datasource.go

package data

import (
	"fmt"
	"io"
	"io/ioutil"
	"mime"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strings"

	"github.com/spf13/afero"

	"github.com/pkg/errors"

	"github.com/hairyhenderson/gomplate/libkv"
	"github.com/hairyhenderson/gomplate/vault"
)

// stdin - for overriding in tests
var stdin io.Reader

func regExtension(ext, typ string) {
	err := mime.AddExtensionType(ext, typ)
	if err != nil {
		panic(err)
	}
}

func init() {
	// Add some types we want to be able to handle which can be missing by default
	regExtension(".json", jsonMimetype)
	regExtension(".yml", yamlMimetype)
	regExtension(".yaml", yamlMimetype)
	regExtension(".csv", csvMimetype)
	regExtension(".toml", tomlMimetype)
	regExtension(".env", envMimetype)
}

// registerReaders registers the source-reader functions
func (d *Data) registerReaders() {
	d.sourceReaders = make(map[string]func(*Source, ...string) ([]byte, error))

	d.sourceReaders["aws+smp"] = readAWSSMP
	d.sourceReaders["boltdb"] = readBoltDB
	d.sourceReaders["consul"] = readConsul
	d.sourceReaders["consul+http"] = readConsul
	d.sourceReaders["consul+https"] = readConsul
	d.sourceReaders["env"] = readEnv
	d.sourceReaders["file"] = readFile
	d.sourceReaders["http"] = readHTTP
	d.sourceReaders["https"] = readHTTP
	d.sourceReaders["merge"] = d.readMerge
	d.sourceReaders["stdin"] = readStdin
	d.sourceReaders["vault"] = readVault
	d.sourceReaders["vault+http"] = readVault
	d.sourceReaders["vault+https"] = readVault
}

// lookupReader - return the reader function for the given scheme
func (d *Data) lookupReader(scheme string) (func(*Source, ...string) ([]byte, error), error) {
	if d.sourceReaders == nil {
		d.registerReaders()
	}
	r, ok := d.sourceReaders[scheme]
	if !ok {
		return nil, errors.Errorf("scheme %s not registered", scheme)
	}
	return r, nil
}

// Data -
type Data struct {
	Sources map[string]*Source

	sourceReaders map[string]func(*Source, ...string) ([]byte, error)
	cache         map[string][]byte

	// headers from the --datasource-header/-H option that don't reference datasources from the commandline
	extraHeaders map[string]http.Header
}

// Cleanup - clean up datasources before shutting the process down - things
// like Logging out happen here
func (d *Data) Cleanup() {
	for _, s := range d.Sources {
		s.cleanup()
	}
}

// NewData - constructor for Data
func NewData(datasourceArgs, headerArgs []string) (*Data, error) {
	headers, err := parseHeaderArgs(headerArgs)
	if err != nil {
		return nil, err
	}

	data := &Data{
		Sources:      make(map[string]*Source),
		extraHeaders: headers,
	}

	for _, v := range datasourceArgs {
		s, err := parseSource(v)
		if err != nil {
			return nil, errors.Wrapf(err, "error parsing datasource")
		}
		s.header = headers[s.Alias]
		// pop the header out of the map, so we end up with only the unreferenced ones
		delete(headers, s.Alias)

		data.Sources[s.Alias] = s
	}
	return data, nil
}

// Source - a data source
type Source struct {
	Alias     string
	URL       *url.URL
	mediaType string
	fs        afero.Fs     // used for file: URLs, nil otherwise
	hc        *http.Client // used for http[s]: URLs, nil otherwise
	vc        *vault.Vault // used for vault: URLs, nil otherwise
	kv        *libkv.LibKV // used for consul:, etcd:, zookeeper: & boltdb: URLs, nil otherwise
	asmpg     awssmpGetter // used for aws+smp:, nil otherwise
	header    http.Header  // used for http[s]: URLs, nil otherwise
}

func (s *Source) inherit(parent *Source) {
	s.fs = parent.fs
	s.hc = parent.hc
	s.vc = parent.vc
	s.kv = parent.kv
	s.asmpg = parent.asmpg
}

func (s *Source) cleanup() {
	if s.vc != nil {
		s.vc.Logout()
	}
	if s.kv != nil {
		s.kv.Logout()
	}
}

