/*
 * This file is subject to the terms and conditions defined in
 * file 'LICENSE.md', which is part of this source code package.
 */

package tests

import (
	"archive/zip"
	"bytes"
	"crypto/md5"
	"fmt"
	"image"
	"image/jpeg"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"github.com/unidoc/unipdf/v3/common"
	"github.com/unidoc/unipdf/v3/core"
)

// TestImageEncodeDecodeJBIG2 tests the encode and decode process for the JBIG2 encoder.
func TestImageEncodeDecodeJBIG2(t *testing.T) {
	dirName := os.Getenv(EnvImageDirectory)
	if dirName == "" {
		t.Skipf("no environment variable: '%s' provided", EnvImageDirectory)
	}

	// get the file names within given directory
	fileNames, err := readFileNames(dirName, "jpg")
	require.NoError(t, err)

	if len(fileNames) == 0 {
		t.Skipf("no files found in the '%s' directory", dirName)
	}

	// prepare temporary directory where the jbig2 files would be stored
	tempDir := filepath.Join(os.TempDir(), "unipdf", "jbig2", "encoded-decoded")
	err = os.MkdirAll(tempDir, 0700)
	require.NoError(t, err)

	var f *os.File
	switch {
	case logToFile:
		fileName := filepath.Join(tempDir, fmt.Sprintf("log_%s.txt", time.Now().Format("20060102")))
		f, err = os.Create(fileName)
		require.NoError(t, err)
		common.SetLogger(common.NewWriterLogger(common.LogLevelTrace, f))
	case testing.Verbose():
		common.SetLogger(common.NewConsoleLogger(common.LogLevelDebug))
	}

	// clear all the temporary files
	defer func() {
		if f != nil {
			f.Close()
		}

		switch {
		case !keepImageFiles && !logToFile:
			err = os.RemoveAll(filepath.Join(tempDir))
		case !keepImageFiles:
			err = filepath.Walk(tempDir, func(path string, info os.FileInfo, err error) error {
				if err != nil {
					return err
				}
				if strings.HasSuffix(info.Name(), "zip") {
					return os.Remove(path)
				}
				return nil
			})
		}
		if err != nil {
			common.Log.Error(err.Error())
		}
	}()

	defer func() {
		if !keepImageFiles {
			os.RemoveAll(tempDir)
		}
	}()

	buf := &bytes.Buffer{}
	h := md5.New()
	edp := []goldenValuePair{}
	for _, fileName := range fileNames {
		// read the file
		f, err := getFile(dirName, fileName)
		require.NoError(t, err)
		defer f.Close()

		// try to read the file as image.
		img, _, err := image.Decode(f)
		if err != nil {
			// if the image is of unknown decoding or is not an image skip the test.
			common.Log.Debug("File: '%s' couldn't be read as an image")
			continue
		}
		rawName := rawFileName(fileName)

		t.Run(rawName, func(t *testing.T) {
			zipFileName := filepath.Join(tempDir, rawName+".zip")
			// create zip file containing encoded images
			zf, err := os.Create(zipFileName)
			require.NoError(t, err)
			defer zf.Close()

			// wrap zip writer over the file writer.
			zw := zip.NewWriter(zf)
			defer zw.Close()

			// convert the input image into jbig2 1bpp acceptable binary image.
			jimg, err := core.GoImageToJBIG2(img, core.JB2ImageAutoThreshold)
			require.NoError(t, err)

			// create the encoder
			e := &core.JBIG2Encoder{}
			err = e.AddPageImage(jimg, &core.JBIG2EncoderSettings{DuplicatedLinesRemoval: true, FileMode: true})
			require.NoError(t, err)

			data, err := e.Encode()
			require.NoError(t, err)

			if keepEncodedFile {
				// create .jbig2 file within the zip file
				jbf, err := zw.Create(rawName + ".jbig2")
				require.NoError(t, err)

				// write encoded data into jb2 file
				_, err = jbf.Write(data)
				require.NoError(t, err)
			}

			// create golang image and store it within zip file
			bwImage, err := jimg.ToGoImage()
			require.NoError(t, err)

			buf.Reset()

			// store the binary image in the 'jpeg' format.
			err = jpeg.Encode(buf, bwImage, &jpeg.Options{Quality: jpeg.DefaultQuality})
			require.NoError(t, err)

			// write images if the flag is set to true
			if keepImageFiles {
				// create a jpeg file to show the black white image.
				df, err := zw.Create(rawName + ".jpg")
				require.NoError(t, err)

				_, err = buf.WriteTo(df)
				require.NoError(t, err)
			}
			h.Reset()
			_, err = h.Write(buf.Bytes())
			require.NoError(t, err)

			hashOrig := h.Sum(nil)

			// decode the encoded data and store it's results in the zipped file.
			d := &core.JBIG2Encoder{}
			decoded, err := d.DecodeImages(data)
			require.NoError(t, err)
			require.Len(t, decoded, 1)

			// reset buffer
			buf.Reset()
			h.Reset()

			// write the decoded image
			err = jpeg.Encode(buf, decoded[0], &jpeg.Options{Quality: jpeg.DefaultQuality})
			require.NoError(t, err)

			_, err = h.Write(buf.Bytes())
			require.NoError(t, err)

			if keepImageFiles {
				// create decoded image file within the zip file.
				dimg, err := zw.Create(rawName + "_encdec.jpg")
				require.NoError(t, err)

				_, err = buf.WriteTo(dimg)
				require.NoError(t, err)
			}

			hashEncoded := h.Sum(nil)
			assert.True(t, bytes.Equal(hashOrig, hashEncoded))

			edp = append(edp, goldenValuePair{
				Filename: fileName,
				Hash:     hashEncoded,
			})
		})
	}
	const goldenFileName = "encoded-decoded"
	checkGoldenValuePairs(t, dirName, goldenFileName, edp...)
}