refactor(go): removed jsonpointer dependency and refactored existing …

…unit test (#77)

go.mod

@@ -1,13 +1,3 @@
 module github.com/apimatic/go-core-runtime
 
 go 1.18
-
-require github.com/go-openapi/jsonpointer v0.20.2
-
-require (
-	github.com/go-openapi/swag v0.22.5 // indirect
-	github.com/josharian/intern v1.0.0 // indirect
-	github.com/mailru/easyjson v0.7.7 // indirect
-	github.com/rogpeppe/go-internal v1.12.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
-)

https/apiError.go

@@ -2,15 +2,11 @@
 package https
 
 import (
-	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
-	"reflect"
 	"regexp"
 	"strings"
-
-	"github.com/go-openapi/jsonpointer"
 )
 
 // ApiError is the base struct for all error responses from the server.
@@ -112,32 +108,3 @@ func renderPlaceholder(placeholder string, res http.Response) any {
 
 	return placeholder
 }
-
-func getValueFromJSON(rawJSON []byte, jsonPtr string) any {
-	var jsonBody any
-	if err := json.Unmarshal(rawJSON, &jsonBody); err != nil {
-		return ""
-	}
-
-	p, err := jsonpointer.New(jsonPtr)
-	if err != nil {
-		return ""
-	}
-
-	val, kind, err := p.Get(jsonBody)
-	if err != nil {
-		return ""
-	}
-
-	switch kind {
-	case reflect.Map:
-		obj, err := json.Marshal(val)
-		if err != nil {
-			return ""
-		}
-
-		return string(obj)
-	}
-
-	return val
-}

https/rawJsonPointer.go

@@ -0,0 +1,126 @@
+package https
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+func getValueFromJSON(rawJSON []byte, jsonPtr string) any {
+	var jsonBody any
+	var result any = ""
+	if err := json.Unmarshal(rawJSON, &jsonBody); err == nil {
+		val, kind, err := getValueFromJSONPtr(jsonPtr, jsonBody)
+		if err == nil {
+			switch kind {
+			case reflect.Map:
+				obj, err := json.Marshal(val)
+				if err == nil {
+					result = string(obj)
+				}
+				return result
+			}
+			result = val
+		}
+	}
+	return result
+}
+
+func parseJsonPtr(jsonPtrStr string) ([]string, error) {
+	ptrSeparator := `/`
+	var err error
+	var referenceTokens []string
+
+	if jsonPtrStr != `` {
+		if !strings.HasPrefix(jsonPtrStr, ptrSeparator) {
+			err = errors.New(`JSON pointer must be empty or start with a "` + ptrSeparator)
+		} else {
+			refTokens := strings.Split(jsonPtrStr, ptrSeparator)
+			referenceTokens = append(referenceTokens, refTokens[1:]...)
+		}
+	}
+	return referenceTokens, err
+}
+
+func getValueFromJSONPtr(jsonPtr string, node any) (any, reflect.Kind, error) {
+
+	kind := reflect.Invalid
+
+	referenceTokens, err := parseJsonPtr(jsonPtr)
+	if err != nil {
+		return node, kind, err
+	}
+
+	for _, token := range referenceTokens {
+		decodedToken := Unescape(token)
+		r, knd, err := getSingleImpl(node, decodedToken)
+		if err != nil {
+			return nil, knd, err
+		}
+		node = r
+	}
+	rValue := reflect.ValueOf(node)
+	kind = rValue.Kind()
+	return node, kind, nil
+}
+
+// Unescape unescapes a json pointer reference token string to the original representation
+func Unescape(token string) string {
+	step1 := strings.ReplaceAll(token, `~1`, `/`)
+	step2 := strings.ReplaceAll(step1, `~0`, `~`)
+	return step2
+}
+
+func isNil(input any) bool {
+	switch reflect.TypeOf(input).Kind() {
+	case reflect.Ptr, reflect.Map, reflect.Slice, reflect.Chan:
+		return reflect.ValueOf(input).IsNil()
+	default:
+		return false
+	}
+}
+
+func getSingleImpl(node any, decodedToken string) (any, reflect.Kind, error) {
+	rValue := reflect.Indirect(reflect.ValueOf(node))
+	kind := rValue.Kind()
+	var result any = nil
+	var resultErr error = nil
+	if isNil(node) {
+		return result, kind, fmt.Errorf("nil value has not field %q", decodedToken)
+	}
+
+	switch typed := node.(type) {
+	case *any: // case of a pointer to interface, that is not resolved by reflect.Indirect
+		return getSingleImpl(*typed, decodedToken)
+	}
+
+	switch kind {
+	case reflect.Map:
+		kv := reflect.ValueOf(decodedToken)
+		mv := rValue.MapIndex(kv)
+
+		if mv.IsValid() {
+			result = mv.Interface()
+		} else {
+			resultErr = fmt.Errorf("object has no key %q", decodedToken)
+		}
+	case reflect.Slice:
+		var tokenIndex int
+		tokenIndex, resultErr = strconv.Atoi(decodedToken)
+		if resultErr == nil {
+			sLength := rValue.Len()
+			if tokenIndex < 0 || tokenIndex >= sLength {
+				resultErr = fmt.Errorf("index out of bounds array[0,%d] index '%d'", sLength-1, tokenIndex)
+			} else {
+				elem := rValue.Index(tokenIndex)
+				result = elem.Interface()
+			}
+		}
+	default:
+		resultErr = fmt.Errorf("invalid token reference %q", decodedToken)
+	}
+	return result, kind, resultErr
+}