package health

import (
	"context"
	"fmt"
	"sync"
	"time"

	"tyapi-server/internal/shared/interfaces"

	"go.uber.org/zap"
)

// HealthChecker 健康检查器实现
type HealthChecker struct {
	services map[string]interfaces.Service
	cache    map[string]*interfaces.HealthStatus
	cacheTTL time.Duration
	mutex    sync.RWMutex
	logger   *zap.Logger
}

// NewHealthChecker 创建健康检查器
func NewHealthChecker(logger *zap.Logger) *HealthChecker {
	return &HealthChecker{
		services: make(map[string]interfaces.Service),
		cache:    make(map[string]*interfaces.HealthStatus),
		cacheTTL: 30 * time.Second, // 缓存30秒
		logger:   logger,
	}
}

// RegisterService 注册服务
func (h *HealthChecker) RegisterService(service interfaces.Service) {
	h.mutex.Lock()
	defer h.mutex.Unlock()

	h.services[service.Name()] = service
	h.logger.Info("服务已注册健康检查", zap.String("service", service.Name()))
}

// CheckHealth 检查单个服务健康状态
func (h *HealthChecker) CheckHealth(ctx context.Context, serviceName string) *interfaces.HealthStatus {
	h.mutex.RLock()
	service, exists := h.services[serviceName]
	if !exists {
		h.mutex.RUnlock()
		return &interfaces.HealthStatus{
			Status:       "DOWN",
			Message:      "服务未找到",
			Details:      map[string]interface{}{"error": "服务未注册"},
			CheckedAt:    time.Now().Unix(),
			ResponseTime: 0,
		}
	}

	// 检查缓存
	if cached, exists := h.cache[serviceName]; exists {
		if time.Since(time.Unix(cached.CheckedAt, 0)) < h.cacheTTL {
			h.mutex.RUnlock()
			return cached
		}
	}
	h.mutex.RUnlock()

	// 执行健康检查
	start := time.Now()
	status := &interfaces.HealthStatus{
		CheckedAt: start.Unix(),
	}

	// 设置超时上下文
	checkCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
	defer cancel()

	err := service.HealthCheck(checkCtx)
	responseTime := time.Since(start).Milliseconds()
	status.ResponseTime = responseTime

	if err != nil {
		status.Status = "DOWN"
		status.Message = "健康检查失败"
		status.Details = map[string]interface{}{
			"error":        err.Error(),
			"service_name": serviceName,
			"check_time":   start.Format(time.RFC3339),
		}
		h.logger.Warn("服务健康检查失败",
			zap.String("service", serviceName),
			zap.Error(err),
			zap.Int64("response_time_ms", responseTime))
	} else {
		status.Status = "UP"
		status.Message = "服务运行正常"
		status.Details = map[string]interface{}{
			"service_name": serviceName,
			"check_time":   start.Format(time.RFC3339),
		}
		h.logger.Debug("服务健康检查通过",
			zap.String("service", serviceName),
			zap.Int64("response_time_ms", responseTime))
	}

	// 更新缓存
	h.mutex.Lock()
	h.cache[serviceName] = status
	h.mutex.Unlock()

	return status
}

// CheckAllHealth 检查所有服务的健康状态
func (h *HealthChecker) CheckAllHealth(ctx context.Context) map[string]*interfaces.HealthStatus {
	h.mutex.RLock()
	serviceNames := make([]string, 0, len(h.services))
	for name := range h.services {
		serviceNames = append(serviceNames, name)
	}
	h.mutex.RUnlock()

	results := make(map[string]*interfaces.HealthStatus)
	var wg sync.WaitGroup
	var mutex sync.Mutex

