package validator

import (
	"fmt"

	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/reflect/protoreflect"

	validate "git.ikuban.com/server/kubanapis/kuban/api/validate"
)

// Engine 验证引擎
type Engine struct {
	celExecutor *CELExecutor
}

// NewEngine 创建验证引擎
func NewEngine(celExecutor *CELExecutor) *Engine {
	return &Engine{
		celExecutor: celExecutor,
	}
}

// Validate 验证消息
func (e *Engine) Validate(vctx *ValidationContext, msg proto.Message) error {
	if msg == nil {
		return nil
	}

	errors := &ValidationErrors{}

	// 获取消息的反射对象
	msgReflect := msg.ProtoReflect()
	msgDescriptor := msgReflect.Descriptor()

	// 1. 验证消息级别规则
	if err := e.validateMessageRules(vctx, msgReflect, msgDescriptor, errors); err != nil {
		return err
	}

	// 2. 验证字段
	if err := e.validateFields(vctx, msgReflect, msgDescriptor, errors); err != nil {
		return err
	}

	// 3. 验证 oneof
	if err := e.validateOneofs(vctx, msgReflect, msgDescriptor, errors); err != nil {
		return err
	}

	// 返回错误(如果有)
	if errors.HasErrors() {
		return errors.ToKratosError()
	}

	return nil
}

// validateMessageRules 验证消息级别规则
func (e *Engine) validateMessageRules(
	vctx *ValidationContext,
	msgReflect protoreflect.Message,
	msgDescriptor protoreflect.MessageDescriptor,
	errors *ValidationErrors,
) error {
	// 获取消息选项
	opts := msgDescriptor.Options()
	if opts == nil {
		return nil
	}

	// 检查是否有验证规则扩展
	if !proto.HasExtension(opts, validate.E_Message) {
		return nil
	}

	// 获取消息验证规则
	msgRules := proto.GetExtension(opts, validate.E_Message).(*validate.MessageRules)
	if msgRules == nil {
		return nil
	}

	// 检查是否被禁用
	if msgRules.Disabled {
		return nil
	}

	// 检查验证组
	if !vctx.HasAnyGroup(msgRules.Groups) {
		return nil
	}

	// 执行 CEL 规则
	for _, celRule := range msgRules.Cel {
		if err := e.executeCELRule(vctx, celRule, msgReflect.Interface(), "", errors); err != nil {
			if vctx.ShouldFailFast() {
				return err
			}
		}
	}

	return nil
}

// validateFields 验证所有字段
func (e *Engine) validateFields(
	vctx *ValidationContext,
	msgReflect protoreflect.Message,
	msgDescriptor protoreflect.MessageDescriptor,
	errors *ValidationErrors,
) error {
	fields := msgDescriptor.Fields()

	for i := 0; i < fields.Len(); i++ {
		field := fields.Get(i)
		fieldPath := string(field.Name())

		// 检查是否达到最大错误数
		if vctx.MaxErrorsReached(errors.Count()) {
			break
		}

		// 验证字段
		if err := e.validateField(vctx, msgReflect, field, fieldPath, errors); err != nil {
			if vctx.ShouldFailFast() {
				return err
			}
		}
	}

	return nil
}

// validateField 验证单个字段
func (e *Engine) validateField(
	vctx *ValidationContext,
	msgReflect protoreflect.Message,
	field protoreflect.FieldDescriptor,
	fieldPath string,
	errors *ValidationErrors,
) error {
	// 获取字段选项
	opts := field.Options()
	if opts == nil {
		return nil
	}

	// 检查是否有验证规则
	if !proto.HasExtension(opts, validate.E_Field) {
		return nil
	}

	// 获取字段验证规则
	fieldRules := proto.GetExtension(opts, validate.E_Field).(*validate.FieldRules)
	if fieldRules == nil {
		return nil
	}

