package server

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"

	"ops-mcp/internal/tool"

	"github.com/mark3labs/mcp-go/server"
)

const version = "0.1.0"

// Run 启动 MCP Server，处理信号优雅关闭。
func Run(cfg *Config, tools ...tool.Tool) error {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// 监听终止信号
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		sig := <-sigCh
		slog.Info("received signal, shutting down", "signal", sig)
		cancel()
	}()

	// 创建注册中心
	registry := NewRegistry()
	for _, t := range tools {
		if err := registry.Register(t); err != nil {
			return fmt.Errorf("register: %w", err)
		}
	}

	// 系统工具总是最后注册，确保它能看到所有工具
	sysTool := tool.NewSystemTool(version, registry)
	if err := registry.Register(sysTool); err != nil {
		return fmt.Errorf("register system tool: %w", err)
	}

	// 初始化所有工具
	if err := registry.InitializeAll(ctx); err != nil {
		return fmt.Errorf("initialize: %w", err)
	}
	defer func() {
		for _, err := range registry.ShutdownAll(ctx) {
			slog.Error("shutdown error", "err", err)
		}
	}()

	// 创建 MCP Server
	mcpServer := server.NewMCPServer(
		"ops-mcp",
		version,
		server.WithLogging(),
	)

	// 注册所有工具处理器
	if err := registry.RegisterAll(mcpServer); err != nil {
		return fmt.Errorf("register all: %w", err)
	}

	// 选择传输模式
	switch cfg.Server.Transport {
	case "stdio":
		return runStdio(ctx, mcpServer)
	case "sse":
		return runSSE(ctx, mcpServer, cfg)
	default:
		return fmt.Errorf("unknown transport: %s (expect stdio or sse)", cfg.Server.Transport)
	}
}

func runStdio(ctx context.Context, mcpServer *server.MCPServer) error {
	slog.Info("starting MCP server", "transport", "stdio")
	go func() {
		<-ctx.Done()
		slog.Info("shutting down stdio server")
	}()
	return server.ServeStdio(mcpServer)
}

func runSSE(ctx context.Context, mcpServer *server.MCPServer, cfg *Config) error {
	sseServer := server.NewSSEServer(mcpServer)

	addr := cfg.Server.Addr
	if addr == "" {
		addr = ":8080"
	}

	slog.Info("starting MCP server", "transport", "sse", "addr", addr)

	httpServer := &http.Server{Addr: addr, Handler: sseServer}

	go func() {
		<-ctx.Done()
		slog.Info("shutting down HTTP server")
		httpServer.Shutdown(context.Background())
	}()

	if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
		return err
	}
	return nil
}