package profilepicture

import (
	"bytes"
	"encoding/binary"
	"io"
	"testing"

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

func TestStripMetadata(t *testing.T) {
	t.Run("removes WEBP EXIF and XMP chunks", func(t *testing.T) {
		input := webpFile(
			webpChunk("VP8X", []byte{0x0c, 0, 0, 0, 0, 0, 0, 0, 0, 0}),
			webpChunk("VP8 ", []byte{1, 2, 3, 4}),
			webpChunk("EXIF", []byte("gps")),
			webpChunk("XMP ", []byte("xmp")),
			webpChunk("ICCP", []byte("profile")),
		)

		output := stripReader(t, input, "webp")

		assert.Contains(t, string(output), "VP8 ")
		assert.NotContains(t, string(output), "gps")
		assert.NotContains(t, string(output), "xmp")
		assert.Contains(t, string(output), "profile")
		assert.Equal(t, byte(0), output[20]&0x0c)
	})

	t.Run("leaves non photo metadata formats unchanged", func(t *testing.T) {
		input := []byte(`<svg><metadata>secret</metadata><path d="M0 0"/></svg>`)

		output := stripReader(t, input, "svg")

		assert.Equal(t, input, output)
	})

	t.Run("leaves malformed photo data unchanged", func(t *testing.T) {
		input := []byte("fake-png-content")

		output := stripReader(t, input, "png")

		assert.Equal(t, input, output)
	})
}

func stripReader(t *testing.T, input []byte, ext string) []byte {
	t.Helper()

	reader, err := StripMetadata(bytes.NewReader(input), ext)
	require.NoError(t, err)

	output, err := io.ReadAll(reader)
	require.NoError(t, err)
	return output
}

func webpFile(chunks ...[]byte) []byte {
	var out bytes.Buffer
	out.WriteString("RIFF")
	out.Write([]byte{0, 0, 0, 0})
	out.WriteString("WEBP")
	for _, chunk := range chunks {
		out.Write(chunk)
	}
	binary.LittleEndian.PutUint32(out.Bytes()[4:8], uint32(out.Len()-8)) //nolint:gosec
	return out.Bytes()
}

func webpChunk(chunkType string, data []byte) []byte {
	var out bytes.Buffer
	out.WriteString(chunkType)
	_ = binary.Write(&out, binary.LittleEndian, uint32(len(data))) //nolint:gosec
	out.Write(data)
	if len(data)%2 == 1 {
		out.WriteByte(0)
	}
	return out.Bytes()
}