package server

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/edgeai/gateway/internal/adapter"
	"github.com/edgeai/gateway/internal/auth"
	"github.com/edgeai/gateway/internal/config"
	"github.com/edgeai/gateway/internal/handler"
	"github.com/edgeai/gateway/internal/middleware"
	"github.com/edgeai/gateway/internal/observability"
)

// handleAdminKeys 处理 /v1/admin/keys（GET 列出所有 Key，POST 创建新 Key）。
func (s *Server) handleAdminKeys(w http.ResponseWriter, r *http.Request) {
	requestID := middleware.GetRequestID(r.Context())

	switch r.Method {
	case http.MethodGet:
		keys, err := s.auth.ListKeys()
		if err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInternalError, err.Error(), requestID))
			return
		}
		handler.WriteJSON(w, http.StatusOK, map[string]any{"keys": keys})

	case http.MethodPost:
		var req struct {
			AppID             string   `json:"app_id"`
			TenantID          string   `json:"tenant_id"`
			Name              string   `json:"name"`
			AllowedModels     []string `json:"allowed_models"`
			AllowedPriorities []int    `json:"allowed_priorities"`
			IsAdmin           bool     `json:"is_admin"`
			ExpiresAt         string   `json:"expires_at"` // RFC3339 格式，空表示永不过期
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "invalid JSON body", requestID))
			return
		}
		if req.AppID == "" {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "app_id is required", requestID))
			return
		}
		if req.Name == "" {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "name is required", requestID))
			return
		}

		apiKey := auth.GenerateAPIKey()
		identity := &auth.AppIdentity{
			AppID:             req.AppID,
			TenantID:          req.TenantID,
			Name:              req.Name,
			AllowedModels:     req.AllowedModels,
			AllowedPriorities: req.AllowedPriorities,
			IsAdmin:           req.IsAdmin,
		}
		if req.ExpiresAt != "" {
			if t, err := time.Parse(time.RFC3339, req.ExpiresAt); err == nil {
				identity.ExpiresAt = &t
			}
		}

		if err := s.auth.AddKey(apiKey, identity); err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInternalError, err.Error(), requestID))
			return
		}

		// 审计日志
		actor := ""
		if id := auth.GetAppIdentityFromRequest(r); id != nil {
			actor = id.AppID
		}
		s.audit.RecordFromRequest(r, actor, "create_key", "api_key", req.AppID, http.StatusCreated, map[string]interface{}{
			"app_id":         req.AppID,
			"name":           req.Name,
			"is_admin":       req.IsAdmin,
			"allowed_models": req.AllowedModels,
		})

		handler.WriteJSON(w, http.StatusCreated, map[string]any{
			"api_key":        apiKey,
			"app_id":         req.AppID,
			"name":           req.Name,
			"is_admin":       req.IsAdmin,
			"allowed_models": req.AllowedModels,
			"expires_at":     req.ExpiresAt,
			"message":        "请妥善保存此 API Key，之后将无法再次查看",
		})

	default:
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
	}
}

// handleAdminKeyByID 处理 /v1/admin/keys/{id}（DELETE 删除，PATCH 禁用，PUT 轮换）。
func (s *Server) handleAdminKeyByID(w http.ResponseWriter, r *http.Request) {
	requestID := middleware.GetRequestID(r.Context())
	idStr := strings.TrimPrefix(r.URL.Path, "/v1/admin/keys/")
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "invalid key id", requestID))
		return
	}

	switch r.Method {
	case http.MethodDelete:
		if err := s.auth.DeleteKey(id); err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, err.Error(), requestID))
			return
		}
		// 审计日志
		actor := ""
		if ident := auth.GetAppIdentityFromRequest(r); ident != nil {
			actor = ident.AppID
		}
		s.audit.RecordFromRequest(r, actor, "delete_key", "api_key", strconv.FormatInt(id, 10), http.StatusOK, nil)
		handler.WriteJSON(w, http.StatusOK, map[string]string{"status": "deleted"})

	case http.MethodPatch:
		if err := s.auth.DisableKey(id); err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, err.Error(), requestID))
			return
		}
		handler.WriteJSON(w, http.StatusOK, map[string]string{"status": "disabled"})

	case http.MethodPut:
		// Key 轮换：生成新 Key，禁用旧 Key
		newKey, err := s.auth.RotateKey(id)
		if err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, err.Error(), requestID))
			return
		}
		// 审计日志
		actor := ""
		if ident := auth.GetAppIdentityFromRequest(r); ident != nil {
			actor = ident.AppID
		}
		s.audit.RecordFromRequest(r, actor, "rotate_key", "api_key", strconv.FormatInt(id, 10), http.StatusOK, nil)
		handler.WriteJSON(w, http.StatusOK, map[string]any{
			"status":  "rotated",
			"api_key": newKey,
			"message": "旧 Key 已禁用，请妥善保存新 Key",
		})

	default:
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
	}
}

// handleAdminUsage 处理 /v1/admin/usage（GET 返回所有 app 的用量统计）。
func (s *Server) handleAdminUsage(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
		return
	}

	usage := s.usageTracker.GetAll()
	handler.WriteJSON(w, http.StatusOK, map[string]any{"usage": usage})
}

// handleAdminUsageByApp 处理 /v1/admin/usage/{app_id}（GET 返回指定 app 的用量统计，支持 ?history=hours 查询历史）。
func (s *Server) handleAdminUsageByApp(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
		return
	}

	appID := strings.TrimPrefix(r.URL.Path, "/v1/admin/usage/")
	if appID == "" {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "app_id is required"))
		return
	}

