package pkg

import (
	"fmt"
	"geo/tmpl/errcode"
	"reflect"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"github.com/go-playground/validator/v10"
	"github.com/gofiber/fiber/v2"
)

const (
	// 验证标签常量
	TagRequired = "required"
	TagEmail    = "email"
	TagMin      = "min"
	TagMax      = "max"
	TagLen      = "len"
	TagNumeric  = "numeric"
	TagOneof    = "oneof"
	TagGte      = "gte"
	TagGt       = "gt"
	TagLte      = "lte"
	TagLt       = "lt"
	TagURL      = "url"
	TagUUID     = "uuid"
	TagDatetime = "datetime"

	// 中文标签常量
	//LabelComment = "comment"
	//LabelLabel   = "label"
	LabelZh = "zh"

	// 上下文Key
	CtxRequestBody = "request_body"

	// 性能优化常量
	InitialBuilderSize   = 64
	MaxCacheSize         = 5000
	CacheCleanupInterval = 10 * time.Minute
)

// ValidatorConfig 验证器配置
type ValidatorConfig struct {
	StatusCode    int                                       // 验证失败时的HTTP状态码，默认422
	ErrorHandler  func(c *fiber.Ctx, err error) error       // 自定义错误处理
	BeforeParse   func(c *fiber.Ctx) error                  // 解析前执行
	AfterParse    func(c *fiber.Ctx, req interface{}) error // 解析后执行
	DisableCache  bool                                      // 是否禁用缓存
	MaxCacheSize  int                                       // 最大缓存数量
	UseChinese    bool                                      // 是否使用中文提示
	EnableMetrics bool                                      // 是否启用指标收集
}

// CacheStats 缓存统计
type CacheStats struct {
	hitCount    int64
	missCount   int64
	evictCount  int64
	errorCount  int64
	accessCount int64
}

// Metrics 指标收集
type Metrics struct {
	totalRequests  int64
	validationTime int64
	cacheHitRate   float64
	mu             sync.RWMutex
}

// fieldInfo 字段信息
type fieldInfo struct {
	label       string
	index       int
	typeKind    reflect.Kind
	accessCount int64
	lastAccess  time.Time
}

// typeInfo 类型信息
type typeInfo struct {
	fields      map[string]*fieldInfo
	fieldNames  []string
	mu          sync.RWMutex
	accessCount int64
	createdAt   time.Time
	lastAccess  time.Time
	typeKey     string
}

// ValidatorHelper 验证器助手
type ValidatorHelper struct {
	validate       *validator.Validate
	config         *ValidatorConfig
	typeCache      sync.Map
	cacheStats     *CacheStats
	errorFnCache   map[string]func(string, string) string
	errorFnCacheMu sync.RWMutex
	pruneLock      sync.Mutex
	stopCleanup    chan struct{}
	cleanupOnce    sync.Once
	metrics        *Metrics
}

var (
	ChineseErrorTemplates = map[string]string{
		TagRequired: "%s不能为空",
		TagEmail:    "%s格式不正确",
		TagMin:      "%s不能小于%s",
		TagMax:      "%s不能大于%s",
		TagLen:      "%s长度必须为%s位",
		TagNumeric:  "%s必须是数字",
		TagOneof:    "%s必须是以下值之一: %s",
		TagGte:      "%s不能小于%s",
		TagGt:       "%s必须大于%s",
		TagLte:      "%s不能大于%s",
		TagLt:       "%s必须小于%s",
		TagURL:      "%s必须是有效的URL地址",
		TagUUID:     "%s必须是有效的UUID",
		TagDatetime: "%s日期格式不正确",
	}

	defaultErrorTemplates = map[string]string{
		TagRequired: "%s is required",
		TagEmail:    "invalid email format",
		TagMin:      "%s must be at least %s",
		TagMax:      "%s must be at most %s",
		TagLen:      "%s must be exactly %s characters",
		TagNumeric:  "%s must be numeric",
		TagOneof:    "%s must be one of: %s",
		TagGte:      "%s must be greater than or equal to %s",
		TagGt:       "%s must be greater than %s",
		TagLte:      "%s must be less than or equal to %s",
		TagLt:       "%s must be less than %s",
		TagURL:      "%s must be a valid URL",
		TagUUID:     "%s must be a valid UUID",
		TagDatetime: "%s invalid datetime format",
	}
)

var (
	//  对象池
	builderPool = sync.Pool{
		New: func() interface{} {
			b := &strings.Builder{}
			b.Grow(InitialBuilderSize)
			return b
		},
	}

