package main

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"os/exec"
	"os/signal"
	"path/filepath"
	"runtime/debug"
	"syscall"
	"time"
)

var version = "dev"

func main() {
	os.Exit(realMain())
}

func realMain() (exitCode int) {
	defer func() {
		if recovered := recover(); recovered != nil {
			fmt.Fprintf(os.Stderr, "readcard-go panic: %v\n%s\n", recovered, debug.Stack())
			exitCode = 2
		}
	}()
	if isWorker() {
		return runWorker()
	}
	return runSupervisor()
}

func isWorker() bool {
	if os.Getenv("CARD_NO_SUPERVISOR") == "1" {
		return true
	}
	for _, arg := range os.Args[1:] {
		if arg == "--worker" {
			return true
		}
	}
	return false
}

func runWorker() int {
	cfg, err := loadConfig()
	if err != nil {
		logBootstrapFailure("worker_config_failure", err)
		fmt.Fprintln(os.Stderr, err)
		return 1
	}
	logger, err := newAppLogger(cfg, "worker")
	if err != nil {
		fmt.Fprintf(os.Stderr, "初始化日志失败: %v\n", err)
		return 1
	}
	defer logger.Close()
	defer func() {
		if recovered := recover(); recovered != nil {
			logger.Error("工作进程 panic", "event", "worker_panic", "panic", fmt.Sprint(recovered), "stack", string(debug.Stack()))
			panic(recovered)
		}
	}()

	reader := newDLLReader(cfg)
	status := reader.Status()
	if status.Loaded {
		logger.Info("读卡 DLL 初始化成功", "event", "dll_loaded", "dll_dir", status.DLLDir)
	} else {
		logger.Error("读卡 DLL 初始化失败", "event", "dll_load_failure", "dll_dir", status.DLLDir, "error", status.Error)
	}

	address := net.JoinHostPort(cfg.Host, fmt.Sprint(cfg.Port))
	listener, err := net.Listen("tcp", address)
	if err != nil {
		logger.Error("HTTP 服务监听失败", "event", "listen_failure", "address", address, "error", err)
		return 1
	}
	server := &http.Server{
		Handler:           newHandler(cfg, reader, logger),
		ReadHeaderTimeout: 10 * time.Second,
		ReadTimeout:       30 * time.Second,
		WriteTimeout:      5 * time.Minute,
		IdleTimeout:       120 * time.Second,
		MaxHeaderBytes:    1 << 20,
	}
	logger.Info("读卡服务已启动", "event", "service_started", "version", version, "url", "http://"+address, "dll_dir", status.DLLDir, "arch", status.Arch)

	serveErr := make(chan error, 1)
	go func() { serveErr <- server.Serve(listener) }()
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, os.Interrupt, syscall.SIGTERM)
	defer signal.Stop(signals)

	select {
	case sig := <-signals:
		logger.Info("收到停止信号", "event", "shutdown_signal", "signal", sig.String())
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		if err = server.Shutdown(ctx); err != nil {
			logger.Error("HTTP 服务优雅停止失败", "event", "shutdown_failure", "error", err)
			return 1
		}
		logger.Info("读卡服务已停止", "event", "service_stopped")
		return 0
	case err = <-serveErr:
		if errors.Is(err, http.ErrServerClosed) {
			return 0
		}
		logger.Error("HTTP 服务异常退出", "event", "server_failure", "error", err)
		return 1
	}
}

func runSupervisor() int {
	cfg, err := loadConfig()
	if err != nil {
		logBootstrapFailure("supervisor_config_failure", err)
		fmt.Fprintln(os.Stderr, err)
		return 1
	}
	logger, err := newAppLogger(cfg, "supervisor")
	if err != nil {
		fmt.Fprintf(os.Stderr, "初始化日志失败: %v\n", err)
		return 1
	}
	defer logger.Close()

	exe, err := os.Executable()
	if err != nil {
		logger.Error("获取程序路径失败", "event", "supervisor_failure", "error", err)
		return 1
	}
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, os.Interrupt, syscall.SIGTERM)
	defer signal.Stop(signals)

	rapidRestarts := 0
	for {
		started := time.Now()
		cmd := exec.Command(exe, "--worker")
		cmd.Dir = cfg.AppRoot
		cmd.Env = append(os.Environ(), "CARD_APP_ROOT="+cfg.AppRoot)
		cmd.Stdout = os.Stdout
		crashWriter, crashErr := newDailyWriter(
			cfg.LogDir,
			"crash",
			cfg.LogRetentionDays,
			int64(cfg.LogMaxFileMB)*1024*1024,
			int64(cfg.LogMaxTotalMB)*1024*1024,
		)
		if crashErr != nil {
			logger.Error("打开崩溃日志失败", "event", "crash_log_failure", "error", crashErr)
			cmd.Stderr = os.Stderr
		} else {
			cmd.Stderr = io.MultiWriter(os.Stderr, crashWriter)
		}

		if err = cmd.Start(); err != nil {
			if crashWriter != nil {
				_ = crashWriter.Close()
			}
			logger.Error("启动工作进程失败", "event", "worker_start_failure", "error", err)
			return 1
		}
		logger.Info("工作进程已启动", "event", "worker_started", "worker_pid", cmd.Process.Pid)
		waitDone := make(chan error, 1)
		go func() { waitDone <- cmd.Wait() }()

		select {
		case sig := <-signals:
			logger.Info("守护进程收到停止信号", "event", "supervisor_shutdown", "signal", sig.String(), "worker_pid", cmd.Process.Pid)
			_ = cmd.Process.Signal(os.Interrupt)
			select {
			case <-waitDone:
			case <-time.After(10 * time.Second):
				logger.Error("工作进程停止超时，强制结束", "event", "worker_kill", "worker_pid", cmd.Process.Pid)
				_ = cmd.Process.Kill()
				<-waitDone
			}
			if crashWriter != nil {
				_ = crashWriter.Close()
			}
			return 0
		case waitErr := <-waitDone:
			if crashWriter != nil {
				_ = crashWriter.Close()
			}
			runFor := time.Since(started)
			exitCode := 0
			if cmd.ProcessState != nil {
				exitCode = cmd.ProcessState.ExitCode()
			}
			logger.Error("工作进程异常退出", "event", "worker_crash", "worker_pid", cmd.Process.Pid, "exit_code", exitCode, "runtime_ms", runFor.Milliseconds(), "error", waitErr)
			if runFor < 30*time.Second {
				rapidRestarts++
			} else {
				rapidRestarts = 0
			}
			if rapidRestarts >= cfg.MaxRapidRestarts {
				logger.Error("工作进程短时间内连续崩溃，停止自动重启", "event", "restart_limit", "rapid_restarts", rapidRestarts)
				return 1
			}
			logger.Warn("即将自动重启工作进程", "event", "worker_restart", "delay_ms", cfg.RestartDelayMS, "rapid_restarts", rapidRestarts)
			select {
			case sig := <-signals:
				logger.Info("重启等待期间收到停止信号", "event", "supervisor_shutdown", "signal", sig.String())
				return 0
			case <-time.After(time.Duration(cfg.RestartDelayMS) * time.Millisecond):
			}
		}
	}
}

func logBootstrapFailure(event string, failure error) {
	root, err := resolveAppRoot()
	if err != nil {
		return
	}
	cfg := defaultConfig(root)
	cfg.LogDir = filepath.Join(root, cfg.LogDir)
	logger, err := newAppLogger(cfg, "bootstrap")
	if err != nil {
		return
	}
	logger.Error("程序启动失败", "event", event, "error", failure)
	_ = logger.Close()
}