// Package app wires together every subsystem (database, auth, scanner,
// cover art, web UI) into a single running VibeSonic process.
package app

import (
	"context"
	"database/sql"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"path/filepath"
	"time"

	"git.noroutes.net/NoRoutes/vibetunes/internal/auth"
	"git.noroutes.net/NoRoutes/vibetunes/internal/config"
	"git.noroutes.net/NoRoutes/vibetunes/internal/coverart"
	"git.noroutes.net/NoRoutes/vibetunes/internal/database"
	"git.noroutes.net/NoRoutes/vibetunes/internal/metadata"
	"git.noroutes.net/NoRoutes/vibetunes/internal/scanner"
	"git.noroutes.net/NoRoutes/vibetunes/internal/subsonic"
	"git.noroutes.net/NoRoutes/vibetunes/internal/web"
)

type App struct {
	Cfg      config.Config
	DB       *sql.DB
	Log      *slog.Logger
	Scanner  *scanner.Scanner
	Web      *web.Web
	Subsonic *subsonic.Server
}

// Open initializes the database and every subsystem, and imports
// VIBESONIC_MUSIC_DIRS as music folders on first run. It does not start
// any listeners or background loops.
func Open(cfg config.Config, log *slog.Logger) (*App, error) {
	if err := os.MkdirAll(cfg.DataDir, 0o700); err != nil {
		return nil, fmt.Errorf("create data dir: %w", err)
	}
	db, err := database.Open(cfg.DBPath)
	if err != nil {
		return nil, fmt.Errorf("open database: %w", err)
	}

	if err := importConfiguredMusicDirs(db, cfg.MusicDirs); err != nil {
		db.Close()
		return nil, fmt.Errorf("importing VIBESONIC_MUSIC_DIRS: %w", err)
	}

	if cfg.SessionSecret == "" {
		log.Warn("VIBESONIC_SESSION_SECRET is not set; sessions are still database-backed and safe, but set this in production for defense in depth")
	}

	prober := &metadata.Prober{FFprobePath: cfg.FFprobePath}
	sc := scanner.New(db, prober, log)

	coverCache := filepath.Join(cfg.DataDir, "cache", "covers")
	covers := coverart.New(coverCache, cfg.FFmpegPath)

	sessions := &auth.Sessions{DB: db, CookieSecure: cfg.CookieSecure}
	extauth := &auth.ExtAuth{DB: db, Config: cfg.ExtAuth}
	mw := &auth.Middleware{Sessions: sessions, ExtAuth: extauth}
	csrf := &auth.CSRF{CookieSecure: cfg.CookieSecure}

	encryptionKey, err := auth.EncryptionKey(db, cfg.SessionSecret)
	if err != nil {
		db.Close()
		return nil, fmt.Errorf("deriving auth encryption key: %w", err)
	}

	webApp := &web.Web{
		DB:            db,
		Config:        cfg,
		Sessions:      sessions,
		CSRF:          csrf,
		Middleware:    mw,
		Scanner:       sc,
		CoverArt:      covers,
		EncryptionKey: encryptionKey,
		Log:           log,
	}

	subsonicSrv := &subsonic.Server{
		DB:            db,
		Config:        cfg,
		EncryptionKey: encryptionKey,
		Scanner:       sc,
		CoverArt:      covers,
		Log:           log,
	}

	return &App{Cfg: cfg, DB: db, Log: log, Scanner: sc, Web: webApp, Subsonic: subsonicSrv}, nil
}

func (a *App) Close() error {
	return a.DB.Close()
}

// importConfiguredMusicDirs adds any VIBESONIC_MUSIC_DIRS entries not
// already present as music folders, keyed by path so restarts don't
// create duplicates.
func importConfiguredMusicDirs(db *sql.DB, dirs []string) error {
	if len(dirs) == 0 {
		return nil
	}
	existing, err := database.ListMusicFolders(db)
	if err != nil {
		return err
	}
	byPath := make(map[string]bool, len(existing))
	for _, f := range existing {
		byPath[f.Path] = true
	}
	for _, dir := range dirs {
		if byPath[dir] {
			continue
		}
		name := filepath.Base(dir)
		if _, err := database.CreateMusicFolder(db, name, dir, "music"); err != nil {
			return err
		}
	}
	return nil
}

// Run starts the HTTP server and the scheduled scanner loop, blocking
// until ctx is cancelled, then shuts down gracefully.
func (a *App) Run(ctx context.Context) error {
	go a.Scanner.RunScheduled(ctx, a.Cfg.ScanInterval)

	go func() {
		ticker := time.NewTicker(time.Hour)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				if err := database.DeleteExpiredSessions(a.DB); err != nil {
					a.Log.Warn("session cleanup failed", "err", err)
				}
			}
		}
	}()

	mux := http.NewServeMux()
	mux.Handle("/rest/", a.Subsonic.Router())
	mux.Handle("/", a.Web.NewRouter())

	srv := &http.Server{
		Addr:    a.Cfg.ListenAddr,
		Handler: mux,
	}

	errCh := make(chan error, 1)
	go func() {
		a.Log.Info("listening", "addr", a.Cfg.ListenAddr)
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			errCh <- err
		}
	}()

	select {
	case <-ctx.Done():
	case err := <-errCh:
		return err
	}

	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	return srv.Shutdown(shutdownCtx)
}