package question

import (
	"image"
	"image/color"
	"image/draw"
	"image/png"
	"os"
	"path/filepath"
	"testing"

	"github.com/golang/freetype"
	"github.com/golang/freetype/truetype"
	qrcode "github.com/skip2/go-qrcode"

	"github.com/tamakyi/TamaBox/internal/conf"
	"github.com/tamakyi/TamaBox/internal/db"
)

// 分享卡测试需要一份真实字体；中文站点部署时 conf.App.FontPath 必然存在，
// 本机开发/CI 缺失时跳过，避免把「没有字体」当成排版错误。
func TestMain(m *testing.M) {
	if _, err := os.Stat(conf.App.FontPath); err != nil {
		for _, candidate := range []string{
			"C:/Windows/Fonts/NotoSansSC-VF.ttf",
			"C:/Windows/Fonts/msyh.ttc",
			"/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc",
		} {
			if _, err := os.Stat(candidate); err == nil {
				conf.App.FontPath = candidate
				break
			}
		}
	}
	os.Exit(m.Run())
}

func requireFont(t *testing.T) *truetype.Font {
	t.Helper()
	ft, err := getFont()
	if err != nil {
		t.Skipf("no usable font (%v), skip share card layout tests", err)
	}
	return ft
}

// measureTextWidth 必须与 freetype 实际笔位推进一致，否则居中会重新出现偏移。
func TestMeasureTextWidthMatchesAdvance(t *testing.T) {
	requireFont(t)
	cases := []struct {
		text string
		size float64
	}{
		{"https://box.shiroko.one/_/tamakyi", FontSizeLink},
		{"box.shiroko.one/_/tamakyi", 13},
		{"ask.some-quite-long-domain-name.example.com", LinkMinSize},
		{"Powered by 狼的提问箱", FontSizeFooter},
		{"扫码向我匿名提问", FontSizeQRHint},
	}
	for _, c := range cases {
		dst := image.NewRGBA(image.Rect(0, 0, 1400, 80))
		fctx := freetype.NewContext()
		fctx.SetFont(requireFont(t))
		fctx.SetDPI(72)
		fctx.SetFontSize(c.size)
		fctx.SetSrc(image.NewUniform(color.Black))
		fctx.SetDst(dst)
		pen, err := fctx.DrawString(c.text, freetype.Pt(0, 60))
		if err != nil {
			t.Fatalf("draw %q: %v", c.text, err)
		}
		want := float64(pen.X) / 64.0
		if got := measureTextWidth(c.text, c.size); got != want {
			t.Errorf("%q @%.1f: measure=%.2f, advance=%.2f", c.text, c.size, got, want)
		}
	}
}

// 任意长度的链接都必须收进卡片，且不得缩到不可读。
func TestLayoutLinkFitsCard(t *testing.T) {
	requireFont(t)
	urls := []string{
		"box.shiroko.one/_/tamakyi",
		"box-dev-api.337845818.best/_/tamakyi",
		"ask.some-quite-long-domain-name.example.com/_/tamakyi",
		"questions.tamabox-community.example.org/anon/box/_/a-rather-long-handle-name",
		"averyveryveryverylongdomainnamethatkeepsgoingandonandonforever.example/_/x",
	}
	for _, u := range urls {
		lines, size := layoutLink(u)
		if size < LinkMinSize {
			t.Errorf("%q: font size %.2f below floor %.2f", u, size, LinkMinSize)
		}
		if len(lines) > 2 {
			t.Errorf("%q: got %d lines, want <=2", u, len(lines))
		}
		for _, line := range lines {
			if w := measureTextWidth(line, size); w > float64(LinkMaxWidth) {
				t.Errorf("%q: line %q is %.1fpx, card allows %dpx", u, line, w, LinkMaxWidth)
			}
		}
	}
}