	// 检查验证组
	if !vctx.HasAnyGroup(fieldRules.Groups) {
		return nil
	}

	// 获取字段值
	fieldValue := msgReflect.Get(field)
	hasValue := msgReflect.Has(field)

	// 检查忽略策略
	if e.shouldIgnoreField(fieldRules, hasValue, fieldValue, field) {
		return nil
	}

	// 验证 required
	if fieldRules.Required {
		if !hasValue {
			defaultMsg := fmt.Sprintf("字段 %s 是必填的", fieldPath)
			message := e.getErrorMessage(fieldRules, vctx, "required", defaultMsg)
			errors.Add(NewValidationError(
				fieldPath,
				ErrCodeRequired,
				message,
			))
			if vctx.ShouldFailFast() {
				return errors
			}
		}
	}

	// 如果字段未设置且不是 required,跳过后续验证
	if !hasValue && !fieldRules.Required {
		return nil
	}

	// 执行 CEL 规则
	for _, celRule := range fieldRules.Cel {
		if err := e.executeCELFieldRule(
			vctx,
			celRule,
			fieldValue.Interface(),
			msgReflect.Interface(),
			fieldPath,
			errors,
		); err != nil {
			if vctx.ShouldFailFast() {
				return err
			}
		}
	}

	// 根据字段类型执行类型特定验证
	return e.validateFieldType(vctx, fieldRules, fieldValue, field, fieldPath, errors)
}

// validateFieldType 根据字段类型执行验证
func (e *Engine) validateFieldType(
	vctx *ValidationContext,
	fieldRules *validate.FieldRules,
	fieldValue protoreflect.Value,
	field protoreflect.FieldDescriptor,
	fieldPath string,
	errors *ValidationErrors,
) error {
	// 根据规则类型分发
	switch rule := fieldRules.Type.(type) {
	case *validate.FieldRules_String_:
		return e.validateString(vctx, fieldRules, rule.String_, fieldValue.String(), fieldPath, errors)
	case *validate.FieldRules_Int32:
		return e.validateInt32(vctx, fieldRules, rule.Int32, int32(fieldValue.Int()), fieldPath, errors)
	case *validate.FieldRules_Int64:
		return e.validateInt64(vctx, fieldRules, rule.Int64, fieldValue.Int(), fieldPath, errors)
	case *validate.FieldRules_Uint32:
		return e.validateUInt32(vctx, fieldRules, rule.Uint32, uint32(fieldValue.Uint()), fieldPath, errors)
	case *validate.FieldRules_Uint64:
		return e.validateUInt64(vctx, fieldRules, rule.Uint64, fieldValue.Uint(), fieldPath, errors)
	case *validate.FieldRules_Sint32:
		return e.validateInt32(vctx, fieldRules, (*validate.Int32Rules)(rule.Sint32), int32(fieldValue.Int()), fieldPath, errors)
	case *validate.FieldRules_Sint64:
		return e.validateInt64(vctx, fieldRules, (*validate.Int64Rules)(rule.Sint64), fieldValue.Int(), fieldPath, errors)
	case *validate.FieldRules_Fixed32:
		return e.validateUInt32(vctx, fieldRules, (*validate.UInt32Rules)(rule.Fixed32), uint32(fieldValue.Uint()), fieldPath, errors)
	case *validate.FieldRules_Fixed64:
		return e.validateUInt64(vctx, fieldRules, (*validate.UInt64Rules)(rule.Fixed64), fieldValue.Uint(), fieldPath, errors)
	case *validate.FieldRules_Sfixed32:
		return e.validateInt32(vctx, fieldRules, (*validate.Int32Rules)(rule.Sfixed32), int32(fieldValue.Int()), fieldPath, errors)
	case *validate.FieldRules_Sfixed64:
		return e.validateInt64(vctx, fieldRules, (*validate.Int64Rules)(rule.Sfixed64), fieldValue.Int(), fieldPath, errors)
	case *validate.FieldRules_Float:
		return e.validateFloat(vctx, fieldRules, rule.Float, float32(fieldValue.Float()), fieldPath, errors)
	case *validate.FieldRules_Double:
		return e.validateDouble(vctx, fieldRules, rule.Double, fieldValue.Float(), fieldPath, errors)
	case *validate.FieldRules_Bool:
		return e.validateBool(vctx, fieldRules, rule.Bool, fieldValue.Bool(), fieldPath, errors)
	case *validate.FieldRules_Bytes:
		return e.validateBytes(vctx, fieldRules, rule.Bytes, fieldValue.Bytes(), fieldPath, errors)
	case *validate.FieldRules_Enum:
		return e.validateEnum(vctx, fieldRules, rule.Enum, fieldValue.Enum(), field, fieldPath, errors)
	case *validate.FieldRules_Repeated:
		return e.validateRepeated(vctx, fieldRules, rule.Repeated, fieldValue.List(), field, fieldPath, errors)
	case *validate.FieldRules_Map:
		return e.validateMap(vctx, fieldRules, rule.Map, fieldValue.Map(), field, fieldPath, errors)
	}

