import config from '../../config.js';
import log4js from 'log4js';
import { getModelByName } from './model.js';
import { listObjectsOData } from '../../database/odata.js';
import { getFilter } from '../../utils.js';
import { getModelFilterFields, parseOrderBy } from './export.js';

const logger = log4js.getLogger('RSS');
logger.level = config.server.logLevel;

function escapeXml(str) {
  return String(str)
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&apos;');
}

function getItemTitle(objectType, row) {
  const preferredTitle = row.name || row.title || row.label || row.code;
  if (preferredTitle) return String(preferredTitle);
  return `${objectType} ${row._id || 'entry'}`;
}

function getItemDescription(row) {
  const ignoredKeys = new Set(['_id', 'createdAt', 'updatedAt']);
  const summary = Object.entries(row || {})
    .filter(
      ([key, val]) => !ignoredKeys.has(key) && val !== null && val !== undefined && val !== ''
    )
    .slice(0, 10)
    .map(([key, val]) => `${key}: ${typeof val === 'object' ? JSON.stringify(val) : String(val)}`)
    .join(' | ');

  if (summary) return summary;
  return JSON.stringify(row || {});
}

function buildRssXml({ objectType, feedUrl, rows }) {
  const now = new Date().toUTCString();
  const itemsXml = rows
    .map((row) => {
      const rowId = row?._id ? String(row._id) : `${objectType}-${Date.now()}`;
      const pubDateSource = row?.updatedAt || row?.createdAt;
      const pubDate = pubDateSource ? new Date(pubDateSource).toUTCString() : now;
      const itemLink = `${feedUrl}#${encodeURIComponent(rowId)}`;
      return [
        '<item>',
        `  <title>${escapeXml(getItemTitle(objectType, row || {}))}</title>`,
        `  <link>${escapeXml(itemLink)}</link>`,
        `  <guid isPermaLink="false">${escapeXml(`${objectType}:${rowId}`)}</guid>`,
        `  <description>${escapeXml(getItemDescription(row || {}))}</description>`,
        `  <pubDate>${escapeXml(pubDate)}</pubDate>`,
        '</item>',
      ].join('\n');
    })
    .join('\n');

  return `<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
  <channel>
    <title>${escapeXml(`FarmControl ${objectType} RSS Feed`)}</title>
    <link>${escapeXml(feedUrl)}</link>
    <description>${escapeXml(`Recent ${objectType} updates from FarmControl`)}</description>
    <lastBuildDate>${escapeXml(now)}</lastBuildDate>
${itemsXml}
  </channel>
</rss>`;
}

/**
 * Route handler for GET /rss/:objectType
 * Supports OData-style query options: $top, $skip, $orderby and allowed filters.
 */
export const listRssRouteHandler = async (req, res) => {
  const objectType = req.params.objectType;
  const entry = getModelByName(objectType);

  if (!entry?.model) {
    logger.warn(`RSS: unknown object type "${objectType}"`);
    return res.status(404).send({ error: `Unknown object type: ${objectType}` });
  }

  const { $top, $skip, $orderby } = req.query;
  const queryWithoutAuth = { ...req.query };
  delete queryWithoutAuth.u;
  delete queryWithoutAuth.p;
  const limit = $top ? Math.min(parseInt($top, 10) || 25, 1000) : 25;
  const skip = $skip ? Math.max(0, parseInt($skip, 10) || 0) : 0;
  const page = Math.floor(skip / limit) + 1;
  const { sort, order } = parseOrderBy($orderby);
  const allowedFilters = getModelFilterFields(objectType);
  const filter = getFilter(queryWithoutAuth, allowedFilters);

  const result = await listObjectsOData({
    model: entry.model,
    populate: [],
    page,
    limit,
    filter,
    sort,
    order,
    pagination: true,
    project: '-__v',
    count: false,
  });

  if (result?.error) {
    logger.error('RSS list error:', result.error);
    return res.status(result.code || 500).send(result);
  }

  const baseUrl = config.app?.urlApi || '';
  const feedUrl = `${baseUrl}/rss/${objectType}`;
  const rows = result?.value || [];
  const xml = buildRssXml({ objectType, feedUrl, rows });

  res.set('Content-Type', 'application/rss+xml; charset=utf-8');
  res.send(xml);
};