// 居中必须落在二维码卡片中线上（按真实着墨边界判断，允许左右侧边距带来的 3px 内偏差）。
func TestDrawTextCenteredIsCentered(t *testing.T) {
	requireFont(t)
	cx := QRCardX + QRCardW/2
	for _, text := range []string{
		"box.shiroko.one/_/tamakyi",
		"box-dev-api.337845818.best/_/tamakyi",
		"Powered by 狼的提问箱",
	} {
		canvas := image.NewRGBA(image.Rect(0, 0, CardWidth, CardHeight))
		draw.Draw(canvas, canvas.Bounds(), &image.Uniform{ColorWhite}, image.Point{}, draw.Src)
		fctx := freetype.NewContext()
		fctx.SetFont(requireFont(t))
		fctx.SetDPI(72)
		drawTextCentered(canvas, text, cx, 300, FontSizeLink, ColorDarkText, fctx)

		minX, maxX := -1, -1
		for x := 0; x < CardWidth; x++ {
			for y := 250; y < 320; y++ {
				if r, _, _, a := canvas.At(x, y).RGBA(); a > 40 && r < 0x8000 {
					if minX < 0 {
						minX = x
					}
					maxX = x
					break
				}
			}
		}
		if minX < 0 {
			t.Fatalf("%q: nothing drawn", text)
		}
		if center := (minX + maxX) / 2; abs(center-cx) > 3 {
			t.Errorf("%q: ink center %d, want %d (±3)", text, center, cx)
		}
		if maxX > QRCardX+QRCardW || minX < QRCardX {
			t.Errorf("%q: ink [%d,%d] escapes card [%d,%d]", text, minX, maxX, QRCardX, QRCardX+QRCardW)
		}
	}
}

// 内嵌头像必须画在中心，且符号本身不被裁切（四角是定位图案，应当是黑的）。
func TestGenerateQRWithLogo(t *testing.T) {
	logo := image.NewRGBA(image.Rect(0, 0, 64, 40))
	draw.Draw(logo, logo.Bounds(), &image.Uniform{color.RGBA{200, 40, 40, 255}}, image.Point{}, draw.Src)

	img, err := generateQR("https://box.shiroko.one/_/tamakyi", logo, QRCodeSize)
	if err != nil {
		t.Fatal(err)
	}
	cx, cy := img.Bounds().Dx()/2, img.Bounds().Dy()/2
	r, _, _, _ := img.At(cx, cy).RGBA()
	if r < 0x8000 || r > 0xf000 {
		t.Errorf("center pixel should be the logo color, got %#x", r)
	}
	for _, p := range []image.Point{{0, 0}, {img.Bounds().Dx() - 1, 0}, {0, img.Bounds().Dy() - 1}} {
		r, g, b, _ := img.At(p.X, p.Y).RGBA()
		if r == 0xffff && g == 0xffff && b == 0xffff {
			t.Errorf("corner %v is white: finder pattern missing, symbol likely cropped", p)
		}
	}
}

func abs(v int) int {
	if v < 0 {
		return -v
	}
	return v
}

// 二维码必须按模块整数倍绘制：任何宽度落差的游程都意味着模块被拉伸，
// 小尺寸（微信/QQ 二次压缩后）最容易出现「扫不动」。同时必须把目标尺寸用满，
// 否则模块像素偏小，实际可扫距离大幅缩水。
func TestGenerateQRIsModuleAligned(t *testing.T) {
	const url = "https://box.shiroko.one/_/tamakyi"
	for _, size := range []int{QRCodeSize, QQRSize} {
		img, err := generateQR(url, nil, size)
		if err != nil {
			t.Fatal(err)
		}

		probe, err := qrcode.New(url, qrcode.High)
		if err != nil {
			t.Fatal(err)
		}
		probe.DisableBorder = true
		modules := len(probe.Bitmap())
		perModule := size / modules
		want := modules * perModule
		if got := img.Bounds().Dx(); got != want {
			t.Fatalf("size %d: got width %d, want %d (%d modules x %dpx)", size, got, want, modules, perModule)
		}
		if got := img.Bounds().Dy(); got != want {
			t.Fatalf("size %d: got height %d, want %d", size, got, want)
		}
		// 至少用掉目标尺寸的 80%，防止静默区/留白再次吃掉模块像素
		if float64(want) < 0.8*float64(size) {
			t.Fatalf("size %d: symbol only %dpx, wastes %.0f%% of the target", size, want, 100*(1-float64(want)/float64(size)))
		}

