package caption_test

import (
	"crypto/sha1"
	"encoding/hex"
	"errors"
	"image"
	"image/color"
	"image/png"
	"testing"

	"git.gensokyo.uk/yonah/caption"
	"github.com/golang/freetype/truetype"
)

var (
	beforeCheck []func(t *testing.T, name string, got image.Image)
)

func TestRender(t *testing.T) {
	testCases := []struct {
		name    string
		line    *caption.Line
		x, y    int
		want    string
		wantErr error
	}{
		{"bad font", &caption.Line{Font: []byte{0xfd}},
			0, 0, "", truetype.FormatError("TTF data is too short")},
		{"colors", &caption.Line{Data: []caption.Segment{
			{"Blue", c(0x55, 0xcd, 0xfc)},
			{"Pink", c(0xf7, 0xa8, 0xb8)},
			{"White", color.White},
			{"Pink", c(0xf7, 0xa8, 0xb8)},
			{"Blue", c(0x55, 0xcd, 0xfc)},
		}}, 7 << 6, 1 << 8, "2af4b09361aeb3a9befc79cc0b28dd3874657fa0", nil},
	}

	var digest []byte
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			got := image.NewRGBA64(image.Rectangle{Max: image.Point{X: 1 << 10, Y: 1 << 9}})
			err := tc.line.Render(got, tc.x, tc.y)
			if err != nil {
				if !errors.Is(err, tc.wantErr) {
					t.Errorf("Render: error = %q, want %q",
						err, tc.wantErr)
				}
				return
			}

			for _, f := range beforeCheck {
				f(t, tc.name, got)
			}

			t.Run("hash", func(t *testing.T) {
				var wantDigest []byte
				if wantDigest, err = hex.DecodeString(tc.want); err != nil {
					t.Errorf("cannot parse expected hash: %v", err)
				}

				h := sha1.New()
				if err = (&png.Encoder{CompressionLevel: png.NoCompression}).Encode(h, got); err != nil {
					t.Fatalf("cannot encode png for hashing: %v", err)
				}
				digest := h.Sum(digest[:0])
				if string(digest) != string(wantDigest) {
					t.Errorf("Render: %x, want %x", digest, wantDigest)
				}
			})
		})
	}
}

func c(r, g, b uint8) color.Color { return color.NRGBA{R: r, G: g, B: b, A: 0xff} }