// is also defined, this latter value is returned for path ["foo", "bar"].
//
// This should be useful only at config level (other maps may not contain dots
// in their keys).
//
// Note: This assumes that the path entries and map keys are lower cased.
func (v *Viper) searchMapWithPathPrefixes(source map[string]interface{}, path []string) interface{} {
    if len(path) == 0 {
        return source
    }

    // search for path prefixes, starting from the longest one
    for i := len(path); i > 0; i-- {
        prefixKey := strings.ToLower(strings.Join(path[0:i], v.keyDelim))

        next, ok := source[prefixKey]
        if ok {
            // Fast path
            if i == len(path) {
                return next
            }

            // Nested case
            var val interface{}
            switch next.(type) {
            case map[interface{}]interface{}:
                val = v.searchMapWithPathPrefixes(cast.ToStringMap(next), path[i:])
            case map[string]interface{}:
                // Type assertion is safe here since it is only reached
                // if the type of `next` is the same as the type being asserted
                val = v.searchMapWithPathPrefixes(next.(map[string]interface{}), path[i:])
            default:
                // got a value but nested key expected, do nothing and look for next prefix
            }
            if val != nil {
                return val
            }
        }
    }

    // not found
    return nil
}

// isPathShadowedInDeepMap makes sure the given path is not shadowed somewhere
// on its path in the map.
// e.g., if "foo.bar" has a value in the given map, it “shadows”
//       "foo.bar.baz" in a lower-priority map
func (v *Viper) isPathShadowedInDeepMap(path []string, m map[string]interface{}) string {
    var parentVal interface{}
    for i := 1; i < len(path); i++ {
        parentVal = v.searchMap(m, path[0:i])
        if parentVal == nil {
            // not found, no need to add more path elements
            return ""
        }
        switch parentVal.(type) {
        case map[interface{}]interface{}:
            continue
        case map[string]interface{}:
            continue
        default:
            // parentVal is a regular value which shadows "path"
            return strings.Join(path[0:i], v.keyDelim)
        }
    }
    return ""
}

// isPathShadowedInFlatMap makes sure the given path is not shadowed somewhere
// in a sub-path of the map.
// e.g., if "foo.bar" has a value in the given map, it “shadows”
//       "foo.bar.baz" in a lower-priority map
func (v *Viper) isPathShadowedInFlatMap(path []string, mi interface{}) string {
    // unify input map
    var m map[string]interface{}
    switch mi.(type) {
    case map[string]string, map[string]FlagValue:
        m = cast.ToStringMap(mi)
    default:
        return ""
    }

    // scan paths
    var parentKey string
    for i := 1; i < len(path); i++ {
        parentKey = strings.Join(path[0:i], v.keyDelim)
        if _, ok := m[parentKey]; ok {
            return parentKey
        }
    }
    return ""
}

// isPathShadowedInAutoEnv makes sure the given path is not shadowed somewhere
// in the environment, when automatic env is on.
// e.g., if "foo.bar" has a value in the environment, it “shadows”
//       "foo.bar.baz" in a lower-priority map
func (v *Viper) isPathShadowedInAutoEnv(path []string) string {
    var parentKey string
    for i := 1; i < len(path); i++ {
        parentKey = strings.Join(path[0:i], v.keyDelim)
        if _, ok := v.getEnv(v.mergeWithEnvPrefix(parentKey)); ok {
            return parentKey
        }
    }
    return ""
}

// SetTypeByDefaultValue enables or disables the inference of a key value's
// type when the Get function is used based upon a key's default value as
// opposed to the value returned based on the normal fetch logic.
//
// For example, if a key has a default value of []string{} and the same key
// is set via an environment variable to "a b c", a call to the Get function
// would return a string slice for the key if the key's type is inferred by
// the default value and the Get function would return:
//
//   []string {"a", "b", "c"}
//
// Otherwise the Get function would return:
//
//   "a b c"
func SetTypeByDefaultValue(enable bool) { v.SetTypeByDefaultValue(enable) }
func (v *Viper) SetTypeByDefaultValue(enable bool) {
    v.typeByDefValue = enable
}

// GetViper gets the global Viper instance.
func GetViper() *Viper {
    return v
}

// Get can retrieve any value given the key to use.
// Get is case-insensitive for a key.
// Get has the behavior of returning the value associated with the first
// place from where it is set. Viper will check in the following order:
// override, flag, env, config file, key/value store, default
//
// Get returns an interface. For a specific value use one of the Get____ methods.
func Get(key string) interface{} { return v.Get(key) }
func (v *Viper) Get(key string) interface{} {
    lcaseKey := strings.ToLower(key)
    val := v.find(lcaseKey, true)
    if val == nil {
        return nil
    }

    if v.typeByDefValue {
        // TODO(bep) this branch isn't covered by a single test.
        valType := val
        path := strings.Split(lcaseKey, v.keyDelim)
        defVal := v.searchMap(v.defaults, path)
        if defVal != nil {
            valType = defVal
        }

        switch valType.(type) {
        case bool:
            return cast.ToBool(val)
        case string:
            return cast.ToString(val)
        case int32, int16, int8, int:
            return cast.ToInt(val)
        case uint:
            return cast.ToUint(val)
        case uint32:
            return cast.ToUint32(val)
        case uint64:
            return cast.ToUint64(val)
        case int64:
            return cast.ToInt64(val)
        case float64, float32:
            return cast.ToFloat64(val)
        case time.Time:
            return cast.ToTime(val)
        case time.Duration:
            return cast.ToDuration(val)
        case []string:
            return cast.ToStringSlice(val)
        case []int:
            return cast.ToIntSlice(val)
        }
    }

    return val
}

// Sub returns new Viper instance representing a sub tree of this instance.
// Sub is case-insensitive for a key.
func Sub(key string) *Viper { return v.Sub(key) }
func (v *Viper) Sub(key string) *Viper {
    subv := New()
    data := v.Get(key)
    if data == nil {
        return nil
    }

    if reflect.TypeOf(data).Kind() == reflect.Map {
        subv.config = cast.ToStringMap(data)
        return subv
    }
    return nil
}

