// Command gitcat 是面向小型工作室的自建 Git 服务。
//
//	gitcat -addr :12747 -data ./data
//
// 首次启动后访问 http://<主机>:12747 会进入安装向导，设置站点名称与管理员账号。
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"gitcat/internal/server"
	"gitcat/internal/store"
)

// version 可在构建时通过 -ldflags "-X main.version=..." 注入。
var version = "1.0.0"

func main() {
	log.SetFlags(log.LstdFlags)
	log.SetPrefix("[gitcat] ")

	addr := flag.String("addr", envOr("GITCAT_ADDR", ":12747"), "HTTP 监听地址")
	dataDir := flag.String("data", envOr("GITCAT_DATA", "./data"), "数据目录（SQLite 数据库、仓库与头像）")
	showVersion := flag.Bool("version", false, "打印版本号后退出")
	flag.Parse()

	if *showVersion {
		fmt.Println("gitcat", version)
		return
	}

	if err := run(*addr, *dataDir); err != nil {
		log.Fatalf("启动失败: %v", err)
	}
}

func run(addr, dataDir string) error {
	if _, err := exec.LookPath("git"); err != nil {
		return errors.New("未找到 git 命令，请先安装 git 并确保在 PATH 中")
	}
	abs, err := filepath.Abs(dataDir)
	if err != nil {
		return err
	}
	if err := os.MkdirAll(abs, 0o755); err != nil {
		return fmt.Errorf("创建数据目录: %w", err)
	}

	st, err := store.Open(filepath.Join(abs, "gitcat.db"))
	if err != nil {
		return fmt.Errorf("打开数据库: %w", err)
	}
	defer st.Close()

	srv, err := server.New(server.Config{Addr: addr, DataDir: abs, Version: version}, st)
	if err != nil {
		return err
	}

	httpSrv := &http.Server{
		Addr:              addr,
		Handler:           srv.Handler(),
		ReadHeaderTimeout: 20 * time.Second,
		IdleTimeout:       90 * time.Second,
	}

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	// 定时清理过期会话。
	go func() {
		t := time.NewTicker(time.Hour)
		defer t.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-t.C:
				if err := st.CleanupSessions(); err != nil {
					log.Printf("清理过期会话失败: %v", err)
				}
			}
		}
	}()

	errCh := make(chan error, 1)
	go func() {
		log.Printf("gitcat %s 已启动", version)
		log.Printf("监听地址: %s", displayAddr(addr))
		log.Printf("数据目录: %s", abs)
		if !st.Installed() {
			log.Printf("尚未安装，请打开 %s 完成初始化", displayAddr(addr))
		}
		if err := httpSrv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			errCh <- err
		}
	}()

	select {
	case err := <-errCh:
		return err
	case <-ctx.Done():
		log.Println("收到退出信号，正在关闭…")
		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		return httpSrv.Shutdown(shutdownCtx)
	}
}

func displayAddr(addr string) string {
	if strings.HasPrefix(addr, ":") {
		return "http://localhost" + addr
	}
	return "http://" + addr
}

func envOr(key, def string) string {
	if v := strings.TrimSpace(os.Getenv(key)); v != "" {
		return v
	}
	return def
}