package validator

import (
	"fmt"
	"strings"

	"tyapi-server/internal/shared/interfaces"

	"github.com/gin-gonic/gin"
	"github.com/gin-gonic/gin/binding"
	"github.com/go-playground/locales/zh"
	ut "github.com/go-playground/universal-translator"
	"github.com/go-playground/validator/v10"
	zh_translations "github.com/go-playground/validator/v10/translations/zh"
)

// RequestValidator HTTP请求验证器
type RequestValidator struct {
	response   interfaces.ResponseBuilder
	translator ut.Translator
	validator  *validator.Validate
}

// NewRequestValidator 创建HTTP请求验证器
func NewRequestValidator(response interfaces.ResponseBuilder) interfaces.RequestValidator {
	// 创建中文locale
	zhLocale := zh.New()
	uni := ut.New(zhLocale, zhLocale)

	// 获取中文翻译器
	trans, _ := uni.GetTranslator("zh")

	// 获取gin默认的validator实例
	ginValidator := binding.Validator.Engine().(*validator.Validate)

	// 注册官方中文翻译
	zh_translations.RegisterDefaultTranslations(ginValidator, trans)

	// 注册自定义验证器到gin的全局validator
	RegisterCustomValidators(ginValidator)

	// 注册自定义翻译
	RegisterCustomTranslations(ginValidator, trans)

	return &RequestValidator{
		response:   response,
		translator: trans,
		validator:  ginValidator,
	}
}

// Validate 验证请求体
func (v *RequestValidator) Validate(c *gin.Context, dto interface{}) error {
	return v.BindAndValidate(c, dto)
}

// ValidateQuery 验证查询参数
func (v *RequestValidator) ValidateQuery(c *gin.Context, dto interface{}) error {
	if err := c.ShouldBindQuery(dto); err != nil {
		if validationErrors, ok := err.(validator.ValidationErrors); ok {
			validationErrorsMap := v.formatValidationErrors(validationErrors)
			v.response.ValidationError(c, validationErrorsMap)
		} else {
			v.response.BadRequest(c, "查询参数格式错误")
		}
		return err
	}

	return nil
}

// ValidateParam 验证路径参数
func (v *RequestValidator) ValidateParam(c *gin.Context, dto interface{}) error {
	if err := c.ShouldBindUri(dto); err != nil {
		if validationErrors, ok := err.(validator.ValidationErrors); ok {
			validationErrorsMap := v.formatValidationErrors(validationErrors)
			v.response.ValidationError(c, validationErrorsMap)
		} else {
			v.response.BadRequest(c, "路径参数格式错误")
		}
		return err
	}

	return nil
}

// BindAndValidate 绑定并验证请求
func (v *RequestValidator) BindAndValidate(c *gin.Context, dto interface{}) error {
	if err := c.ShouldBindJSON(dto); err != nil {
		if validationErrors, ok := err.(validator.ValidationErrors); ok {
			validationErrorsMap := v.formatValidationErrors(validationErrors)
			v.response.ValidationError(c, validationErrorsMap)
		} else {
			v.response.BadRequest(c, "请求体格式错误")
		}
		return err
	}

	return nil
}

// formatValidationErrors 格式化验证错误
func (v *RequestValidator) formatValidationErrors(validationErrors validator.ValidationErrors) map[string][]string {
	errors := make(map[string][]string)

	for _, fieldError := range validationErrors {
		fieldName := v.getFieldName(fieldError)
		errorMessage := v.getErrorMessage(fieldError)

		if _, exists := errors[fieldName]; !exists {
			errors[fieldName] = []string{}
		}
		errors[fieldName] = append(errors[fieldName], errorMessage)
	}

	return errors
}

// getErrorMessage 获取错误消息
func (v *RequestValidator) getErrorMessage(fieldError validator.FieldError) string {
	fieldDisplayName := getFieldDisplayName(fieldError.Field())