// GetString returns the value associated with the key as a string.
func GetString(key string) string { return v.GetString(key) }
func (v *Viper) GetString(key string) string {
    return cast.ToString(v.Get(key))
}

// GetBool returns the value associated with the key as a boolean.
func GetBool(key string) bool { return v.GetBool(key) }
func (v *Viper) GetBool(key string) bool {
    return cast.ToBool(v.Get(key))
}

// GetInt returns the value associated with the key as an integer.
func GetInt(key string) int { return v.GetInt(key) }
func (v *Viper) GetInt(key string) int {
    return cast.ToInt(v.Get(key))
}

// GetInt32 returns the value associated with the key as an integer.
func GetInt32(key string) int32 { return v.GetInt32(key) }
func (v *Viper) GetInt32(key string) int32 {
    return cast.ToInt32(v.Get(key))
}

// GetInt64 returns the value associated with the key as an integer.
func GetInt64(key string) int64 { return v.GetInt64(key) }
func (v *Viper) GetInt64(key string) int64 {
    return cast.ToInt64(v.Get(key))
}

// GetUint returns the value associated with the key as an unsigned integer.
func GetUint(key string) uint { return v.GetUint(key) }
func (v *Viper) GetUint(key string) uint {
    return cast.ToUint(v.Get(key))
}

// GetUint32 returns the value associated with the key as an unsigned integer.
func GetUint32(key string) uint32 { return v.GetUint32(key) }
func (v *Viper) GetUint32(key string) uint32 {
    return cast.ToUint32(v.Get(key))
}

// GetUint64 returns the value associated with the key as an unsigned integer.
func GetUint64(key string) uint64 { return v.GetUint64(key) }
func (v *Viper) GetUint64(key string) uint64 {
    return cast.ToUint64(v.Get(key))
}

// GetFloat64 returns the value associated with the key as a float64.
func GetFloat64(key string) float64 { return v.GetFloat64(key) }
func (v *Viper) GetFloat64(key string) float64 {
    return cast.ToFloat64(v.Get(key))
}

// GetTime returns the value associated with the key as time.
func GetTime(key string) time.Time { return v.GetTime(key) }
func (v *Viper) GetTime(key string) time.Time {
    return cast.ToTime(v.Get(key))
}

// GetDuration returns the value associated with the key as a duration.
func GetDuration(key string) time.Duration { return v.GetDuration(key) }
func (v *Viper) GetDuration(key string) time.Duration {
    return cast.ToDuration(v.Get(key))
}

// GetIntSlice returns the value associated with the key as a slice of int values.
func GetIntSlice(key string) []int { return v.GetIntSlice(key) }
func (v *Viper) GetIntSlice(key string) []int {
    return cast.ToIntSlice(v.Get(key))
}

// GetStringSlice returns the value associated with the key as a slice of strings.
func GetStringSlice(key string) []string { return v.GetStringSlice(key) }
func (v *Viper) GetStringSlice(key string) []string {
    return cast.ToStringSlice(v.Get(key))
}

// GetStringMap returns the value associated with the key as a map of interfaces.
func GetStringMap(key string) map[string]interface{} { return v.GetStringMap(key) }
func (v *Viper) GetStringMap(key string) map[string]interface{} {
    return cast.ToStringMap(v.Get(key))
}

// GetStringMapString returns the value associated with the key as a map of strings.
func GetStringMapString(key string) map[string]string { return v.GetStringMapString(key) }
func (v *Viper) GetStringMapString(key string) map[string]string {
    return cast.ToStringMapString(v.Get(key))
}

// GetStringMapStringSlice returns the value associated with the key as a map to a slice of strings.
func GetStringMapStringSlice(key string) map[string][]string { return v.GetStringMapStringSlice(key) }
func (v *Viper) GetStringMapStringSlice(key string) map[string][]string {
    return cast.ToStringMapStringSlice(v.Get(key))
}

// GetSizeInBytes returns the size of the value associated with the given key
// in bytes.
func GetSizeInBytes(key string) uint { return v.GetSizeInBytes(key) }
func (v *Viper) GetSizeInBytes(key string) uint {
    sizeStr := cast.ToString(v.Get(key))
    return parseSizeInBytes(sizeStr)
}

// UnmarshalKey takes a single key and unmarshals it into a Struct.
func UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error {
    return v.UnmarshalKey(key, rawVal, opts...)
}
func (v *Viper) UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error {
    return decode(v.Get(key), defaultDecoderConfig(rawVal, opts...))
}

// Unmarshal unmarshals the config into a Struct. Make sure that the tags
// on the fields of the structure are properly set.
func Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error {
    return v.Unmarshal(rawVal, opts...)
}
func (v *Viper) Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error {
    return decode(v.AllSettings(), defaultDecoderConfig(rawVal, opts...))
}

// defaultDecoderConfig returns default mapsstructure.DecoderConfig with suppot
// of time.Duration values & string slices
func defaultDecoderConfig(output interface{}, opts ...DecoderConfigOption) *mapstructure.DecoderConfig {
    c := &mapstructure.DecoderConfig{
        Metadata:         nil,
        Result:           output,
        WeaklyTypedInput: true,
        DecodeHook: mapstructure.ComposeDecodeHookFunc(
            mapstructure.StringToTimeDurationHookFunc(),
            mapstructure.StringToSliceHookFunc(","),
        ),
    }
    for _, opt := range opts {
        opt(c)
    }
    return c
}