	// 错误信息切片池
	errorSlicePool = sync.Pool{
		New: func() interface{} {
			slice := make([]string, 0, 8)
			return &slice
		},
	}

	// 字段信息对象池
	fieldInfoPool = sync.Pool{
		New: func() interface{} {
			return &fieldInfo{
				accessCount: 0,
				lastAccess:  time.Now(),
			}
		},
	}

	// 类型信息对象池
	typeInfoPool = sync.Pool{
		New: func() interface{} {
			return &typeInfo{
				fields:     make(map[string]*fieldInfo),
				fieldNames: make([]string, 0, 8),
			}
		},
	}
)

var (
	Vh   *ValidatorHelper
	once sync.Once
)

// NewValidatorHelper 初始化验证器助手
func NewValidatorHelper(config ...*ValidatorConfig) {
	once.Do(func() {
		v := validator.New()

		// 优化JSON标签获取
		v.RegisterTagNameFunc(func(fld reflect.StructField) string {
			return fld.Tag.Get("json")
		})

		// 默认配置
		cfg := &ValidatorConfig{
			StatusCode:    fiber.StatusUnprocessableEntity,
			ErrorHandler:  defaultErrorHandler,
			MaxCacheSize:  MaxCacheSize,
			UseChinese:    true,
			EnableMetrics: false,
		}

		if len(config) > 0 && config[0] != nil {
			if config[0].StatusCode != 0 {
				cfg.StatusCode = config[0].StatusCode
			}
			if config[0].ErrorHandler != nil {
				cfg.ErrorHandler = config[0].ErrorHandler
			}
			if config[0].MaxCacheSize > 0 {
				cfg.MaxCacheSize = config[0].MaxCacheSize
			}
			cfg.DisableCache = config[0].DisableCache
			cfg.BeforeParse = config[0].BeforeParse
			cfg.AfterParse = config[0].AfterParse
			cfg.UseChinese = config[0].UseChinese
			cfg.EnableMetrics = config[0].EnableMetrics
		}

		// 预编译错误函数
		errorFnCache := make(map[string]func(string, string) string)
		templates := ChineseErrorTemplates
		if !cfg.UseChinese {
			templates = defaultErrorTemplates
		}

		for tag, tmpl := range templates {
			t := tmpl // 捕获变量
			errorFnCache[tag] = func(field, param string) string {
				if strings.Contains(t, "%s") && strings.Count(t, "%s") == 2 {
					return fmt.Sprintf(t, field, param)
				}
				return fmt.Sprintf(t, field)
			}
		}

		Vh = &ValidatorHelper{
			validate:       v,
			config:         cfg,
			cacheStats:     &CacheStats{},
			errorFnCache:   errorFnCache,
			errorFnCacheMu: sync.RWMutex{},
			stopCleanup:    make(chan struct{}),
			metrics:        &Metrics{},
		}

		// 启动定期清理
		if !cfg.DisableCache {
			go Vh.periodicCleanup()
		}
	})
}

// ParseAndValidate 解析并验证请求
func ParseAndValidate(c *fiber.Ctx, req interface{}) error {
	if Vh == nil {
		NewValidatorHelper()
	}

	if Vh.config.EnableMetrics {
		atomic.AddInt64(&Vh.metrics.totalRequests, 1)
		defer Vh.recordValidationTime(time.Now())
	}

	// 执行解析前钩子
	if Vh.config.BeforeParse != nil {
		if err := Vh.config.BeforeParse(c); err != nil {
			return err
		}
	}

	// 解析请求体
	err := c.BodyParser(req)
	if err != nil {
		return errcode.ParamErr("请求格式错误:" + err.Error())
	}

	// 执行解析后钩子
	if Vh.config.AfterParse != nil {
		if err = Vh.config.AfterParse(c, req); err != nil {
			return errcode.ParamErr(err.Error())
		}
	}

	// 验证数据
	err = Vh.validate.Struct(req)
	if err != nil {
		c.Locals(CtxRequestBody, req)

		if !Vh.config.DisableCache {
			t := reflect.TypeOf(req)
			if t.Kind() == reflect.Ptr {
				t = t.Elem()
			}
			if t.Kind() == reflect.Struct {
				Vh.safeGetOrCreateTypeInfo(t)
			}
		}

		return Vh.config.ErrorHandler(c, err)
	}

	return nil
}

// Validate 直接验证结构体
func Validate(req interface{}) error {
	if Vh == nil {
		NewValidatorHelper()
	}

	if err := Vh.validate.Struct(req); err != nil {
		return Vh.wrapValidationError(err, req)
	}
	return nil
}

