package buffer

import "testing"

func TestNoSelectionByDefault(t *testing.T) {
	b := NewFromString("abc")

	if _, ok := b.Selection(); ok {
		t.Error("a fresh buffer must have no selection")
	}
	if got := b.SelectedText(); got != "" {
		t.Errorf("SelectedText() = %q, want empty", got)
	}
}

func TestSelectionExtendsFromTheAnchor(t *testing.T) {
	b := NewFromString("hello world")
	b.SetCursor(Position{Line: 0, Col: 6})
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 0, Col: 11})

	r, ok := b.Selection()
	if !ok {
		t.Fatal("Selection() reported none after extending from an anchor")
	}
	if r.Start != (Position{Line: 0, Col: 6}) || r.End != (Position{Line: 0, Col: 11}) {
		t.Errorf("Selection() = %+v, want columns 6 to 11", r)
	}
	if got := b.SelectedText(); got != "world" {
		t.Errorf("SelectedText() = %q, want %q", got, "world")
	}
}

func TestSelectionIsOrderedWhenTheCursorGoesBackwards(t *testing.T) {
	b := NewFromString("hello world")
	b.SetCursor(Position{Line: 0, Col: 5})
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 0, Col: 0})

	if got := b.SelectedText(); got != "hello" {
		t.Errorf("SelectedText() = %q, want %q even though the cursor moved left", got, "hello")
	}
}

func TestSelectionSpanningLinesJoinsWithLineFeeds(t *testing.T) {
	b := NewFromString("one\r\ntwo\r\nthree\r\n")
	b.SetCursor(Position{Line: 0, Col: 1})
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 2, Col: 2})

	if got := b.SelectedText(); got != "ne\ntwo\nth" {
		t.Errorf("SelectedText() = %q, want line feeds regardless of the file's CRLF endings", got)
	}
}

func TestSelectionCollapsedOntoItsAnchorCountsAsAbsent(t *testing.T) {
	b := NewFromString("abc")
	b.SetCursor(Position{Line: 0, Col: 1})
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 0, Col: 2})
	b.SetCursorKeepingSelection(Position{Line: 0, Col: 1})

	if _, ok := b.Selection(); ok {
		t.Error("a selection reduced to nothing must report as absent")
	}
}

func TestClearSelectionDropsTheAnchor(t *testing.T) {
	b := NewFromString("abc")
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 0, Col: 3})

	b.ClearSelection()

	if _, ok := b.Selection(); ok {
		t.Error("ClearSelection left a selection behind")
	}
}

func TestSetCursorDropsTheSelectionButSetCursorKeepingSelectionDoesNot(t *testing.T) {
	b := NewFromString("abcdef")
	b.StartSelection()

	b.SetCursorKeepingSelection(Position{Line: 0, Col: 3})
	if _, ok := b.Selection(); !ok {
		t.Fatal("SetCursorKeepingSelection must keep the anchor")
	}

	b.SetCursor(Position{Line: 0, Col: 5})
	if _, ok := b.Selection(); ok {
		t.Error("SetCursor must drop the anchor")
	}
}

func TestSelectAllCoversTheWholeBuffer(t *testing.T) {
	b := NewFromString("one\ntwo")

	b.SelectAll()

	if got := b.SelectedText(); got != "one\ntwo" {
		t.Errorf("SelectedText() = %q, want the whole text", got)
	}
	if got := b.Cursor(); got != (Position{Line: 1, Col: 3}) {
		t.Errorf("Cursor() = %+v, want the end of the buffer", got)
	}
}

func TestDeleteSelectionRemovesItAndReportsSo(t *testing.T) {
	b := NewFromString("one\ntwo\nthree")
	b.SetCursor(Position{Line: 0, Col: 1})
	b.StartSelection()
	b.SetCursorKeepingSelection(Position{Line: 2, Col: 2})

	if !b.DeleteSelection() {
		t.Fatal("DeleteSelection() = false, want true when something is selected")
	}
	if got := b.Text(); got != "oree" {
		t.Errorf("Text() = %q, want %q", got, "oree")
	}
	if got := b.Cursor(); got != (Position{Line: 0, Col: 1}) {
		t.Errorf("Cursor() = %+v, want the start of the deleted span", got)
	}
}

func TestDeleteSelectionWithoutOneChangesNothing(t *testing.T) {
	b := NewFromString("abc")

	if b.DeleteSelection() {
		t.Error("DeleteSelection() = true, want false when nothing is selected")
	}
	if got := b.Text(); got != "abc" {
		t.Errorf("Text() = %q, want it unchanged", got)
	}
	if b.Modified() {
		t.Error("DeleteSelection with no selection must not mark the buffer modified")
	}
}