// A wrapper around mapstructure.Decode that mimics the WeakDecode functionality
func decode(input interface{}, config *mapstructure.DecoderConfig) error {
    decoder, err := mapstructure.NewDecoder(config)
    if err != nil {
        return err
    }
    return decoder.Decode(input)
}

// UnmarshalExact unmarshals the config into a Struct, erroring if a field is nonexistent
// in the destination struct.
func UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error {
    return v.UnmarshalExact(rawVal, opts...)
}
func (v *Viper) UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error {
    config := defaultDecoderConfig(rawVal, opts...)
    config.ErrorUnused = true

    return decode(v.AllSettings(), config)
}

// BindPFlags binds a full flag set to the configuration, using each flag's long
// name as the config key.
func BindPFlags(flags *pflag.FlagSet) error { return v.BindPFlags(flags) }
func (v *Viper) BindPFlags(flags *pflag.FlagSet) error {
    return v.BindFlagValues(pflagValueSet{flags})
}

// BindPFlag binds a specific key to a pflag (as used by cobra).
// Example (where serverCmd is a Cobra instance):
//
//	 serverCmd.Flags().Int("port", 1138, "Port to run Application server on")
//	 Viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))
//
func BindPFlag(key string, flag *pflag.Flag) error { return v.BindPFlag(key, flag) }
func (v *Viper) BindPFlag(key string, flag *pflag.Flag) error {
    return v.BindFlagValue(key, pflagValue{flag})
}

// BindFlagValues binds a full FlagValue set to the configuration, using each flag's long
// name as the config key.
func BindFlagValues(flags FlagValueSet) error { return v.BindFlagValues(flags) }
func (v *Viper) BindFlagValues(flags FlagValueSet) (err error) {
    flags.VisitAll(func(flag FlagValue) {
        if err = v.BindFlagValue(flag.Name(), flag); err != nil {
            return
        }
    })
    return nil
}

// BindFlagValue binds a specific key to a FlagValue.
func BindFlagValue(key string, flag FlagValue) error { return v.BindFlagValue(key, flag) }
func (v *Viper) BindFlagValue(key string, flag FlagValue) error {
    if flag == nil {
        return fmt.Errorf("flag for %q is nil", key)
    }
    v.pflags[strings.ToLower(key)] = flag
    return nil
}

// BindEnv binds a Viper key to a ENV variable.
// ENV variables are case sensitive.
// If only a key is provided, it will use the env key matching the key, uppercased.
// EnvPrefix will be used when set when env name is not provided.
func BindEnv(input ...string) error { return v.BindEnv(input...) }
func (v *Viper) BindEnv(input ...string) error {
    var key, envkey string
    if len(input) == 0 {
        return fmt.Errorf("missing key to bind to")
    }

    key = strings.ToLower(input[0])

    if len(input) == 1 {
        envkey = v.mergeWithEnvPrefix(key)
    } else {
        envkey = input[1]
    }

    v.env[key] = envkey

    return nil
}

// Given a key, find the value.
//
// Viper will check to see if an alias exists first.
// Viper will then check in the following order:
// flag, env, config file, key/value store.
// Lastly, if no value was found and flagDefault is true, and if the key
// corresponds to a flag, the flag's default value is returned.
//
// Note: this assumes a lower-cased key given.
func (v *Viper) find(lcaseKey string, flagDefault bool) interface{} {
    var (
        val    interface{}
        exists bool
        path   = strings.Split(lcaseKey, v.keyDelim)
        nested = len(path) > 1
    )

    // compute the path through the nested maps to the nested value
    if nested && v.isPathShadowedInDeepMap(path, castMapStringToMapInterface(v.aliases)) != "" {
        return nil
    }

    // if the requested key is an alias, then return the proper key
    lcaseKey = v.realKey(lcaseKey)
    path = strings.Split(lcaseKey, v.keyDelim)
    nested = len(path) > 1

    // Set() override first
    val = v.searchMap(v.override, path)
    if val != nil {
        return val
    }
    if nested && v.isPathShadowedInDeepMap(path, v.override) != "" {
        return nil
    }

    // PFlag override next
    flag, exists := v.pflags[lcaseKey]
    if exists && flag.HasChanged() {
        switch flag.ValueType() {
        case "int", "int8", "int16", "int32", "int64":
            return cast.ToInt(flag.ValueString())
        case "bool":
            return cast.ToBool(flag.ValueString())
        case "stringSlice":
            s := strings.TrimPrefix(flag.ValueString(), "[")
            s = strings.TrimSuffix(s, "]")
            res, _ := readAsCSV(s)
            return res
        case "intSlice":
            s := strings.TrimPrefix(flag.ValueString(), "[")
            s = strings.TrimSuffix(s, "]")
            res, _ := readAsCSV(s)
            return cast.ToIntSlice(res)
        case "stringToString":
            return stringToStringConv(flag.ValueString())
        default:
            return flag.ValueString()
        }
    }
    if nested && v.isPathShadowedInFlatMap(path, v.pflags) != "" {
        return nil
    }

    // Env override next
    if v.automaticEnvApplied {
        // even if it hasn't been registered, if automaticEnv is used,
        // check any Get request
        if val, ok := v.getEnv(v.mergeWithEnvPrefix(lcaseKey)); ok {
            return val
        }
        if nested && v.isPathShadowedInAutoEnv(path) != "" {
            return nil
        }
    }
    envkey, exists := v.env[lcaseKey]
    if exists {
        if val, ok := v.getEnv(envkey); ok {
            return val
        }
    }
    if nested && v.isPathShadowedInFlatMap(path, v.env) != "" {
        return nil
    }

    // Config file next
    val = v.searchMapWithPathPrefixes(v.config, path)
    if val != nil {
        return val
    }
    if nested && v.isPathShadowedInDeepMap(path, v.config) != "" {
        return nil
    }

