/*
Copyright 2023 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package queryutil

import (
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/url"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"time"

	"k8s.io/autoscaler/cluster-autoscaler/cloudprovider/volcengine/volcengine-go-sdk/private/protocol"
)

// Parse parses an object i and fills a url.Values object. The isEC2 flag
// indicates if this is the EC2 Query sub-protocol.
func Parse(body url.Values, i interface{}, isEC2 bool) error {
	q := queryParser{isEC2: isEC2}
	return q.parseValue(body, reflect.ValueOf(i), "", "")
}

func elemOf(value reflect.Value) reflect.Value {
	for value.Kind() == reflect.Ptr {
		value = value.Elem()
	}
	return value
}

type queryParser struct {
	isEC2 bool
}

func (q *queryParser) parseValue(v url.Values, value reflect.Value, prefix string, tag reflect.StructTag) error {
	value = elemOf(value)

	// no need to handle zero values
	if !value.IsValid() {
		return nil
	}

	t := tag.Get("type")
	if t == "" {
		switch value.Kind() {
		case reflect.Struct:
			t = "structure"
		case reflect.Slice:
			t = "list"
		case reflect.Map:
			t = "map"
		}
	}

	switch t {
	case "structure":
		return q.parseStruct(v, value, prefix)
	case "list":
		return q.parseList(v, value, prefix, tag)
	case "map":
		return q.parseMap(v, value, prefix, tag)
	default:
		return q.parseScalar(v, value, prefix, tag)
	}
}

func (q *queryParser) parseStruct(v url.Values, value reflect.Value, prefix string) error {
	if !value.IsValid() {
		return nil
	}

	t := value.Type()
	for i := 0; i < value.NumField(); i++ {
		elemValue := elemOf(value.Field(i))
		field := t.Field(i)

		if field.PkgPath != "" {
			continue // ignore unexported fields
		}
		if field.Tag.Get("ignore") != "" {
			continue
		}

		if protocol.CanSetIdempotencyToken(value.Field(i), field) {
			token := protocol.GetIdempotencyToken()
			elemValue = reflect.ValueOf(token)
		}

		var name string
		if q.isEC2 {
			name = field.Tag.Get("queryName")
		}
		if name == "" {
			if field.Tag.Get("flattened") != "" && field.Tag.Get("locationNameList") != "" {
				name = field.Tag.Get("locationNameList")
			} else if locName := field.Tag.Get("locationName"); locName != "" {
				name = locName
			}
			if name != "" && q.isEC2 {
				name = strings.ToUpper(name[0:1]) + name[1:]
			}
		}
		if name == "" {
			name = field.Name
		}

		if prefix != "" {
			name = prefix + "." + name
		}

		if err := q.parseValue(v, elemValue, name, field.Tag); err != nil {
			return err
		}
	}
	return nil
}

func (q *queryParser) parseList(v url.Values, value reflect.Value, prefix string, tag reflect.StructTag) error {
	// If it's empty, generate an empty value
	if !value.IsNil() && value.Len() == 0 {
		v.Set(prefix, "")
		return nil
	}

	if _, ok := value.Interface().([]byte); ok {
		return q.parseScalar(v, value, prefix, tag)
	}

	// check for unflattened list member
	//if !q.isEC2 && tag.Get("flattened") == "" {
	//	if listName := tag.Get("locationNameList"); listName == "" {
	//		prefix += ".member"
	//	} else {
	//		prefix += "." + listName
	//	}
	//}

	for i := 0; i < value.Len(); i++ {
		slicePrefix := prefix
		if slicePrefix == "" {
			slicePrefix = strconv.Itoa(i + 1)
		} else {
			slicePrefix = slicePrefix + "." + strconv.Itoa(i+1)
		}
		if err := q.parseValue(v, value.Index(i), slicePrefix, ""); err != nil {
			return err
		}
	}
	return nil
}

func (q *queryParser) parseMap(v url.Values, value reflect.Value, prefix string, tag reflect.StructTag) error {
	// If it's empty, generate an empty value
	if !value.IsNil() && value.Len() == 0 {
		v.Set(prefix, "")
		return nil
	}

	// check for unflattened list member
	if !q.isEC2 && tag.Get("flattened") == "" {
		prefix += ".entry"
	}

	// sort keys for improved serialization consistency.
	// this is not strictly necessary for protocol support.
	mapKeyValues := value.MapKeys()
	mapKeys := map[string]reflect.Value{}
	mapKeyNames := make([]string, len(mapKeyValues))
	for i, mapKey := range mapKeyValues {
		name := mapKey.String()
		mapKeys[name] = mapKey
		mapKeyNames[i] = name
	}
	sort.Strings(mapKeyNames)

	for i, mapKeyName := range mapKeyNames {
		mapKey := mapKeys[mapKeyName]
		mapValue := value.MapIndex(mapKey)

		kname := tag.Get("locationNameKey")
		if kname == "" {
			kname = "key"
		}
		vname := tag.Get("locationNameValue")
		if vname == "" {
			vname = "value"
		}

		// serialize key
		var keyName string
		if prefix == "" {
			keyName = strconv.Itoa(i+1) + "." + kname
		} else {
			keyName = prefix + "." + strconv.Itoa(i+1) + "." + kname
		}

		if err := q.parseValue(v, mapKey, keyName, ""); err != nil {
			return err
		}

		// serialize value
		var valueName string
		if prefix == "" {
			valueName = strconv.Itoa(i+1) + "." + vname
		} else {
			valueName = prefix + "." + strconv.Itoa(i+1) + "." + vname
		}

		if err := q.parseValue(v, mapValue, valueName, ""); err != nil {
			return err
		}
	}

	return nil
}

func (q *queryParser) parseScalar(v url.Values, r reflect.Value, name string, tag reflect.StructTag) error {
	switch value := r.Interface().(type) {
	case string:
		v.Set(name, value)
	case []byte:
		if !r.IsNil() {
			v.Set(name, base64.StdEncoding.EncodeToString(value))
		}
	case json.Number:
		v.Set(name, value.String())
	case bool:
		v.Set(name, strconv.FormatBool(value))
	case int64:
		v.Set(name, strconv.FormatInt(value, 10))
	case int32:
		v.Set(name, strconv.FormatInt(int64(value), 10))
	case int16:
		v.Set(name, strconv.FormatInt(int64(value), 10))
	case int8:
		v.Set(name, strconv.FormatInt(int64(value), 10))
	case int:
		v.Set(name, strconv.Itoa(value))
	case float64:
		v.Set(name, strconv.FormatFloat(value, 'f', -1, 64))
	case float32:
		v.Set(name, strconv.FormatFloat(float64(value), 'f', -1, 32))
	case time.Time:
		const ISO8601UTC = "2006-01-02T15:04:05Z"
		format := tag.Get("timestampFormat")
		if len(format) == 0 {
			format = protocol.ISO8601TimeFormatName
		}

		v.Set(name, protocol.FormatTime(format, value))
	default:
		return fmt.Errorf("unsupported value for param %s: %v (%s)", name, r.Interface(), r.Type().Name())
	}
	return nil
}