package spike

import "testing"

func TestLetterboxBGRToNCHWPlacesPixelInScaledImage(t *testing.T) {
	// One bright BGR pixel in a 2:1 frame should be resized into the centred
	// 640x320 image area.  The remaining top/bottom area must stay black.
	frame := []byte{0, 0, 0, 255, 0, 0}

	input, err := LetterboxBGRToNCHW(frame, 2, 1, 640)
	if err != nil {
		t.Fatalf("LetterboxBGRToNCHW returned an error: %v", err)
	}

	const plane = 640 * 640
	if got := len(input); got != 3*plane {
		t.Fatalf("input length = %d, want %d", got, 3*plane)
	}
	padding := float32(114.0 / 255.0)
	if got := input[2*plane+159*640+320]; got != padding {
		t.Fatalf("top padding blue channel = %v, want %v", got, padding)
	}
	if got := input[0*plane+320*640+320]; got != 0 {
		t.Fatalf("red channel = %v, want 0", got)
	}
	if got := input[1*plane+320*640+320]; got != 0 {
		t.Fatalf("green channel = %v, want 0", got)
	}
	if got := input[2*plane+320*640+320]; got != float32(128.0/255.0) {
		t.Fatalf("blue channel = %v, want cv2 INTER_LINEAR value 128/255", got)
	}
}

func TestLetterboxBGRToNCHWRejectsIncorrectFrameSize(t *testing.T) {
	_, err := LetterboxBGRToNCHW([]byte{0}, 2, 1, 640)
	if err == nil {
		t.Fatal("LetterboxBGRToNCHW accepted a truncated BGR frame")
	}
}