    // K/V store next
    val = v.searchMap(v.kvstore, path)
    if val != nil {
        return val
    }
    if nested && v.isPathShadowedInDeepMap(path, v.kvstore) != "" {
        return nil
    }

    // Default next
    val = v.searchMap(v.defaults, path)
    if val != nil {
        return val
    }
    if nested && v.isPathShadowedInDeepMap(path, v.defaults) != "" {
        return nil
    }

    if flagDefault {
        // last chance: if no value is found and a flag does exist for the key,
        // get the flag's default value even if the flag's value has not been set.
        if flag, exists := v.pflags[lcaseKey]; exists {
            switch flag.ValueType() {
            case "int", "int8", "int16", "int32", "int64":
                return cast.ToInt(flag.ValueString())
            case "bool":
                return cast.ToBool(flag.ValueString())
            case "stringSlice":
                s := strings.TrimPrefix(flag.ValueString(), "[")
                s = strings.TrimSuffix(s, "]")
                res, _ := readAsCSV(s)
                return res
            case "intSlice":
                s := strings.TrimPrefix(flag.ValueString(), "[")
                s = strings.TrimSuffix(s, "]")
                res, _ := readAsCSV(s)
                return cast.ToIntSlice(res)
            case "stringToString":
                return stringToStringConv(flag.ValueString())
            default:
                return flag.ValueString()
            }
        }
        // last item, no need to check shadowing
    }

    return nil
}

func readAsCSV(val string) ([]string, error) {
    if val == "" {
        return []string{}, nil
    }
    stringReader := strings.NewReader(val)
    csvReader := csv.NewReader(stringReader)
    return csvReader.Read()
}

// mostly copied from pflag's implementation of this operation here https://github.com/spf13/pflag/blob/master/string_to_string.go#L79
// alterations are: errors are swallowed, map[string]interface{} is returned in order to enable cast.ToStringMap
func stringToStringConv(val string) interface{} {
    val = strings.Trim(val, "[]")
    // An empty string would cause an empty map
    if len(val) == 0 {
        return map[string]interface{}{}
    }
    r := csv.NewReader(strings.NewReader(val))
    ss, err := r.Read()
    if err != nil {
        return nil
    }
    out := make(map[string]interface{}, len(ss))
    for _, pair := range ss {
        kv := strings.SplitN(pair, "=", 2)
        if len(kv) != 2 {
            return nil
        }
        out[kv[0]] = kv[1]
    }
    return out
}

// IsSet checks to see if the key has been set in any of the data locations.
// IsSet is case-insensitive for a key.
func IsSet(key string) bool { return v.IsSet(key) }
func (v *Viper) IsSet(key string) bool {
    lcaseKey := strings.ToLower(key)
    val := v.find(lcaseKey, false)
    return val != nil
}

// AutomaticEnv has Viper check ENV variables for all.
// keys set in config, default & flags
func AutomaticEnv() { v.AutomaticEnv() }
func (v *Viper) AutomaticEnv() {
    v.automaticEnvApplied = true
}

// SetEnvKeyReplacer sets the strings.Replacer on the viper object
// Useful for mapping an environmental variable to a key that does
// not match it.
func SetEnvKeyReplacer(r *strings.Replacer) { v.SetEnvKeyReplacer(r) }
func (v *Viper) SetEnvKeyReplacer(r *strings.Replacer) {
    v.envKeyReplacer = r
}

// RegisterAlias creates an alias that provides another accessor for the same key.
// This enables one to change a name without breaking the application.
func RegisterAlias(alias string, key string) { v.RegisterAlias(alias, key) }
func (v *Viper) RegisterAlias(alias string, key string) {
    v.registerAlias(alias, strings.ToLower(key))
}

func (v *Viper) registerAlias(alias string, key string) {
    alias = strings.ToLower(alias)
    if alias != key && alias != v.realKey(key) {
        _, exists := v.aliases[alias]

        if !exists {
            // if we alias something that exists in one of the maps to another
            // name, we'll never be able to get that value using the original
            // name, so move the config value to the new realkey.
            if val, ok := v.config[alias]; ok {
                delete(v.config, alias)
                v.config[key] = val
            }
            if val, ok := v.kvstore[alias]; ok {
                delete(v.kvstore, alias)
                v.kvstore[key] = val
            }
            if val, ok := v.defaults[alias]; ok {
                delete(v.defaults, alias)
                v.defaults[key] = val
            }
            if val, ok := v.override[alias]; ok {
                delete(v.override, alias)
                v.override[key] = val
            }
            v.aliases[alias] = key
        }
    } else {
        jww.WARN.Println("Creating circular reference alias", alias, key, v.realKey(key))
    }
}

func (v *Viper) realKey(key string) string {
    newkey, exists := v.aliases[key]
    if exists {
        jww.DEBUG.Println("Alias", key, "to", newkey)
        return v.realKey(newkey)
    }
    return key
}

// InConfig checks to see if the given key (or an alias) is in the config file.
func InConfig(key string) bool { return v.InConfig(key) }
func (v *Viper) InConfig(key string) bool {
    // if the requested key is an alias, then return the proper key
    key = v.realKey(key)

    _, exists := v.config[key]
    return exists
}

// SetDefault sets the default value for this key.
// SetDefault is case-insensitive for a key.
// Default only used when no value is provided by the user via flag, config or ENV.
func SetDefault(key string, value interface{}) { v.SetDefault(key, value) }
func (v *Viper) SetDefault(key string, value interface{}) {
    // If alias passed in, then set the proper default
    key = v.realKey(strings.ToLower(key))
    value = toCaseInsensitiveValue(value)

    path := strings.Split(key, v.keyDelim)
    lastKey := strings.ToLower(path[len(path)-1])
    deepestMap := deepSearch(v.defaults, path[0:len(path)-1])

