package rdpgfx

// ClearCodec 解码器单元测试：按 MS-RDPEGFX 2.2.4 逐段手工构造码流，
// 验证 residual 游程、bands 列带（含短 vBar 缓存命中）、RLEX 子编码与 glyph 缓存。

import (
	"encoding/binary"
	"testing"
)

// buildClearStream 组装一个完整 TS_CLEARCODEC_BITMAP_STREAM
func buildClearStream(glyphFlags, seqNumber byte, glyphIndex uint16,
	residual, bands, subcodec []byte) []byte {
	out := []byte{glyphFlags, seqNumber}
	if glyphFlags&(clearFlagGlyphHit|clearFlagGlyphIndex) != 0 {
		out = binary.LittleEndian.AppendUint16(out, glyphIndex)
	}
	out = binary.LittleEndian.AppendUint32(out, uint32(len(residual)))
	out = binary.LittleEndian.AppendUint32(out, uint32(len(bands)))
	out = binary.LittleEndian.AppendUint32(out, uint32(len(subcodec)))
	out = append(out, residual...)
	out = append(out, bands...)
	out = append(out, subcodec...)
	return out
}

// px 取出输出位图中 (x,y) 的 BGRA
func px(out []byte, w, x, y int) [4]byte {
	i := (y*w + x) * 4
	return [4]byte{out[i], out[i+1], out[i+2], out[i+3]}
}

func expectPixel(t *testing.T, out []byte, w, x, y int, want [4]byte, ctx string) {
	t.Helper()
	got := px(out, w, x, y)
	if got != want {
		t.Fatalf("%s: pixel(%d,%d) = %v, want %v", ctx, x, y, got, want)
	}
}

// TestClearResidual：单条游程铺满整幅
func TestClearResidual(t *testing.T) {
	w, h := 4, 2
	// residual: b,g,r=0x10,0x20,0x30 runLen=8
	residual := []byte{0x10, 0x20, 0x30, 8}
	stream := buildClearStream(0, 0, 0, residual, nil, nil)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			expectPixel(t, out, w, x, y, [4]byte{0x10, 0x20, 0x30, 0xFF}, "residual")
		}
	}
}

// TestClearResidualRunEncoding：长游程 2 字节/4 字节变长编码
func TestClearResidualRunEncoding(t *testing.T) {
	w, h := 16, 16 // 256 像素
	// run=255（触发 2 字节编码 0x00FF）+ run=1 → 共 256
	residual := []byte{1, 2, 3, 0xFF, 0xFF, 0x00, 4, 5, 6, 1}
	stream := buildClearStream(0, 0, 0, residual, nil, nil)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	for y := 0; y < 16; y++ {
		for x := 0; x < 16; x++ {
			want := [4]byte{1, 2, 3, 0xFF}
			if y == 15 && x == 15 {
				want = [4]byte{4, 5, 6, 0xFF}
			}
			expectPixel(t, out, w, x, y, want, "residual-run")
		}
	}
}

// TestClearBandsShortVBarCacheMiss：列带 + 短 vBar 存缓存 + 背景合成
func TestClearBandsShortVBarCacheMiss(t *testing.T) {
	w, h := 2, 4
	// band: x0..1, y0..3 → vBarCount=2, vBarHeight=4
	bands := []byte{}
	bands = binary.LittleEndian.AppendUint16(bands, 0) // xStart
	bands = binary.LittleEndian.AppendUint16(bands, 1) // xEnd
	bands = binary.LittleEndian.AppendUint16(bands, 0) // yStart
	bands = binary.LittleEndian.AppendUint16(bands, 3) // yEnd
	bands = append(bands, 0xAA, 0xBB, 0xCC)            // cb,cg,cr 背景色
	// 每列：SHORT_VBAR_CACHE_MISS，yOn=1，yOff=3 → 2 个像素，位于行 1-2
	for col := 0; col < 2; col++ {
		header := uint16(1) | uint16(3)<<8 // yOn=1, yOff=3
		bands = binary.LittleEndian.AppendUint16(bands, header)
		bands = append(bands, byte(col+1), 0x00, 0x10) // 行1: b,g,r
		bands = append(bands, byte(col+2), 0x00, 0x20) // 行2
	}
	stream := buildClearStream(0, 0, 0, nil, bands, nil)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	for col := 0; col < 2; col++ {
		expectPixel(t, out, w, col, 0, [4]byte{0xAA, 0xBB, 0xCC, 0xFF}, "bands-bg-front")
		expectPixel(t, out, w, col, 1, [4]byte{byte(col + 1), 0x00, 0x10, 0xFF}, "bands-short-1")
		expectPixel(t, out, w, col, 2, [4]byte{byte(col + 2), 0x00, 0x20, 0xFF}, "bands-short-2")
		expectPixel(t, out, w, col, 3, [4]byte{0xAA, 0xBB, 0xCC, 0xFF}, "bands-bg-back")
	}
}

