import { createClientFromRequest } from 'npm:@base44/sdk@0.8.23';

/**
 * Fill Escalation Monitor
 * Runs every 15 minutes. Detects events at risk of not being filled
 * and creates escalation alerts in ActivityLog.
 * 
 * Fill probability formula:
 *   score = (assigned / requested) * 60
 *         + timeBuffer * 20   (more time = more chance to fill)
 *         + dayOfWeek * 20    (based on historical fill rate for that day)
 * 
 * If fillProbability < 60% → escalation alert
 */

Deno.serve(async (req) => {
  const base44 = createClientFromRequest(req);

  // Allow scheduled/service calls without user auth
  const now = new Date();
  const in24h = new Date(now.getTime() + 24 * 60 * 60 * 1000);
  const in4h  = new Date(now.getTime() + 4  * 60 * 60 * 1000);

  // Fetch all upcoming active events
  const allEvents = await base44.asServiceRole.entities.Event.list();
  const upcoming  = allEvents.filter(e => {
    if (!e.date) return false;
    const eventDate = new Date(e.date);
    return eventDate > now && eventDate <= in24h &&
           ["Active", "Pending", "Confirmed", "Draft"].includes(e.status);
  });

  // Historical fill rate by day of week
  const completed = allEvents.filter(e => e.status === "Completed" && e.date);
  const dayFillRate = Array(7).fill(null).map((_, dow) => {
    const dayEvents = completed.filter(e => new Date(e.date).getDay() === dow);
    if (dayEvents.length === 0) return 0.75; // default 75%
    const filled = dayEvents.filter(e => (e.assigned_staff?.length || 0) >= (e.requested || 1));
    return filled.length / dayEvents.length;
  });

  const escalations = [];
  const alerts      = [];

  for (const event of upcoming) {
    const assigned    = event.assigned_staff?.length || 0;
    const requested   = event.requested || 0;
    if (requested === 0) continue;

    const fillRatio   = assigned / requested;
    const eventDate   = new Date(event.date);
    const hoursUntil  = (eventDate - now) / (1000 * 60 * 60);
    const dow         = eventDate.getDay();

    // Time buffer score: 0 = within 2h (critical), 1 = 24h out (comfortable)
    const timeBuffer  = Math.min(hoursUntil / 24, 1);

    // Fill probability 0-100
    const fillProbability = Math.round(
      fillRatio * 60 +
      timeBuffer * 20 +
      dayFillRate[dow] * 20
    );

    const isCritical = hoursUntil <= 4 && fillRatio < 1;
    const isAtRisk   = fillProbability < 60;

    if (isCritical || isAtRisk) {
      escalations.push({
        event_id:        event.id,
        event_name:      event.event_name,
        hours_until:     Math.round(hoursUntil),
        fill_ratio:      fillRatio,
        fill_probability: fillProbability,
        assigned,
        requested,
        is_critical:     isCritical,
      });

      // Create ActivityLog alert (avoid duplicates — check if one exists in last 2h)
      const existingAlerts = await base44.asServiceRole.entities.ActivityLog.filter({
        related_entity_id: event.id,
        activity_type:     "event_updated",
      });

      const recentAlert = existingAlerts.find(a => {
        const created = new Date(a.created_date);
        return (now - created) < 2 * 60 * 60 * 1000; // within 2h
      });

      if (!recentAlert) {
        const severity    = isCritical ? "🚨 CRITICAL" : "⚠️ AT RISK";
        const gapCount    = requested - assigned;
        const description = isCritical
          ? `${event.event_name} starts in ${Math.round(hoursUntil)}h — ${gapCount} position${gapCount > 1 ? "s" : ""} still open. Fill immediately.`
          : `${event.event_name} has a ${fillProbability}% fill probability. ${gapCount} position${gapCount > 1 ? "s" : ""} unfilled with ${Math.round(hoursUntil)}h remaining.`;

        alerts.push(
          base44.asServiceRole.entities.ActivityLog.create({
            title:              `${severity}: ${event.event_name} needs staffing`,
            description,
            activity_type:      "event_updated",
            related_entity_type: "event",
            related_entity_id:  event.id,
            action_link:        `EventDetail?id=${event.id}`,
            action_label:       "Assign Staff Now",
            user_id:            event.created_by || "system",
            is_read:            false,
            icon_type:          "alert",
            icon_color:         isCritical ? "red" : "yellow",
          })
        );
      }
    }
  }

  await Promise.all(alerts);

  return Response.json({
    checked:     upcoming.length,
    escalations: escalations.length,
    details:     escalations,
    timestamp:   now.toISOString(),
  });
});