    // set innermost value
    deepestMap[lastKey] = value
}

// Set sets the value for the key in the override register.
// Set is case-insensitive for a key.
// Will be used instead of values obtained via
// flags, config file, ENV, default, or key/value store.
func Set(key string, value interface{}) { v.Set(key, value) }
func (v *Viper) Set(key string, value interface{}) {
    // If alias passed in, then set the proper override
    key = v.realKey(strings.ToLower(key))
    value = toCaseInsensitiveValue(value)

    path := strings.Split(key, v.keyDelim)
    lastKey := strings.ToLower(path[len(path)-1])
    deepestMap := deepSearch(v.override, path[0:len(path)-1])

    // set innermost value
    deepestMap[lastKey] = value
}

// ReadInConfig will discover and load the configuration file from disk
// and key/value stores, searching in one of the defined paths.
func ReadInConfig() error { return v.ReadInConfig() }
func (v *Viper) ReadInConfig() error {
    jww.INFO.Println("Attempting to read in config file")
    filename, err := v.getConfigFile()
    if err != nil {
        return err
    }

    if !stringInSlice(v.getConfigType(), SupportedExts) {
        return UnsupportedConfigError(v.getConfigType())
    }

    jww.DEBUG.Println("Reading file: ", filename)
    file, err := afero.ReadFile(v.fs, filename)
    if err != nil {
        return err
    }

    config := make(map[string]interface{})

    err = v.unmarshalReader(bytes.NewReader(file), config)
    if err != nil {
        return err
    }

    v.config = config
    return nil
}

// MergeInConfig merges a new configuration with an existing config.
func MergeInConfig() error { return v.MergeInConfig() }
func (v *Viper) MergeInConfig() error {
    jww.INFO.Println("Attempting to merge in config file")
    filename, err := v.getConfigFile()
    if err != nil {
        return err
    }

    if !stringInSlice(v.getConfigType(), SupportedExts) {
        return UnsupportedConfigError(v.getConfigType())
    }

    file, err := afero.ReadFile(v.fs, filename)
    if err != nil {
        return err
    }

    return v.MergeConfig(bytes.NewReader(file))
}

// ReadConfig will read a configuration file, setting existing keys to nil if the
// key does not exist in the file.
func ReadConfig(in io.Reader) error { return v.ReadConfig(in) }
func (v *Viper) ReadConfig(in io.Reader) error {
    v.config = make(map[string]interface{})
    return v.unmarshalReader(in, v.config)
}

// MergeConfig merges a new configuration with an existing config.
func MergeConfig(in io.Reader) error { return v.MergeConfig(in) }
func (v *Viper) MergeConfig(in io.Reader) error {
    cfg := make(map[string]interface{})
    if err := v.unmarshalReader(in, cfg); err != nil {
        return err
    }
    return v.MergeConfigMap(cfg)
}

// MergeConfigMap merges the configuration from the map given with an existing config.
// Note that the map given may be modified.
func MergeConfigMap(cfg map[string]interface{}) error { return v.MergeConfigMap(cfg) }
func (v *Viper) MergeConfigMap(cfg map[string]interface{}) error {
    if v.config == nil {
        v.config = make(map[string]interface{})
    }
    insensitiviseMap(cfg)
    mergeMaps(cfg, v.config, nil)
    return nil
}

// WriteConfig writes the current configuration to a file.
func WriteConfig() error { return v.WriteConfig() }
func (v *Viper) WriteConfig() error {
    filename, err := v.getConfigFile()
    if err != nil {
        return err
    }
    return v.writeConfig(filename, true)
}

// SafeWriteConfig writes current configuration to file only if the file does not exist.
func SafeWriteConfig() error { return v.SafeWriteConfig() }
func (v *Viper) SafeWriteConfig() error {
    if len(v.configPaths) < 1 {
        return errors.New("missing configuration for 'configPath'")
    }
    return v.SafeWriteConfigAs(filepath.Join(v.configPaths[0], v.configName+"."+v.configType))
}

// WriteConfigAs writes current configuration to a given filename.
func WriteConfigAs(filename string) error { return v.WriteConfigAs(filename) }
func (v *Viper) WriteConfigAs(filename string) error {
    return v.writeConfig(filename, true)
}

// SafeWriteConfigAs writes current configuration to a given filename if it does not exist.
func SafeWriteConfigAs(filename string) error { return v.SafeWriteConfigAs(filename) }
func (v *Viper) SafeWriteConfigAs(filename string) error {
    alreadyExists, err := afero.Exists(v.fs, filename)
    if alreadyExists && err == nil {
        return ConfigFileAlreadyExistsError(filename)
    }
    return v.writeConfig(filename, false)
}

func (v *Viper) writeConfig(filename string, force bool) error {
    jww.INFO.Println("Attempting to write configuration to file.")
    var configType string

    ext := filepath.Ext(filename)
    if ext != "" {
        configType = ext[1:]
    } else {
        configType = v.configType
    }
    if configType == "" {
        return fmt.Errorf("config type could not be determined for %s", filename)
    }

    if !stringInSlice(configType, SupportedExts) {
        return UnsupportedConfigError(configType)
    }
    if v.config == nil {
        v.config = make(map[string]interface{})
    }
    flags := os.O_CREATE | os.O_TRUNC | os.O_WRONLY
    if !force {
        flags |= os.O_EXCL
    }
    f, err := v.fs.OpenFile(filename, flags, v.configPermissions)
    if err != nil {
        return err
    }
    defer f.Close()

    if err := v.marshalWriter(f, configType); err != nil {
        return err
    }

    return f.Sync()
}

// Unmarshal a Reader into a map.
// Should probably be an unexported function.
func unmarshalReader(in io.Reader, c map[string]interface{}) error {
    return v.unmarshalReader(in, c)
}
func (v *Viper) unmarshalReader(in io.Reader, c map[string]interface{}) error {
    buf := new(bytes.Buffer)
    buf.ReadFrom(in)

