import { ImapFlow } from 'imapflow';
import { appendFileSync } from 'fs';
import type { EmailCredentials } from './multitenancy/credential-store.js';

function logImapError(label: string, err: unknown) {
  const msg = err instanceof Error ? err.message : String(err);
  const stack = err instanceof Error ? (err.stack ?? '') : '';
  const line = `[${new Date().toISOString()}] [imap-error] ${label}: ${msg}\n${stack}\n---\n`;
  console.error(line);
  try { appendFileSync('/vaults/imap-errors.log', line); } catch { /* ignore */ }
}

export type Account = 'yahoo' | 'fetcherpay' | 'garfield' | 'sales' | 'leads' | 'founder' | 'gmail' | 'sqcp_garfield' | 'sqcp_info' | 'sqcp_sales' | 'sqcp_support' | 'sqcp_founder' | 'sqcp_contact' | 'sqcp_admin';
export type EmailCtx = Account | EmailCredentials;

const FETCHERPAY_IMAP_HOST = process.env['FETCHERPAY_IMAP_HOST'] ?? 'mail.fetcherpay.com';
const FETCHERPAY_IMAP_PORT = parseInt(process.env['FETCHERPAY_IMAP_PORT'] ?? '30993');

// squaremcp.com mail is on a separate server (mail.squaremcp.com / 104.190.60.129)
// same custom port as fetcherpay but different host
const SQCP_IMAP_HOST = process.env['SQCP_IMAP_HOST'] ?? 'mail.squaremcp.com';
const SQCP_IMAP_PORT = parseInt(process.env['SQCP_IMAP_PORT'] ?? '30993');

function fetcherpayImapConfig(user: string, pass: string) {
  return {
    host: FETCHERPAY_IMAP_HOST,
    port: FETCHERPAY_IMAP_PORT,
    secure: true,
    auth: { user, pass },
    tls: { rejectUnauthorized: false },
  };
}

function sqcpImapConfig(user: string, pass: string) {
  return {
    host: SQCP_IMAP_HOST,
    port: SQCP_IMAP_PORT,
    secure: true,
    auth: { user, pass },
    tls: { rejectUnauthorized: false },
  };
}

function getEnvConfig(account: Account = 'yahoo') {
  switch (account) {
    case 'fetcherpay':
      return fetcherpayImapConfig(process.env['FETCHERPAY_EMAIL']!, process.env['FETCHERPAY_PASSWORD']!);
    case 'garfield':
      return fetcherpayImapConfig(process.env['GARFIELD_EMAIL']!, process.env['GARFIELD_PASSWORD']!);
    case 'sales':
      return fetcherpayImapConfig(process.env['SALES_EMAIL']!, process.env['SALES_PASSWORD']!);
    case 'leads':
      return fetcherpayImapConfig(process.env['LEADS_EMAIL']!, process.env['LEADS_PASSWORD']!);
    case 'founder':
      return fetcherpayImapConfig(process.env['FOUNDER_EMAIL']!, process.env['FOUNDER_PASSWORD']!);
    case 'sqcp_garfield':
      return sqcpImapConfig(process.env['SQCP_GARFIELD_EMAIL']!, process.env['SQCP_GARFIELD_PASSWORD']!);
    case 'sqcp_info':
      return sqcpImapConfig(process.env['SQCP_INFO_EMAIL']!, process.env['SQCP_INFO_PASSWORD']!);
    case 'sqcp_sales':
      return sqcpImapConfig(process.env['SQCP_SALES_EMAIL']!, process.env['SQCP_SALES_PASSWORD']!);
    case 'sqcp_support':
      return sqcpImapConfig(process.env['SQCP_SUPPORT_EMAIL']!, process.env['SQCP_SUPPORT_PASSWORD']!);
    case 'sqcp_founder':
      return sqcpImapConfig(process.env['SQCP_FOUNDER_EMAIL']!, process.env['SQCP_FOUNDER_PASSWORD']!);
    case 'sqcp_contact':
      return sqcpImapConfig(process.env['SQCP_CONTACT_EMAIL']!, process.env['SQCP_CONTACT_PASSWORD']!);
    case 'sqcp_admin':
      return sqcpImapConfig(process.env['SQCP_ADMIN_EMAIL']!, process.env['SQCP_ADMIN_PASSWORD']!);
    case 'gmail':
      return {
        host: 'imap.gmail.com',
        port: 993,
        secure: true,
        auth: {
          user: process.env['GMAIL_EMAIL']!,
          pass: process.env['GMAIL_APP_PASSWORD']!,
        },
      };
    default:
      return {
        host: 'imap.mail.yahoo.com',
        port: 993,
        secure: true,
        auth: {
          user: process.env['YAHOO_EMAIL']!,
          pass: process.env['YAHOO_APP_PASSWORD']!,
        },
      };
  }
}

