package main

import (
	"context"
	"flag"
	"log"
	"os"

	"ai-agent-scaffold-go/internal/config"
	"ai-agent-scaffold-go/internal/handler"
	"ai-agent-scaffold-go/internal/model"
	"ai-agent-scaffold-go/internal/service"

	"github.com/gin-gonic/gin"
	"github.com/joho/godotenv"
	"go.uber.org/zap"
)

func main() {
	envPath := flag.String("env", ".env", "path to dotenv file (empty to skip)")
	configPath := flag.String("config", "configs/application.yaml", "path to application.yaml")
	flag.Parse()

	// 1. 加载 .env 文件
	loadDotenv(*envPath)

	// 2. 加载应用配置
	appCfg, err := config.LoadApplication(*configPath)
	if err != nil {
		log.Fatalf("load config: %v", err)
	}

	// 3. 初始化日志
	logger, _ := zap.NewProduction()
	if appCfg.App.Env == "local" || appCfg.App.Env == "dev" {
		logger, _ = zap.NewDevelopment()
	}
	defer logger.Sync()

	// 4. 组装 Agent
	registry := model.NewInMemoryAgentRegistry()
	sessions := model.NewInMemorySessionStore()

	timeout, _ := appCfg.LLM.RequestTimeoutDuration()
	agents, err := service.LoadAndAssemble(context.Background(), appCfg.Agent.ConfigPaths, timeout)
	if err != nil {
		logger.Fatal("assemble agents failed", zap.Error(err))
	}
	for _, agent := range agents {
		if err := registry.Register(agent); err != nil {
			logger.Fatal("register agent failed", zap.Error(err))
		}
	}

	chatService := service.NewChatService(registry, sessions)

	// 5. 配置 HTTP 路由
	router := gin.Default()
	router.Use(corsMiddleware())
	router.GET("/healthz", func(c *gin.Context) {
		c.JSON(200, gin.H{"status": "ok"})
	})
	handler.RegisterRoutes(router, chatService)

	// 6. 启动服务
	addr := appCfg.Server.Addr
	logger.Info("server starting", zap.String("addr", addr), zap.Int("agents", len(agents)))
	if err := router.Run(addr); err != nil {
		logger.Fatal("server stopped", zap.Error(err))
	}
}

// corsMiddleware 跨域中间件
func corsMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		origin := c.GetHeader("Origin")
		if origin != "" {
			c.Header("Access-Control-Allow-Origin", origin)
			c.Header("Vary", "Origin")
		} else {
			c.Header("Access-Control-Allow-Origin", "*")
		}
		c.Header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		c.Header("Access-Control-Allow-Headers", "Content-Type, Authorization")
		c.Header("Access-Control-Allow-Credentials", "true")
		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(204)
			return
		}
		c.Next()
	}
}

// loadDotenv 加载 dotenv 文件，已有环境变量不会被覆盖
func loadDotenv(path string) {
	if path == "" {
		return
	}
	if _, err := os.Stat(path); os.IsNotExist(err) {
		return
	}
	pairs, err := godotenv.Read(path)
	if err != nil {
		log.Fatalf("read dotenv: %v", err)
	}
	for key, value := range pairs {
		if _, exists := os.LookupEnv(key); !exists {
			os.Setenv(key, value)
		}
	}
}