package tag

import (
	"git.sxidc.com/go-tools/utils/reflectutils"
	"git.sxidc.com/go-tools/utils/strutils"
	"git.sxidc.com/service-supports/fserr"
	"git.sxidc.com/service-supports/fslog"
	"reflect"
	"strings"
	"time"
)

func AssignTo[T any](from any) (T, error) {
	var zero T

	if from == nil {
		return zero, nil
	}

	fromValue := reflect.ValueOf(from)
	retType := reflect.TypeOf(zero)
	retValue := reflect.New(retType).Elem()
	if retValue.Kind() == reflect.Ptr {
		retValue.Set(reflect.New(retType.Elem()))
	}

	// 类型校验
	if fromValue.Kind() != reflect.Ptr && fromValue.Kind() != reflect.Struct {
		return zero, fserr.New("参数不是结构或结构指针")
	}

	if fromValue.Kind() == reflect.Ptr && fromValue.Elem().Kind() != reflect.Struct {
		return zero, fserr.New("参数不是结构或结构指针")
	}

	if retValue.Kind() != reflect.Ptr && retValue.Kind() != reflect.Struct {
		return zero, fserr.New("返回类型不是结构或结构指针")
	}

	if retValue.Kind() == reflect.Ptr && retValue.Elem().Kind() != reflect.Struct {
		return zero, fserr.New("返回类型不是结构或结构指针")
	}

	fromElemValue := fromValue
	if fromValue.Kind() == reflect.Ptr {
		fromElemValue = fromValue.Elem()
	}

	retElemValue := retValue
	if retValue.Kind() == reflect.Ptr {
		retElemValue = retValue.Elem()
	}

	err := assignTo(fromElemValue, &retElemValue)
	if err != nil {
		return zero, err
	}

	return retValue.Interface().(T), nil
}

func assignTo(fromElemValue reflect.Value, retElemValue *reflect.Value) error {
	for i := 0; i < fromElemValue.NumField(); i++ {
		fromField := fromElemValue.Type().Field(i)
		tagStr := fromField.Tag.Get(assignTagKey)

		// 结构上没有添加Tag, 先尝试直接按照字段赋值结构，如果失败，进一步进入内部尝试
		if strutils.IsStringEmpty(tagStr) &&
			((fromField.Type.Kind() == reflect.Struct && fromField.Type.String() != "time.Time") ||
				(fromField.Type.Kind() == reflect.Ptr &&
					fromField.Type.Elem().Kind() == reflect.Struct &&
					fromField.Type.Elem().String() != "time.Time")) {
			fromStructElemValue := fromElemValue.Field(i)
			if fromField.Type.Kind() == reflect.Ptr {
				if !fromStructElemValue.IsValid() || fromStructElemValue.IsZero() {
					continue
				}

				fromStructElemValue = fromStructElemValue.Elem()
			}

			err := assignTo(fromStructElemValue, retElemValue)
			if err != nil {
				return err
			}
		}

		tag, err := parseAssignTag(fromField, tagStr)
		if err != nil {
			return err
		}

		if tag == nil {
			continue
		}

		fromFieldValue := fromElemValue.Field(i)

		// 无效零值，不进行赋值
		if !fromFieldValue.IsValid() || fromFieldValue.IsZero() {
			continue
		}

		fromFieldElemValue := fromFieldValue
		if fromFieldValue.Kind() == reflect.Ptr {
			fromFieldElemValue = fromFieldValue.Elem()
		}

		retFieldValue := retElemValue.FieldByName(tag.ToField)

		// 不存在对应的字段
		if !retFieldValue.IsValid() {
			continue
		}

		retFieldElemValue := retFieldValue
		if retFieldValue.Kind() == reflect.Ptr {
			if !retFieldValue.IsValid() {
				continue
			}

			if !retFieldValue.CanSet() {
				continue
			}

			// 空值针，初始化
			if retFieldValue.IsNil() {
				retFieldValue.Set(reflect.New(retFieldValue.Type().Elem()))
			}

			retFieldElemValue = retFieldValue.Elem()
		}

		err = assignField(fromFieldElemValue, retFieldElemValue, tag)
		if err != nil {
			return err
		}
	}

	return nil
}

func assignField(fromFieldElemValue reflect.Value, retFieldElemValue reflect.Value, tag *assignTag) error {
	fromKind := reflectutils.GroupValueKind(fromFieldElemValue)
	retKind := reflectutils.GroupValueKind(retFieldElemValue)

	var fromAny any
	switch fromKind {
	case reflect.Struct:
		if fromFieldElemValue.Type().String() == "time.Time" && retKind == reflect.String {
			fromString := fromFieldElemValue.Interface().(time.Time).Format(tag.FormatTime)
			fromAny = trimFromString(fromString, tag)
			break
		}

		if fromFieldElemValue.Type().String() != "time.Time" && retKind == reflect.Struct {
			return assignTo(fromFieldElemValue, &retFieldElemValue)
		}

		fromAny = fromFieldElemValue.Interface()
	case reflect.Slice:
		if fromFieldElemValue.Elem().Kind() == reflect.String && retKind == reflect.String {
			fromString := strings.Join(fromFieldElemValue.Interface().([]string), tag.JoinWith)
			fromAny = trimFromString(fromString, tag)
			break
		}