function resolveImapConfig(ctx: EmailCtx) {
  if (typeof ctx === 'object') {
    return {
      host: ctx.host,
      port: ctx.port,
      secure: ctx.port === 993,
      auth: { user: ctx.user, pass: ctx.password },
      tls: { rejectUnauthorized: false },
    };
  }
  return getEnvConfig(ctx);
}

function isGmail(ctx: EmailCtx): boolean {
  if (typeof ctx === 'string') return ctx === 'gmail';
  return ctx.host === 'imap.gmail.com';
}

async function withClient<T>(ctx: EmailCtx, fn: (client: ImapFlow) => Promise<T>): Promise<T> {
  const client = new ImapFlow(resolveImapConfig(ctx));
  client.on('error', (err) => logImapError('client-error-event', err));
  try {
    await client.connect();
    return await fn(client);
  } catch (err) {
    logImapError('withClient', err);
    throw err;
  } finally {
    try { await client.logout(); } catch { /* ignore logout errors */ }
  }
}

export interface MessageSummary {
  uid: number;
  messageId: string;
  subject: string;
  from: string;
  date: string;
  seen: boolean;
  size: number;
  folder: string;
}

export interface FullMessage {
  uid: number;
  messageId: string;
  subject: string;
  from: string;
  to: string;
  date: string;
  body: string;
  seen: boolean;
}

function parseSearchCriteria(query: string): object {
  const trimmed = query.trim();
  if (!trimmed) return { all: true };

  const tokens: { key: string; value: string }[] = [];
  const regex = /(\w+):("([^"]*)"|([^\s]+))/g;
  let m: RegExpExecArray | null;
  let lastIndex = 0;
  while ((m = regex.exec(trimmed)) !== null) {
    tokens.push({ key: m[1].toLowerCase(), value: m[3] ?? m[4] });
    lastIndex = regex.lastIndex;
  }

  const remaining = trimmed.slice(lastIndex).trim();
  if (remaining) {
    tokens.push({ key: 'keyword', value: remaining });
  }

  if (tokens.length === 0) {
    return { or: [{ subject: trimmed }, { from: trimmed }] };
  }

  const parts: object[] = [];
  for (const t of tokens) {
    switch (t.key) {
      case 'from':    parts.push({ from: t.value }); break;
      case 'subject': parts.push({ subject: t.value }); break;
      case 'to':      parts.push({ to: t.value }); break;
      case 'after':
      case 'since': {
        const d = new Date(t.value);
        if (!isNaN(d.getTime())) parts.push({ since: d });
        break;
      }
      case 'before': {
        const d = new Date(t.value);
        if (!isNaN(d.getTime())) parts.push({ before: d });
        break;
      }
      case 'keyword':
      default:
        parts.push({ or: [{ subject: t.value }, { from: t.value }] });
        break;
    }
  }

  if (parts.length === 1) return parts[0];
  return { and: parts };
}

async function searchInFolder(
  client: ImapFlow,
  folder: string,
  query: string,
  maxResults: number,
  ctx: EmailCtx
): Promise<MessageSummary[]> {
  const mailbox = await client.mailboxOpen(folder);
  const total = mailbox.exists ?? 0;
  if (total === 0) return [];

  const buildSummary = (msg: { uid: number; envelope?: { messageId?: string; subject?: string; from?: Array<{ name?: string; address?: string }>; to?: Array<{ address?: string }>; date?: Date }; flags?: Set<string>; size?: number }) => {
    const env = msg.envelope;
    return {
      uid: msg.uid,
      messageId: env?.messageId ?? '',
      subject: env?.subject ?? '(no subject)',
      from: env?.from?.[0]
        ? `${env.from[0].name ?? ''} <${env.from[0].address ?? ''}>`.trim()
        : '',
      date: env?.date?.toISOString() ?? '',
      seen: msg.flags?.has('\\Seen') ?? false,
      size: msg.size ?? 0,
      folder,
    };
  };

  const criteria = isGmail(ctx)
    ? { gmailraw: query }
    : parseSearchCriteria(query);

  // Try SEARCH first; some Poste.io builds return malformed error responses that
  // crash ImapFlow's parser. Fall back to fetching the N most recent by sequence.
  let uidList: number[] = [];
  let searchWorked = false;
  try {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const uids = await client.search(criteria as any, { uid: true });
    uidList = Array.isArray(uids) ? uids : [];
    searchWorked = true;
  } catch (err) {
    console.warn(`[imap] SEARCH failed on ${folder}, using sequence fallback:`, (err as Error).message);
  }

  if (searchWorked) {
    const recentUids = uidList.slice(-maxResults).reverse();
    if (recentUids.length === 0) return [];
    const messages: MessageSummary[] = [];
    for await (const msg of client.fetch(recentUids, { envelope: true, flags: true, size: true }, { uid: true })) {
      messages.push(buildSummary(msg));
    }
    return messages;
  }

