const fs = require("node:fs/promises");
const path = require("node:path");
const { collectFilesByExtensions } = require("./content");

const DEFAULT_URL_TEXT_EXTENSIONS = Object.freeze([
  ".json",
  ".markdown",
  ".md",
  ".yaml",
  ".yml",
]);

/**
 * Compte les occurrences exactes d'une chaine dans un texte.
 * @param {string} text Texte a analyser.
 * @param {string} needle Chaine recherchee.
 * @returns {number} Nombre d'occurrences trouvees.
 */
function countOccurrences(text, needle) {
  if (typeof text !== "string") {
    return 0;
  }
  if (typeof needle !== "string" || !needle) {
    return 0;
  }
  return text.split(needle).length - 1;
}

/**
 * Retourne la liste des fichiers textuels contenant une URL donnee.
 * @param {string} rootDir Racine a parcourir.
 * @param {string} targetUrl URL a rechercher.
 * @param {{ extensions?: string[] }} options Options de recherche.
 * @returns {Promise<Array<{ filePath: string, occurrences: number }>>}
 */
async function findUrlOccurrences(rootDir, targetUrl, options = {}) {
  let extensions = DEFAULT_URL_TEXT_EXTENSIONS;
  if (Array.isArray(options.extensions)) {
    extensions = options.extensions;
  }
  const files = await collectFilesByExtensions(rootDir, extensions);
  const matches = [];

  for (const filePath of files) {
    const content = await fs.readFile(filePath, "utf8");
    const occurrences = countOccurrences(content, targetUrl);
    if (occurrences <= 0) {
      continue;
    }
    matches.push({ filePath, occurrences });
  }

  return matches;
}

/**
 * Remplace toutes les occurrences exactes d'une URL dans une liste de fichiers.
 * @param {string} rootDir Racine de recherche.
 * @param {string} targetUrl URL a remplacer.
 * @param {string} replacementUrl URL de remplacement.
 * @param {{ extensions?: string[], matches?: Array<{ filePath: string, occurrences: number }> }} options Options d'ecriture.
 * @returns {Promise<{ changedFiles: string[], totalOccurrences: number }>}
 */
async function replaceUrlInFiles(rootDir, targetUrl, replacementUrl, options = {}) {
  let matches = [];
  if (Array.isArray(options.matches)) {
    matches = options.matches;
  } else {
    matches = await findUrlOccurrences(rootDir, targetUrl, options);
  }

  const changedFiles = [];
  let totalOccurrences = 0;

  for (const match of matches) {
    const filePath = path.resolve(match.filePath);
    const content = await fs.readFile(filePath, "utf8");
    const updatedContent = content.split(targetUrl).join(replacementUrl);
    await fs.writeFile(filePath, updatedContent, "utf8");
    changedFiles.push(filePath);
    totalOccurrences += match.occurrences;
  }

  return { changedFiles, totalOccurrences };
}

module.exports = {
  DEFAULT_URL_TEXT_EXTENSIONS,
  countOccurrences,
  findUrlOccurrences,
  replaceUrlInFiles,
};