// Microsoft Teams integration: posts alerts to a Teams channel/chat via an incoming webhook URL.
// Supports the modern Power Automate "Workflows" webhook (Adaptive Card envelope) and the legacy
// Office 365 connector ("MessageCard"). Best-effort delivery — failures are counted, never thrown,
// so a bad Teams endpoint can't break the alert cycle.
const { all, audit, now, run } = require('../db');

const TIMEOUT_MS = 10000;
const FORMATS = ['adaptive', 'messagecard'];
const SEVERITY_RANK = { info: 0, warning: 1, critical: 2 };

function readSettings() {
  const rows = all("SELECT key, value FROM app_settings WHERE key LIKE 'teams_%'");
  return Object.fromEntries(rows.map((r) => [r.key, r.value]));
}

// Raw config used for delivery.
function getConfig() {
  const s = readSettings();
  return {
    enabled: s.teams_enabled === 'true',
    webhookUrl: s.teams_webhook_url || '',
    format: FORMATS.includes(s.teams_format) ? s.teams_format : 'adaptive',
    minSeverity: SEVERITY_RANK[s.teams_min_severity] !== undefined ? s.teams_min_severity : 'warning'
  };
}

// Safe config for the API/UI.
function publicConfig() {
  const c = getConfig();
  return {
    teams_enabled: c.enabled,
    teams_webhook_url: c.webhookUrl,
    teams_format: c.format,
    teams_min_severity: c.minSeverity,
    teams_configured: Boolean(c.webhookUrl)
  };
}

function setValue(key, value) {
  run(
    'INSERT INTO app_settings (key, value, updated_at) VALUES (?, ?, ?) ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = excluded.updated_at',
    [key, String(value), now()]
  );
}

function saveConfig(body, userId) {
  if (body.teams_enabled !== undefined) setValue('teams_enabled', body.teams_enabled ? 'true' : 'false');
  if (body.teams_webhook_url !== undefined) setValue('teams_webhook_url', body.teams_webhook_url || '');
  if (body.teams_format !== undefined) setValue('teams_format', FORMATS.includes(body.teams_format) ? body.teams_format : 'adaptive');
  if (body.teams_min_severity !== undefined) setValue('teams_min_severity', SEVERITY_RANK[body.teams_min_severity] !== undefined ? body.teams_min_severity : 'warning');
  audit(userId, 'update', 'teams_settings', null, null, body);
  return publicConfig();
}

// ---- Card builders ---------------------------------------------------------

function adaptiveColor(severity) {
  if (severity === 'critical') return 'attention';
  if (severity === 'warning') return 'warning';
  return 'accent';
}

function messageCardColor(severity) {
  if (severity === 'critical') return 'b3261e';
  if (severity === 'warning') return 'a56a00';
  return '2457a6';
}

function highestSeverity(alerts) {
  return alerts.reduce((top, a) => (SEVERITY_RANK[a.severity] > SEVERITY_RANK[top] ? a.severity : top), 'info');
}

function alertFacts(alert) {
  const facts = [];
  if (alert.due_date) facts.push({ title: 'Due', value: String(alert.due_date), name: 'Due' });
  if (alert.asset_code) facts.push({ title: 'Asset', value: String(alert.asset_code), name: 'Asset' });
  if (alert.type) facts.push({ title: 'Type', value: String(alert.type), name: 'Type' });
  return facts;
}