		// 逐行扫描：所有黑白游程都必须是模块宽度的整数倍
		for _, y := range []int{want / 2, want / 3} {
			runLen := 0
			for x := 0; x < want; x++ {
				r, _, _, _ := img.At(x, y).RGBA()
				black := r < 0x8000
				if x == 0 {
					runLen = 1
					continue
				}
				prevR, _, _, _ := img.At(x-1, y).RGBA()
				if (prevR < 0x8000) != black {
					if runLen%perModule != 0 {
						t.Fatalf("size %d: run of %dpx at x=%d is not a multiple of module %d",
							size, runLen, x-runLen, perModule)
					}
					runLen = 1
					continue
				}
				runLen++
			}
			if runLen%perModule != 0 {
				t.Fatalf("size %d: trailing run %dpx not a multiple of %d", size, runLen, perModule)
			}
		}
	}
}

// 模块像素是扫码能力的唯一硬指标：实测 5px/模块的卡缩到 320 宽仍可解码，
// 4px 时缩到 480 就解不出。这里锁住常见链接长度下的模块尺寸。
func TestGenerateQRModuleSizeAtLeast5(t *testing.T) {
	for _, url := range []string{
		"https://box.shiroko.one/_/tamakyi",
		"https://box-dev-api.337845818.best/_/tbunread1022181904",
		"https://box.shiroko.one/_/a-rather-long-handle-name",
	} {
		img, err := generateQR(url, nil, QRCodeSize)
		if err != nil {
			t.Fatal(err)
		}
		probe, err := qrcode.New(url, qrcode.High)
		if err != nil {
			t.Fatal(err)
		}
		probe.DisableBorder = true
		mods := len(probe.Bitmap())
		if per := img.Bounds().Dx() / mods; per < 5 {
			t.Errorf("%s: %d modules in %dpx -> %dpx/module, want >=5",
				url, mods, img.Bounds().Dx(), per)
		}
	}
}

// 单题卡的二维码卡片：模块必须够大、整块落在卡内、提示语不越界。
func TestQuestionQRCardLayout(t *testing.T) {
	requireFont(t)
	saved := conf.App.ExternalURL
	conf.App.ExternalURL = "https://box-dev-api.337845818.best"
	t.Cleanup(func() { conf.App.ExternalURL = saved })

	user := &db.User{Domain: "tbunread1022181904"}
	question := &db.Question{ID: 113}
	question.UserID = user.ID

	canvas := image.NewRGBA(image.Rect(0, 0, CardWidth, CardHeight))
	draw.Draw(canvas, canvas.Bounds(), &image.Uniform{ColorWhite}, image.Point{}, draw.Src)

	fctx := freetype.NewContext()
	fctx.SetFont(requireFont(t))
	fctx.SetDPI(72)
	if err := drawQuestionQRCard(canvas, user, question, nil, fctx); err != nil {
		t.Fatal(err)
	}

	// 二维码：着墨边界必须落在卡片内且四周留白 ≥20px，模块 ≥5px
	card := image.Rect(QQRCardX, QQRCardY, QQRCardX+QQRCardW, QQRCardY+QQRCardH)
	minX, minY, maxX, maxY := CardWidth, CardHeight, -1, -1
	for y := card.Min.Y; y < card.Min.Y+220; y++ {
		for x := card.Min.X; x < card.Max.X; x++ {
			if r, _, _, _ := canvas.At(x, y).RGBA(); r < 0x4000 {
				if x < minX {
					minX = x
				}
				if y < minY {
					minY = y
				}
				if x > maxX {
					maxX = x
				}
				if y > maxY {
					maxY = y
				}
			}
		}
	}
	if maxX < 0 {
		t.Fatal("nothing drawn in the QR card")
	}
	size := maxX - minX + 1
	if size != maxY-minY+1 {
		t.Fatalf("QR is not square: %dx%d", size, maxY-minY+1)
	}
	if per := size / qrModules(t, conf.App.ExternalURL+"/_/"+user.Domain+"/113"); per < 5 {
		t.Errorf("QR module is %dpx, want >=5", per)
	}
	for _, gap := range []struct {
		name       string
		got, limit int
	}{
		{"left", minX - card.Min.X, 20},
		{"right", card.Max.X - maxX - 1, 20},
		{"top", minY - card.Min.Y, 20},
		{"bottom", card.Max.Y - maxY - 1, 20},
	} {
		if gap.got < gap.limit {
			t.Errorf("%s margin %dpx < %dpx", gap.name, gap.got, gap.limit)
		}
	}

