package core

import "testing"

func TestComputeBufferEditReplaceLine(t *testing.T) {
	oldSource := "abc\ndef"
	newSource := "abc\nxyz"

	edit, ok := computeBufferEdit(oldSource, newSource)
	if !ok {
		t.Fatalf("expected edit to be detected")
	}

	if edit.StartPoint.Row != 1 || edit.StartPoint.Column != 0 {
		t.Fatalf("unexpected start point: %+v", edit.StartPoint)
	}
	if edit.OldEndPoint.Row != 1 || edit.OldEndPoint.Column != 3 {
		t.Fatalf("unexpected old end point: %+v", edit.OldEndPoint)
	}
	if edit.NewEndPoint.Row != 1 || edit.NewEndPoint.Column != 3 {
		t.Fatalf("unexpected new end point: %+v", edit.NewEndPoint)
	}
}

func TestComputeBufferEditInsertAtEnd(t *testing.T) {
	oldSource := "a\nb"
	newSource := "a\nbb"

	edit, ok := computeBufferEdit(oldSource, newSource)
	if !ok {
		t.Fatalf("expected edit to be detected")
	}

	if edit.StartByte != 3 || edit.OldEndByte != 3 || edit.NewEndByte != 4 {
		t.Fatalf("unexpected byte offsets: %+v", edit)
	}
	if edit.StartPoint.Row != 1 || edit.StartPoint.Column != 1 {
		t.Fatalf("unexpected start point: %+v", edit.StartPoint)
	}
}

func TestByteOffsetToPoint(t *testing.T) {
	src := []byte("ab\ncd\nef")

	p := byteOffsetToPoint(src, 0)
	if p.Row != 0 || p.Column != 0 {
		t.Fatalf("offset 0 mismatch: %+v", p)
	}

	p = byteOffsetToPoint(src, 4) // right after 'c'
	if p.Row != 1 || p.Column != 1 {
		t.Fatalf("offset 4 mismatch: %+v", p)
	}

	p = byteOffsetToPoint(src, len(src))
	if p.Row != 2 || p.Column != 2 {
		t.Fatalf("end offset mismatch: %+v", p)
	}
}

func TestUndoRedoEmitBufferChange(t *testing.T) {
	b := NewBufferBuilder().WithFiletype("go").WithLines([]string{"one", "two"}).Build()
	buf := &b

	win := NewWindowBuilder().WithBuffer(buf).Build()
	w := &win

	buf.UndoStack.BeginBlock(Position{Line: 0, Col: 0})
	buf.SetLine(0, "ONE")
	buf.UndoStack.EndBlock(Position{Line: 0, Col: 3})

	changes := []BufferChange{}
	buf.OnChange = func(change BufferChange) {
		changes = append(changes, change)
	}

	if !buf.Undo(w) {
		t.Fatalf("expected undo to succeed")
	}
	if len(changes) != 1 {
		t.Fatalf("expected one change notification on undo, got %d", len(changes))
	}
	if changes[0].Edit == nil {
		t.Fatalf("expected undo change to include edit metadata")
	}
	if got := buf.Line(0); got != "one" {
		t.Fatalf("undo did not restore content, got %q", got)
	}

	changes = nil
	if !buf.Redo(w) {
		t.Fatalf("expected redo to succeed")
	}
	if len(changes) != 1 {
		t.Fatalf("expected one change notification on redo, got %d", len(changes))
	}
	if changes[0].Edit == nil {
		t.Fatalf("expected redo change to include edit metadata")
	}
	if got := buf.Line(0); got != "ONE" {
		t.Fatalf("redo did not reapply content, got %q", got)
	}
}