// TestClearBandsShortVBarCacheHit：第二帧复用第一帧的短 vBar 缓存
func TestClearBandsShortVBarCacheHit(t *testing.T) {
	w, h := 1, 4
	mkBands := func(hit bool) []byte {
		bands := []byte{}
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 3)
		bands = append(bands, 0x01, 0x02, 0x03) // 背景
		if hit {
			// SHORT_VBAR_CACHE_HIT：idx=0 + 1 字节 yOn=2
			bands = binary.LittleEndian.AppendUint16(bands, 0x4000|0)
			bands = append(bands, 2)
		} else {
			// MISS：yOn=2，yOff=4 → 2 像素
			bands = binary.LittleEndian.AppendUint16(bands, 2|4<<8)
			bands = append(bands, 0x10, 0x20, 0x30)
			bands = append(bands, 0x40, 0x50, 0x60)
		}
		return bands
	}
	ctx := newClearCodecCtx()
	ctx.decode(buildClearStream(0, 0, 0, nil, mkBands(false), nil), w, h)
	out := ctx.decode(buildClearStream(0, 1, 0, nil, mkBands(true), nil), w, h)
	// 缓存命中：行 2-3 = 缓存的两像素，行 0-1 = 背景
	expectPixel(t, out, w, 0, 0, [4]byte{0x01, 0x02, 0x03, 0xFF}, "hit-bg-0")
	expectPixel(t, out, w, 0, 1, [4]byte{0x01, 0x02, 0x03, 0xFF}, "hit-bg-1")
	expectPixel(t, out, w, 0, 2, [4]byte{0x10, 0x20, 0x30, 0xFF}, "hit-short-2")
	expectPixel(t, out, w, 0, 3, [4]byte{0x40, 0x50, 0x60, 0xFF}, "hit-short-3")
}

// TestClearSubcodecBGR24：未压缩 BGR24 子编码
func TestClearSubcodecBGR24(t *testing.T) {
	w, h := 2, 2
	sub := []byte{}
	sub = binary.LittleEndian.AppendUint16(sub, 1)          // xStart
	sub = binary.LittleEndian.AppendUint16(sub, 1)          // yStart
	sub = binary.LittleEndian.AppendUint16(sub, 1)          // width
	sub = binary.LittleEndian.AppendUint16(sub, 1)          // height
	sub = binary.LittleEndian.AppendUint32(sub, 3) // bitmapDataByteCount
	sub = append(sub, 0)                           // subcodecId = BGR24
	sub = append(sub, 0x77, 0x88, 0x99)            // b,g,r
	stream := buildClearStream(0, 0, 0, nil, nil, sub)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	expectPixel(t, out, w, 0, 0, [4]byte{0, 0, 0, 0}, "bgr24-untouched")
	expectPixel(t, out, w, 1, 1, [4]byte{0x77, 0x88, 0x99, 0xFF}, "bgr24-hit")
}

