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package editor

// MoveLineUp swaps the current line with the line above, keeping the cursor on
// the moved line (same column). No-op at the top of the document. Returns true
// if a swap happened (TASK-024).
func (e *Editor) MoveLineUp() bool {
	r := e.Cursor.Row
	if r <= 0 {
		return false
	}
	e.Lines[r-1], e.Lines[r] = e.Lines[r], e.Lines[r-1]
	e.Cursor.Row = r - 1
	e.afterMoveLine()
	return true
}

// MoveLineDown swaps the current line with the line below, keeping the cursor on
// the moved line (same column). No-op at the bottom of the document. Returns
// true if a swap happened (TASK-024).
func (e *Editor) MoveLineDown() bool {
	r := e.Cursor.Row
	if r >= len(e.Lines)-1 {
		return false
	}
	e.Lines[r+1], e.Lines[r] = e.Lines[r], e.Lines[r+1]
	e.Cursor.Row = r + 1
	e.afterMoveLine()
	return true
}

// afterMoveLine clamps the column to the moved line and refreshes editor state.
func (e *Editor) afterMoveLine() {
	if n := len([]rune(e.Lines[e.Cursor.Row])); e.Cursor.Col > n {
		e.Cursor.Col = n
	}
	e.Dirty = true
	e.setGoal()
	e.followCursor()
}