package main

import (
	"context"
	"flag"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"jukebox_maker/internal/api"
	"jukebox_maker/internal/config"
	"jukebox_maker/internal/copier"
	"jukebox_maker/internal/db"
	"jukebox_maker/internal/disk"
	"jukebox_maker/internal/task"
	"jukebox_maker/internal/watcher"
)

func main() {
	configPath := flag.String("config", "/config/config.json", "path to config file")
	addr := flag.String("addr", ":8080", "HTTP listen address")
	mediaPath := flag.String("media", "/media", "path to media source directory")
	mountPath := flag.String("mount", "/mnt/usb", "path to USB mount point")
	flag.Parse()

	cfg, err := config.Load(*configPath)
	if err != nil {
		log.Fatalf("load config: %v", err)
	}

	taskStore := task.NewStore()
	cp := copier.New(taskStore)

	activeDBs := make(map[string]*db.DB)
	mountToDiskID := make(map[string]string)

	openDiskDB := func(info disk.DiskInfo) {
		if info.DiskID == "" {
			return
		}

		if prevDiskID, ok := mountToDiskID[info.MountPath]; ok && prevDiskID != info.DiskID {
			if prevDB := activeDBs[prevDiskID]; prevDB != nil {
				prevDB.Close()
				delete(activeDBs, prevDiskID)
				cp.SetDB(prevDiskID, nil)
			}
		}
		mountToDiskID[info.MountPath] = info.DiskID

		if _, ok := activeDBs[info.DiskID]; ok {
			return
		}

		d, err := db.Open(disk.DBPath(info.MountPath))
		if err != nil {
			log.Printf("open disk DB: %v", err)
			return
		}
		activeDBs[info.DiskID] = d
		cp.SetDB(info.DiskID, d)
		log.Printf("disk DB opened for %s", info.DiskID)
	}

	closeDiskDB := func(info disk.DiskInfo) {
		diskID := info.DiskID
		if diskID == "" {
			diskID = mountToDiskID[info.MountPath]
		}
		if diskID == "" {
			return
		}

		cp.Cancel(diskID)
		cp.SetDB(diskID, nil)

		if d := activeDBs[diskID]; d != nil {
			d.Close()
			delete(activeDBs, diskID)
			log.Printf("disk DB closed for %s", diskID)
		}
		delete(mountToDiskID, info.MountPath)
	}

	watcherReady := false
	w := watcher.New(*mountPath, 5*time.Second, func(ev watcher.DiskEvent) {
		log.Printf("disk: %s %s -> %s", ev.Info.MountPath, ev.Prev.State, ev.Info.State)
		switch ev.Info.State {
		case disk.DiskKnown:
			openDiskDB(ev.Info)
			if watcherReady && ev.Prev.State != disk.DiskKnown && cfg.AutoCopy {
				triggerAutoCopy(cp, cfg, ev.Info, *mediaPath)
			}
		case disk.DiskForeign:
			closeDiskDB(ev.Prev)
		case disk.DiskAbsent:
			closeDiskDB(ev.Prev)
		}
	})
	w.ProbeNow()
	watcherReady = true

	srv, err := api.New(api.Deps{
		Config:     cfg,
		ConfigPath: *configPath,
		Watcher:    w,
		Copier:     cp,
		Tasks:      taskStore,
		MediaPath:  *mediaPath,
		MountPath:  *mountPath,
		OnDiskInit: func(mountPath, diskID string) {
			openDiskDB(disk.DiskInfo{
				State:     disk.DiskKnown,
				DiskID:    diskID,
				MountPath: mountPath,
			})
		},
	})
	if err != nil {
		log.Fatalf("init server: %v", err)
	}

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

	go w.Run(ctx)

	httpSrv := &http.Server{Addr: *addr, Handler: srv}
	go func() {
		log.Printf("jukebox_maker listening on %s", *addr)
		if err := httpSrv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("http: %v", err)
		}
	}()

	<-ctx.Done()
	log.Println("shutting down…")
	shutCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	httpSrv.Shutdown(shutCtx)
	for _, info := range w.ListDisks() {
		closeDiskDB(info)
	}
}

func triggerAutoCopy(cp *copier.Copier, cfg *config.Config, info disk.DiskInfo, mediaPath string) {
	var sources []string
	for _, s := range cfg.Sources {
		if s.Enabled {
			sources = append(sources, s.Path)
		}
	}
	if len(sources) == 0 {
		return
	}
	go func() {
		_, err := cp.Start(context.Background(), copier.Options{
			DiskID:         info.DiskID,
			MountPath:      info.MountPath,
			MediaPath:      mediaPath,
			DestFolder:     cfg.DestFolder,
			EnabledSources: sources,
			ReserveFreeGB:  cfg.ReserveFreeGB,
			OverwriteMode:  cfg.OverwriteMode,
			FileSelectMode: cfg.FileSelectMode,
		})
		if err != nil {
			log.Printf("auto-copy: %v", err)
		}
	}()
}