package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"runtime"
	"syscall"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/pressly/goose/v3"
	"go.uber.org/zap"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
	"gorm.io/gorm/logger"

	"nex/backend/internal/config"
	"nex/backend/internal/handler"
	"nex/backend/internal/handler/middleware"
	"nex/backend/internal/provider"
	"nex/backend/internal/repository"
	"nex/backend/internal/service"
	pkgLogger "nex/backend/pkg/logger"
)

func main() {
	// 1. 加载配置
	cfg, err := config.LoadConfig()
	if err != nil {
		log.Fatalf("加载配置失败: %v", err)
	}
	if err := cfg.Validate(); err != nil {
		log.Fatalf("配置验证失败: %v", err)
	}

	// 2. 初始化日志
	zapLogger, err := pkgLogger.New(pkgLogger.Config{
		Level:      cfg.Log.Level,
		Path:       cfg.Log.Path,
		MaxSize:    cfg.Log.MaxSize,
		MaxBackups: cfg.Log.MaxBackups,
		MaxAge:     cfg.Log.MaxAge,
		Compress:   cfg.Log.Compress,
	})
	if err != nil {
		log.Fatalf("初始化日志失败: %v", err)
	}
	defer zapLogger.Sync()

	// 3. 初始化数据库
	db, err := initDatabase(cfg)
	if err != nil {
		zapLogger.Fatal("初始化数据库失败", zap.String("error", err.Error()))
	}
	defer closeDB(db)

	// 4. 初始化 repository 层
	providerRepo := repository.NewProviderRepository(db)
	modelRepo := repository.NewModelRepository(db)
	statsRepo := repository.NewStatsRepository(db)

	// 5. 初始化 service 层
	providerService := service.NewProviderService(providerRepo)
	modelService := service.NewModelService(modelRepo, providerRepo)
	routingService := service.NewRoutingService(modelRepo, providerRepo)
	statsService := service.NewStatsService(statsRepo)

	// 6. 初始化 provider client
	providerClient := provider.NewClient()

	// 7. 初始化 handler 层
	openaiHandler := handler.NewOpenAIHandler(providerClient, routingService, statsService)
	anthropicHandler := handler.NewAnthropicHandler(providerClient, routingService, statsService)
	providerHandler := handler.NewProviderHandler(providerService)
	modelHandler := handler.NewModelHandler(modelService)
	statsHandler := handler.NewStatsHandler(statsService)

	// 8. 创建 Gin 引擎
	gin.SetMode(gin.ReleaseMode)
	r := gin.New()

	// 注册中间件（按正确顺序）
	r.Use(middleware.RequestID())
	r.Use(middleware.Recovery(zapLogger))
	r.Use(middleware.Logging(zapLogger))
	r.Use(middleware.CORS())

	// 注册路由
	setupRoutes(r, openaiHandler, anthropicHandler, providerHandler, modelHandler, statsHandler)

	// 9. 启动服务器
	srv := &http.Server{
		Addr:         formatAddr(cfg.Server.Port),
		Handler:      r,
		ReadTimeout:  cfg.Server.ReadTimeout,
		WriteTimeout: cfg.Server.WriteTimeout,
	}

	go func() {
		zapLogger.Info("AI Gateway 启动", zap.String("addr", srv.Addr))
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			zapLogger.Fatal("服务器启动失败", zap.String("error", err.Error()))
		}
	}()

	// 等待中断信号
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
	<-quit

	zapLogger.Info("正在关闭服务器...")