		fromAny = fromFieldElemValue.Interface()
	case reflect.String:
		fromString := fromFieldElemValue.String()

		if retKind == reflect.Struct && retFieldElemValue.Type().String() == "time.Time" {
			retTimeField, err := time.ParseInLocation(tag.ParseTime, fromString, time.Local)
			if err != nil {
				return err
			}

			fromAny = retTimeField
			break
		}

		if retFieldElemValue.Kind() == reflect.Slice && retFieldElemValue.Elem().Kind() == reflect.String {
			fromAny = strings.Split(fromString, tag.SplitWith)
			break
		}

		fromAny = trimFromString(fromString, tag)
	default:
		fromAny = fromFieldElemValue.Interface()
	}

	switch retKind {
	case reflect.Int64:
		return reflectutils.AssignInt64Value(fromAny, retFieldElemValue)
	case reflect.Uint64:
		return reflectutils.AssignUint64Value(fromAny, retFieldElemValue)
	case reflect.Float64:
		return reflectutils.AssignFloat64Value(fromAny, retFieldElemValue)
	case reflect.Bool:
		return reflectutils.AssignBoolValue(fromAny, retFieldElemValue)
	case reflect.String:
		return reflectutils.AssignStringValue(fromAny, retFieldElemValue)
	default:
		retFieldElemValue.Set(reflect.ValueOf(fromAny))
		return nil
	}
}

func trimFromString(fromString string, tag *assignTag) string {
	if strutils.IsStringNotEmpty(tag.Trim) {
		return strings.Trim(fromString, tag.Trim)
	} else {
		if strutils.IsStringNotEmpty(tag.TrimPrefix) {
			return strings.TrimPrefix(fromString, tag.TrimPrefix)
		}

		if strutils.IsStringNotEmpty(tag.TrimSuffix) {
			return strings.TrimSuffix(fromString, tag.TrimSuffix)
		}
	}

	return fromString
}

const (
	assignDefaultStringSliceSeparator = "::"
	assignTagPartSeparator            = ";"
	assignTagPartKeyValueSeparator    = ":"
)

const (
	assignTagKey     = "assign"
	assignIgnore     = "-"
	assignToField    = "toField"
	assignParseTime  = "parseTime"
	assignFormatTime = "formatTime"
	assignJoinWith   = "joinWith"
	assignSplitWith  = "splitWith"
	assignTrim       = "trim"
	assignTrimPrefix = "trimPrefix"
	assignTrimSuffix = "trimSuffix"
)

type assignTag struct {
	ToField    string
	ParseTime  string
	FormatTime string
	JoinWith   string
	SplitWith  string
	Trim       string
	TrimPrefix string
	TrimSuffix string
}

func parseAssignTag(field reflect.StructField, tagStr string) (*assignTag, error) {
	if tagStr == assignIgnore {
		return nil, nil
	}

	tag := &assignTag{
		ToField:    field.Name,
		ParseTime:  time.DateTime,
		FormatTime: time.DateTime,
		JoinWith:   assignDefaultStringSliceSeparator,
		SplitWith:  assignDefaultStringSliceSeparator,
		Trim:       "",
		TrimPrefix: "",
		TrimSuffix: "",
	}

	if strutils.IsStringEmpty(tagStr) {
		return tag, nil
	}

	assignParts := strings.Split(tagStr, assignTagPartSeparator)
	if assignParts != nil || len(assignParts) != 0 {
		for _, assignPart := range assignParts {
			assignPartKeyValue := strings.SplitN(strings.TrimSpace(assignPart), assignTagPartKeyValueSeparator, 2)
			if assignPartKeyValue != nil && len(assignPartKeyValue) == 2 && strutils.IsStringNotEmpty(assignPartKeyValue[1]) {
				// 可以支持' ' '，获取到'字符
				assignPartKeyValue[1] = strings.TrimSpace(strings.Trim(assignPartKeyValue[1], "'"))
			}

			switch assignPartKeyValue[0] {
			case assignToField:
				tag.ToField = assignPartKeyValue[1]
			case assignParseTime:
				tag.ParseTime = assignPartKeyValue[1]
			case assignFormatTime:
				tag.FormatTime = assignPartKeyValue[1]
			case assignJoinWith:
				if strutils.IsStringEmpty(assignPartKeyValue[1]) {
					return nil, fserr.New(assignJoinWith + "没有赋值分隔符")
				}

				tag.JoinWith = assignPartKeyValue[1]
			case assignSplitWith:
				if strutils.IsStringEmpty(assignPartKeyValue[1]) {
					return nil, fserr.New(assignSplitWith + "没有赋值分隔符")
				}

				tag.SplitWith = assignPartKeyValue[1]
			case assignTrim:
				tag.Trim = assignPartKeyValue[1]
			case assignTrimPrefix:
				tag.TrimPrefix = assignPartKeyValue[1]
			case assignTrimSuffix:
				tag.TrimSuffix = assignPartKeyValue[1]
			default:
				err := fserr.New(assignTagKey + "不支持的tag: " + assignPartKeyValue[0])
				fslog.Error(err)
				continue
			}
		}
	}

	return tag, nil
}