	if os.Getenv("TEST_PREVIEW") != "" {
		outDir := os.Getenv("TEST_PREVIEW_DIR")
		if outDir == "" {
			outDir = filepath.Join("..", "..", "outputs", "sharecard-preview")
		}
		if err := os.MkdirAll(outDir, 0o755); err != nil {
			t.Fatal(err)
		}
		f, err := os.Create(filepath.Join(outDir, "question-card.png"))
		if err != nil {
			t.Fatal(err)
		}
		if err := png.Encode(f, canvas); err != nil {
			t.Fatal(err)
		}
		f.Close()
	}
}

func qrModules(t *testing.T, content string) int {
	t.Helper()
	q, err := qrcode.New(content, qrcode.High)
	if err != nil {
		t.Fatal(err)
	}
	q.DisableBorder = true
	return len(q.Bitmap())
}

// 视觉自检：TEST_PREVIEW=1 时把链接区渲成 PNG，人工确认断行与对齐。
func TestShareCardLinkPreview(t *testing.T) {
	if os.Getenv("TEST_PREVIEW") == "" {
		t.Skip("set TEST_PREVIEW=1 to write preview images")
	}
	requireFont(t)
	outDir := os.Getenv("TEST_PREVIEW_DIR")
	if outDir == "" {
		outDir = filepath.Join("..", "..", "outputs", "sharecard-preview")
	}
	if err := os.MkdirAll(outDir, 0o755); err != nil {
		t.Fatal(err)
	}

	cases := map[string]string{
		"short":    "box.shiroko.one/_/tamakyi",
		"dev":      "box-dev-api.337845818.best/_/tamakyi",
		"long":     "ask.some-quite-long-domain-name.example.com/_/tamakyi",
		"verylong": "questions.tamabox-community.example.org/anon/box/_/a-rather-long-handle-name",
	}
	for name, display := range cases {
		canvas := image.NewRGBA(image.Rect(0, 0, QRCardW, QRCardH))
		draw.Draw(canvas, canvas.Bounds(), &image.Uniform{color.NRGBA{246, 246, 246, 255}}, image.Point{}, draw.Src)
		drawRoundedRect(canvas, canvas.Bounds(), ColorWhite, 18)

		fctx := freetype.NewContext()
		fctx.SetFont(requireFont(t))
		fctx.SetDPI(72)

		lines, size := layoutLink(display)
		const qrToHintGap, hintLineHeight, hintToSepGap, sepHeight, sepToLinkGap, linkLineHeight = 24, 17, 20, 1, 20, 16

		qr, err := generateQR("https://"+display, nil, QRCodeSize)
		if err != nil {
			t.Fatal(err)
		}
		qrSize := qr.Bounds().Dx()
		total := qrSize + qrToHintGap + hintLineHeight + hintToSepGap + sepHeight + sepToLinkGap + linkLineHeight*len(lines)
		startY := (QRCardH - total) / 2

		draw.Draw(canvas, image.Rect((QRCardW-qrSize)/2, startY, (QRCardW+qrSize)/2, startY+qrSize), qr, image.Point{}, draw.Over)

		hintY := startY + qrSize + qrToHintGap + hintLineHeight
		drawTextCentered(canvas, "扫码向我匿名提问", QRCardW/2, hintY, FontSizeQRHint, ColorHintGray, fctx)
		sepY := hintY + hintToSepGap
		drawLine(canvas, QRCardW/2-90, sepY, QRCardW/2+90, sepY, color.NRGBA{200, 200, 200, 180})
		linkY := sepY + sepToLinkGap + linkLineHeight
		for i, line := range lines {
			drawTextCentered(canvas, line, QRCardW/2, linkY+i*linkLineHeight, size, ColorDarkText, fctx)
		}

		f, err := os.Create(filepath.Join(outDir, name+".png"))
		if err != nil {
			t.Fatal(err)
		}
		if err := png.Encode(f, canvas); err != nil {
			t.Fatal(err)
		}
		f.Close()
	}
}