// 默认错误处理
func defaultErrorHandler(c *fiber.Ctx, err error) error {
	validationErrors, ok := err.(validator.ValidationErrors)
	if !ok {
		return errcode.SystemError
	}

	if len(validationErrors) == 0 {
		return nil
	}

	// 快速路径：单个错误
	if len(validationErrors) == 1 {
		e := validationErrors[0]
		msg := Vh.safeGetErrorMessage(c, e)
		return errcode.ParamErr(msg)
	}

	// 从对象池获取builder
	builder := builderPool.Get().(*strings.Builder)
	builder.Reset()
	defer builderPool.Put(builder)

	req := c.Locals(CtxRequestBody)

	for i, e := range validationErrors {
		if i > 0 {
			builder.WriteByte('\n')
		}
		builder.WriteString(Vh.safeGetErrorMessageWithReq(req, e))
	}

	return errcode.ParamErr(builder.String())
}

// 包装验证错误
func (vh *ValidatorHelper) wrapValidationError(err error, req interface{}) error {
	validationErrors, ok := err.(validator.ValidationErrors)
	if !ok {
		return err
	}

	if len(validationErrors) == 0 {
		return nil
	}

	// 构建错误消息
	builder := builderPool.Get().(*strings.Builder)
	builder.Reset()
	defer builderPool.Put(builder)

	for i, e := range validationErrors {
		if i > 0 {
			builder.WriteByte('\n')
		}
		builder.WriteString(vh.safeGetErrorMessageWithReq(req, e))
	}

	return errcode.ParamErr(builder.String())
}

// 安全获取错误消息
func (vh *ValidatorHelper) safeGetErrorMessage(c *fiber.Ctx, e validator.FieldError) string {
	req := c.Locals(CtxRequestBody)
	return vh.safeGetErrorMessageWithReq(req, e)
}

// 安全获取错误消息（带请求体）
func (vh *ValidatorHelper) safeGetErrorMessageWithReq(req interface{}, e validator.FieldError) string {
	if req == nil {
		return vh.safeFormatFieldError(e, nil)
	}

	t := reflect.TypeOf(req)
	if t.Kind() == reflect.Ptr {
		t = t.Elem()
	}
	if t.Kind() != reflect.Struct {
		return vh.safeFormatFieldError(e, nil)
	}

	// 安全获取类型信息 - 这里需要先声明变量
	var typeInfoObj *typeInfo // 这里声明变量
	if !vh.config.DisableCache {
		if cached, ok := vh.typeCache.Load(t); ok {
			typeInfoObj = cached.(*typeInfo)
			atomic.AddInt64(&typeInfoObj.accessCount, 1)
		}
	}

	return vh.safeFormatFieldError(e, typeInfoObj)
}

// 安全格式化字段错误
func (vh *ValidatorHelper) safeFormatFieldError(e validator.FieldError, typeInfo *typeInfo) string {
	structField := e.StructField()
	fieldName := e.Field()

	// 获取字段标签
	var label string
	if typeInfo != nil {
		typeInfo.mu.RLock()
		if info, ok := typeInfo.fields[structField]; ok {
			label = info.label
			atomic.AddInt64(&info.accessCount, 1)
		}
		typeInfo.mu.RUnlock()
	}

	// 如果没有标签，返回默认消息
	if label == "" {
		return vh.safeGetDefaultErrorMessage(fieldName, e)
	}

	// 使用预编译的错误函数生成消息
	vh.errorFnCacheMu.RLock()
	fn, ok := vh.errorFnCache[e.Tag()]
	vh.errorFnCacheMu.RUnlock()

	if ok {
		return fn(label, e.Param())
	}

	return label + "格式不正确"
}

// 安全获取默认错误消息
func (vh *ValidatorHelper) safeGetDefaultErrorMessage(field string, e validator.FieldError) string {
	vh.errorFnCacheMu.RLock()
	defer vh.errorFnCacheMu.RUnlock()

	if fn, ok := vh.errorFnCache[e.Tag()]; ok {
		return fn(field, e.Param())
	}

	return field + "验证失败"
}

// safeGetOrCreateTypeInfo 安全地获取或创建类型信息
func (vh *ValidatorHelper) safeGetOrCreateTypeInfo(t reflect.Type) *typeInfo {
	if vh.config.DisableCache || t == nil || t.Kind() != reflect.Struct {
		return nil
	}