    switch strings.ToLower(v.getConfigType()) {
    case "yaml", "yml":
        if err := yaml.Unmarshal(buf.Bytes(), &c); err != nil {
            return ConfigParseError{err}
        }

    case "json":
        if err := json.Unmarshal(buf.Bytes(), &c); err != nil {
            return ConfigParseError{err}
        }

    case "hcl":
        obj, err := hcl.Parse(buf.String())
        if err != nil {
            return ConfigParseError{err}
        }
        if err = hcl.DecodeObject(&c, obj); err != nil {
            return ConfigParseError{err}
        }

    case "toml":
        tree, err := toml.LoadReader(buf)
        if err != nil {
            return ConfigParseError{err}
        }
        tmap := tree.ToMap()
        for k, v := range tmap {
            c[k] = v
        }

    case "dotenv", "env":
        env, err := gotenv.StrictParse(buf)
        if err != nil {
            return ConfigParseError{err}
        }
        for k, v := range env {
            c[k] = v
        }

    case "properties", "props", "prop":
        v.properties = properties.NewProperties()
        var err error
        if v.properties, err = properties.Load(buf.Bytes(), properties.UTF8); err != nil {
            return ConfigParseError{err}
        }
        for _, key := range v.properties.Keys() {
            value, _ := v.properties.Get(key)
            // recursively build nested maps
            path := strings.Split(key, ".")
            lastKey := strings.ToLower(path[len(path)-1])
            deepestMap := deepSearch(c, path[0:len(path)-1])
            // set innermost value
            deepestMap[lastKey] = value
        }

    case "ini":
        cfg := ini.Empty()
        err := cfg.Append(buf.Bytes())
        if err != nil {
            return ConfigParseError{err}
        }
        sections := cfg.Sections()
        for i := 0; i < len(sections); i++ {
            section := sections[i]
            keys := section.Keys()
            for j := 0; j < len(keys); j++ {
                key := keys[j]
                value := cfg.Section(section.Name()).Key(key.Name()).String()
                c[section.Name()+"."+key.Name()] = value
            }
        }
    }

    insensitiviseMap(c)
    return nil
}

// Marshal a map into Writer.
func (v *Viper) marshalWriter(f afero.File, configType string) error {
    c := v.AllSettings()
    switch configType {
    case "json":
        b, err := json.MarshalIndent(c, "", "  ")
        if err != nil {
            return ConfigMarshalError{err}
        }
        _, err = f.WriteString(string(b))
        if err != nil {
            return ConfigMarshalError{err}
        }

    case "hcl":
        b, err := json.Marshal(c)
        if err != nil {
            return ConfigMarshalError{err}
        }
        ast, err := hcl.Parse(string(b))
        if err != nil {
            return ConfigMarshalError{err}
        }
        err = printer.Fprint(f, ast.Node)
        if err != nil {
            return ConfigMarshalError{err}
        }

    case "prop", "props", "properties":
        if v.properties == nil {
            v.properties = properties.NewProperties()
        }
        p := v.properties
        for _, key := range v.AllKeys() {
            _, _, err := p.Set(key, v.GetString(key))
            if err != nil {
                return ConfigMarshalError{err}
            }
        }
        _, err := p.WriteComment(f, "#", properties.UTF8)
        if err != nil {
            return ConfigMarshalError{err}
        }

    case "dotenv", "env":
        lines := []string{}
        for _, key := range v.AllKeys() {
            envName := strings.ToUpper(strings.Replace(key, ".", "_", -1))
            val := v.Get(key)
            lines = append(lines, fmt.Sprintf("%v=%v", envName, val))
        }
        s := strings.Join(lines, "\n")
        if _, err := f.WriteString(s); err != nil {
            return ConfigMarshalError{err}
        }

    case "toml":
        t, err := toml.TreeFromMap(c)
        if err != nil {
            return ConfigMarshalError{err}
        }
        s := t.String()
        if _, err := f.WriteString(s); err != nil {
            return ConfigMarshalError{err}
        }

    case "yaml", "yml":
        b, err := yaml.Marshal(c)
        if err != nil {
            return ConfigMarshalError{err}
        }
        if _, err = f.WriteString(string(b)); err != nil {
            return ConfigMarshalError{err}
        }

    case "ini":
        keys := v.AllKeys()
        cfg := ini.Empty()
        ini.PrettyFormat = false
        for i := 0; i < len(keys); i++ {
            key := keys[i]
            lastSep := strings.LastIndex(key, ".")
            sectionName := key[:(lastSep)]
            keyName := key[(lastSep + 1):]
            if sectionName == "default" {
                sectionName = ""
            }
            cfg.Section(sectionName).Key(keyName).SetValue(v.Get(key).(string))
        }
        cfg.WriteTo(f)
    }
    return nil
}

func keyExists(k string, m map[string]interface{}) string {
    lk := strings.ToLower(k)
    for mk := range m {
        lmk := strings.ToLower(mk)
        if lmk == lk {
            return mk
        }
    }
    return ""
}

func castToMapStringInterface(
    src map[interface{}]interface{}) map[string]interface{} {
    tgt := map[string]interface{}{}
    for k, v := range src {
        tgt[fmt.Sprintf("%v", k)] = v
    }
    return tgt
}

func castMapStringToMapInterface(src map[string]string) map[string]interface{} {
    tgt := map[string]interface{}{}
    for k, v := range src {
        tgt[k] = v
    }
    return tgt
}

func castMapFlagToMapInterface(src map[string]FlagValue) map[string]interface{} {
    tgt := map[string]interface{}{}
    for k, v := range src {
        tgt[k] = v
    }
    return tgt
}