  // Sequence-range fallback: fetch last N messages without SEARCH
  const start = Math.max(1, total - maxResults + 1);
  const messages: MessageSummary[] = [];
  for await (const msg of client.fetch(`${start}:${total}`, { envelope: true, flags: true, size: true })) {
    messages.push(buildSummary(msg));
  }
  return messages.reverse();
}

export async function searchMessages(
  query: string,
  maxResults = 20,
  ctx: EmailCtx = 'yahoo',
  folder?: string
): Promise<MessageSummary[]> {
  return withClient(ctx, async (client) => {
    const foldersToSearch: string[] = [];

    if (folder) {
      foldersToSearch.push(folder);
    } else {
      foldersToSearch.push('INBOX');
    }

    for (const f of foldersToSearch) {
      const results = await searchInFolder(client, f, query, maxResults, ctx);
      if (results.length > 0) return results;
    }

    if (isGmail(ctx) && !folder) {
      const allMailResults = await searchInFolder(client, '[Gmail]/All Mail', query, maxResults, ctx);
      if (allMailResults.length > 0) return allMailResults;
    }

    return [];
  });
}

export async function readMessage(uid: number, ctx: EmailCtx = 'yahoo', folder = 'INBOX'): Promise<FullMessage> {
  return withClient(ctx, async (client) => {
    console.log(`[imap] readMessage uid=${uid} folder=${folder}`);
    await client.mailboxOpen(folder);

    let result: FullMessage | null = null;

    for await (const msg of client.fetch([uid], {
      envelope: true,
      flags: true,
      bodyParts: ['TEXT'],
    }, { uid: true })) {
      const env = msg.envelope;

      const bpKeys = msg.bodyParts ? [...msg.bodyParts.keys()] : [];
      console.log(`[imap] bodyParts keys:`, JSON.stringify(bpKeys));

      const textBuf =
        msg.bodyParts?.get('text') ??
        msg.bodyParts?.get('TEXT') ??
        msg.bodyParts?.get('1');

      const rawBody = textBuf ? textBuf.toString('utf-8') : '';
      const body = rawBody
        .replace(/<style[^>]*>[\s\S]*?<\/style>/gi, '')
        .replace(/<script[^>]*>[\s\S]*?<\/script>/gi, '')
        .replace(/<[^>]+>/g, ' ')
        .replace(/\s+/g, ' ')
        .trim()
        .slice(0, 10000);

      result = {
        uid: msg.uid,
        messageId: env?.messageId ?? '',
        subject: env?.subject ?? '(no subject)',
        from: env?.from?.[0]
          ? `${env.from[0].name ?? ''} <${env.from[0].address ?? ''}>`.trim()
          : '',
        to: env?.to?.[0]?.address ?? '',
        date: env?.date?.toISOString() ?? '',
        body,
        seen: true,
      };
    }

    if (!result) throw new Error(`Message UID ${uid} not found`);

    console.log(`[imap] marking uid=${uid} as seen`);
    await client.messageFlagsAdd([uid], ['\\Seen'], { uid: true });

    return result;
  });
}

export async function getProfile(ctx: EmailCtx = 'yahoo'): Promise<{ email: string; name: string; account: string }> {
  if (typeof ctx === 'object') {
    return { email: ctx.user, name: ctx.user.split('@')[0], account: 'custom' };
  }
  const emailMap: Record<Account, string> = {
    yahoo:      process.env['YAHOO_EMAIL']      ?? '',
    fetcherpay: process.env['FETCHERPAY_EMAIL'] ?? '',
    garfield:   process.env['GARFIELD_EMAIL']   ?? '',
    sales:      process.env['SALES_EMAIL']      ?? '',
    leads:      process.env['LEADS_EMAIL']      ?? '',
    founder:    process.env['FOUNDER_EMAIL']    ?? '',
    gmail:      process.env['GMAIL_EMAIL']      ?? '',
    sqcp_garfield: process.env['SQCP_GARFIELD_EMAIL'] ?? '',
    sqcp_info:     process.env['SQCP_INFO_EMAIL']     ?? '',
    sqcp_sales:    process.env['SQCP_SALES_EMAIL']    ?? '',
    sqcp_support:  process.env['SQCP_SUPPORT_EMAIL']  ?? '',
    sqcp_founder:  process.env['SQCP_FOUNDER_EMAIL']  ?? '',
    sqcp_contact:  process.env['SQCP_CONTACT_EMAIL']  ?? '',
    sqcp_admin:    process.env['SQCP_ADMIN_EMAIL']    ?? '',
  };
  const email = emailMap[ctx] ?? '';
  return { email, name: email.split('@')[0], account: ctx };
}

export async function listFolders(ctx: EmailCtx = 'yahoo'): Promise<string[]> {
  return withClient(ctx, async (client) => {
    const mailboxes = await client.list();
    return mailboxes.map((m) => m.path);
  });
}