	// 首先尝试从缓存读取
	if cached, ok := vh.typeCache.Load(t); ok {
		info := cached.(*typeInfo)
		atomic.AddInt64(&info.accessCount, 1)
		atomic.AddInt64(&vh.cacheStats.hitCount, 1)
		info.lastAccess = time.Now()
		return info
	}

	atomic.AddInt64(&vh.cacheStats.missCount, 1)

	// 从对象池获取typeInfo
	info := typeInfoPool.Get().(*typeInfo)

	// 重置并初始化
	info.mu.Lock()

	// 清空现有map
	for k := range info.fields {
		delete(info.fields, k)
	}
	info.fieldNames = info.fieldNames[:0]

	info.accessCount = 0
	info.createdAt = time.Now()
	info.lastAccess = time.Now()
	info.typeKey = t.String()

	// 预计算所有字段信息
	for i := 0; i < t.NumField(); i++ {
		field := t.Field(i)

		// 获取标签
		//label := field.Tag.Get(LabelComment)
		//if label == "" {
		//	label = field.Tag.Get(LabelLabel)
		//}
		//if label == "" {
		//	label = field.Tag.Get(LabelZh)
		//}
		label := field.Tag.Get(LabelZh)
		// 从对象池获取或创建字段信息
		fieldInfo := fieldInfoPool.Get().(*fieldInfo)
		fieldInfo.label = label
		fieldInfo.index = i
		fieldInfo.typeKind = field.Type.Kind()
		fieldInfo.accessCount = 0
		fieldInfo.lastAccess = time.Now()

		info.fields[field.Name] = fieldInfo
		info.fieldNames = append(info.fieldNames, field.Name)
	}

	info.mu.Unlock()

	// 使用原子操作确保线程安全的存储
	if existing, loaded := vh.typeCache.LoadOrStore(t, info); loaded {
		// 如果已经有其他goroutine存储了，使用已有的并回收新创建的
		info.mu.Lock()
		for _, fieldInfo := range info.fields {
			fieldInfoPool.Put(fieldInfo)
		}
		info.mu.Unlock()
		typeInfoPool.Put(info)

		existingInfo := existing.(*typeInfo)
		atomic.AddInt64(&existingInfo.accessCount, 1)
		return existingInfo
	}

	return info
}

// 定期清理缓存
func (vh *ValidatorHelper) periodicCleanup() {
	ticker := time.NewTicker(CacheCleanupInterval)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			vh.safeCleanupCache()
		case <-vh.stopCleanup:
			return
		}
	}
}

// safeCleanupCache 安全清理缓存
func (vh *ValidatorHelper) safeCleanupCache() {
	vh.pruneLock.Lock()
	defer vh.pruneLock.Unlock()

	var keysToDelete []interface{}
	now := time.Now()

	vh.typeCache.Range(func(key, value interface{}) bool {
		info, ok := value.(*typeInfo)
		if !ok {
			return true
		}

		// 检查是否需要清理
		accessCount := atomic.LoadInt64(&info.accessCount)
		age := now.Sub(info.createdAt)
		idleTime := now.Sub(info.lastAccess)

		// 清理条件：
		// 1. 很少访问的缓存（访问次数 < 10）
		// 2. 空闲时间超过30分钟
		// 3. 缓存年龄超过1小时且访问次数较少
		if (accessCount < 10 && idleTime > 30*time.Minute) ||
			(age > 1*time.Hour && accessCount < 100) {
			keysToDelete = append(keysToDelete, key)
			atomic.AddInt64(&vh.cacheStats.evictCount, 1)
		}

		return true
	})

	// 删除选中的缓存
	for _, key := range keysToDelete {
		if val, ok := vh.typeCache.Load(key); ok {
			if info, ok := val.(*typeInfo); ok {
				// 安全回收字段信息
				info.mu.Lock()
				for _, fieldInfo := range info.fields {
					fieldInfoPool.Put(fieldInfo)
				}
				info.mu.Unlock()
				typeInfoPool.Put(info)
			}
			vh.typeCache.Delete(key)
		}
	}
}

// ==================== 指标收集 ====================

func (vh *ValidatorHelper) recordValidationTime(start time.Time) {
	if !vh.config.EnableMetrics {
		return
	}
	duration := time.Since(start).Nanoseconds()
	atomic.AddInt64(&vh.metrics.validationTime, duration)
}

