import fs from 'node:fs';
import path from 'node:path';

const SKIP_REFERENCE = /^(?:https?:|mailto:|javascript:|data:|tel:|#|\/\/)/i;
const DOWNLOAD_EXTENSIONS = /\.(?:docx|doc|pdf|xlsx|xls|pptx|ppt|zip|rar|7z|csv)$/i;

export function isFilesystemPublicReference(raw) {
  const value = String(raw ?? '').trim();
  if (!value) return false;
  if (SKIP_REFERENCE.test(value)) return false;
  // /api/... and /MindSpace/... are server routes, not on-disk siblings of public HTML.
  if (value.startsWith('/')) return false;
  return true;
}

/** @deprecated use isFilesystemPublicReference */
export function isRelativePublicReference(raw) {
  return isFilesystemPublicReference(raw);
}

export function isDownloadLikeReference(raw, source = '') {
  if (!isFilesystemPublicReference(raw)) return false;
  const ref = normalizeReferencePath(raw);
  if (DOWNLOAD_EXTENSIONS.test(ref)) return true;
  return /\bdownload\b/i.test(String(source ?? ''));
}

export function normalizeReferencePath(raw) {
  const trimmed = String(raw ?? '')
    .trim()
    .split('#')[0]
    .split('?')[0]
    .trim();
  if (!trimmed) return '';
  try {
    return decodeURIComponent(trimmed);
  } catch {
    return trimmed;
  }
}

export function resolveReferencePath(htmlDir, raw) {
  const ref = normalizeReferencePath(raw);
  if (!ref) return null;
  return path.resolve(htmlDir, ref);
}

function parseMindspaceCoverPaths(contentAttr) {
  const paths = [];
  if (!contentAttr) return paths;
  let parsed = null;
  try {
    parsed = JSON.parse(contentAttr);
  } catch {
    for (const key of ['cover', 'image']) {
      const match = contentAttr.match(new RegExp(`"${key}"\\s*:\\s*"([^"]+)"`));
      if (match?.[1]) paths.push(match[1]);
    }
    return paths;
  }
  for (const key of ['cover', 'image']) {
    if (parsed?.[key]) paths.push(String(parsed[key]));
  }
  return paths;
}

export function collectPublicHtmlReferences(html, htmlDir, { downloadsOnly = false } = {}) {
  const refs = [];
  const seen = new Set();

  const add = (raw, source) => {
    if (downloadsOnly && !isDownloadLikeReference(raw, source)) return;
    if (!downloadsOnly && !isFilesystemPublicReference(raw)) return;
    const ref = normalizeReferencePath(raw);
    if (!ref) return;
    const key = `${source}\0${ref}`;
    if (seen.has(key)) return;
    seen.add(key);
    refs.push({
      ref,
      source,
      resolvedPath: resolveReferencePath(htmlDir, ref),
    });
  };

  for (const match of String(html ?? '').matchAll(/\b(?:href|src)\s*=\s*["']([^"']+)["']/gi)) {
    add(match[1], match[0]);
  }

  if (!downloadsOnly) {
    for (const match of String(html ?? '').matchAll(
      /<meta\b[^>]*\bname\s*=\s*["']mindspace-cover["'][^>]*>/gi,
    )) {
      const tag = match[0];
      const contentMatch =
        tag.match(/\bcontent\s*=\s*"([^"]*)"/i) ?? tag.match(/\bcontent\s*=\s*'([^']*)'/i);
      for (const coverPath of parseMindspaceCoverPaths(contentMatch?.[1])) {
        add(coverPath, 'mindspace-cover');
      }
    }
  }

  return refs;
}

export function findMissingPublicHtmlReferences(htmlPath, html = null, options = {}) {
  const resolvedHtmlPath = path.resolve(htmlPath);
  const content = html ?? fs.readFileSync(resolvedHtmlPath, 'utf8');
  const htmlDir = path.dirname(resolvedHtmlPath);
  const missing = [];
  const seen = new Set();

  for (const item of collectPublicHtmlReferences(content, htmlDir, options)) {
    const key = item.ref;
    if (seen.has(key)) continue;
    seen.add(key);
    if (!item.resolvedPath || !fs.existsSync(item.resolvedPath)) {
      missing.push({ htmlPath: resolvedHtmlPath, ...item });
    }
  }

  return missing;
}

export function listPublicHtmlFiles(publishRoot, { userId = null } = {}) {
  const root = path.resolve(publishRoot);
  if (!fs.existsSync(root)) return [];

  const userDirs = userId
    ? [path.join(root, userId)]
    : fs.readdirSync(root, { withFileTypes: true }).filter((d) => d.isDirectory()).map((d) => path.join(root, d.name));

  const files = [];
  for (const userDir of userDirs) {
    const publicDir = path.join(userDir, 'public');
    if (!fs.existsSync(publicDir) || !fs.statSync(publicDir).isDirectory()) continue;
    for (const name of fs.readdirSync(publicDir)) {
      if (!name.toLowerCase().endsWith('.html')) continue;
      files.push(path.join(publicDir, name));
    }
  }
  return files.sort();
}

export function scanPublicHtmlLinks(publishRoot, options = {}) {
  const issues = [];
  for (const htmlPath of listPublicHtmlFiles(publishRoot, options)) {
    issues.push(...findMissingPublicHtmlReferences(htmlPath, null, options));
  }
  return issues;
}