package main

import (
	"context"
	"embed"
	"encoding/json"
	"flag"
	"fmt"
	"github.com/jhalter/mobius/hotline"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
)

//go:embed mobius/config
var cfgTemplate embed.FS

const (
	defaultPort = 5500
)

func main() {
	ctx, cancel := context.WithCancel(context.Background())

	// TODO: implement graceful shutdown by closing context
	// c := make(chan os.Signal, 1)
	// signal.Notify(c, os.Interrupt)
	// defer func() {
	// 	signal.Stop(c)
	// 	cancel()
	// }()
	// go func() {
	// 	select {
	// 	case <-c:
	// 		cancel()
	// 	case <-ctx.Done():
	// 	}
	// }()

	netInterface := flag.String("interface", "", "IP addr of interface to listen on.  Defaults to all interfaces.")
	basePort := flag.Int("bind", defaultPort, "Base Hotline server port.  File transfer port is base port + 1.")
	statsPort := flag.String("stats-port", "", "Enable stats HTTP endpoint on address and port")
	configDir := flag.String("config", defaultConfigPath(), "Path to config root")
	version := flag.Bool("version", false, "print version and exit")
	logLevel := flag.String("log-level", "info", "Log level")
	logFile := flag.String("log-file", "", "Path to log file")

	init := flag.Bool("init", false, "Populate the config dir with default configuration")

	flag.Parse()

	if *version {
		fmt.Printf("v%s\n", hotline.VERSION)
		os.Exit(0)
	}

	zapLvl, ok := zapLogLevel[*logLevel]
	if !ok {
		fmt.Printf("Invalid log level %s.  Must be debug, info, warn, or error.\n", *logLevel)
		os.Exit(0)
	}

	cores := []zapcore.Core{
		newStdoutCore(zapLvl),
	}

	if *logFile != "" {
		cores = append(cores, newLogFileCore(*logFile, zapLvl))
	}

	l := zap.New(zapcore.NewTee(cores...))
	defer func() { _ = l.Sync() }()
	logger := l.Sugar()

	if *init {
		if _, err := os.Stat(filepath.Join(*configDir, "/config.yaml")); os.IsNotExist(err) {
			if err := os.MkdirAll(*configDir, 0750); err != nil {
				logger.Fatal(err)
			}

			if err := copyDir("mobius/config", *configDir); err != nil {
				logger.Fatal(err)
			}
			logger.Infow("Config dir initialized at " + *configDir)
		} else {
			logger.Infow("Existing config dir found.  Skipping initialization.")
		}
	}

	if _, err := os.Stat(*configDir); os.IsNotExist(err) {
		logger.Fatalw("Configuration directory not found.  Correct the path or re-run with -init to generate initial config.", "path", configDir)
	}

	srv, err := hotline.NewServer(*configDir, *netInterface, *basePort, logger, &hotline.OSFileStore{})
	if err != nil {
		logger.Fatal(err)
	}

	sh := statHandler{hlServer: srv}
	if *statsPort != "" {
		http.HandleFunc("/", sh.RenderStats)

		go func(srv *hotline.Server) {
			// Use the default DefaultServeMux.
			err = http.ListenAndServe(":"+*statsPort, nil)
			if err != nil {
				log.Fatal(err)
			}
		}(srv)
	}

	// Serve Hotline requests until program exit
	logger.Fatal(srv.ListenAndServe(ctx, cancel))
}

type statHandler struct {
	hlServer *hotline.Server
}

func (sh *statHandler) RenderStats(w http.ResponseWriter, _ *http.Request) {
	u, err := json.Marshal(sh.hlServer.CurrentStats())
	if err != nil {
		panic(err)
	}

	_, _ = io.WriteString(w, string(u))
}

func newStdoutCore(level zapcore.Level) zapcore.Core {
	encoderCfg := zap.NewProductionEncoderConfig()
	encoderCfg.TimeKey = "timestamp"
	encoderCfg.EncodeTime = zapcore.ISO8601TimeEncoder

	return zapcore.NewCore(
		zapcore.NewConsoleEncoder(encoderCfg),
		zapcore.Lock(os.Stdout),
		level,
	)
}

func newLogFileCore(path string, level zapcore.Level) zapcore.Core {
	encoderCfg := zap.NewProductionEncoderConfig()
	encoderCfg.TimeKey = "timestamp"
	encoderCfg.EncodeTime = zapcore.ISO8601TimeEncoder
	writer := zapcore.AddSync(&lumberjack.Logger{
		Filename:   path,
		MaxSize:    100, // MB
		MaxBackups: 3,
		MaxAge:     365, // days
	})

	return zapcore.NewCore(
		zapcore.NewConsoleEncoder(encoderCfg),
		writer,
		level,
	)
}

var zapLogLevel = map[string]zapcore.Level{
	"debug": zap.DebugLevel,
	"info":  zap.InfoLevel,
	"warn":  zap.WarnLevel,
	"error": zap.ErrorLevel,
}

func defaultConfigPath() (cfgPath string) {
	switch runtime.GOOS {
	case "windows":
		cfgPath = "config/"
	case "darwin":
		if _, err := os.Stat("/usr/local/var/mobius/config/"); err == nil {
			cfgPath = "/usr/local/var/mobius/config/"
		} else if _, err := os.Stat("/opt/homebrew/var/mobius/config"); err == nil {
			cfgPath = "/opt/homebrew/var/mobius/config/"
		}
	case "linux":
		cfgPath = "/usr/local/var/mobius/config/"
	default:
		fmt.Printf("unsupported OS")
	}

	return cfgPath
}

// TODO: Simplify this mess.  Why is it so difficult to recursively copy a directory?
func copyDir(src, dst string) error {
	entries, err := cfgTemplate.ReadDir(src)
	if err != nil {
		return err
	}
	for _, dirEntry := range entries {
		if dirEntry.IsDir() {
			if err := os.MkdirAll(filepath.Join(dst, dirEntry.Name()), 0777); err != nil {
				panic(err)
			}
			subdirEntries, _ := cfgTemplate.ReadDir(filepath.Join(src, dirEntry.Name()))
			for _, subDirEntry := range subdirEntries {
				f, err := os.Create(filepath.Join(dst, dirEntry.Name(), subDirEntry.Name()))
				if err != nil {
					return err
				}

				srcFile, err := cfgTemplate.Open(filepath.Join(src, dirEntry.Name(), subDirEntry.Name()))
				if err != nil {
					return err
				}
				_, err = io.Copy(f, srcFile)
				if err != nil {
					return err
				}
				f.Close()
			}
		} else {
			f, err := os.Create(filepath.Join(dst, dirEntry.Name()))
			if err != nil {
				return err
			}

			srcFile, err := cfgTemplate.Open(filepath.Join(src, dirEntry.Name()))
			if err != nil {
				return err
			}
			_, err = io.Copy(f, srcFile)
			if err != nil {
				return err
			}
			f.Close()
		}
	}

	return nil
}