	return nil
}

// shouldIgnoreField 检查是否应该忽略字段验证
func (e *Engine) shouldIgnoreField(
	rules *validate.FieldRules,
	hasValue bool,
	value protoreflect.Value,
	field protoreflect.FieldDescriptor,
) bool {
	switch rules.Ignore {
	case validate.IgnoreRule_IGNORE_ALWAYS:
		return true
	case validate.IgnoreRule_IGNORE_IF_ZERO:
		return !hasValue || isZeroValue(value, field)
	case validate.IgnoreRule_IGNORE_NEVER:
		return false
	default:
		// IGNORE_UNSPECIFIED: 未设置时不验证
		return !hasValue
	}
}

// isZeroValue 检查是否为零值
func isZeroValue(value protoreflect.Value, field protoreflect.FieldDescriptor) bool {
	switch field.Kind() {
	case protoreflect.BoolKind:
		return !value.Bool()
	case protoreflect.Int32Kind, protoreflect.Sint32Kind, protoreflect.Sfixed32Kind,
		protoreflect.Int64Kind, protoreflect.Sint64Kind, protoreflect.Sfixed64Kind:
		return value.Int() == 0
	case protoreflect.Uint32Kind, protoreflect.Fixed32Kind,
		protoreflect.Uint64Kind, protoreflect.Fixed64Kind:
		return value.Uint() == 0
	case protoreflect.FloatKind, protoreflect.DoubleKind:
		return value.Float() == 0.0
	case protoreflect.StringKind:
		return value.String() == ""
	case protoreflect.BytesKind:
		return len(value.Bytes()) == 0
	case protoreflect.MessageKind:
		return !value.Message().IsValid()
	default:
		return false
	}
}

// validateOneofs 验证所有 oneof
func (e *Engine) validateOneofs(
	vctx *ValidationContext,
	msgReflect protoreflect.Message,
	msgDescriptor protoreflect.MessageDescriptor,
	errors *ValidationErrors,
) error {
	oneofs := msgDescriptor.Oneofs()

	for i := 0; i < oneofs.Len(); i++ {
		oneof := oneofs.Get(i)

		// 获取 oneof 选项
		opts := oneof.Options()
		if opts == nil {
			continue
		}

		// 检查是否有验证规则
		if !proto.HasExtension(opts, validate.E_Oneof) {
			continue
		}

		// 获取 oneof 验证规则
		oneofRules := proto.GetExtension(opts, validate.E_Oneof).(*validate.OneofRules)
		if oneofRules == nil {
			continue
		}