// mimeType returns the MIME type to use as a hint for parsing the datasource.
// It's expected that the datasource will have already been read before
// this function is called, and so the Source's Type property may be already set.
//
// The MIME type is determined by these rules:
// 1. the 'type' URL query parameter is used if present
// 2. otherwise, the Type property on the Source is used, if present
// 3. otherwise, a MIME type is calculated from the file extension, if the extension is registered
// 4. otherwise, the default type of 'text/plain' is used
func (s *Source) mimeType() (mimeType string, err error) {
	mediatype := s.URL.Query().Get("type")
	if mediatype == "" {
		mediatype = s.mediaType
	}
	if mediatype == "" {
		ext := filepath.Ext(s.URL.Path)
		mediatype = mime.TypeByExtension(ext)
	}

	if mediatype != "" {
		t, _, err := mime.ParseMediaType(mediatype)
		if err != nil {
			return "", err
		}
		mediatype = t
		return mediatype, nil
	}

	return textMimetype, nil
}

// String is the method to format the flag's value, part of the flag.Value interface.
// The String method's output will be used in diagnostics.
func (s *Source) String() string {
	return fmt.Sprintf("%s=%s (%s)", s.Alias, s.URL.String(), s.mediaType)
}

// parseSource creates a *Source by parsing the value provided to the
// --datasource/-d commandline flag
func parseSource(value string) (source *Source, err error) {
	source = &Source{}
	parts := strings.SplitN(value, "=", 2)
	if len(parts) == 1 {
		f := parts[0]
		source.Alias = strings.SplitN(value, ".", 2)[0]
		if path.Base(f) != f {
			err = errors.Errorf("Invalid datasource (%s). Must provide an alias with files not in working directory", value)
			return nil, err
		}
		source.URL, err = absURL(f)
		if err != nil {
			return nil, err
		}
	} else if len(parts) == 2 {
		source.Alias = parts[0]
		source.URL, err = parseSourceURL(parts[1])
		if err != nil {
			return nil, err
		}
	}

	return source, nil
}

func parseSourceURL(value string) (*url.URL, error) {
	if value == "-" {
		value = "stdin://"
	}
	value = filepath.ToSlash(value)
	// handle absolute Windows paths
	volName := ""
	if volName = filepath.VolumeName(value); volName != "" {
		// handle UNCs
		if len(volName) > 2 {
			value = "file:" + value
		} else {
			value = "file:///" + value
		}
	}
	srcURL, err := url.Parse(value)
	if err != nil {
		return nil, err
	}

	if volName != "" {
		if strings.HasPrefix(srcURL.Path, "/") && srcURL.Path[2] == ':' {
			srcURL.Path = srcURL.Path[1:]
		}
	}

	if !srcURL.IsAbs() {
		srcURL, err = absURL(value)
		if err != nil {
			return nil, err
		}
	}
	return srcURL, nil
}

func absURL(value string) (*url.URL, error) {
	cwd, err := os.Getwd()
	if err != nil {
		return nil, errors.Wrapf(err, "can't get working directory")
	}
	urlCwd := filepath.ToSlash(cwd)
	baseURL := &url.URL{
		Scheme: "file",
		Path:   urlCwd + "/",
	}
	relURL := &url.URL{
		Path: value,
	}
	resolved := baseURL.ResolveReference(relURL)
	// deal with Windows drive letters
	if !strings.HasPrefix(urlCwd, "/") && resolved.Path[2] == ':' {
		resolved.Path = resolved.Path[1:]
	}
	return resolved, nil
}

// DefineDatasource -
func (d *Data) DefineDatasource(alias, value string) (string, error) {
	if alias == "" {
		return "", errors.New("datasource alias must be provided")
	}
	if d.DatasourceExists(alias) {
		return "", nil
	}
	srcURL, err := parseSourceURL(value)
	if err != nil {
		return "", err
	}
	s := &Source{
		Alias:  alias,
		URL:    srcURL,
		header: d.extraHeaders[alias],
	}
	if d.Sources == nil {
		d.Sources = make(map[string]*Source)
	}
	d.Sources[alias] = s
	return "", nil
}

