// api/data.js — Vercel Serverless Function
// Consulta Jira en tiempo real y devuelve los datos procesados del dashboard.
// Variables de entorno requeridas: JIRA_EMAIL, JIRA_TOKEN
const JIRA_HOST   = 'invera.atlassian.net';
const JQL         = 'project = LABS AND cf[10016] is not EMPTY ORDER BY updated DESC';
const FIELDS      = [
  'summary', 'status', 'assignee',
  'customfield_10016',  // Story point estimate
  'customfield_11019',  // Story Points Finales
  'customfield_10622',  // Desarrollador (multi-user)
  'parent', 'resolutiondate', 'created',
].join(',');
const MAX_RESULTS = 100;
const CACHE_MS    = 24 * 60 * 60 * 1000; // 24 horas
// Cache en memoria (se reinicia con cada cold start de la función)
let _cache     = null;
let _cacheTime = 0;
// ─── Jira fetch ──────────────────────────────────────────────────────────────
async function fetchJiraIssues(email, token) {
  const auth = Buffer.from(`${email}:${token}`).toString('base64');
  const url  = `https://${JIRA_HOST}/rest/api/3/search/jql`
    + `?jql=${encodeURIComponent(JQL)}`
    + `&fields=${encodeURIComponent(FIELDS)}`
    + `&maxResults=${MAX_RESULTS}`;
  const res = await fetch(url, {
    headers: {
      'Authorization': `Basic ${auth}`,
      'Accept':        'application/json',
    },
  });
  if (!res.ok) {
    const text = await res.text();
    throw new Error(`Jira API ${res.status}: ${text.slice(0, 200)}`);
  }
  return res.json();
}
// ─── Data processing ─────────────────────────────────────────────────────────
function processIssues(issues) {
  const assigneeData = {};
  const monthlyDone  = {};
  const epicMap      = {};
  for (const issue of issues) {
    const f = issue.fields;
    // Desarrollador (customfield_10622 multi-user), fallback a assignee
    const devs = f.customfield_10622?.length
      ? f.customfield_10622.map(d => d.displayName)
      : f.assignee
        ? [f.assignee.displayName]
        : ['Sin asignar'];
    // SP: SP Finales si está cargado, si no el estimate
    const sp = (f.customfield_11019 != null ? f.customfield_11019 : f.customfield_10016) ?? 0;
    // Estado
    const catKey = f.status?.statusCategory?.key ?? 'new';
    // Fechas (YYYY-MM)
    const resMonth = f.resolutiondate ? f.resolutiondate.slice(0, 7) : null;
    const creMonth = f.created        ? f.created.slice(0, 7)        : null;
    // Épica (parent)
    const epic = f.parent?.fields?.summary ?? 'Sin épica';
    // ── Acumular por desarrollador ──
    for (const dev of devs) {
      if (!assigneeData[dev]) assigneeData[dev] = { done: 0, in_progress: 0, todo: 0 };
      if      (catKey === 'done')          assigneeData[dev].done        += sp;
      else if (catKey === 'indeterminate') assigneeData[dev].in_progress += sp;
      else                                assigneeData[dev].todo        += sp;
    }
    // ── Acumular completados por mes ──
    if (catKey === 'done') {
      const month = resMonth || creMonth;
      if (month) {
        if (!monthlyDone[month]) monthlyDone[month] = {};
        for (const dev of devs) {
          monthlyDone[month][dev] = (monthlyDone[month][dev] ?? 0) + sp;
        }
      }
    }
    // ── Acumular por épica ──
    if (!epicMap[epic]) epicMap[epic] = { name: epic, done: 0, in_progress: 0, todo: 0 };
    if      (catKey === 'done')          epicMap[epic].done        += sp;
    else if (catKey === 'indeterminate') epicMap[epic].in_progress += sp;
    else                                epicMap[epic].todo        += sp;
  }
  return {
    lastUpdated:  new Date().toISOString(),
    totalIssues:  issues.length,
    assigneeData,
    monthlyDone,
    epicData: Object.values(epicMap)
      .sort((a, b) => (b.done + b.in_progress + b.todo) - (a.done + a.in_progress + a.todo)),
  };
}
// ─── Handler ─────────────────────────────────────────────────────────────────
module.exports = async (req, res) => {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET');
  // CDN cache: 24hs fresco, sirve stale mientras recarga
  res.setHeader('Cache-Control', 's-maxage=86400, stale-while-revalidate=3600');
  // Force refresh si se pasa ?refresh=1
  const forceRefresh = req.query?.refresh === '1';
  // Servir desde caché si está fresco
  if (!forceRefresh && _cache && (Date.now() - _cacheTime) < CACHE_MS) {
    return res.status(200).json({ ..._cache, fromCache: true });
  }
  const email = process.env.JIRA_EMAIL;
  const token = process.env.JIRA_TOKEN;
  if (!email || !token) {
    return res.status(500).json({
      error: 'Faltan variables de entorno: JIRA_EMAIL y/o JIRA_TOKEN',
      hint:  'Configurarlas en Vercel → Settings → Environment Variables',
    });
  }
  try {
    const { issues, total } = await fetchJiraIssues(email, token);
    const data = processIssues(issues);
    data.jiraTotal = total; // total real en Jira (puede ser > 100)
    _cache     = data;
    _cacheTime = Date.now();
    return res.status(200).json({ ...data, fromCache: false });
  } catch (err) {
    console.error('[dashboard/api/data]', err.message);
    return res.status(500).json({ error: err.message });
  }
};