package main

import (
	"context"
	"errors"
	"log"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"ddc/internal/auth"
	"ddc/internal/config"
	"ddc/internal/jobs"
	"ddc/internal/preferences"
	"ddc/internal/server"
)

const settingsFileName = ".settings.json"

func main() {
	settings, err := config.Load()
	if err != nil {
		log.Fatalf("configuration error: %v", err)
	}

	if err := os.MkdirAll(settings.DownloadDir, 0o755); err != nil {
		log.Fatalf("download directory error: %v", err)
	}
	resolvedDownloadDir, err := filepath.EvalSymlinks(settings.DownloadDir)
	if err != nil {
		log.Fatalf("download directory error: %v", err)
	}
	settings.DownloadDir = resolvedDownloadDir
	if err := ensureWritable(settings.DownloadDir); err != nil {
		log.Fatalf("download directory %s is not writable by uid %d gid %d: %v", settings.DownloadDir, os.Getuid(), os.Getgid(), err)
	}

	store, err := preferences.Open(filepath.Join(settings.DownloadDir, settingsFileName), settings.Defaults)
	if err != nil {
		log.Fatalf("settings error: %v", err)
	}

	manager := jobs.NewManager(settings, store)
	if err := manager.RestoreExisting(); err != nil {
		log.Printf("could not restore existing downloads: %v", err)
	}

	sessions := auth.NewSessionStore(settings.SessionTTL)
	httpServer := &http.Server{
		Addr:              settings.ListenAddr,
		Handler:           server.New(settings, sessions, manager),
		ReadHeaderTimeout: 10 * time.Second,
		ReadTimeout:       30 * time.Second,
		WriteTimeout:      60 * time.Second,
		IdleTimeout:       120 * time.Second,
	}

	shutdownSignal, stopListening := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stopListening()

	go func() {
		log.Printf("listening on %s", settings.ListenAddr)
		if err := httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			log.Fatalf("server error: %v", err)
		}
	}()

	<-shutdownSignal.Done()
	log.Printf("shutting down")
	manager.CancelAll()

	shutdownContext, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := httpServer.Shutdown(shutdownContext); err != nil {
		log.Printf("shutdown error: %v", err)
	}
}

func ensureWritable(directory string) error {
	probe, err := os.CreateTemp(directory, ".write-test-*")
	if err != nil {
		return err
	}
	probe.Close()
	return os.Remove(probe.Name())
}