import fs from 'node:fs/promises';
import path from 'node:path';
import { execFile } from 'node:child_process';
import { promisify } from 'node:util';
import { archiveRawEmail } from './mailArchive.js';

const DEFAULT_MAIL_ROOT = '/Users/kavi/Library/Mail/V10';
const DEFAULT_ENVELOPE_INDEX = path.join(DEFAULT_MAIL_ROOT, 'MailData', 'Envelope Index');
const DEFAULT_ACCOUNTS_DB = '/Users/kavi/Library/Accounts/Accounts4.sqlite';
const execFileAsync = promisify(execFile);

export async function listAppleMailSources(mailRoot = DEFAULT_MAIL_ROOT) {
  const sources = [];
  const accountDirs = await safeReaddir(mailRoot, { withFileTypes: true });

  for (const accountDir of accountDirs.filter((entry) => entry.isDirectory())) {
    if (accountDir.name === 'MailData') continue;
    const accountPath = path.join(mailRoot, accountDir.name);
    const mailboxes = await findMailboxDirs(accountPath);
    if (!mailboxes.length) continue;
    sources.push({
      accountDir: accountDir.name,
      accountPath,
      mailboxes: mailboxes.map((mailbox) => ({
        path: mailbox,
        label: mailboxLabel(mailbox, accountPath),
      })),
    });
  }

  return sources;
}

export async function importAppleMailEmlx({ account, sourcePath, archiveRoot, limit = 25, since }) {
  const files = await findFiles(sourcePath, (file) => file.endsWith('.emlx') && !file.endsWith('.partial.emlx'));
  const selectedFiles = [];
  const sinceDate = since ? new Date(since) : null;

  for (const file of files.sort()) {
    if (sinceDate) {
      const stat = await fs.stat(file);
      if (stat.mtime < sinceDate) continue;
    }
    selectedFiles.push(file);
    if (selectedFiles.length >= limit) break;
  }

  const records = [];
  for (const file of selectedFiles) {
    const source = await readEmlxRawMessage(file);
    const record = await archiveRawEmail({
      account,
      mailbox: mailboxLabel(file, sourcePath),
      uid: path.basename(file, '.emlx'),
      source,
      archiveRoot,
    });
    record.localSource = file;
    records.push(record);
  }

  return {
    sourcePath,
    archiveRoot,
    imported: records.length,
    scanned: files.length,
    records,
  };
}

export async function importAppleMailFromIndex({
  account,
  email = account.email || account.auth?.user,
  mailRoot = DEFAULT_MAIL_ROOT,
  indexPath = DEFAULT_ENVELOPE_INDEX,
  accountsDbPath = DEFAULT_ACCOUNTS_DB,
  mailbox = 'all',
  archiveRoot,
  limit = 25,
  since,
}) {
  if (!email) throw new Error('email is required to resolve Apple Mail account');

  const { imapAccount, mailboxRecord } = await resolveAppleMailAccountMailbox({
    email,
    accountsDbPath,
    indexPath,
    mailbox,
  });
  const sourcePath = mailboxPathForUrl(mailRoot, mailboxRecord.url);
  const sinceTimestamp = since ? Math.floor(new Date(since).getTime() / 1000) : 0;
  const importLimit = Number(limit);
  const candidateLimit = Math.max(importLimit * 20, importLimit + 100);

  const messages = await queryJson(indexPath, `
    select m.ROWID as rowid, m.remote_id as remoteId, m.date_received as dateReceived
    from messages m
    where m.mailbox = ${Number(mailboxRecord.rowid)}
      and m.deleted = 0
      and m.date_received >= ${Number.isFinite(sinceTimestamp) ? sinceTimestamp : 0}
    order by m.date_received desc
    limit ${Number.isFinite(candidateLimit) ? candidateLimit : 25}
  `);

  const records = [];
  const missing = [];
  for (const message of messages) {
    const localSource = await findEmlxByRowId(sourcePath, message.rowid);
    if (!localSource) {
      missing.push(message.rowid);
      continue;
    }
    if (records.length >= importLimit) break;

    const source = await readEmlxRawMessage(localSource);
    const record = await archiveRawEmail({
      account,
      mailbox: decodeMailboxUrl(mailboxRecord.url),
      uid: String(message.rowid),
      source,
      archiveRoot,
    });
    record.localSource = localSource;
    record.appleMail = {
      accountIdentifier: imapAccount.identifier,
      mailboxUrl: mailboxRecord.url,
      rowid: message.rowid,
      remoteId: message.remoteId,
      dateReceived: message.dateReceived,
    };
    records.push(record);
  }

  return {
    email,
    imapAccount,
    mailbox: mailboxRecord,
    sourcePath,
    archiveRoot,
    imported: records.length,
    scanned: messages.length,
    missing,
    records,
  };
}