// mergeMaps merges two maps. The `itgt` parameter is for handling go-yaml's
// insistence on parsing nested structures as `map[interface{}]interface{}`
// instead of using a `string` as the key for nest structures beyond one level
// deep. Both map types are supported as there is a go-yaml fork that uses
// `map[string]interface{}` instead.
func mergeMaps(
    src, tgt map[string]interface{}, itgt map[interface{}]interface{}) {
    for sk, sv := range src {
        tk := keyExists(sk, tgt)
        if tk == "" {
            jww.TRACE.Printf("tk=\"\", tgt[%s]=%v", sk, sv)
            tgt[sk] = sv
            if itgt != nil {
                itgt[sk] = sv
            }
            continue
        }

        tv, ok := tgt[tk]
        if !ok {
            jww.TRACE.Printf("tgt[%s] != ok, tgt[%s]=%v", tk, sk, sv)
            tgt[sk] = sv
            if itgt != nil {
                itgt[sk] = sv
            }
            continue
        }

        svType := reflect.TypeOf(sv)
        tvType := reflect.TypeOf(tv)
        if svType != tvType {
            jww.ERROR.Printf(
                "svType != tvType; key=%s, st=%v, tt=%v, sv=%v, tv=%v",
                sk, svType, tvType, sv, tv)
            continue
        }

        jww.TRACE.Printf("processing key=%s, st=%v, tt=%v, sv=%v, tv=%v",
            sk, svType, tvType, sv, tv)

        switch ttv := tv.(type) {
        case map[interface{}]interface{}:
            jww.TRACE.Printf("merging maps (must convert)")
            tsv := sv.(map[interface{}]interface{})
            ssv := castToMapStringInterface(tsv)
            stv := castToMapStringInterface(ttv)
            mergeMaps(ssv, stv, ttv)
        case map[string]interface{}:
            jww.TRACE.Printf("merging maps")
            mergeMaps(sv.(map[string]interface{}), ttv, nil)
        default:
            jww.TRACE.Printf("setting value")
            tgt[tk] = sv
            if itgt != nil {
                itgt[tk] = sv
            }
        }
    }
}

// ReadRemoteConfig attempts to get configuration from a remote source
// and read it in the remote configuration registry.
func ReadRemoteConfig() error { return v.ReadRemoteConfig() }
func (v *Viper) ReadRemoteConfig() error {
    return v.getKeyValueConfig()
}

func WatchRemoteConfig() error { return v.WatchRemoteConfig() }
func (v *Viper) WatchRemoteConfig() error {
    return v.watchKeyValueConfig()
}

func (v *Viper) WatchRemoteConfigOnChannel() error {
    return v.watchKeyValueConfigOnChannel()
}

// Retrieve the first found remote configuration.
func (v *Viper) getKeyValueConfig() error {
    if RemoteConfig == nil {
        return RemoteConfigError("Enable the remote features by doing a blank import of the viper/remote package: '_ github.com/spf13/viper/remote'")
    }

    for _, rp := range v.remoteProviders {
        val, err := v.getRemoteConfig(rp)
        if err != nil {
            continue
        }
        v.kvstore = val
        return nil
    }
    return RemoteConfigError("No Files Found")
}

func (v *Viper) getRemoteConfig(provider RemoteProvider) (map[string]interface{}, error) {
    reader, err := RemoteConfig.Get(provider)
    if err != nil {
        return nil, err
    }
    err = v.unmarshalReader(reader, v.kvstore)
    return v.kvstore, err
}

// Retrieve the first found remote configuration.
func (v *Viper) watchKeyValueConfigOnChannel() error {
    for _, rp := range v.remoteProviders {
        respc, quit := RemoteConfig.WatchChannel(rp)
        // Todo: Add quit channel
        go func(rc <-chan *RemoteResponse) {
            for {
                b := <-rc
                reader := bytes.NewReader(b.Value)
                v.unmarshalReader(reader, v.kvstore)
            }
        }(respc)
        v.quitList = append(v.quitList, quit)
        return nil
    }
    return RemoteConfigError("No Files Found")
}

// Retrieve the first found remote configuration.
func (v *Viper) watchKeyValueConfig() error {
    for _, rp := range v.remoteProviders {
        val, err := v.watchRemoteConfig(rp)
        if err != nil {
            continue
        }
        v.kvstore = val
        return nil
    }
    return RemoteConfigError("No Files Found")
}

func (v *Viper) watchRemoteConfig(provider RemoteProvider) (map[string]interface{}, error) {
    reader, err := RemoteConfig.Watch(provider)
    if err != nil {
        return nil, err
    }
    err = v.unmarshalReader(reader, v.kvstore)
    return v.kvstore, err
}

// AllKeys returns all keys holding a value, regardless of where they are set.
// Nested keys are returned with a v.keyDelim separator
func AllKeys() []string { return v.AllKeys() }
func (v *Viper) AllKeys() []string {
    m := map[string]bool{}
    // add all paths, by order of descending priority to ensure correct shadowing
    m = v.flattenAndMergeMap(m, castMapStringToMapInterface(v.aliases), "")
    m = v.flattenAndMergeMap(m, v.override, "")
    m = v.mergeFlatMap(m, castMapFlagToMapInterface(v.pflags))
    m = v.mergeFlatMap(m, castMapStringToMapInterface(v.env))
    m = v.flattenAndMergeMap(m, v.config, "")
    m = v.flattenAndMergeMap(m, v.kvstore, "")
    m = v.flattenAndMergeMap(m, v.defaults, "")

    // convert set of paths to list
    a := make([]string, 0, len(m))
    for x := range m {
        a = append(a, x)
    }
    return a
}

