package imgedit

import (
	"encoding/json"
	"io"
	"os"
	"path/filepath"

	"lmika.dev/lmika/weiro/models"
)

type sessionStore struct {
	baseDir string
}

func (ss *sessionStore) save(newSession *models.ImageEditSession) error {
	sessionMeta, err := json.Marshal(newSession)
	if err != nil {
		return err
	}

	if err := os.MkdirAll(filepath.Join(ss.baseDir, newSession.GUID), 0755); err != nil {
		return err
	}
	if err := os.WriteFile(filepath.Join(ss.baseDir, newSession.GUID, "session.json"), sessionMeta, 0644); err != nil {
		return err
	}
	return nil
}

func (ss *sessionStore) get(guid string) (*models.ImageEditSession, error) {
	sessionDataBts, err := os.ReadFile(filepath.Join(ss.baseDir, guid, "session.json"))
	if err != nil {
		return nil, err
	}

	sessionData := models.ImageEditSession{}
	if err := json.Unmarshal(sessionDataBts, &sessionData); err != nil {
		return nil, err
	}

	return &sessionData, nil
}

func (ss *sessionStore) getImage(session *models.ImageEditSession, imageFilename string) (string, func() (io.ReadCloser, error), error) {
	fullPath := filepath.Join(ss.baseDir, session.GUID, imageFilename)
	if s, err := os.Stat(fullPath); err != nil {
		return "", nil, err
	} else if s.IsDir() {
		return "", nil, os.ErrNotExist
	}

	var mimeType string
	switch filepath.Ext(imageFilename) {
	case ".jpg", ".jpeg":
		mimeType = "image/jpeg"
	case ".png":
		mimeType = "image/png"
	default:
		return "", nil, models.UnsupportedImageFormat
	}

	return mimeType, func() (io.ReadCloser, error) {
		return os.Open(fullPath)
	}, nil
}