import { createClient } from '@supabase/supabase-js';

const DIRECTORY_USAGE_CACHE_TTL_MS = 2 * 60 * 1000;
const directoryUsageCache = new Map();

function json(res, status, body) {
  res.status(status).setHeader('Content-Type', 'application/json');
  res.setHeader('Cache-Control', 'no-store');
  res.send(JSON.stringify(body));
}

function normalizeBaseUrl(url) {
  return String(url || '').trim().replace(/\/+$/, '');
}

function normalizePath(path) {
  const raw = String(path || '/').trim();
  const parts = raw.split('/').filter(Boolean);
  const clean = [];

  for (const part of parts) {
    if (part === '.' || part === '') continue;
    if (part === '..') throw new Error('Invalid path');
    clean.push(part);
  }

  return `/${clean.join('/')}`;
}

function joinPath(...parts) {
  return normalizePath(parts.join('/'));
}

function safeName(value, fallback) {
  const cleaned = String(value || '')
    .trim()
    .replace(/[\\/:*?"<>|#%{}^~[\]`]+/g, '-')
    .replace(/\s+/g, ' ')
    .replace(/^-+|-+$/g, '');

  return cleaned || fallback;
}

function fillTemplate(template, profile) {
  const name = safeName(profile.name, profile.id);
  const companyName = safeName(profile.company?.name, name);
  const email = safeName(profile.email, profile.id);
  const emailName = safeName(String(profile.email || '').split('@')[0], profile.id);

  return String(template || '')
    .replaceAll('{id}', profile.id)
    .replaceAll('{name}', name)
    .replaceAll('{companyName}', companyName)
    .replaceAll('{email}', email)
    .replaceAll('{emailName}', emailName);
}

function getConfig() {
  const serverUrl = normalizeBaseUrl(process.env.SEAFILE_SERVER_URL);
  const apiToken = process.env.SEAFILE_API_TOKEN;
  const repoId = process.env.SEAFILE_REPO_ID;

  return {
    serverUrl,
    webUrl: normalizeBaseUrl(process.env.SEAFILE_WEB_URL || serverUrl),
    apiToken,
    repoId,
    teamRoot: normalizePath(process.env.SEAFILE_TEAM_ROOT_PATH || '/'),
    externalRoot: normalizePath(process.env.SEAFILE_EXTERNAL_ROOT_PATH || '/Subcontractors'),
    externalTemplate: process.env.SEAFILE_EXTERNAL_FOLDER_TEMPLATE || '{name}',
    clientRoot: normalizePath(process.env.SEAFILE_CLIENT_ROOT_PATH || '/Clients'),
    clientTemplate: process.env.SEAFILE_CLIENT_FOLDER_TEMPLATE || '{companyName}',
    configured: Boolean(serverUrl && apiToken && repoId),
  };
}

async function createCallerClient(authHeader) {
  const supabaseUrl = process.env.VITE_SUPABASE_URL || process.env.SUPABASE_URL;
  const supabaseAnonKey = process.env.VITE_SUPABASE_ANON_KEY || process.env.SUPABASE_ANON_KEY;

  if (!supabaseUrl || !supabaseAnonKey) {
    throw new Error('Supabase auth env is not configured on Vercel.');
  }

  return createClient(supabaseUrl, supabaseAnonKey, {
    auth: { persistSession: false, autoRefreshToken: false },
    global: { headers: { Authorization: authHeader } },
  });
}

async function requirePortalUser(authHeader) {
  const callerClient = await createCallerClient(authHeader);

  const { data: userData, error: userError } = await callerClient.auth.getUser();
  if (userError || !userData?.user) {
    return { ok: false, status: 401, message: 'Unauthorized' };
  }

  const { data: profile, error: profileError } = await callerClient
    .from('profiles')
    .select('id, name, role, company:companies(id, name)')
    .eq('id', userData.user.id)
    .single();

  if (profileError) {
    return { ok: false, status: 500, message: profileError.message };
  }

  if (!['team', 'external', 'client'].includes(profile?.role)) {
    return { ok: false, status: 403, message: 'Forbidden' };
  }

  return {
    ok: true,
    callerClient,
    profile: {
      ...profile,
      email: userData.user.email,
    },
  };
}

function getUserRoot(config, profile) {
  if (profile.role === 'team') return config.teamRoot;

