package question

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

	"github.com/disintegration/imaging"
	"github.com/golang/freetype"
	"github.com/golang/freetype/truetype"

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

// 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)
		}
	}
}

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

// 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 = 26, 17, 21, 1, 21, 15
		total := QRCodeSize + qrToHintGap + hintLineHeight + hintToSepGap + sepHeight + sepToLinkGap + linkLineHeight*len(lines)
		startY := (QRCardH - total) / 2

		qr, err := generateQR("https://"+display, nil, nil)
		if err != nil {
			t.Fatal(err)
		}
		qrResized := imaging.Resize(qr, QRCodeSize, QRCodeSize, imaging.NearestNeighbor)
		draw.Draw(canvas, image.Rect(QRCodeX, startY, QRCodeX+QRCodeSize, startY+QRCodeSize), qrResized, image.Point{}, draw.Over)

		hintY := startY + QRCodeSize + 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()
	}
}