package attach_test

import (
	"bytes"
	"encoding/binary"
	"hash/crc32"
	"image"
	"image/color"
	"image/gif"
	"image/jpeg"
	"image/png"
	"testing"

	"git.golem15.com/golem15/summercms/modules/lagoon/attach"
)

// guardWebP is a 16x12 lossless WebP.
var guardWebP = []byte{
	0x52, 0x49, 0x46, 0x46, 0x2a, 0x00, 0x00, 0x00, 0x57, 0x45, 0x42, 0x50, 0x56, 0x50, 0x38, 0x4c,
	0x1d, 0x00, 0x00, 0x00, 0x2f, 0x0f, 0xc0, 0x02, 0x00, 0x0f, 0x70, 0x14, 0xfb, 0x53, 0xd0, 0x5e,
	0x88, 0x7b, 0xfe, 0x83, 0x07, 0x62, 0xc1, 0x64, 0xfe, 0xd2, 0xbd, 0x21, 0x44, 0xf4, 0x3f, 0x74,
	0x01, 0x00,
}

func guardGIF(t *testing.T) []byte {
	t.Helper()
	var buf bytes.Buffer
	if err := gif.Encode(&buf, image.NewPaletted(image.Rect(0, 0, 3, 2), []color.Color{color.Black, color.White}), nil); err != nil {
		t.Fatal(err)
	}
	return buf.Bytes()
}

func guardJPEG(t *testing.T) []byte {
	t.Helper()
	var buf bytes.Buffer
	if err := jpeg.Encode(&buf, image.NewRGBA(image.Rect(0, 0, 3, 2)), nil); err != nil {
		t.Fatal(err)
	}
	return buf.Bytes()
}

// pngHeader is a PNG signature and a valid IHDR chunk for w x h, the part
// image.DecodeConfig reads, without pixel data.
func pngHeader(w, h uint32) []byte {
	var ihdr bytes.Buffer
	ihdr.WriteString("IHDR")
	_ = binary.Write(&ihdr, binary.BigEndian, w)
	_ = binary.Write(&ihdr, binary.BigEndian, h)
	ihdr.Write([]byte{8, 0, 0, 0, 0}) // 8-bit grayscale, no interlace
	var out bytes.Buffer
	out.Write([]byte("\x89PNG\r\n\x1a\n"))
	_ = binary.Write(&out, binary.BigEndian, uint32(13))
	out.Write(ihdr.Bytes())
	_ = binary.Write(&out, binary.BigEndian, crc32.ChecksumIEEE(ihdr.Bytes()))
	return out.Bytes()
}

// TestIsAllowedImageAccepts the four formats the thumbnailer decodes, and
// an image exactly at the pixel ceiling.
func TestIsAllowedImageAccepts(t *testing.T) {
	var p bytes.Buffer
	if err := png.Encode(&p, image.NewRGBA(image.Rect(0, 0, 2, 2))); err != nil {
		t.Fatal(err)
	}
	for name, data := range map[string][]byte{
		"png":             p.Bytes(),
		"gif":             guardGIF(t),
		"jpeg":            guardJPEG(t),
		"webp":            guardWebP,
		"at the ceiling":  pngHeader(4096, 4096),
		"one tall column": pngHeader(1, 4096*4096),
	} {
		if !attach.IsAllowedImage(data) {
			t.Errorf("%s refused", name)
		}
	}
	if attach.MaxImagePixels != 4096*4096 {
		t.Fatalf("MaxImagePixels = %d", attach.MaxImagePixels)
	}
}

// TestIsAllowedImageRefuses SVG, HTML, a GIF signature followed by script,
// a truncated PNG, empty input, an image over 4096x4096 pixels, a zero-size
// image and a BMP (a real image the thumbnailer does not decode).
func TestIsAllowedImageRefuses(t *testing.T) {
	var p bytes.Buffer
	if err := png.Encode(&p, image.NewRGBA(image.Rect(0, 0, 8, 8))); err != nil {
		t.Fatal(err)
	}
	bmp := append([]byte("BM"), make([]byte, 60)...)
	for name, data := range map[string][]byte{
		"svg":              []byte(`<svg xmlns="http://www.w3.org/2000/svg"><script>alert(1)</script></svg>`),
		"html":             []byte("<!DOCTYPE html><html><script>alert(1)</script></html>"),
		"gif polyglot":     []byte("GIF89a<script>alert(document.domain)</script>"),
		"png polyglot":     append([]byte("\x89PNG\r\n\x1a\n"), []byte("<html><script>alert(1)</script>")...),
		"truncated png":    p.Bytes()[:20],
		"empty":            nil,
		"over the ceiling": pngHeader(4097, 4096),
		"huge":             pngHeader(100000, 100000),
		"zero width":       pngHeader(0, 10),
		"bmp":              bmp,
		"text":             []byte("just text"),
	} {
		if attach.IsAllowedImage(data) {
			t.Errorf("%s accepted", name)
		}
	}
}