  if (profile.role === 'client') {
    const templated = fillTemplate(config.clientTemplate, profile);
    if (templated.startsWith('/')) return normalizePath(templated);

    return joinPath(config.clientRoot, templated);
  }

  const templated = fillTemplate(config.externalTemplate, profile);
  if (templated.startsWith('/')) return normalizePath(templated);

  return joinPath(config.externalRoot, templated);
}

function resolveSeafilePath(config, profile, requestedPath = '/') {
  const root = getUserRoot(config, profile);
  const virtualPath = normalizePath(requestedPath);
  return {
    root,
    virtualPath,
    seafilePath: joinPath(root, virtualPath),
  };
}

async function seafileRequest(config, endpoint, options = {}) {
  const response = await fetch(`${config.serverUrl}${endpoint}`, {
    ...options,
    headers: {
      Authorization: `Token ${config.apiToken}`,
      Accept: 'application/json',
      ...(options.headers || {}),
    },
  });

  const text = await response.text();
  let body = text;
  try {
    body = text ? JSON.parse(text) : null;
  } catch {
    body = text;
  }

  if (!response.ok) {
    const message = typeof body === 'object' && body?.error_msg ? body.error_msg : text || `Seafile returned ${response.status}`;
    const error = new Error(message);
    error.status = response.status;
    throw error;
  }

  return body;
}

async function createSeafileFolder(config, path) {
  const body = new URLSearchParams({ operation: 'mkdir', create_parents: 'true' });
  await seafileRequest(config, `/api2/repos/${encodeURIComponent(config.repoId)}/dir/?p=${encodeURIComponent(path)}`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body,
  });
}

async function createSeafileFolderIfMissing(config, path) {
  try {
    await createSeafileFolder(config, path);
    return true;
  } catch (error) {
    const message = String(error.message || '').toLowerCase();
    if (error.status === 400 || message.includes('already') || message.includes('exist')) return false;
    throw error;
  }
}

function getCachedDirectoryUsage(cacheKey) {
  const cached = directoryUsageCache.get(cacheKey);
  if (!cached) return null;
  if ((Date.now() - cached.timestamp) > DIRECTORY_USAGE_CACHE_TTL_MS) {
    directoryUsageCache.delete(cacheKey);
    return null;
  }

  return cached.bytes;
}

function setCachedDirectoryUsage(cacheKey, bytes) {
  directoryUsageCache.set(cacheKey, {
    bytes: Number(bytes) || 0,
    timestamp: Date.now(),
  });
}

async function listDirectoryEntries(config, path) {
  const entries = await seafileRequest(
    config,
    `/api2/repos/${encodeURIComponent(config.repoId)}/dir/?p=${encodeURIComponent(path)}`
  );

  return Array.isArray(entries) ? entries : [];
}

async function getDirectoryUsageBytes(config, path, prefetchedEntries = null) {
  const normalizedPath = normalizePath(path);
  const cacheKey = `${config.repoId}:${normalizedPath}`;
  const cached = getCachedDirectoryUsage(cacheKey);
  if (cached != null) return cached;

  const entries = prefetchedEntries || await listDirectoryEntries(config, normalizedPath);
  let total = 0;

  for (const entry of entries) {
    if (entry.type === 'file') {
      total += Number(entry.size || 0);
      continue;
    }

    if (entry.type === 'dir') {
      total += await getDirectoryUsageBytes(config, joinPath(normalizedPath, entry.name));
    }
  }

  setCachedDirectoryUsage(cacheKey, total);
  return total;
}

function clearDirectoryUsageCache(config, path) {
  const normalizedPath = normalizePath(path);
  const prefixes = [];
  let cursor = normalizedPath;

  while (true) {
    prefixes.push(`${config.repoId}:${cursor}`);
    if (cursor === '/') break;
    cursor = parentDir(cursor);
  }

  for (const key of prefixes) {
    directoryUsageCache.delete(key);
  }
}

function entryPath(parent, name) {
  return joinPath(parent, name);
}

function parentDir(path) {
  const normalized = normalizePath(path);
  const parts = normalized.split('/').filter(Boolean);
  parts.pop();
  return `/${parts.join('/')}`;
}

function basename(path) {
  const parts = normalizePath(path).split('/').filter(Boolean);
  return parts[parts.length - 1] || '';
}

