package braille

import (
	"bytes"
	"reflect"
	"testing"
)

func TestDisplayMasksPreserveEveryRawCell(t *testing.T) {
	text := make([]rune, 256)
	dots := make([]byte, 256)
	for index := range text {
		text[index] = rune(0x2800 + index)
		dots[index] = 0x40
	}
	andMask, orMask, err := displayMasks(string(text), nil)
	if err != nil {
		t.Fatal(err)
	}
	for index := range text {
		if andMask[index] != 0 || orMask[index] != byte(index) {
			t.Fatalf("cell %d: and=%x or=%x", index, andMask[index], orMask[index])
		}
	}
	andMask, orMask, err = displayMasks(string(text), dots)
	if err != nil {
		t.Fatal(err)
	}
	for index := range text {
		if andMask[index] != 0 || orMask[index] != byte(index)|0x40 {
			t.Fatalf("cell %d lost raw dots or attributes", index)
		}
	}
}

func TestDisplayMasksRetainTextTranslation(t *testing.T) {
	andMask, orMask, err := displayMasks("a界 ⠁", []byte{0x40, 0, 0, 0x80})
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(andMask, []byte{0xff, 0xff, 0xff, 0}) ||
		!bytes.Equal(orMask, []byte{0x40, 0, 0, 0x81}) {
		t.Fatalf("and=%x or=%x", andMask, orMask)
	}
	for _, tc := range []struct {
		text string
		dots []byte
	}{{"\xff", nil}, {"界", []byte{1, 2}}, {"", []byte{1}}} {
		if _, _, err := displayMasks(tc.text, tc.dots); err == nil {
			t.Fatal("accepted invalid frame")
		}
	}
}

func TestRawCellsCursorPaddingAndSnapshotOwnership(t *testing.T) {
	v := viewport{width: 4}
	if err := v.setFrame(Frame{ID: 8, Text: "⠁⠃", Cursor: 2, Dots: []byte{0x40, 0}}); err != nil {
		t.Fatal(err)
	}
	cells, err := v.rawCells(0xc0)
	if err != nil || !bytes.Equal(cells, []byte{0x41, 3, 0xc0, 0}) {
		t.Fatalf("cells=%x error=%v", cells, err)
	}
	if route, ok := v.route(RouteBase + 2); !ok || route != (RoutingEvent{ID: 8, Offset: 2}) {
		t.Fatalf("end-of-line route=%+v ok=%v", route, ok)
	}
	if _, ok := v.route(RouteBase + 3); ok {
		t.Fatal("padding has a routing target")
	}
	cells[0] = 0xff
	withoutCursor, err := v.rawCells(0)
	if err != nil || !bytes.Equal(withoutCursor, []byte{0x41, 3, 0, 0}) {
		t.Fatalf("snapshot or cursor mutated viewport: %x, %v", withoutCursor, err)
	}
	if err := v.setFrame(Frame{ID: 9, Cursor: -1}); err != nil {
		t.Fatal(err)
	}
	cleared, err := v.rawCells(0xc0)
	if err != nil || !bytes.Equal(cleared, make([]byte, 4)) {
		t.Fatalf("empty replacement=%x, %v", cleared, err)
	}
	if _, ok := v.route(RouteBase); ok {
		t.Fatal("empty replacement retained routing")
	}
	if cells[1] != 3 {
		t.Fatal("replacement changed an earlier snapshot")
	}
}

func TestRawCellsRequireTranslationAndValidWidth(t *testing.T) {
	v := viewport{width: 4}
	if err := v.setFrame(Frame{Text: "cat", Cursor: -1}); err != nil {
		t.Fatal(err)
	}
	if _, err := v.rawCells(0xc0); err == nil {
		t.Fatal("ordinary text was exported as guessed dots")
	}
	for _, width := range []int{-1, 0, 4097} {
		invalid := viewport{width: width}
		if _, err := invalid.rawCells(0); err == nil {
			t.Fatalf("accepted width %d", width)
		}
	}
	v = viewport{width: 4096}
	if err := v.setFrame(Frame{Cursor: -1}); err != nil {
		t.Fatal(err)
	}
	cells, err := v.rawCells(0)
	if err != nil || len(cells) != 4096 {
		t.Fatalf("maximum width: %d, %v", len(cells), err)
	}
}

func TestRawCellsFailureDoesNotAlterViewport(t *testing.T) {
	v := viewport{width: 2}
	if err := v.setFrame(Frame{Text: "abcd", Cursor: -1}); err != nil {
		t.Fatal(err)
	}
	v.pan(PanRight)
	before := v
	if _, err := v.rawCells(0xc0); err == nil {
		t.Fatal("accepted untranslated text")
	}
	if !reflect.DeepEqual(v, before) {
		t.Fatal("failed export changed local presentation")
	}
}