// flattenAndMergeMap recursively flattens the given map into a map[string]bool
// of key paths (used as a set, easier to manipulate than a []string):
// - each path is merged into a single key string, delimited with v.keyDelim
// - if a path is shadowed by an earlier value in the initial shadow map,
//   it is skipped.
// The resulting set of paths is merged to the given shadow set at the same time.
func (v *Viper) flattenAndMergeMap(shadow map[string]bool, m map[string]interface{}, prefix string) map[string]bool {
    if shadow != nil && prefix != "" && shadow[prefix] {
        // prefix is shadowed => nothing more to flatten
        return shadow
    }
    if shadow == nil {
        shadow = make(map[string]bool)
    }

    var m2 map[string]interface{}
    if prefix != "" {
        prefix += v.keyDelim
    }
    for k, val := range m {
        fullKey := prefix + k
        switch val.(type) {
        case map[string]interface{}:
            m2 = val.(map[string]interface{})
        case map[interface{}]interface{}:
            m2 = cast.ToStringMap(val)
        default:
            // immediate value
            shadow[strings.ToLower(fullKey)] = true
            continue
        }
        // recursively merge to shadow map
        shadow = v.flattenAndMergeMap(shadow, m2, fullKey)
    }
    return shadow
}

// mergeFlatMap merges the given maps, excluding values of the second map
// shadowed by values from the first map.
func (v *Viper) mergeFlatMap(shadow map[string]bool, m map[string]interface{}) map[string]bool {
    // scan keys
outer:
    for k := range m {
        path := strings.Split(k, v.keyDelim)
        // scan intermediate paths
        var parentKey string
        for i := 1; i < len(path); i++ {
            parentKey = strings.Join(path[0:i], v.keyDelim)
            if shadow[parentKey] {
                // path is shadowed, continue
                continue outer
            }
        }
        // add key
        shadow[strings.ToLower(k)] = true
    }
    return shadow
}

// AllSettings merges all settings and returns them as a map[string]interface{}.
func AllSettings() map[string]interface{} { return v.AllSettings() }
func (v *Viper) AllSettings() map[string]interface{} {
    m := map[string]interface{}{}
    // start from the list of keys, and construct the map one value at a time
    for _, k := range v.AllKeys() {
        value := v.Get(k)
        if value == nil {
            // should not happen, since AllKeys() returns only keys holding a value,
            // check just in case anything changes
            continue
        }
        path := strings.Split(k, v.keyDelim)
        lastKey := strings.ToLower(path[len(path)-1])
        deepestMap := deepSearch(m, path[0:len(path)-1])
        // set innermost value
        deepestMap[lastKey] = value
    }
    return m
}

// SetFs sets the filesystem to use to read configuration.
func SetFs(fs afero.Fs) { v.SetFs(fs) }
func (v *Viper) SetFs(fs afero.Fs) {
    v.fs = fs
}

// SetConfigName sets name for the config file.
// Does not include extension.
func SetConfigName(in string) { v.SetConfigName(in) }
func (v *Viper) SetConfigName(in string) {
    if in != "" {
        v.configName = in
        v.configFile = ""
    }
}

// SetConfigType sets the type of the configuration returned by the
// remote source, e.g. "json".
func SetConfigType(in string) { v.SetConfigType(in) }
func (v *Viper) SetConfigType(in string) {
    if in != "" {
        v.configType = in
    }
}

// SetConfigPermissions sets the permissions for the config file.
func SetConfigPermissions(perm os.FileMode) { v.SetConfigPermissions(perm) }
func (v *Viper) SetConfigPermissions(perm os.FileMode) {
    v.configPermissions = perm.Perm()
}

func (v *Viper) Exit() {
    defer func() {
        if e := recover(); e != nil {
            log.Printf("close quit err: %v\n", e)
        }
    }()
    for _, quit := range v.quitList {
        quit <- true
    }
}

func (v *Viper) getConfigType() string {
    if v.configType != "" {
        return v.configType
    }

    cf, err := v.getConfigFile()
    if err != nil {
        return ""
    }

    ext := filepath.Ext(cf)

    if len(ext) > 1 {
        return ext[1:]
    }

    return ""
}

func (v *Viper) getConfigFile() (string, error) {
    if v.configFile == "" {
        cf, err := v.findConfigFile()
        if err != nil {
            return "", err
        }
        v.configFile = cf
    }
    return v.configFile, nil
}

func (v *Viper) searchInPath(in string) (filename string) {
    jww.DEBUG.Println("Searching for config in ", in)
    for _, ext := range SupportedExts {
        jww.DEBUG.Println("Checking for", filepath.Join(in, v.configName+"."+ext))
        if b, _ := exists(v.fs, filepath.Join(in, v.configName+"."+ext)); b {
            jww.DEBUG.Println("Found: ", filepath.Join(in, v.configName+"."+ext))
            return filepath.Join(in, v.configName+"."+ext)
        }
    }

    if v.configType != "" {
        if b, _ := exists(v.fs, filepath.Join(in, v.configName)); b {
            return filepath.Join(in, v.configName)
        }
    }

    return ""
}

// Search all configPaths for any config file.
// Returns the first path that exists (and is a config file).
func (v *Viper) findConfigFile() (string, error) {
    jww.INFO.Println("Searching for config in ", v.configPaths)

    for _, cp := range v.configPaths {
        file := v.searchInPath(cp)
        if file != "" {
            return file, nil
        }
    }
    return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
}

// Debug prints all configuration registries for debugging
// purposes.
func Debug() { v.Debug() }
func (v *Viper) Debug() {
    fmt.Printf("Aliases:\n%#v\n", v.aliases)
    fmt.Printf("Override:\n%#v\n", v.override)
    fmt.Printf("PFlags:\n%#v\n", v.pflags)
    fmt.Printf("Env:\n%#v\n", v.env)
    fmt.Printf("Key/Value Store:\n%#v\n", v.kvstore)
    fmt.Printf("Config:\n%#v\n", v.config)
    fmt.Printf("Defaults:\n%#v\n", v.defaults)
}