// TestClearRLEX：调色板游程子编码（套位打包索引）
func TestClearRLEX(t *testing.T) {
	w, h := 4, 1
	sub := []byte{}
	sub = binary.LittleEndian.AppendUint16(sub, 0) // xStart
	sub = binary.LittleEndian.AppendUint16(sub, 0) // yStart
	sub = binary.LittleEndian.AppendUint16(sub, 4) // width
	sub = binary.LittleEndian.AppendUint16(sub, 1) // height
	sub = binary.LittleEndian.AppendUint32(sub, 15)
	// RLEX: subcodecId=2 + paletteCount=4 + 4×(b,g,r)
	sub = append(sub, 2)
	sub = append(sub, 4)
	sub = append(sub, 0x10, 0x00, 0x00)
	sub = append(sub, 0x20, 0x00, 0x00)
	sub = append(sub, 0x30, 0x00, 0x00)
	sub = append(sub, 0x40, 0x00, 0x00)
	// paletteCount=4 → numBits=2；suiteDepth=3, stopIndex=3 → tmp=(3<<2)|3=0x0F
	// runLen=0（1 字节）→ 输出 4 像素 palette[0..3]
	sub = append(sub, 0x0F, 0)
	stream := buildClearStream(0, 0, 0, nil, nil, sub)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	expectPixel(t, out, w, 0, 0, [4]byte{0x10, 0, 0, 0xFF}, "rlex-0")
	expectPixel(t, out, w, 1, 0, [4]byte{0x20, 0, 0, 0xFF}, "rlex-1")
	expectPixel(t, out, w, 2, 0, [4]byte{0x30, 0, 0, 0xFF}, "rlex-2")
	expectPixel(t, out, w, 3, 0, [4]byte{0x40, 0, 0, 0xFF}, "rlex-3")
}

// TestClearGlyphIndexThenHit：GLYPH_INDEX 缓存输出，GLYPH_HIT 直接取缓存
func TestClearGlyphIndexThenHit(t *testing.T) {
	w, h := 2, 2
	residual := []byte{0x11, 0x22, 0x33, 4}
	ctx := newClearCodecCtx()
	// 第一帧：GLYPH_INDEX，缓存到 index=7
	ctx.decode(buildClearStream(clearFlagGlyphIndex, 0, 7, residual, nil, nil), w, h)
	// 第二帧：GLYPH_HIT|GLYPH_INDEX（合法命中组合），无载荷也应输出缓存
	out := ctx.decode(buildClearStream(clearFlagGlyphHit|clearFlagGlyphIndex, 1, 7, nil, nil, nil), w, h)
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			expectPixel(t, out, w, x, y, [4]byte{0x11, 0x22, 0x33, 0xFF}, "glyph-hit")
		}
	}
	// 单独的 GLYPH_HIT 是非法组合 → 整帧拒绝（nil，调用方保留 surface）
	out = ctx.decode(buildClearStream(clearFlagGlyphHit, 2, 7, nil, nil, nil), w, h)
	if out != nil {
		t.Fatalf("invalid glyph flags: want nil frame, got %d bytes", len(out))
	}
	// 空更新流（子编码矩形完全越界，服务器真实样本形态）→ 整帧拒绝
	sub := []byte{}
	sub = binary.LittleEndian.AppendUint16(sub, 32) // xStart == w（越界）
	sub = binary.LittleEndian.AppendUint16(sub, 64) // yStart == h（越界）
	sub = binary.LittleEndian.AppendUint16(sub, 8)  // width
	sub = binary.LittleEndian.AppendUint16(sub, 0)  // height
	sub = binary.LittleEndian.AppendUint32(sub, 15)
	sub = append(sub, 2) // subcodecId = RLEX
	sub = append(sub, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
	out = ctx.decode(buildClearStream(0, 3, 0, nil, nil, sub), 32, 64)
	if out != nil {
		t.Fatalf("out-of-bounds subcodec rect: want nil frame, got %d bytes", len(out))
	}
}