export async function resolveAppleMailAccountMailbox({
  email,
  accountsDbPath = DEFAULT_ACCOUNTS_DB,
  indexPath = DEFAULT_ENVELOPE_INDEX,
  mailbox = 'all',
}) {
  const imapAccounts = await resolveAppleMailImapAccounts({ email, accountsDbPath });
  const attempts = [];

  for (const imapAccount of imapAccounts) {
    try {
      const mailboxRecord = await resolveMailboxRecord({ indexPath, imapAccountId: imapAccount.identifier, mailbox });
      attempts.push({ imapAccount, mailboxRecord });
    } catch {
      // Some macOS account records are stale or have no Mail mailbox. Try the next candidate.
    }
  }

  if (!attempts.length) {
    throw new Error(`Apple Mail mailbox not found for ${email}/${mailbox}`);
  }

  return attempts.sort((a, b) => Number(b.mailboxRecord.totalCount || 0) - Number(a.mailboxRecord.totalCount || 0))[0];
}

export async function resolveAppleMailImapAccount({ email, accountsDbPath = DEFAULT_ACCOUNTS_DB }) {
  const rows = await resolveAppleMailImapAccounts({ email, accountsDbPath });
  if (!rows.length) {
    throw new Error(`Apple Mail IMAP account not found for ${email}`);
  }
  return rows[0];
}

export async function resolveAppleMailImapAccounts({ email, accountsDbPath = DEFAULT_ACCOUNTS_DB }) {
  const childRows = await queryJson(accountsDbPath, `
    select child.ZIDENTIFIER as identifier,
           parent.ZUSERNAME as email,
           parent.ZACCOUNTDESCRIPTION as description,
           parent.ZIDENTIFIER as parentIdentifier,
           'child' as source
    from ZACCOUNT parent
    join ZACCOUNT child on child.ZPARENTACCOUNT = parent.Z_PK
    join ZACCOUNTTYPE childType on child.ZACCOUNTTYPE = childType.Z_PK
    where lower(parent.ZUSERNAME) = lower('${sqlString(email)}')
      and childType.ZIDENTIFIER = 'com.apple.account.IMAP'
    order by child.Z_PK
  `);

  const directRows = await queryJson(accountsDbPath, `
    select account.ZIDENTIFIER as identifier,
           account.ZUSERNAME as email,
           account.ZACCOUNTDESCRIPTION as description,
           null as parentIdentifier,
           'direct' as source
    from ZACCOUNT account
    join ZACCOUNTTYPE accountType on account.ZACCOUNTTYPE = accountType.Z_PK
    where lower(account.ZUSERNAME) = lower('${sqlString(email)}')
      and accountType.ZIDENTIFIER = 'com.apple.account.IMAP'
    order by account.Z_PK
  `);

  const rows = [...directRows, ...childRows];
  const unique = new Map();
  for (const row of rows) {
    if (!unique.has(row.identifier)) unique.set(row.identifier, row);
  }

  const result = [...unique.values()];
  if (!rows.length) {
    throw new Error(`Apple Mail IMAP account not found for ${email}`);
  }
  return result;
}

export async function resolveMailboxRecord({ indexPath = DEFAULT_ENVELOPE_INDEX, imapAccountId, mailbox = 'all' }) {
  const accountPrefix = `imap://${imapAccountId}/`;
  const candidates = mailboxCandidates(mailbox)
    .map((name) => `${accountPrefix}${encodeMailboxPath(name)}`);

  for (const url of candidates) {
    const rows = await queryJson(indexPath, `
      select ROWID as rowid, url, total_count as totalCount, unread_count as unreadCount, unseen_count as unseenCount
      from mailboxes
      where url = '${sqlString(url)}'
      limit 1
    `);
    if (rows.length) return rows[0];
  }

  const available = await queryJson(indexPath, `
    select ROWID as rowid, url, total_count as totalCount
    from mailboxes
    where url like '${sqlString(accountPrefix)}%'
    order by total_count desc
    limit 20
  `);
  throw new Error(`Apple Mail mailbox not found for ${imapAccountId}/${mailbox}. Available: ${available.map((row) => row.url).join(', ')}`);
}

export async function readEmlxRawMessage(filePath) {
  const content = await fs.readFile(filePath);
  const newlineIndex = content.indexOf(0x0a);
  if (newlineIndex < 0) throw new Error(`invalid emlx file without first line: ${filePath}`);

  const sizeText = content.subarray(0, newlineIndex).toString('utf8').trim();
  const declaredSize = Number(sizeText);
  if (!Number.isFinite(declaredSize) || declaredSize <= 0) {
    return content.subarray(newlineIndex + 1);
  }