		// 验证 required
		if oneofRules.Required {
			hasField := false
			fields := oneof.Fields()
			for j := 0; j < fields.Len(); j++ {
				if msgReflect.Has(fields.Get(j)) {
					hasField = true
					break
				}
			}

			if !hasField {
				errors.Add(NewValidationError(
					string(oneof.Name()),
					ErrCodeRequired,
					fmt.Sprintf("oneof %s 必须选择一个字段", oneof.Name()),
				))
				if vctx.ShouldFailFast() {
					return errors
				}
			}
		}
	}

	return nil
}

// executeCELRule 执行 CEL 规则
func (e *Engine) executeCELRule(
	vctx *ValidationContext,
	rule *validate.Rule,
	msg proto.Message,
	fieldPath string,
	errors *ValidationErrors,
) error {
	// 执行表达式
	result, err := e.celExecutor.EvaluateWithProto(rule.Expression, msg)
	if err != nil {
		// CEL 执行错误
		errors.Add(&ValidationError{
			FieldPath: fieldPath,
			RuleID:    rule.Id,
			Message:   fmt.Sprintf("CEL 表达式执行失败: %v", err),
		})
		return nil
	}

	// 如果验证失败
	if !result {
		message := rule.Message
		if message == "" && vctx.Language == "en-US" && rule.MessageEn != "" {
			message = rule.MessageEn
		}
		if message == "" {
			message = fmt.Sprintf("验证规则 %s 失败", rule.Id)
		}

		errors.Add(&ValidationError{
			FieldPath: fieldPath,
			RuleID:    rule.Id,
			Message:   message,
			MessageEN: rule.MessageEn,
		})
	}

	return nil
}

// executeCELFieldRule 执行字段级 CEL 规则
func (e *Engine) executeCELFieldRule(
	vctx *ValidationContext,
	rule *validate.Rule,
	fieldValue interface{},
	parent proto.Message,
	fieldPath string,
	errors *ValidationErrors,
) error {
	// 执行表达式
	result, err := e.celExecutor.EvaluateFieldRule(rule.Expression, fieldValue, parent)
	if err != nil {
		// CEL 执行错误
		errors.Add(&ValidationError{
			FieldPath: fieldPath,
			RuleID:    rule.Id,
			Message:   fmt.Sprintf("CEL 表达式执行失败: %v", err),
		})
		return nil
	}

	// 如果验证失败
	if !result {
		message := rule.Message
		if message == "" && vctx.Language == "en-US" && rule.MessageEn != "" {
			message = rule.MessageEn
		}
		if message == "" {
			message = fmt.Sprintf("验证规则 %s 失败", rule.Id)
		}

		errors.Add(&ValidationError{
			FieldPath: fieldPath,
			RuleID:    rule.Id,
			Message:   message,
			MessageEN: rule.MessageEn,
			Value:     fieldValue,
		})
	}

	return nil
}

// getErrorMessage 获取错误消息,按优先级返回
// 优先级: 特定消息(required_message) > 通用消息(error_message) > 默认消息
func (e *Engine) getErrorMessage(
	fieldRules *validate.FieldRules,
	vctx *ValidationContext,
	ruleType string,
	defaultMessage string,
) string {
	// 1. 检查是否有特定规则的自定义消息 (如 required_message)
	if ruleType == "required" {
		if vctx.Language == "en-US" && fieldRules.RequiredMessageEn != "" {
			return fieldRules.RequiredMessageEn
		}
		if fieldRules.RequiredMessage != "" {
			return fieldRules.RequiredMessage
		}
	}

	// 2. 检查通用自定义消息 (error_message)
	if vctx.Language == "en-US" && fieldRules.ErrorMessageEn != "" {
		return fieldRules.ErrorMessageEn
	}
	if fieldRules.ErrorMessage != "" {
		return fieldRules.ErrorMessage
	}

	// 3. 返回默认消息
	return defaultMessage
}

// ValidateField 验证单个字段(外部接口)
func (e *Engine) ValidateField(vctx *ValidationContext, fieldPath string, value interface{}, rules interface{}) error {
	errors := &ValidationErrors{}

	// TODO: 实现单字段验证逻辑

	if errors.HasErrors() {
		return errors.ToKratosError()
	}
	return nil
}