// DatasourceExists -
func (d *Data) DatasourceExists(alias string) bool {
	_, ok := d.Sources[alias]
	return ok
}

func (d *Data) lookupSource(alias string) (*Source, error) {
	source, ok := d.Sources[alias]
	if !ok {
		srcURL, err := url.Parse(alias)
		if err != nil || !srcURL.IsAbs() {
			return nil, errors.Errorf("Undefined datasource '%s'", alias)
		}
		source = &Source{
			Alias:  alias,
			URL:    srcURL,
			header: d.extraHeaders[alias],
		}
		d.Sources[alias] = source
	}
	if source.Alias == "" {
		source.Alias = alias
	}
	return source, nil
}

func (d *Data) readDataSource(alias string, args ...string) (data, mimeType string, err error) {
	source, err := d.lookupSource(alias)
	if err != nil {
		return "", "", err
	}
	b, err := d.readSource(source, args...)
	if err != nil {
		return "", "", errors.Wrapf(err, "Couldn't read datasource '%s'", alias)
	}

	mimeType, err = source.mimeType()
	if err != nil {
		return "", "", err
	}
	return string(b), mimeType, nil
}

// Include -
func (d *Data) Include(alias string, args ...string) (string, error) {
	data, _, err := d.readDataSource(alias, args...)
	return data, err
}

// Datasource -
func (d *Data) Datasource(alias string, args ...string) (interface{}, error) {
	data, mimeType, err := d.readDataSource(alias, args...)
	if err != nil {
		return nil, err
	}

	return parseData(mimeType, data)
}

func parseData(mimeType, s string) (out interface{}, err error) {
	switch mimeType {
	case jsonMimetype:
		out, err = JSON(s)
	case jsonArrayMimetype:
		out, err = JSONArray(s)
	case yamlMimetype:
		out, err = YAML(s)
	case csvMimetype:
		out, err = CSV(s)
	case tomlMimetype:
		out, err = TOML(s)
	case envMimetype:
		out, err = dotEnv(s)
	case textMimetype:
		out = s
	default:
		return nil, errors.Errorf("Datasources of type %s not yet supported", mimeType)
	}
	return out, err
}

// DatasourceReachable - Determines if the named datasource is reachable with
// the given arguments. Reads from the datasource, and discards the returned data.
func (d *Data) DatasourceReachable(alias string, args ...string) bool {
	source, ok := d.Sources[alias]
	if !ok {
		return false
	}
	_, err := d.readSource(source, args...)
	return err == nil
}

// readSource returns the (possibly cached) data from the given source,
// as referenced by the given args
func (d *Data) readSource(source *Source, args ...string) ([]byte, error) {
	if d.cache == nil {
		d.cache = make(map[string][]byte)
	}
	cacheKey := source.Alias
	for _, v := range args {
		cacheKey += v
	}
	cached, ok := d.cache[cacheKey]
	if ok {
		return cached, nil
	}
	r, err := d.lookupReader(source.URL.Scheme)
	if err != nil {
		return nil, errors.Wrap(err, "Datasource not yet supported")
	}
	data, err := r(source, args...)
	if err != nil {
		return nil, err
	}
	d.cache[cacheKey] = data
	return data, nil
}

func readStdin(source *Source, args ...string) ([]byte, error) {
	if stdin == nil {
		stdin = os.Stdin
	}
	b, err := ioutil.ReadAll(stdin)
	if err != nil {
		return nil, errors.Wrapf(err, "Can't read %s", stdin)
	}
	return b, nil
}

func readConsul(source *Source, args ...string) (data []byte, err error) {
	if source.kv == nil {
		source.kv, err = libkv.NewConsul(source.URL)
		if err != nil {
			return nil, err
		}
		err = source.kv.Login()
		if err != nil {
			return nil, err
		}
	}

	p := source.URL.Path
	if len(args) == 1 {
		p = p + "/" + args[0]
	}

	data, err = source.kv.Read(p)
	if err != nil {
		return nil, err
	}

	return data, nil
}

func readBoltDB(source *Source, args ...string) (data []byte, err error) {
	if source.kv == nil {
		source.kv, err = libkv.NewBoltDB(source.URL)
		if err != nil {
			return nil, err
		}
	}

	if len(args) != 1 {
		return nil, errors.New("missing key")
	}
	p := args[0]

	data, err = source.kv.Read(p)
	if err != nil {
		return nil, err
	}

	return data, nil
}