// GetMetrics 获取性能指标
func (vh *ValidatorHelper) GetMetrics() map[string]interface{} {
	if !vh.config.EnableMetrics {
		return nil
	}

	vh.metrics.mu.RLock()
	defer vh.metrics.mu.RUnlock()

	hitCount := atomic.LoadInt64(&vh.cacheStats.hitCount)
	missCount := atomic.LoadInt64(&vh.cacheStats.missCount)
	totalRequests := hitCount + missCount

	var hitRate float64
	if totalRequests > 0 {
		hitRate = float64(hitCount) / float64(totalRequests) * 100
	}

	var cacheSize int64
	vh.typeCache.Range(func(_, _ interface{}) bool {
		cacheSize++
		return true
	})

	return map[string]interface{}{
		"cache_hit_count":   hitCount,
		"cache_miss_count":  missCount,
		"cache_evict_count": atomic.LoadInt64(&vh.cacheStats.evictCount),
		"cache_hit_rate":    fmt.Sprintf("%.2f%%", hitRate),
		"cache_size":        cacheSize,
		"error_count":       atomic.LoadInt64(&vh.cacheStats.errorCount),
		"total_requests":    atomic.LoadInt64(&vh.metrics.totalRequests),
		"avg_validation_time_ns": atomic.LoadInt64(&vh.metrics.validationTime) /
			max(atomic.LoadInt64(&vh.metrics.totalRequests), 1),
	}
}

// RegisterValidation 注册自定义验证规则
func (vh *ValidatorHelper) RegisterValidation(tag string, fn validator.Func, callValidationEvenIfNull ...bool) error {
	return vh.validate.RegisterValidation(tag, fn, callValidationEvenIfNull...)
}

// RegisterTranslation 注册自定义翻译
func (vh *ValidatorHelper) RegisterTranslation(tag string, template string) {
	vh.errorFnCacheMu.Lock()
	defer vh.errorFnCacheMu.Unlock()

	t := template
	vh.errorFnCache[tag] = func(field, param string) string {
		if strings.Contains(t, "%s") && strings.Count(t, "%s") == 2 {
			return fmt.Sprintf(t, field, param)
		}
		return fmt.Sprintf(t, field)
	}
}

// Stop 停止后台清理任务
func (vh *ValidatorHelper) Stop() {
	close(vh.stopCleanup)
}

// Reset 重置验证器状态
func (vh *ValidatorHelper) Reset() {
	vh.ClearCache()
	atomic.StoreInt64(&vh.cacheStats.hitCount, 0)
	atomic.StoreInt64(&vh.cacheStats.missCount, 0)
	atomic.StoreInt64(&vh.cacheStats.evictCount, 0)
	atomic.StoreInt64(&vh.cacheStats.errorCount, 0)
	atomic.StoreInt64(&vh.metrics.totalRequests, 0)
	atomic.StoreInt64(&vh.metrics.validationTime, 0)
}

// ClearCache 清理所有缓存
func (vh *ValidatorHelper) ClearCache() {
	vh.pruneLock.Lock()
	defer vh.pruneLock.Unlock()

	// 安全回收所有缓存
	vh.typeCache.Range(func(key, value interface{}) bool {
		if info, ok := value.(*typeInfo); ok {
			info.mu.Lock()
			for _, fieldInfo := range info.fields {
				fieldInfoPool.Put(fieldInfo)
			}
			info.mu.Unlock()
			typeInfoPool.Put(info)
		}
		vh.typeCache.Delete(key)
		return true
	})
}

// SetLanguage 设置语言
func (vh *ValidatorHelper) SetLanguage(useChinese bool) {
	vh.config.UseChinese = useChinese

	templates := defaultErrorTemplates
	if useChinese {
		templates = ChineseErrorTemplates
	}

	vh.errorFnCacheMu.Lock()
	defer vh.errorFnCacheMu.Unlock()

	for tag, tmpl := range templates {
		t := tmpl
		vh.errorFnCache[tag] = func(field, param string) string {
			if strings.Contains(t, "%s") && strings.Count(t, "%s") == 2 {
				return fmt.Sprintf(t, field, param)
			}
			return fmt.Sprintf(t, field)
		}
	}
}

func max(a, b int64) int64 {
	if a > b {
		return a
	}
	return b
}

func GetErr(tag, field, param string) string {
	t := ChineseErrorTemplates[tag]
	if strings.Contains(t, "%s") && strings.Count(t, "%s") == 2 {
		return fmt.Sprintf(t, field, param)
	}
	return fmt.Sprintf(t, field)
}