// Adaptive Card (Power Automate Workflows webhook). One card summarizing all alerts.
function buildAdaptiveCard(alerts, heading, intro) {
  const body = [
    { type: 'TextBlock', size: 'Large', weight: 'Bolder', text: heading },
    { type: 'TextBlock', text: intro, isSubtle: true, wrap: true, spacing: 'None' }
  ];
  for (const alert of alerts) {
    body.push({
      type: 'TextBlock', weight: 'Bolder', color: adaptiveColor(alert.severity),
      text: `${String(alert.severity || 'info').toUpperCase()} · ${alert.title}`, wrap: true, separator: true
    });
    if (alert.message) body.push({ type: 'TextBlock', text: alert.message, wrap: true, spacing: 'None' });
    const facts = alertFacts(alert);
    if (facts.length) body.push({ type: 'FactSet', facts: facts.map((f) => ({ title: f.title, value: f.value })) });
  }
  return {
    type: 'message',
    attachments: [{
      contentType: 'application/vnd.microsoft.card.adaptive',
      content: {
        $schema: 'http://adaptivecards.io/schemas/adaptive-card.json',
        type: 'AdaptiveCard',
        version: '1.4',
        msteams: { width: 'Full' },
        body
      }
    }]
  };
}

// Legacy MessageCard (Office 365 connector).
function buildMessageCard(alerts, heading, intro) {
  return {
    '@type': 'MessageCard',
    '@context': 'http://schema.org/extensions',
    themeColor: messageCardColor(highestSeverity(alerts)),
    summary: heading,
    title: `${heading} — ${intro}`,
    sections: alerts.map((alert) => ({
      activityTitle: `${String(alert.severity || 'info').toUpperCase()} · ${alert.title}`,
      text: alert.message || '',
      facts: alertFacts(alert).map((f) => ({ name: f.name, value: f.value }))
    }))
  };
}

function buildPayload(alerts, config, { heading = 'DepreCore alerts', intro } = {}) {
  const text = intro || `${alerts.length} item(s) need attention.`;
  return config.format === 'messagecard'
    ? buildMessageCard(alerts, heading, text)
    : buildAdaptiveCard(alerts, heading, text);
}

// ---- Delivery --------------------------------------------------------------

async function postPayload(url, payload) {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), TIMEOUT_MS);
  try {
    const response = await fetch(url, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(payload),
      signal: controller.signal
    });
    return { ok: response.ok, status: response.status };
  } finally {
    clearTimeout(timer);
  }
}

// Post the pending alerts as a single digest card. Honors the configured minimum severity so the
// channel isn't flooded with low-priority items.
async function deliverAlerts(alerts) {
  const c = getConfig();
  if (!c.enabled || !c.webhookUrl || !alerts.length) {
    return { attempted: false, delivered: 0, failed: 0 };
  }
  const threshold = SEVERITY_RANK[c.minSeverity] ?? 1;
  const relevant = alerts.filter((a) => (SEVERITY_RANK[a.severity] ?? 0) >= threshold);
  if (!relevant.length) return { attempted: false, delivered: 0, failed: 0 };
  try {
    const result = await postPayload(c.webhookUrl, buildPayload(relevant, c));
    return { attempted: true, delivered: result.ok ? 1 : 0, failed: result.ok ? 0 : 1, status: result.status, count: relevant.length };
  } catch {
    return { attempted: true, delivered: 0, failed: 1 };
  }
}

// Post a test card to verify the webhook URL.
async function sendTest(userId) {
  const c = getConfig();
  if (!c.webhookUrl) throw Object.assign(new Error('A Teams webhook URL is not configured'), { status: 400 });
  const sample = [{ severity: 'info', title: 'DepreCore Teams test', message: 'If you can see this card in your channel, the Teams integration is configured correctly.', type: 'test' }];
  const payload = buildPayload(sample, c, { heading: 'DepreCore Teams test', intro: 'Connection test' });
  let result;
  try {
    result = await postPayload(c.webhookUrl, payload);
  } catch (error) {
    throw Object.assign(new Error(`Teams request failed: ${error.message}`), { status: 400 });
  }
  audit(userId, 'send', 'teams_test', null, null, { status: result.status });
  if (!result.ok) throw Object.assign(new Error(`Teams endpoint returned HTTP ${result.status}`), { status: 400 });
  return { ok: true, status: result.status };
}

module.exports = { buildPayload, deliverAlerts, getConfig, publicConfig, saveConfig, sendTest };