package main

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

	"estus-shots/internal/server"
)

type appConfig struct {
	MediaDir string `json:"media_dir"`
}

func main() {
	cfg := resolveConfig()

	srv, err := server.New(server.Config{MediaDir: cfg.MediaDir})
	if err != nil {
		log.Fatalf("failed to configure server: %v", err)
	}

	httpServer := &http.Server{
		Addr:         srv.Address(),
		Handler:      srv.Router(),
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 15 * time.Second,
		IdleTimeout:  60 * time.Second,
	}

	log.Printf(
		"Estus Shots web server running on http://127.0.0.1%s (media: %s)",
		srv.Address(),
		cfg.MediaDir,
	)

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

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

	<-ctx.Done()
	shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	if err := httpServer.Shutdown(shutdownCtx); err != nil {
		log.Printf("graceful shutdown failed: %v", err)
	} else {
		log.Println("server stopped")
	}
}

func resolveConfig() appConfig {
	mediaDirFlag := flag.String("media-dir", "", "path to the media directory served at /media")
	configPath := flag.String("config", "", "optional path to a JSON config file")
	flag.Parse()

	cfg := appConfig{}
	if *configPath != "" {
		fileCfg, err := loadConfig(*configPath)
		if err != nil {
			log.Fatalf("failed to read config file: %v", err)
		}
		cfg = fileCfg
	}

	if *mediaDirFlag != "" {
		cfg.MediaDir = *mediaDirFlag
	}

	if cfg.MediaDir == "" {
		cfg.MediaDir = defaultMediaDir()
	}

	return cfg
}

func loadConfig(path string) (appConfig, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return appConfig{}, err
	}

	cfg := appConfig{}
	if err := json.Unmarshal(data, &cfg); err != nil {
		return appConfig{}, err
	}
	return cfg, nil
}

func defaultMediaDir() string {
	if cwd, err := os.Getwd(); err == nil {
		candidate := filepath.Join(cwd, "media")
		if info, err := os.Stat(candidate); err == nil && info.IsDir() {
			return candidate
		}
	}

	if exe, err := os.Executable(); err == nil {
		candidate := filepath.Join(filepath.Dir(exe), "media")
		if info, err := os.Stat(candidate); err == nil && info.IsDir() {
			return candidate
		}
	}

	return filepath.Join(".", "media")
}