	// 优先使用翻译器
	errorMessage := fieldError.Translate(v.translator)
	if errorMessage != fieldError.Error() {
		// 替换字段名为中文
		if fieldDisplayName != fieldError.Field() {
			errorMessage = strings.ReplaceAll(errorMessage, fieldError.Field(), fieldDisplayName)
		}
		return errorMessage
	}

	// 回退到手动翻译
	return v.getFallbackErrorMessage(fieldError, fieldDisplayName)
}

// getFallbackErrorMessage 获取回退错误消息
func (v *RequestValidator) getFallbackErrorMessage(fieldError validator.FieldError, fieldDisplayName string) string {
	tag := fieldError.Tag()
	param := fieldError.Param()

	switch tag {
	case "required":
		return fmt.Sprintf("%s不能为空", fieldDisplayName)
	case "email":
		return fmt.Sprintf("%s必须是有效的邮箱地址", fieldDisplayName)
	case "min":
		return fmt.Sprintf("%s长度不能少于%s位", fieldDisplayName, param)
	case "max":
		return fmt.Sprintf("%s长度不能超过%s位", fieldDisplayName, param)
	case "len":
		return fmt.Sprintf("%s长度必须为%s位", fieldDisplayName, param)
	case "eqfield":
		paramDisplayName := getFieldDisplayName(param)
		return fmt.Sprintf("%s必须与%s一致", fieldDisplayName, paramDisplayName)
	case "phone":
		return fmt.Sprintf("%s必须是有效的手机号", fieldDisplayName)
	case "username":
		return fmt.Sprintf("%s格式不正确，只能包含字母、数字、下划线，且必须以字母开头，长度3-20位", fieldDisplayName)
	case "strong_password":
		return fmt.Sprintf("%s强度不足，必须包含大小写字母和数字，且不少于8位", fieldDisplayName)
	case "social_credit_code":
		return fmt.Sprintf("%s格式不正确，必须是18位统一社会信用代码", fieldDisplayName)
	case "id_card":
		return fmt.Sprintf("%s格式不正确，必须是18位身份证号", fieldDisplayName)
	case "price":
		return fmt.Sprintf("%s必须是非负数", fieldDisplayName)
	case "sort_order":
		return fmt.Sprintf("%s必须是 asc 或 desc", fieldDisplayName)
	case "product_code":
		return fmt.Sprintf("%s格式不正确，只能包含字母、数字、下划线、连字符、中英文括号，长度3-50位", fieldDisplayName)
	case "uuid":
		return fmt.Sprintf("%s必须是有效的UUID格式", fieldDisplayName)
	case "url":
		return fmt.Sprintf("%s必须是有效的URL地址", fieldDisplayName)
	case "oneof":
		return fmt.Sprintf("%s必须是以下值之一: %s", fieldDisplayName, param)
	case "gt":
		return fmt.Sprintf("%s必须大于%s", fieldDisplayName, param)
	default:
		return fmt.Sprintf("%s格式不正确", fieldDisplayName)
	}
}

// getFieldName 获取字段名
func (v *RequestValidator) getFieldName(fieldError validator.FieldError) string {
	fieldName := fieldError.Field()
	return v.toSnakeCase(fieldName)
}

// toSnakeCase 转换为snake_case
func (v *RequestValidator) toSnakeCase(str string) string {
	var result strings.Builder
	for i, r := range str {
		if i > 0 && (r >= 'A' && r <= 'Z') {
			result.WriteRune('_')
		}
		result.WriteRune(r)
	}
	return strings.ToLower(result.String())
}

// GetValidator 获取validator实例（用于业务逻辑）
func (v *RequestValidator) GetValidator() *validator.Validate {
	return v.validator
}

// ValidateValue 验证单个值（用于业务逻辑）
func (v *RequestValidator) ValidateValue(field interface{}, tag string) error {
	return v.validator.Var(field, tag)
}

// ValidateStruct 验证结构体（用于业务逻辑）
func (v *RequestValidator) ValidateStruct(s interface{}) error {
	return v.validator.Struct(s)
}