package zxchainsdk

import (
	"bytes"
	"context"
	"image/color"
	"image/png"
	"testing"

	"github.com/fogleman/gg"
)

func TestGenerateHashCertificateWithExplicitFontPath(t *testing.T) {
	fontPath := firstAvailableTestFont(t)

	result, err := GenerateHashCertificate(context.Background(), HashCertificateRequest{
		Title:            "数字作品区块链存证证明",
		CertNo:           "2026051315081710006",
		UserName:         "测试用户",
		UserID:           "10006",
		WorkName:         "测试作品",
		TaskID:           "task-10006",
		CompletedAt:      "2026.05.13 15:08:17",
		EvidenceID:       "ev-test",
		TxID:             "tx-test",
		BlockHeight:      "123456",
		FinalHash:        "final-hash-test",
		EvidenceHash:     "evidence-hash-test",
		TrustedAt:        "2026.05.13 15:08:17",
		VerifyURL:        "https://example.com/certificates/ev-test/certificate.png",
		WorkPreviewBytes: solidPNG(t, 120, 80, color.RGBA{R: 0x33, G: 0x66, B: 0xcc, A: 0xff}),
		BackgroundBytes:  solidPNG(t, 1369, 1920, color.RGBA{R: 0xff, G: 0xfd, B: 0xf8, A: 0xff}),
		LogoBytes:        solidPNG(t, 304, 60, color.RGBA{R: 0x11, G: 0x11, B: 0x11, A: 0xff}),
		FontPath:         fontPath,
		BucketBaseURL:    "https://example.com",
	})
	if err != nil {
		t.Fatalf("GenerateHashCertificate() error = %v", err)
	}
	if len(result.PNG) == 0 {
		t.Fatal("GenerateHashCertificate() returned empty PNG")
	}
	if _, err := png.Decode(bytes.NewReader(result.PNG)); err != nil {
		t.Fatalf("generated certificate is not a valid PNG: %v", err)
	}
}

func firstAvailableTestFont(t *testing.T) string {
	t.Helper()

	for _, candidate := range certificateFontCandidates() {
		if _, err := validateCertificateFont(candidate); err == nil {
			return candidate
		}
	}
	t.Skip("no loadable certificate font installed")
	return ""
}

func solidPNG(t *testing.T, width, height int, c color.Color) []byte {
	t.Helper()

	dc := gg.NewContext(width, height)
	dc.SetColor(c)
	dc.DrawRectangle(0, 0, float64(width), float64(height))
	dc.Fill()

	var buf bytes.Buffer
	if err := png.Encode(&buf, dc.Image()); err != nil {
		t.Fatalf("encode test PNG: %v", err)
	}
	return buf.Bytes()
}