	// 支持 ?history=24 查询历史用量
	if historyHours := r.URL.Query().Get("history"); historyHours != "" {
		hours := 24
		fmt.Sscanf(historyHours, "%d", &hours)
		history, err := s.usageTracker.GetHistory(appID, hours)
		if err != nil {
			handler.WriteError(w, handler.NewGatewayError(handler.ErrInternalError, err.Error()))
			return
		}
		handler.WriteJSON(w, http.StatusOK, map[string]any{
			"app_id":  appID,
			"hours":   hours,
			"history": history,
		})
		return
	}

	usage := s.usageTracker.Get(appID)
	handler.WriteJSON(w, http.StatusOK, usage)
}

// handleAdminRateLimit 处理 /v1/admin/ratelimit/{app_id}（GET 查看限流，PUT 设置自定义限流）。
func (s *Server) handleAdminRateLimit(w http.ResponseWriter, r *http.Request) {
	requestID := middleware.GetRequestID(r.Context())
	appID := strings.TrimPrefix(r.URL.Path, "/v1/admin/ratelimit/")
	if appID == "" {
		handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "app_id is required", requestID))
		return
	}

	switch r.Method {
	case http.MethodGet:
		burst, ratePerMin := s.rateLimiter.GetLimit(appID)
		handler.WriteJSON(w, http.StatusOK, map[string]any{
			"app_id":          appID,
			"burst":           burst,
			"rate_per_minute": ratePerMin,
		})

	case http.MethodPut:
		var req struct {
			Burst         int `json:"burst"`
			RatePerMinute int `json:"rate_per_minute"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "invalid JSON body", requestID))
			return
		}
		if req.Burst <= 0 || req.RatePerMinute <= 0 {
			handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInvalidRequest, "burst and rate_per_minute must be positive", requestID))
			return
		}
		refillPerSec := float64(req.RatePerMinute) / 60.0
		s.rateLimiter.SetLimit(appID, float64(req.Burst), refillPerSec)
		handler.WriteJSON(w, http.StatusOK, map[string]any{
			"app_id":          appID,
			"burst":           req.Burst,
			"rate_per_minute": req.RatePerMinute,
			"status":          "updated",
		})

	default:
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
	}
}

// handleAdminCircuitBreaker 处理 /v1/admin/circuit-breaker（GET 返回熔断器状态）。
func (s *Server) handleAdminCircuitBreaker(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
		return
	}

	stats := s.breaker.Stats()
	handler.WriteJSON(w, http.StatusOK, stats)
}

// handleAdminScheduler 处理 /v1/admin/scheduler（GET 返回调度器状态）。
func (s *Server) handleAdminScheduler(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
		return
	}

	stats := map[string]any{
		"running_tasks":          s.scheduler.RunningCount(),
		"queued_tasks":           s.scheduler.QueueLength(),
		"max_running":            s.cfg.Scheduler.MaxRunningTasks,
		"max_queued":             s.cfg.Scheduler.MaxQueuedTasks,
		"priority_aging_seconds": s.cfg.Scheduler.PriorityAgingSeconds,
		"fairness":               s.cfg.Scheduler.Fairness,
	}
	handler.WriteJSON(w, http.StatusOK, stats)
}

// handleAdminConfigReload 处理 /v1/admin/config/reload（POST 触发配置热重载）。
func (s *Server) handleAdminConfigReload(w http.ResponseWriter, r *http.Request) {
	requestID := middleware.GetRequestID(r.Context())
	if r.Method != http.MethodPost {
		handler.WriteError(w, handler.NewGatewayError(handler.ErrInvalidRequest, "method not allowed"))
		return
	}

	// 重新加载配置文件
	cfgPath := config.ConfigPath()
	newCfg, err := config.Load(cfgPath)
	if err != nil {
		handler.WriteError(w, handler.NewGatewayErrorWithID(handler.ErrInternalError, fmt.Sprintf("reload config failed: %v", err), requestID))
		return
	}

	// 热更新模型映射
	s.modelMap.Update(newCfg)

	// 注册新增 adapter（已有 adapter 不重复注册）
	for _, mc := range newCfg.Models {
		provider := mc.Provider
		endpoint := mc.Endpoint
		switch provider {
		case "ollama":
			s.registry.RegisterIfAbsent(provider, func() adapter.ModelAdapter {
				return adapter.NewOllamaAdapter(endpoint)
			})
		case "vllm":
			s.registry.RegisterIfAbsent(provider, func() adapter.ModelAdapter {
				return adapter.NewVLLMAdapter(endpoint)
			})
		}
	}

	// 更新 Server 持有的配置引用
	s.cfg = newCfg

	s.logger.Info("config hot-reloaded",
		observability.F().
			Event("config_reload").
			Set("config_path", cfgPath))

	// 审计日志
	actor := ""
	if ident := auth.GetAppIdentityFromRequest(r); ident != nil {
		actor = ident.AppID
	}
	s.audit.RecordFromRequest(r, actor, "config_reload", "config", cfgPath, http.StatusOK, map[string]interface{}{
		"models": len(newCfg.Models),
	})

	handler.WriteJSON(w, http.StatusOK, map[string]any{
		"status":  "reloaded",
		"models":  len(newCfg.Models),
		"message": "配置已热重载，模型映射已更新",
	})
}