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		zapLogger.Fatal("服务器强制关闭", zap.String("error", err.Error()))
	}

	zapLogger.Info("服务器已关闭")
}

func initDatabase(cfg *config.Config) (*gorm.DB, error) {
	db, err := gorm.Open(sqlite.Open(cfg.Database.Path), &gorm.Config{
		Logger: logger.Default.LogMode(logger.Info),
	})
	if err != nil {
		return nil, err
	}

	if err := db.Exec("PRAGMA journal_mode=WAL").Error; err != nil {
		log.Printf("警告: 启用 WAL 模式失败: %v", err)
	}

	// 运行数据库迁移
	if err := runMigrations(db); err != nil {
		return nil, fmt.Errorf("数据库迁移失败: %w", err)
	}

	// 配置连接池
	sqlDB, err := db.DB()
	if err != nil {
		return nil, err
	}
	sqlDB.SetMaxIdleConns(cfg.Database.MaxIdleConns)
	sqlDB.SetMaxOpenConns(cfg.Database.MaxOpenConns)
	sqlDB.SetConnMaxLifetime(cfg.Database.ConnMaxLifetime)

	// 记录连接池状态
	log.Printf("数据库连接池配置: MaxIdle=%d, MaxOpen=%d, MaxLifetime=%v",
		cfg.Database.MaxIdleConns, cfg.Database.MaxOpenConns, cfg.Database.ConnMaxLifetime)

	return db, nil
}

// runMigrations 使用 goose 执行数据库迁移
func runMigrations(db *gorm.DB) error {
	sqlDB, err := db.DB()
	if err != nil {
		return err
	}

	migrationsDir := getMigrationsDir()
	if _, err := os.Stat(migrationsDir); os.IsNotExist(err) {
		return fmt.Errorf("迁移目录不存在: %s", migrationsDir)
	}

	goose.SetDialect("sqlite3")
	if err := goose.Up(sqlDB, migrationsDir); err != nil {
		return err
	}

	return nil
}

// getMigrationsDir 获取迁移文件目录路径
func getMigrationsDir() string {
	// 从可执行文件位置推断迁移目录
	_, filename, _, ok := runtime.Caller(0)
	if ok {
		// cmd/server/main.go → backend/ → backend/migrations/
		dir := filepath.Join(filepath.Dir(filename), "..", "..", "migrations")
		if abs, err := filepath.Abs(dir); err == nil {
			return abs
		}
	}
	// 回退到相对路径
	return "./migrations"
}

func closeDB(db *gorm.DB) {
	sqlDB, err := db.DB()
	if err != nil {
		return
	}
	sqlDB.Close()
}

func formatAddr(port int) string {
	return fmt.Sprintf(":%d", port)
}

func setupRoutes(r *gin.Engine, openaiHandler *handler.OpenAIHandler, anthropicHandler *handler.AnthropicHandler, providerHandler *handler.ProviderHandler, modelHandler *handler.ModelHandler, statsHandler *handler.StatsHandler) {
	// OpenAI 协议代理
	r.POST("/v1/chat/completions", openaiHandler.HandleChatCompletions)

	// Anthropic 协议代理
	r.POST("/v1/messages", anthropicHandler.HandleMessages)

	// 供应商管理 API
	providers := r.Group("/api/providers")
	{
		providers.GET("", providerHandler.ListProviders)
		providers.POST("", providerHandler.CreateProvider)
		providers.GET("/:id", providerHandler.GetProvider)
		providers.PUT("/:id", providerHandler.UpdateProvider)
		providers.DELETE("/:id", providerHandler.DeleteProvider)
	}

	// 模型管理 API
	models := r.Group("/api/models")
	{
		models.GET("", modelHandler.ListModels)
		models.POST("", modelHandler.CreateModel)
		models.GET("/:id", modelHandler.GetModel)
		models.PUT("/:id", modelHandler.UpdateModel)
		models.DELETE("/:id", modelHandler.DeleteModel)
	}

	// 统计查询 API
	stats := r.Group("/api/stats")
	{
		stats.GET("", statsHandler.GetStats)
		stats.GET("/aggregate", statsHandler.AggregateStats)
	}

	// 健康检查
	r.GET("/health", func(c *gin.Context) {
		c.JSON(200, gin.H{"status": "ok"})
	})
}