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chained.go
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chained.go
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package runner
import (
"encoding/json"
"fmt"
"github.com/b2wdigital/restQL-golang/v5/internal/domain"
"github.com/b2wdigital/restQL-golang/v5/pkg/restql"
"github.com/pkg/errors"
"math"
"strings"
)
// EmptyChained in a token used to represent a chained parameter value
// that could not be resolved due to a failed response from the upstream dependency.
const EmptyChained = "__EMPTY_CHAINED__"
// ErrInvalidChainedParameter represents an error when a chain parameter value
// references an unknown statement.
var ErrInvalidChainedParameter = errors.New("chained parameter targeting unknown statement")
// ResolveChainedValues takes an unresolved Resource collection and replace
// chain parameter values by data present in the done Resource collection.
func ResolveChainedValues(resources domain.Resources, doneResources domain.Resources) domain.Resources {
for resourceID, stmt := range resources {
resources[resourceID] = resolveStatement(stmt, doneResources)
}
return resources
}
func resolveStatement(stmt interface{}, doneResources domain.Resources) interface{} {
switch stmt := stmt.(type) {
case domain.Statement:
params := stmt.With.Values
for paramName, value := range params {
v := resolveValue(value, doneResources, resolverOptions{explode: true})
if v == nil {
continue
}
params[paramName] = v
}
headers := stmt.Headers
for name, value := range headers {
resolved := resolveValue(value, doneResources, resolverOptions{explode: true})
if resolved == nil {
continue
}
headerValue, err := stringify(resolved)
if err != nil {
headers[name] = EmptyChained
continue
}
headers[name] = headerValue
}
case []interface{}:
result := make([]interface{}, len(stmt))
for i, s := range stmt {
result[i] = resolveStatement(s, doneResources)
}
return result
}
return stmt
}
func stringify(value interface{}) (string, error) {
switch value := value.(type) {
case string:
return value, nil
case map[string]interface{}:
b, err := json.Marshal(value)
return string(b), err
case []interface{}:
b, err := json.Marshal(value)
return string(b), err
default:
return fmt.Sprintf("%v", value), nil
}
}
type resolverOptions struct {
explode bool
}
func resolveValue(value interface{}, doneResources domain.Resources, options resolverOptions) interface{} {
switch param := value.(type) {
case domain.Chain:
return resolveChainParam(param, doneResources)
case domain.NoExplode:
return resolveValue(param.Target(), doneResources, resolverOptions{explode: false})
case domain.Function:
return param.Map(func(target interface{}) interface{} {
return resolveValue(target, doneResources, options)
})
case []interface{}:
return resolveListParam(param, doneResources, options)
case map[string]interface{}:
return resolveObjectParam(param, doneResources, options)
default:
return value
}
}
func resolveObjectParam(objectParam map[string]interface{}, doneResources domain.Resources, options resolverOptions) interface{} {
result := make(map[string]interface{})
for key, value := range objectParam {
v := resolveValue(value, doneResources, options)
if v == nil {
continue
}
result[key] = v
}
if options.explode {
return explodeListValuesInNewMaps(result)
}
return result
}
func explodeListValuesInNewMaps(m map[string]interface{}) interface{} {
n := minimumListValueLength(m)
if n == 0 {
return m
}
result := make([]interface{}, n)
for i := 0; i < n; i++ {
newMap := make(map[string]interface{})
for k, v := range m {
var newValue interface{}
switch v := v.(type) {
case []interface{}:
newValue = v[i]
default:
newValue = v
}
if newValue == nil {
continue
}
newMap[k] = newValue
}
result[i] = newMap
}
return result
}
func minimumListValueLength(m map[string]interface{}) int {
var result uint64 = math.MaxInt64
for _, v := range m {
if v, ok := v.([]interface{}); ok {
length := uint64(len(v))
if length < result {
result = length
}
}
}
if result == math.MaxInt64 {
return 0
}
return int(result)
}