  const start = newlineIndex + 1;
  const end = Math.min(start + declaredSize, content.length);
  return content.subarray(start, end);
}

export async function findEmlxByRowId(sourcePath, rowid) {
  const fileName = `${rowid}.emlx`;
  const baseDirs = await mailDataBaseDirs(sourcePath);
  const bucketParts = bucketPathParts(rowid);

  for (const baseDir of baseDirs) {
    const candidate = path.join(baseDir, 'Data', ...bucketParts, 'Messages', fileName);
    if (await fileExists(candidate)) return candidate;
  }

  return findFirstFile(sourcePath, fileName);
}

export function bucketPathParts(rowid) {
  const bucket = Math.floor(Number(rowid) / 1000);
  if (!bucket) return [];
  return String(bucket).split('').reverse();
}

export function mailboxPathForUrl(mailRoot, url) {
  const withoutScheme = url.replace(/^imap:\/\//, '');
  const slashIndex = withoutScheme.indexOf('/');
  const accountDir = slashIndex >= 0 ? withoutScheme.slice(0, slashIndex) : withoutScheme;
  const mailboxPath = slashIndex >= 0 ? withoutScheme.slice(slashIndex + 1) : '';
  const mailboxParts = mailboxPath
    .split('/')
    .filter(Boolean)
    .map((part) => decodeURIComponent(part));

  return path.join(mailRoot, accountDir, ...mailboxParts.map((part) => `${part}.mbox`));
}

export function decodeMailboxUrl(url) {
  const withoutScheme = url.replace(/^imap:\/\//, '');
  const slashIndex = withoutScheme.indexOf('/');
  const mailboxPath = slashIndex >= 0 ? withoutScheme.slice(slashIndex + 1) : '';
  return mailboxPath
    .split('/')
    .filter(Boolean)
    .map((part) => decodeURIComponent(part))
    .join('/');
}

async function findMailboxDirs(root) {
  const dirs = [];
  const entries = await safeReaddir(root, { withFileTypes: true });
  for (const entry of entries) {
    if (!entry.isDirectory()) continue;
    const fullPath = path.join(root, entry.name);
    if (entry.name.endsWith('.mbox')) dirs.push(fullPath);
    const nested = await findMailboxDirs(fullPath);
    dirs.push(...nested);
  }
  return dirs;
}

async function findFiles(root, predicate) {
  const found = [];
  const entries = await safeReaddir(root, { withFileTypes: true });
  for (const entry of entries) {
    const fullPath = path.join(root, entry.name);
    if (entry.isDirectory()) {
      found.push(...await findFiles(fullPath, predicate));
    } else if (entry.isFile() && predicate(fullPath)) {
      found.push(fullPath);
    }
  }
  return found;
}

async function findFirstFile(root, fileName) {
  const entries = await safeReaddir(root, { withFileTypes: true });
  for (const entry of entries) {
    const fullPath = path.join(root, entry.name);
    if (entry.isFile() && entry.name === fileName) return fullPath;
    if (entry.isDirectory()) {
      const nested = await findFirstFile(fullPath, fileName);
      if (nested) return nested;
    }
  }
  return null;
}

async function mailDataBaseDirs(sourcePath) {
  const baseDirs = [sourcePath];
  const entries = await safeReaddir(sourcePath, { withFileTypes: true });
  for (const entry of entries) {
    if (!entry.isDirectory()) continue;
    const fullPath = path.join(sourcePath, entry.name);
    if (await fileExists(path.join(fullPath, 'Data'))) baseDirs.push(fullPath);
  }
  return baseDirs;
}

async function queryJson(dbPath, sql) {
  const { stdout } = await execFileAsync('sqlite3', ['-json', dbPath, sql], {
    maxBuffer: 1024 * 1024 * 20,
  });
  return stdout.trim() ? JSON.parse(stdout) : [];
}

function mailboxCandidates(mailbox) {
  if (!mailbox || mailbox === 'all') return ['[Gmail]/Todos', '[Gmail]/All Mail', 'INBOX'];
  if (mailbox === 'inbox') return ['INBOX'];
  return [mailbox];
}

function encodeMailboxPath(mailboxPath) {
  return mailboxPath
    .split('/')
    .map((part) => encodeURIComponent(part))
    .join('/');
}

function sqlString(value) {
  return String(value).replaceAll("'", "''");
}

async function fileExists(filePath) {
  try {
    await fs.access(filePath);
    return true;
  } catch {
    return false;
  }
}

async function safeReaddir(dir, options) {
  try {
    return await fs.readdir(dir, options);
  } catch {
    return [];
  }
}

function mailboxLabel(itemPath, rootPath) {
  return path.relative(rootPath, itemPath)
    .split(path.sep)
    .filter((part) => part && part !== 'Data' && part !== 'Messages')
    .join('/');
}