grep.ts

type GrepOptions = {
  context?: number | { before?: number; after?: number };
  colors?: boolean;
  caseSensitive?: boolean;
  multiline?: boolean;
};

function grep(
  content: string | string[],
  matchPattern: string,
  options?: GrepOptions
): string[] {
  const lines: string[] = Array.isArray(content)
    ? content
    : content.split("\n");

  const {
    context = 0,
    colors = false,
    caseSensitive = false,
    multiline = false,
  } = options || {};

  const contextBefore =
    typeof context === "number" ? context : context.before || 0;
  const contextAfter =
    typeof context === "number" ? context : context.after || 0;
  const pattern = caseSensitive ? matchPattern : matchPattern.toLowerCase();

  const matches: string[] = [];

  for (let i = 0; i < lines.length; i++) {
    const lineContent = multiline
      ? lines[i]
      : caseSensitive
      ? lines[i]
      : lines[i].toLowerCase();
    if (lineContent.includes(pattern)) {
      const from = Math.max(i - contextBefore, 0);
      const to = Math.min(i + contextAfter + 1, lines.length);

      for (let j = from; j < i; j++) {
        matches.push(formatLine(lines[j], "", colors));
      }

      matches.push(formatLine(lines[i], pattern, colors, caseSensitive));

      for (let j = i + 1; j < to; j++) {
        matches.push(formatLine(lines[j], "", colors));
      }

      // Adjust the index to skip lines added as after context to avoid duplication
      i += contextAfter;
    }
  }

  return matches;
}

function formatLine(
  line: string,
  pattern: string,
  colors: boolean,
  caseSensitive: boolean = false
): string {
  if (!colors || pattern === "") {
    return line;
  }

  // Pattern highlighting
  const regex = new RegExp(pattern, caseSensitive ? "g" : "gi");
  return line.replace(regex, (match) => `\x1b[42m\x1b[30m${match}\x1b[0m`);
}

// Usage example
const content = `This project is powered by [@marko/run](https://github.com/marko-js/run).

- Run \`pnpm run dev\` to start the development server
- Run \`pnpm run build\` to build a production-ready node.js server
- Run \`pnpm run preview\` to run the production server
The Storybook Links addon can be used to create links that navigate between stories in Storybook.

[Create a custom ChatGPT to create stories](https://storybook.js.org/blog/build-your-own-storybook-gpt/)
Speeding up Development`;

console.log(
  "CONTENT -----------------",
  content,
  "--------------------------------------"
);
const matchedLines = grep(content, "dev", {
  context: { before: 3, after: 5 },
  colors: true,
  multiline: true,
});

console.log(matchedLines);