func resolveListParam(listParam []interface{}, doneResources domain.Resources, options resolverOptions) []interface{} {
result := make([]interface{}, len(listParam))
copy(result, listParam)
for i, value := range result {
result[i] = resolveValue(value, doneResources, options)
}
return result
}
func resolveChainParam(chain domain.Chain, doneResources domain.Resources) interface{} {
path := toPath(chain)
resourceID := domain.ResourceID(path[0])
switch done := doneResources[resourceID].(type) {
case restql.DoneResources:
return resolveWithMultiplexedRequests(path[1:], done)
case restql.DoneResource:
return resolveWithSingleRequest(path[1:], done)
default:
return nil
}
}
func resolveWithMultiplexedRequests(path []string, doneRequests restql.DoneResources) []interface{} {
var result []interface{}
for _, request := range doneRequests {
switch request := request.(type) {
case restql.DoneResource:
result = append(result, resolveWithSingleRequest(path, request))
case restql.DoneResources:
result = append(result, resolveWithMultiplexedRequests(path, request))
}
}
return result
}
func resolveWithSingleRequest(path []string, done restql.DoneResource) interface{} {
if done.Status < 200 || done.Status >= 400 {
return EmptyChained
}
body := done.ResponseBody.Unmarshal()
valueFromBody, found := getValueFromBody(path, body)
if found {
return valueFromBody
}
valueFromHeader, found := getValueFromHeader(path[0], done.ResponseHeaders)
if found {
return valueFromHeader
}
return nil
}
func toPath(chain domain.Chain) []string {
r := make([]string, len(chain))
for i, c := range chain {
r[i] = c.(string)
}
return r
}
func getValueFromBody(pathToValue []string, b restql.Body) (interface{}, bool) {
if b == nil {
return nil, false
}
if len(pathToValue) == 0 {
return b, true
}
switch body := b.(type) {
case map[string]interface{}:
v, found := body[pathToValue[0]]
if !found {
return nil, false
}
return getValueFromBody(pathToValue[1:], v)
case []interface{}:
result := make([]interface{}, len(body))
for i, v := range body {
result[i], _ = getValueFromBody(pathToValue, v)
}
return result, true
default:
return nil, false
}
}
func getValueFromHeader(name string, headers map[string]string) (string, bool) {
name = strings.ToLower(name)
for k, v := range headers {
if strings.ToLower(k) == name {
return v, true
}
}
return "", false
}
// ValidateChainedValues returns an error if a chain
// parameter value references an unknown statement.
func ValidateChainedValues(resources domain.Resources) error {
for _, stmt := range resources {
err := validateStatement(stmt, resources)
if err != nil {
return err
}
}
return nil
}
func validateStatement(stmt interface{}, resources domain.Resources) error {
switch stmt := stmt.(type) {
case domain.Statement:
params := stmt.With.Values
for _, value := range params {
err := validateParam(value, resources)
if err != nil {
return err
}
}
return nil
case []interface{}:
for _, s := range stmt {
err := validateStatement(s, resources)
if err != nil {
return err
}
}
return nil
}
return nil
}
func validateParam(value interface{}, resources domain.Resources) error {
switch param := value.(type) {
case domain.Chain:
return validateChainParam(param, resources)
case domain.Function:
return validateParam(param.Target(), resources)
case []interface{}:
return validateListParam(param, resources)
case map[string]interface{}:
return validateObjectParam(param, resources)
default:
return nil
}
}
func validateObjectParam(objectParam map[string]interface{}, resources domain.Resources) error {
for _, value := range objectParam {
err := validateParam(value, resources)
if err != nil {
return err
}
}
return nil
}
func validateListParam(listParam []interface{}, resources domain.Resources) error {
for _, value := range listParam {
err := validateParam(value, resources)
if err != nil {
return err
}
}
return nil
}
func validateChainParam(chain domain.Chain, resources domain.Resources) error {
path := toPath(chain)
resourceID := domain.ResourceID(path[0])
_, found := resources[resourceID]
if !found {
return fmt.Errorf("%w : %s", ErrInvalidChainedParameter, strings.Join(path, "."))
}
return nil
}