async function syncManagedFolders(config, auth) {
  if (auth.profile.role !== 'team') {
    const error = new Error('Team only');
    error.status = 403;
    throw error;
  }

  const [{ data: companies, error: companiesError }, { data: externals, error: externalsError }] = await Promise.all([
    auth.callerClient.from('companies').select('id, name').order('name'),
    auth.callerClient.from('profiles').select('id, name, email, role').eq('role', 'external').order('name'),
  ]);

  if (companiesError) throw new Error(companiesError.message);
  if (externalsError) throw new Error(externalsError.message);

  const folderPaths = [
    config.clientRoot,
    config.externalRoot,
    ...(companies || []).map(company => {
      const profile = { id: company.id, name: company.name, email: '', company };
      const templated = fillTemplate(config.clientTemplate, profile);
      return templated.startsWith('/') ? normalizePath(templated) : joinPath(config.clientRoot, templated);
    }),
    ...(externals || []).map(profile => {
      const templated = fillTemplate(config.externalTemplate, profile);
      return templated.startsWith('/') ? normalizePath(templated) : joinPath(config.externalRoot, templated);
    }),
  ];

  const uniquePaths = [...new Set(folderPaths)].filter(path => path !== '/');
  let created = 0;

  for (const path of uniquePaths) {
    if (await createSeafileFolderIfMissing(config, path)) created += 1;
  }

  return {
    created,
    checked: uniquePaths.length,
    clients: companies?.length || 0,
    subcontractors: externals?.length || 0,
  };
}

export default async function handler(req, res) {
  try {
    const authHeader = req.headers.authorization || '';
    if (!authHeader) return json(res, 401, { error: 'No authorization header' });

    const auth = await requirePortalUser(authHeader);
    if (!auth.ok) return json(res, auth.status, { error: auth.message });

    const config = getConfig();
    if (!config.configured) {
      return json(res, 200, {
        configured: false,
        error: 'Seafile is not configured yet.',
        requiredEnv: ['SEAFILE_SERVER_URL', 'SEAFILE_API_TOKEN', 'SEAFILE_REPO_ID'],
      });
    }

    const action = req.query.action || (req.method === 'GET' ? 'list' : '');
    const requestedPath = req.query.path || req.body?.path;
    const resolved = resolveSeafilePath(config, auth.profile, requestedPath || '/');
    const invalidateUsage = req.query.invalidateUsage === '1';

    if (req.method === 'POST' && action === 'sync-folders') {
      const result = await syncManagedFolders(config, auth);
      return json(res, 200, { success: true, ...result });
    }

    if (req.method === 'GET' && action === 'config') {
      return json(res, 200, {
        configured: true,
        role: auth.profile.role,
        root: resolved.root,
        webUrl: config.webUrl,
      });
    }

    if (req.method === 'GET' && action === 'list') {
      if (invalidateUsage) clearDirectoryUsageCache(config, resolved.seafilePath);
      let entries;
      try {
        entries = await listDirectoryEntries(config, resolved.seafilePath);
      } catch (error) {
        if (!['external', 'client'].includes(auth.profile.role) || resolved.virtualPath !== '/') throw error;
        await createSeafileFolder(config, resolved.root);
        entries = await listDirectoryEntries(config, resolved.seafilePath);
      }

      const normalizedEntries = (Array.isArray(entries) ? entries : []).map((item) => {
        const itemPath = entryPath(resolved.virtualPath, item.name);

        return {
          id: item.id,
          name: item.name,
          type: item.type,
          size: item.type === 'file' ? Number(item.size || 0) : 0,
          aggregateSize: item.type === 'file' ? Number(item.size || 0) : null,
          mtime: item.mtime || null,
          permission: item.permission || null,
          path: itemPath,
        };
      }).sort((a, b) => {
        if (a.type !== b.type) return a.type === 'dir' ? -1 : 1;
        return a.name.localeCompare(b.name);
      });

      return json(res, 200, {
        configured: true,
        path: resolved.virtualPath,
        canGoUp: resolved.virtualPath !== '/',
        parentPath: parentDir(resolved.virtualPath),
        entries: normalizedEntries,
        webUrl: config.webUrl,
      });
    }