	// 并发检查所有服务
	for _, serviceName := range serviceNames {
		wg.Add(1)
		go func(name string) {
			defer wg.Done()
			status := h.CheckHealth(ctx, name)

			mutex.Lock()
			results[name] = status
			mutex.Unlock()
		}(serviceName)
	}

	wg.Wait()
	return results
}

// GetOverallStatus 获取整体健康状态
func (h *HealthChecker) GetOverallStatus(ctx context.Context) *interfaces.HealthStatus {
	allStatus := h.CheckAllHealth(ctx)

	overall := &interfaces.HealthStatus{
		CheckedAt:    time.Now().Unix(),
		ResponseTime: 0,
		Details:      make(map[string]interface{}),
	}

	var totalResponseTime int64
	healthyCount := 0
	totalCount := len(allStatus)

	for serviceName, status := range allStatus {
		overall.Details[serviceName] = map[string]interface{}{
			"status":        status.Status,
			"message":       status.Message,
			"response_time": status.ResponseTime,
		}

		totalResponseTime += status.ResponseTime
		if status.Status == "UP" {
			healthyCount++
		}
	}

	if totalCount > 0 {
		overall.ResponseTime = totalResponseTime / int64(totalCount)
	}

	// 确定整体状态
	if healthyCount == totalCount {
		overall.Status = "UP"
		overall.Message = "所有服务运行正常"
	} else if healthyCount == 0 {
		overall.Status = "DOWN"
		overall.Message = "所有服务均已下线"
	} else {
		overall.Status = "DEGRADED"
		overall.Message = fmt.Sprintf("%d/%d 个服务运行正常", healthyCount, totalCount)
	}

	return overall
}

// GetServiceNames 获取所有注册的服务名称
func (h *HealthChecker) GetServiceNames() []string {
	h.mutex.RLock()
	defer h.mutex.RUnlock()

	names := make([]string, 0, len(h.services))
	for name := range h.services {
		names = append(names, name)
	}
	return names
}

// RemoveService 移除服务
func (h *HealthChecker) RemoveService(serviceName string) {
	h.mutex.Lock()
	defer h.mutex.Unlock()

	delete(h.services, serviceName)
	delete(h.cache, serviceName)

	h.logger.Info("服务已从健康检查中移除", zap.String("service", serviceName))
}

// ClearCache 清除缓存
func (h *HealthChecker) ClearCache() {
	h.mutex.Lock()
	defer h.mutex.Unlock()

	h.cache = make(map[string]*interfaces.HealthStatus)
	h.logger.Debug("健康检查缓存已清除")
}

// GetCacheStats 获取缓存统计
func (h *HealthChecker) GetCacheStats() map[string]interface{} {
	h.mutex.RLock()
	defer h.mutex.RUnlock()

	stats := map[string]interface{}{
		"total_services":    len(h.services),
		"cached_results":    len(h.cache),
		"cache_ttl_seconds": h.cacheTTL.Seconds(),
	}

	// 计算缓存命中率
	if len(h.services) > 0 {
		hitRate := float64(len(h.cache)) / float64(len(h.services)) * 100
		stats["cache_hit_rate"] = fmt.Sprintf("%.2f%%", hitRate)
	}

	return stats
}

// SetCacheTTL 设置缓存TTL
func (h *HealthChecker) SetCacheTTL(ttl time.Duration) {
	h.mutex.Lock()
	defer h.mutex.Unlock()

	h.cacheTTL = ttl
	h.logger.Info("健康检查缓存TTL已更新", zap.Duration("ttl", ttl))
}

// StartPeriodicCheck 启动定期健康检查
func (h *HealthChecker) StartPeriodicCheck(ctx context.Context, interval time.Duration) {
	ticker := time.NewTicker(interval)
	defer ticker.Stop()

	h.logger.Info("已启动定期健康检查", zap.Duration("interval", interval))

	for {
		select {
		case <-ctx.Done():
			h.logger.Info("已停止定期健康检查")
			return
		case <-ticker.C:
			h.performPeriodicCheck(ctx)
		}
	}
}

// performPeriodicCheck 执行定期检查
func (h *HealthChecker) performPeriodicCheck(ctx context.Context) {
	overall := h.GetOverallStatus(ctx)

	h.logger.Info("定期健康检查已完成",
		zap.String("overall_status", overall.Status),
		zap.String("message", overall.Message),
		zap.Int64("response_time_ms", overall.ResponseTime))

	// 如果有服务下线，记录警告
	if overall.Status != "UP" {
		h.logger.Warn("部分服务不健康",
			zap.String("status", overall.Status),
			zap.Any("details", overall.Details))
	}
}