const fs = require("node:fs");
const path = require("node:path");
const yaml = require("js-yaml");
const { loadToolsConfig } = require("./config");

const DEFAULT_CACHE_DIR = "tools/cache";
const DEFAULT_CACHE_FILE = "external_links.yaml";

/**
 * Resout le chemin du rapport des liens externes a partir de la configuration.
 * @param {string} siteRoot Racine du projet.
 * @returns {Promise<string>} Chemin absolu du rapport YAML.
 */
async function resolveExternalLinksReportPath(siteRoot) {
  const rootDir = path.resolve(siteRoot);
  const configPath = path.join(rootDir, "tools", "config", "config.json");
  const config = await loadToolsConfig(configPath);

  let cacheDir = DEFAULT_CACHE_DIR;
  const externalLinks = config.externalLinks;
  if (externalLinks && typeof externalLinks.cacheDir === "string" && externalLinks.cacheDir.trim()) {
    cacheDir = externalLinks.cacheDir.trim();
  }

  let cacheFile = DEFAULT_CACHE_FILE;
  if (externalLinks && typeof externalLinks.cacheFile === "string" && externalLinks.cacheFile.trim()) {
    cacheFile = externalLinks.cacheFile.trim();
  }

  let resolvedCacheDir = cacheDir;
  if (!path.isAbsolute(resolvedCacheDir)) {
    resolvedCacheDir = path.join(rootDir, resolvedCacheDir);
  }

  if (path.isAbsolute(cacheFile)) {
    return cacheFile;
  }

  return path.join(resolvedCacheDir, cacheFile);
}

/**
 * Normalise la liste des emplacements associes a un lien.
 * @param {unknown[]} rawLocations Emplacements bruts.
 * @returns {Array<{ file: string, line: number|null, page: string|null }>}
 */
function normalizeLocations(rawLocations) {
  if (!Array.isArray(rawLocations)) {
    return [];
  }

  const locations = [];
  for (const rawLocation of rawLocations) {
    if (!rawLocation || typeof rawLocation !== "object") {
      continue;
    }

    let file = null;
    if (typeof rawLocation.file === "string" && rawLocation.file.trim()) {
      file = rawLocation.file.trim();
    }
    if (!file) {
      continue;
    }

    let line = null;
    if (typeof rawLocation.line === "number" && Number.isFinite(rawLocation.line)) {
      line = rawLocation.line;
    }

    let page = null;
    if (typeof rawLocation.page === "string" && rawLocation.page.trim()) {
      page = rawLocation.page.trim();
    }

    locations.push({ file, line, page });
  }

  return locations;
}

/**
 * Normalise une entree du rapport.
 * @param {unknown} rawLink Entree brute.
 * @returns {{ url: string, status: number|null, locations: Array<{ file: string, line: number|null, page: string|null }> }|null}
 */
function normalizeLink(rawLink) {
  if (!rawLink || typeof rawLink !== "object") {
    return null;
  }
  if (typeof rawLink.url !== "string" || !rawLink.url.trim()) {
    return null;
  }

  let status = null;
  if (typeof rawLink.status === "number" && Number.isFinite(rawLink.status)) {
    status = rawLink.status;
  }
  if (typeof rawLink.status === "string" && rawLink.status.trim()) {
    const parsedStatus = Number.parseInt(rawLink.status, 10);
    if (!Number.isNaN(parsedStatus)) {
      status = parsedStatus;
    }
  }

  return {
    url: rawLink.url.trim(),
    status,
    locations: normalizeLocations(rawLink.locations),
  };
}

/**
 * Reconstitue une liste de liens a partir de la section entries du cache.
 * @param {Record<string, unknown>} entries Entrees brutes.
 * @returns {Array<{ url: string, status: number|null, locations: Array<{ file: string, line: number|null, page: string|null }> }>}
 */
function buildLinksFromEntries(entries) {
  const links = [];
  for (const [url, rawEntry] of Object.entries(entries)) {
    let status = null;
    let locations = null;
    if (rawEntry && typeof rawEntry === "object") {
      status = rawEntry.status;
      locations = rawEntry.locations;
    }
    const normalized = normalizeLink({
      url,
      status,
      locations,
    });
    if (normalized) {
      links.push(normalized);
    }
  }
  return links;
}

/**
 * Charge le rapport des liens externes.
 * @param {string} reportPath Chemin absolu ou relatif du rapport YAML.
 * @returns {{ generatedAt: string|null, links: Array<{ url: string, status: number|null, locations: Array<{ file: string, line: number|null, page: string|null }> }> }}
 */
function loadExternalLinksReport(reportPath) {
  const resolvedPath = path.resolve(reportPath);
  if (!fs.existsSync(resolvedPath)) {
    return { generatedAt: null, links: [] };
  }

  const raw = yaml.load(fs.readFileSync(resolvedPath, "utf8")) || {};
  let links = [];
  if (Array.isArray(raw.links)) {
    for (const rawLink of raw.links) {
      const normalized = normalizeLink(rawLink);
      if (normalized) {
        links.push(normalized);
      }
    }
  } else if (raw.entries && typeof raw.entries === "object") {
    links = buildLinksFromEntries(raw.entries);
  }

  return {
    generatedAt: raw.generatedAt || null,
    links,
  };
}

/**
 * Filtre les liens du rapport par code de statut HTTP.
 * @param {{ links?: Array<{ status: number|null }> }} report Rapport charge.
 * @param {number} statusCode Code a retenir.
 * @returns {Array<{ url: string, status: number|null, locations: Array<{ file: string, line: number|null, page: string|null }> }>}
 */
function getLinksByStatus(report, statusCode) {
  if (!report || !Array.isArray(report.links)) {
    return [];
  }

  const links = [];
  for (const link of report.links) {
    if (!link || typeof link !== "object") {
      continue;
    }
    if (link.status !== statusCode) {
      continue;
    }
    links.push(link);
  }

  return links;
}

module.exports = {
  resolveExternalLinksReportPath,
  loadExternalLinksReport,
  getLinksByStatus,
};