package backend

import (
	"bufio"
	"fmt"
	"image"
	"io"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/chai2010/webp"
	"github.com/disintegration/imaging"
	"github.com/google/uuid"
)

var ErrUnsupportedFormat error = image.ErrFormat // used internally by imaging

func SaveImage(src io.Reader, maxHeight, maxWidth int, path string) (string, error) {
	img, err := imaging.Decode(src, imaging.AutoOrientation(true))
	if err != nil {
		if err == ErrUnsupportedFormat {
			return "", ErrUnsupportedFormat
		}
		return "", fmt.Errorf("error decoding image: %v", err)
	}

	if img.Bounds().Dy() > maxHeight {
		img = imaging.Resize(img, 0, maxHeight, imaging.Lanczos)
	}
	if img.Bounds().Dx() > maxWidth {
		img = imaging.Resize(img, maxWidth, 0, imaging.Lanczos)
	}

	filename := fmt.Sprint(uuid.New(), ".webp")
	file, err := os.Create(filepath.Join(path, filename))
	if err != nil {
		return "", fmt.Errorf("error creating new image file: %v", err)
	}
	defer file.Close()

	if err = webp.Encode(file, img, &webp.Options{Quality: 80}); err != nil {
		return "", fmt.Errorf("error encoding image as webp: %v", err)
	}

	return filename, nil
}

func CleanUpImages(c *Config) {
	for {
		if err := filepath.Walk(c.PicsDir, func(path string, info fs.FileInfo, err error) error {
			if err != nil {
				return err
			}

			if !info.IsDir() {
				imageName := info.Name()
				absImageName := path

				if err = filepath.Walk(c.ArticleDir, func(path string, info fs.FileInfo, err error) error {
					if err != nil {
						return err
					}

					if !info.IsDir() {
						mdFile, err := os.Open(path)
						if err != nil {
							return err
						}
						defer mdFile.Close()

						scanner := bufio.NewScanner(mdFile)
						imageWasFound := false

						for scanner.Scan() {
							if strings.Contains(scanner.Text(), imageName) {
								imageWasFound = true
							}
						}

						if !imageWasFound {
							if err = os.Remove(absImageName); err != nil {
								return err
							}
						}

						return scanner.Err()
					}

					return nil
				}); err != nil {
					return err
				}
			}

			return nil
		}); err != nil {
			log.Println(err)
		}

		time.Sleep(time.Hour)
	}
}