    if (req.method === 'GET' && action === 'download') {
      const url = await seafileRequest(
        config,
        `/api2/repos/${encodeURIComponent(config.repoId)}/file/?p=${encodeURIComponent(resolved.seafilePath)}&reuse=1`
      );

      return json(res, 200, { url });
    }

    if (req.method === 'POST' && action === 'mkdir') {
      const folderName = safeName(req.body?.name, '');
      if (!folderName) return json(res, 400, { error: 'Folder name is required.' });

      const folderPath = joinPath(resolved.seafilePath, folderName);
      await createSeafileFolder(config, folderPath);
      clearDirectoryUsageCache(config, resolved.seafilePath);

      return json(res, 200, { success: true });
    }

    if (req.method === 'POST' && action === 'upload-link') {
      const uploadLink = await seafileRequest(
        config,
        `/api2/repos/${encodeURIComponent(config.repoId)}/upload-link/?p=${encodeURIComponent(resolved.seafilePath)}`
      );

      return json(res, 200, {
        uploadLink: typeof uploadLink === 'string' ? uploadLink : String(uploadLink || ''),
        parentDir: resolved.seafilePath,
      });
    }

    if (req.method === 'POST' && action === 'rename') {
      const newName = safeName(req.body?.name, '');
      if (!newName) return json(res, 400, { error: 'New name is required.' });

      const type = req.body?.type || 'file';
      const endpoint = type === 'dir'
        ? `/api2/repos/${encodeURIComponent(config.repoId)}/dir/?p=${encodeURIComponent(resolved.seafilePath)}`
        : `/api2/repos/${encodeURIComponent(config.repoId)}/file/?p=${encodeURIComponent(resolved.seafilePath)}`;

      const body = new URLSearchParams({ operation: 'rename', newname: newName });
      await seafileRequest(config, endpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        body,
      });

      return json(res, 200, { success: true });
    }

    if (req.method === 'POST' && action === 'move') {
      const srcPath = req.body?.srcPath;
      const dstDir = req.body?.dstDir;
      if (!srcPath || !dstDir) return json(res, 400, { error: 'srcPath and dstDir are required.' });

      const resolvedSrc = resolveSeafilePath(config, auth.profile, srcPath);
      const resolvedDst = resolveSeafilePath(config, auth.profile, dstDir);
      const itemName = basename(resolvedSrc.seafilePath);
      const srcDir = parentDir(resolvedSrc.seafilePath);
      if (!itemName) return json(res, 400, { error: 'Cannot move root.' });

      const type = req.body?.type || 'file';
      const endpoint = type === 'dir'
        ? `/api2/repos/${encodeURIComponent(config.repoId)}/dir/?p=${encodeURIComponent(resolvedSrc.seafilePath)}`
        : `/api2/repos/${encodeURIComponent(config.repoId)}/file/?p=${encodeURIComponent(resolvedSrc.seafilePath)}`;

      const body = new URLSearchParams({
        operation: 'move',
        dst_repo: config.repoId,
        dst_dir: resolvedDst.seafilePath,
      });

      await seafileRequest(config, endpoint, {
        method: 'POST',
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        body,
      });

      clearDirectoryUsageCache(config, srcDir);
      clearDirectoryUsageCache(config, resolvedDst.seafilePath);

      return json(res, 200, { success: true });
    }

    if (req.method === 'DELETE' && action === 'delete') {
      const type = req.query.type || req.body?.type;
      if (!['file', 'dir'].includes(type)) return json(res, 400, { error: 'Valid item type is required.' });

      const itemName = basename(resolved.seafilePath);
      const itemParent = parentDir(resolved.seafilePath);
      if (!itemName) return json(res, 400, { error: 'Cannot delete the root folder.' });

      const body = new URLSearchParams({
        file_names: itemName,
      });

      await seafileRequest(
        config,
        `/api2/repos/${encodeURIComponent(config.repoId)}/fileops/delete/?p=${encodeURIComponent(itemParent)}`,
        {
          method: 'POST',
          headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
          body,
        }
      );

      clearDirectoryUsageCache(config, itemParent);

      return json(res, 200, { success: true });
    }

    return json(res, 405, { error: 'Method not allowed' });
  } catch (error) {
    return json(res, error.status || 500, { error: error.message || 'Unexpected Seafile error' });
  }
}