package wpdf

import (
	"bytes"
	"image"
	"image/color"
	"image/png"
	"strings"
	"testing"
)

func makeTestPNG(t *testing.T, w, h int) []byte {
	t.Helper()
	img := image.NewRGBA(image.Rect(0, 0, w, h))
	for y := range h {
		for x := range w {
			img.Set(x, y, color.RGBA{R: uint8(x), G: uint8(y), B: 128, A: 255})
		}
	}
	var buf bytes.Buffer
	if err := png.Encode(&buf, img); err != nil {
		t.Fatalf("png encode: %v", err)
	}
	return buf.Bytes()
}

func TestRegisterImageDetectsPNG(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	bin := makeTestPNG(t, 16, 16)
	ref := b.RegisterImage(bin)

	if ref == nil {
		t.Fatal("RegisterImage returned nil")
	}
	if !strings.HasPrefix(ref.Name, "fpdf_img_") {
		t.Errorf("default name not prefixed: %q", ref.Name)
	}
	if ref.Mime != "image/png" {
		t.Errorf("mime = %q, want image/png", ref.Mime)
	}
	if ref.Info == nil {
		t.Error("info is nil")
	}
	if !bytes.Equal(ref.Bin, bin) {
		t.Error("Bin not stored correctly")
	}
}

func TestRegisterImageWithCustomName(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	bin := makeTestPNG(t, 8, 8)
	ref := b.RegisterImage(bin, NewPDFImageRegisterOpt().Name("custom_image"))

	if ref.Name != "custom_image" {
		t.Errorf("custom name not used: %q", ref.Name)
	}
}

func TestRegisterImageWithExplicitType(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	bin := makeTestPNG(t, 8, 8)
	ref := b.RegisterImage(bin, NewPDFImageRegisterOpt().ImageType("PNG"))

	if ref.Info == nil {
		t.Error("info is nil")
	}
}

func TestRegisterImageLargeBuffer(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	// Larger than 512 bytes to exercise that branch in detection.
	bin := makeTestPNG(t, 256, 256)
	if len(bin) <= 512 {
		t.Fatalf("test png unexpectedly small: %d bytes", len(bin))
	}
	ref := b.RegisterImage(bin)

	if ref.Mime != "image/png" {
		t.Errorf("mime = %q, want image/png", ref.Mime)
	}
}

func TestImageDrawing(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	bin := makeTestPNG(t, 16, 16)
	ref := b.RegisterImage(bin)

	b.Image(ref, NewPDFImageOpt().X(10).Y(10).Width(20).Height(20))

	out, err := b.Build()
	if err != nil {
		t.Fatalf("Build error: %v", err)
	}
	if !bytes.HasPrefix(out, []byte("%PDF-")) {
		t.Error("output not a PDF")
	}
}

func TestImageDrawingDefaults(t *testing.T) {
	b := NewPDFBuilder(Portrait, SizeA4, false)
	b.AddPage()

	bin := makeTestPNG(t, 16, 16)
	ref := b.RegisterImage(bin)

	b.Image(ref) // no opts: use info defaults

	out, err := b.Build()
	if err != nil {
		t.Fatalf("Build error: %v", err)
	}
	if !bytes.HasPrefix(out, []byte("%PDF-")) {
		t.Error("output not a PDF")
	}
}