Add prune orphaned todos command

[tylerbecks]

Currently, there is no command to remove orphaned todos. There are 2 ways that todos can become orphaned (that I can think of):

1. the file for the todo no longer exists (it was moved or deleted)
2. the rule the todo was created for was removed/disabled

After realizing the performance impact of the lint-todo system with many todos, we are prioritizing reducing the line count in the .lint-todo file as much as possible.

Here is an example of a command I wrote to clean up todo for files that no longer exist (case 1)

const fs = require('fs');

/**
 * This script parses a .lint-todo file and removes lines for non-existent files in the current working directory.
 *
 * Usage:
 *     node scripts/lint-todo-dead-file-cleaner.js /path/to/your/.lint-todo
 *
 * Replace '/path/to/your/.lint-todo' with the actual path to your .lint-todo file.
 *
 */

/**
 * Parses the contents of a .lint-todo file and returns a set of unique file paths and a list of lines from the file.
 * @param {string} filePath - The path to the .lint-todo file.
 * @returns {[Set<string>, string[]]} - A tuple containing a set of unique file paths and a list of lines from the file.
 */
function parseLintTodoFile(filePath) {
  const lines = fs.readFileSync(filePath, { encoding: 'utf8' }).split('\n');
  const filePaths = lines.map((line) => line.split('|').pop().trim()).filter(Boolean);
  return {
    filePaths: new Set(filePaths),
    lines
  };
}

/**
 * Checks if a file exists.
 * @param {string} filePath - The path to the file.
 * @returns {boolean} - `true` if the file exists, `false` otherwise.
 */
function checkFileExists(filePath) {
  return fs.existsSync(filePath);
}

/**
 * Removes lines for non-existent files from a .lint-todo file.
 * @param {string} filePath - The path to the .lint-todo file.
 * @param {string[]} lines - A list of lines from the .lint-todo file.
 * @param {Set<string>} nonexistentFiles - A set of non-existent file paths.
 */
function removeNonexistentFiles(filePath, lines, nonexistentFiles) {
  fs.writeFileSync(
    filePath,
    lines
      .filter((line) => {
        const filePath = line.split('|').pop().trim();
        return !nonexistentFiles.has(filePath);
      })
      .join('\n')
  );
}

/**
 * Entry point for the script. Parses command line arguments, checks for non-existent files, and removes their lines from the .lint-todo file.
 */
function main() {
  const filePath = process.argv[2];

  const { filePaths, lines } = parseLintTodoFile(filePath);
  const nonexistentFiles = new Set(Array.from(filePaths).filter((filePath) => !checkFileExists(filePath)));

  if (nonexistentFiles.size > 0) {
    removeNonexistentFiles(filePath, lines, nonexistentFiles);
    console.log(`${nonexistentFiles.size} dead files detected in .lint-todo:`);
    for (const filePath of nonexistentFiles) {
      console.log(`  - ${filePath}`);
    }

    const { lines: newLines } = parseLintTodoFile(filePath);
    console.log(`Removed ${lines.length - newLines.length} lines from the .lint-todo file`);
  } else {
    console.log('All files listed in the .lint-todo file exist.');
  }
}

main();

[Techn1x]

Noticed this the other day as well - would love for this to run as part of compacting the todo list