package html_components

import (
	"bytes"
	"test/crud"
	"fmt"
	. "github.com/labstack/echo/v4"
	"golang.org/x/image/draw"
	"image"
	"image/jpeg"
	"image/png"
	"io"
	"math"
	"net/http"
	"os"
)

const todotransPixel = "\x47\x49\x46\x38\x39\x61\x01\x00\x01\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x21\xF9\x04\x01\x00\x00\x00\x00\x2C\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02\x44\x01\x00\x3B"

func ReturnEmptyPixel(c Context) error {
	return c.Blob(http.StatusOK, "image/gif", []byte(todotransPixel))
}

func ReturnImage(c Context, path string) error {
	height := ParseIntWithDefault(c.QueryParam("height"), -1)
	width := ParseIntWithDefault(c.QueryParam("width"), -1)
	tmpFilePath := getTmpFilePath(path, width, height)
	// if tmp file path exists
	if _, err := os.Stat(tmpFilePath); err == nil {
		// read from the tmp file
		return sendImage(c, tmpFilePath)
	} else {
		filePath := "files/" + path
		if width > 0 || height > 0 {
			data, err := os.ReadFile(filePath)
			mimeType := http.DetectContentType(data)
			if err != nil {
				return ReturnEmptyPixel(c)
			}
			return getResized(c, data, mimeType, width, height, path)
		}
		crud.Debug("returning the full image: ", filePath)
		return sendImage(c, filePath)
	}
}

func sendImage(c Context, filePath string) error {
	data, err := os.ReadFile(filePath)
	if err != nil {
		return ReturnEmptyPixel(c)
	}
	mimeType := http.DetectContentType(data)
	return c.Blob(http.StatusOK, mimeType, data)
}

func getResized(c Context, data []byte, mimeType string, width int, height int, path string) error {
	// create thumbnail and save to tmp
	err := os.MkdirAll("tmp", os.ModePerm)
	if err != nil {
		crud.Error("Failed to create tmp directory: ", err)
		return c.Blob(http.StatusOK, mimeType, data)
	}
	buffer, err := createThumbnailBuffer(c, data, mimeType, width, height)
	if err != nil {
		crud.Error("Failed to create thumbnail: ", err)
		return c.Blob(http.StatusOK, mimeType, data)
	}
	filePath := getTmpFilePath(path, width, height)
	err = CreateFile(filePath, buffer)
	if err != nil {
		crud.Error("Failed to save thumbnail: ", err)
		return sendImage(c, path)
	}
	return sendImage(c, filePath)
}

func getTmpFilePath(path string, width int, height int) string {
	tmpFilePath := fmt.Sprint("tmp/", path, "_", width, "_", height)
	return tmpFilePath
}

func createThumbnailBuffer(c Context, data []byte, mimeType string, width int, height int) (*bytes.Buffer, error) {
	reader := bytes.NewReader(data)
	buffer := new(bytes.Buffer)
	err := ThumbnailImage(reader, buffer, mimeType, width, height)
	if err != nil {
		return nil, err
	}
	return buffer, nil
}

// ThumbnailImage https://roeber.dev/posts/resize-an-image-in-go/
// creates a resized image from the reader and writes it to
// the writer. The mimetype determines how the image will be decoded
// and must be either "image/jpeg" or "image/png". The desired width
// of the ThumbnailImage is specified in pixels, and the resulting height
// will be calculated to preserve the aspect ratio.
func ThumbnailImage(r io.Reader, w io.Writer, mimetype string, width int, height int) error {
	var src image.Image
	var err error

	switch mimetype {
	case "image/jpeg":
		src, err = jpeg.Decode(r)
	case "image/png":
		src, err = png.Decode(r)
	}

	if err != nil {
		return err
	}

	ratio := (float64)(src.Bounds().Max.Y) / (float64)(src.Bounds().Max.X)
	if height == -1 {
		height = int(math.Round(float64(width) * ratio))
	}
	if width == -1 {
		width = int(math.Round(float64(height) / ratio))
	}

	dst := image.NewRGBA(image.Rect(0, 0, width, height))

	draw.CatmullRom.Scale(dst, dst.Rect, src, src.Bounds(), draw.Over, nil)

	err = jpeg.Encode(w, dst, nil)
	if err != nil {
		return err
	}

	return nil
}