Function replaceRangeInternal

packages/cli/src/ui/components/shared/text-buffer.ts:425–496

(
  state: TextBufferState,
  startRow: number,
  startCol: number,
  endRow: number,
  endCol: number,
  text: string,
)

};

export const replaceRangeInternal = (
  state: TextBufferState,
  startRow: number,
  startCol: number,
  endRow: number,
  endCol: number,
  text: string,
): TextBufferState => {
  const currentLine = (row: number) => state.lines[row] || '';
  const currentLineLen = (row: number) => cpLen(currentLine(row));
  const clamp = (value: number, min: number, max: number) =>
    Math.min(Math.max(value, min), max);

  if (
    startRow > endRow ||
    (startRow === endRow && startCol > endCol) ||
    startRow < 0 ||
    startCol < 0 ||
    endRow >= state.lines.length ||
    (endRow < state.lines.length && endCol > currentLineLen(endRow))
  ) {
    return state; // Invalid range
  }

  const newLines = [...state.lines];

  const sCol = clamp(startCol, 0, currentLineLen(startRow));
  const eCol = clamp(endCol, 0, currentLineLen(endRow));

  const prefix = cpSlice(currentLine(startRow), 0, sCol);
  const suffix = cpSlice(currentLine(endRow), eCol);

  const normalisedReplacement = text
    .replace(/\r\n/g, '\n')
    .replace(/\r/g, '\n');
  const replacementParts = normalisedReplacement.split('\n');

  // The combined first line of the new text
  const firstLine = prefix + replacementParts[0];

  if (replacementParts.length === 1) {
    // No newlines in replacement: combine prefix, replacement, and suffix on one line.
    newLines.splice(startRow, endRow - startRow + 1, firstLine + suffix);
  } else {
    // Newlines in replacement: create new lines.
    const lastLine = replacementParts[replacementParts.length - 1] + suffix;
    const middleLines = replacementParts.slice(1, -1);
    newLines.splice(
      startRow,
      endRow - startRow + 1,
      firstLine,
      ...middleLines,
      lastLine,
    );
  }

  const finalCursorRow = startRow + replacementParts.length - 1;
  const finalCursorCol =