import { mkdir, readdir } from 'node:fs/promises';
import { join } from 'node:path';
import { simpleParser } from 'mailparser';
import type { EmailSummary, EmailMessage } from 'types';
import { rebuildIndex } from '@@/queue/handlers/gmail-sync';
import { createRouter } from '../../create-router';
import { getUserEmailDir } from '@@/data-path';

const parseHeadersOnly = async (filePath: string, id: string): Promise<EmailSummary | null> => {
  try {
    const file = Bun.file(filePath);
    const buffer = Buffer.from(await file.arrayBuffer());
    const parsed = await simpleParser(buffer, { skipHtmlToText: true, skipTextToHtml: true, skipImageLinks: true });

    const text = parsed.text ?? '';
    const snippet = text.slice(0, 120).replace(/\s+/g, ' ').trim();
    const attachmentCount = parsed.attachments?.length ?? 0;

    return {
      id,
      from: parsed.from?.text ?? '',
      to: parsed.to ? (Array.isArray(parsed.to) ? parsed.to.map((a) => a.text).join(', ') : parsed.to.text) : '',
      subject: parsed.subject ?? '(no subject)',
      date: (parsed.date ?? new Date()).toISOString(),
      snippet,
      ...(attachmentCount > 0 ? { attachmentCount } : {}),
    };
  } catch {
    return null;
  }
};

export const emailRouter = createRouter();

emailRouter.get('/messages', async (ctx) => {
  const email = ctx.get('user').email;
  const dir = getUserEmailDir(email);

  let filenames: string[];
  try {
    const entries = await readdir(dir);
    filenames = entries.filter((f) => f.endsWith('.eml'));
  } catch {
    return ctx.json({ messages: [], total: 0 });
  }

  const page = Number(ctx.req.query('page') ?? '1');
  const limit = Number(ctx.req.query('limit') ?? '50');
  const start = (page - 1) * limit;

  const indexFile = Bun.file(join(dir, 'index.json'));
  if (await indexFile.exists()) {
    try {
      const raw = await indexFile.json();
      const index = Array.isArray(raw) ? null : (raw as { v?: number; entries: EmailSummary[] });
      if (index?.v === 3 && index.entries.length === filenames.length) {
        return ctx.json({ messages: index.entries.slice(start, start + limit), total: index.entries.length });
      }
    } catch {
      /* index corrupted, fall through to rebuild */
    }
  }

  // Fallback: rebuild index from .eml files
  const summaries = rebuildIndex(dir);
  return ctx.json({ messages: summaries.slice(start, start + limit), total: summaries.length });
});

emailRouter.get('/messages/:id', async (ctx) => {
  const email = ctx.get('user').email;
  const id = ctx.req.param('id');
  const filePath = join(getUserEmailDir(email), `${id}.eml`);

  const file = Bun.file(filePath);
  if (!(await file.exists())) {
    return ctx.text('Not found', 404);
  }

  try {
    const buffer = Buffer.from(await file.arrayBuffer());
    const parsed = await simpleParser(buffer);

    const attachments = (parsed.attachments ?? []).map((a) => ({
      filename: a.filename ?? 'unknown',
      size: a.size,
      contentType: a.contentType,
    }));

    const message: EmailMessage = {
      id,
      from: parsed.from?.text ?? '',
      to: parsed.to ? (Array.isArray(parsed.to) ? parsed.to.map((a) => a.text).join(', ') : parsed.to.text) : '',
      cc: parsed.cc ? (Array.isArray(parsed.cc) ? parsed.cc.map((a) => a.text).join(', ') : parsed.cc.text) : undefined,
      subject: parsed.subject ?? '(no subject)',
      date: (parsed.date ?? new Date()).toISOString(),
      snippet: (parsed.text ?? '').slice(0, 120).replace(/\s+/g, ' ').trim(),
      html: parsed.html || undefined,
      text: parsed.text || undefined,
      attachments,
    };

    return ctx.json(message);
  } catch {
    return ctx.text('Failed to parse email', 500);
  }
});

emailRouter.post('/messages/:id/attachments/:index/extract', async (ctx) => {
  const email = ctx.get('user').email;
  const id = ctx.req.param('id');
  const index = Number(ctx.req.param('index'));
  const filePath = join(getUserEmailDir(email), `${id}.eml`);

  const file = Bun.file(filePath);
  if (!(await file.exists())) {
    return ctx.text('Not found', 404);
  }

  try {
    const buffer = Buffer.from(await file.arrayBuffer());
    const parsed = await simpleParser(buffer);
    const attachment = parsed.attachments[index];
    if (!attachment) {
      return ctx.text('Attachment not found', 404);
    }

    const fileName = attachment.filename ?? 'unknown';
    const attachDir = join(getUserEmailDir(email), 'attachments');
    const destPath = join(attachDir, fileName);

    const destFile = Bun.file(destPath);
    if (!(await destFile.exists())) {
      await mkdir(attachDir, { recursive: true });
      await Bun.write(destPath, attachment.content);
    }

    return ctx.json({ filePath: `Gmail/emails/attachments/${fileName}`, fileName, root: 'user-data' });
  } catch {
    return ctx.text('Failed to extract attachment', 500);
  }
});