package photosapi

import (
	"context"
	"crypto/ed25519"
	"errors"
	"math/rand"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"time"

	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

var (
	ErrReqNotFound            = errors.New("this route doesn't exists")
	ErrStorePathNotADirectory = errors.New("store path is not a directory")
)

type Service struct {
	Gin                  *gin.Engine
	DB                   *gorm.DB
	Config               *ServiceConfig
	StorageTmp           *Storage
	StorageUpload        *Storage
	LogOk                *Logger
	LogErr               *Logger
	SessionKey           ed25519.PrivateKey
	SessionKeyValidation ed25519.PublicKey
}

type ServiceConfig struct {
	Listen    string
	DB        *DBConfig
	StorePath string
}

func GetOrGenerateKey(storePath string) ed25519.PrivateKey {
	p := filepath.Join(storePath, "photo.key")
	key, err := os.ReadFile(p)
	if errors.Is(err, os.ErrNotExist) {
		_, key, err = ed25519.GenerateKey(nil)
		if err != nil {
			panic(err)
		}
		err = os.WriteFile(p, key, 0600)
		if err != nil {
			panic(err)
		}
	}
	return key
}

func New(config *ServiceConfig) *Service {
	key := GetOrGenerateKey(config.StorePath)
	pubKey := key.Public().(ed25519.PublicKey)
	return &Service{
		Gin:                  gin.New(),
		Config:               config,
		StorageTmp:           NewStorage(config.StorePath, "tmp"),
		StorageUpload:        NewStorage(config.StorePath, "upload"),
		LogOk:                &Logger{os.Stdout, "Photos"},
		LogErr:               &Logger{os.Stderr, "Photos"},
		SessionKey:           key,
		SessionKeyValidation: pubKey,
	}
}

func (s *Service) SetupRoutes() {
	s.Gin.Use(
		gin.Logger(),
		s.Recovery,
		s.DefaultJSON,
		s.HandleError,
	)

	s.AccountInit()
	s.MeInit()
	s.FileInit()
	s.UploadInit()

	s.Gin.NoRoute(func(c *gin.Context) {
		c.AbortWithError(http.StatusNotFound, ErrReqNotFound)
	})
}

func (s *Service) PrepareStore() {
	d, err := os.Stat(s.Config.StorePath)
	if err != nil {
		s.LogErr.Fatal("Store", err)
	}
	if !d.IsDir() {
		s.LogErr.Fatal("Store", ErrStorePathNotADirectory)
	}
}

func (s *Service) Run() error {
	rand.Seed(time.Now().UnixNano())
	s.PrepareStore()
	s.SetupRoutes()
	s.SetupDB()

	srv := &http.Server{
		Addr:    s.Config.Listen,
		Handler: s.Gin,
	}

	quit := make(chan os.Signal, 1)
	var runError error
	go func() {
		// service connections
		if runError = srv.ListenAndServe(); runError != nil {
			quit <- os.Interrupt
		}
	}()

	// Wait for interrupt signal to gracefully shutdown the server with
	// a timeout of 5 seconds.
	signal.Notify(quit, os.Interrupt)
	<-quit
	s.LogOk.Print("Exit", "shutdown ...")

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if err := srv.Shutdown(ctx); err != nil {
		return err
	}

	db, err := s.DB.DB()
	if err != nil {
		return err
	}
	s.LogOk.Print("Exit", "closing database ...")
	if err := db.Close(); err != nil {
		return err
	}

	s.LogOk.Print("Exit", "exiting")
	return runError
}