// TestClearVBarCacheHitAcrossFrames：整 vBar 缓存跨帧复用（CACHE_RESET 后哑填充不崩溃）
func TestClearVBarCacheHitAcrossFrames(t *testing.T) {
	w, h := 1, 2
	mkBands := func(hit bool) []byte {
		bands := []byte{}
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 0)
		bands = binary.LittleEndian.AppendUint16(bands, 1) // yEnd → vBarHeight=2
		bands = append(bands, 0, 0, 0)
		if hit {
			bands = binary.LittleEndian.AppendUint16(bands, 0x8000|0) // VBAR_CACHE_HIT idx 0
		} else {
			// MISS（vBarHeader 最高两位为 00 且 0x8000 未置位）：count=yOn..yOff 不可用，
			// 直接用像素数：yOn=0, yOff=2 → header = 0|2<<8
			bands = binary.LittleEndian.AppendUint16(bands, 0|2<<8)
			bands = append(bands, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F)
		}
		return bands
	}
	ctx := newClearCodecCtx()
	ctx.decode(buildClearStream(0, 0, 0, nil, mkBands(false), nil), w, h)
	// 带 CACHE_RESET 重置 vBar 存储，再用 idx0 命中 → 哑填充不 panic
	out := ctx.decode(buildClearStream(clearFlagCacheReset, 1, 0, nil, mkBands(true), nil), w, h)
	expectPixel(t, out, w, 0, 0, [4]byte{0, 0, 0, 0}, "vbar-reset-dummy")
}

// TestClearNSCodec：NSCodec 子编码（RLE 平面 + YCoCg 恢复 + 空 alpha 平面）
func TestClearNSCodec(t *testing.T) {
	w, h := 8, 2 // org 每平面 16 字节
	// 单平面 RLE：12 字节游程 [v,v,run-2] + 尾部 4 字节原样 = 7 字节
	rle := func(v byte) []byte { return []byte{v, v, 10, v, v, v, v} }
	yPlane := rle(0x80)
	coPlane := rle(0x40)
	cgPlane := rle(0x00)

	sub := []byte{}
	sub = binary.LittleEndian.AppendUint16(sub, 0) // xStart
	sub = binary.LittleEndian.AppendUint16(sub, 0) // yStart
	sub = binary.LittleEndian.AppendUint16(sub, uint16(w)) // width
	sub = binary.LittleEndian.AppendUint16(sub, uint16(h)) // height
	sub = binary.LittleEndian.AppendUint32(sub, uint32(20 + 7 + 7 + 7 + 0))
	sub = append(sub, 1) // subcodecId = NSCodec
	for _, n := range []int{7, 7, 7, 0} {
		sub = binary.LittleEndian.AppendUint32(sub, uint32(n)) // PlaneByteCount
	}
	sub = append(sub, 1, 0, 0, 0) // ColorLossLevel=1, ChromaSubsampling=0, 保留
	sub = append(sub, yPlane...)
	sub = append(sub, coPlane...)
	sub = append(sub, cgPlane...)
	// A 平面 byteCount=0 → 全 0xFF

	stream := buildClearStream(0, 0, 0, nil, nil, sub)
	ctx := newClearCodecCtx()
	out := ctx.decode(stream, w, h)
	// shift=0：r=0x80+0x40-0x00=0xC0, g=0x80, b=0x80-0x40-0x00=0x40
	for y := 0; y < h; y++ {
		for x := 0; x < w; x++ {
			expectPixel(t, out, w, x, y, [4]byte{0x40, 0x80, 0xC0, 0xFF}, "nsc")
		}
	}
}

// TestProgDWTExtrapolateConstant：常数 LL3 + 零高频 → IDWT 输出应为同一常数
func TestProgDWTExtrapolateConstant(t *testing.T) {
	buf := make([]int16, 4096)
	// extrapolate 布局 LL3 在 [4015,4096)，9×9 行主序
	for y := 0; y < 9; y++ {
		for x := 0; x < 9; x++ {
			buf[4015+y*9+x] = 128
		}
	}
	progDWTExtrapolate(buf)
	for y := 0; y < 64; y++ {
		for x := 0; x < 64; x++ {
			if got := buf[y*64+x]; got != 128 {
				t.Fatalf("DWT(%d,%d) = %d, want 128", x, y, got)
			}
		}
	}
}