"use client";

import * as React from "react";

type FleetEvent = {
  id: string;
  workspaceId: string;
  convoyId: string;
  briefId: string | null;
  role: string;
  actor: string | null;
  eventType: string;
  harnessAlias: string | null;
  occurredAt: string;
  metadata: Record<string, unknown> | null;
  classification?: string | null;
  durationS?: number | null;
  outcome?: string | null;
};

function formatRelative(iso: string): string {
  const diff = Date.now() - new Date(iso).getTime();
  const s = Math.floor(diff / 1000);
  if (s < 60) return `${s}s ago`;
  const m = Math.floor(s / 60);
  if (m < 60) return `${m}m ago`;
  const h = Math.floor(m / 60);
  if (h < 24) return `${h}h ago`;
  return `${Math.floor(h / 24)}d ago`;
}

export function FleetActivityFeed() {
  const [events, setEvents] = React.useState<FleetEvent[]>([]);
  const [connected, setConnected] = React.useState(false);
  const seenRef = React.useRef<Set<string>>(new Set());

  React.useEffect(() => {
    const es = new EventSource("/api/fleet/events");

    es.onopen = () => setConnected(true);
    es.onerror = () => setConnected(false);

    es.onmessage = (e) => {
      try {
        const parsed = JSON.parse(e.data) as FleetEvent | FleetEvent[];
        const incoming = Array.isArray(parsed) ? parsed : [parsed];
        // Filter duplicates by id
        const fresh = incoming.filter((ev) => {
          if (!ev?.id || seenRef.current.has(ev.id)) return false;
          seenRef.current.add(ev.id);
          return true;
        });
        if (fresh.length === 0) return;
        setEvents((prev) => {
          const merged = [...fresh, ...prev];
          // keep sort by occurredAt desc, dedup already handled, limit 50
          merged.sort((a, b) => new Date(b.occurredAt).getTime() - new Date(a.occurredAt).getTime());
          return merged.slice(0, 100);
        });
      } catch {
        // ignore malformed
      }
    };

    return () => {
      es.close();
    };
  }, []);

  return (
    <div className="rounded-lg border border-border bg-card">
      <div className="flex items-center justify-between border-b border-border px-4 py-3">
        <h3 className="text-sm font-semibold">Activity feed</h3>
        <span className="text-[10px] text-muted-foreground">{connected ? "live" : "reconnecting…"}</span>
      </div>
      <div className="max-h-[360px] overflow-y-auto">
        {events.length === 0 ? (
          <p className="p-4 text-sm text-muted-foreground">No recent convoy events.</p>
        ) : (
          <ul className="divide-y divide-border">
            {events.map((ev) => (
              <li key={ev.id} className="px-4 py-2.5 text-sm">
                <div className="flex items-center justify-between gap-2">
                  <span className="font-medium">{ev.eventType}</span>
                  <span className="text-xs text-muted-foreground">{formatRelative(ev.occurredAt)}</span>
                </div>
                <p className="text-xs text-muted-foreground">
                  {ev.role}
                  {ev.actor && ev.actor !== ev.role ? ` · ${ev.actor}` : ""}
                  {ev.harnessAlias ? ` · ${ev.harnessAlias}` : ""}
                  {ev.outcome ? ` · ${ev.outcome}` : ""}
                </p>
                <p className="text-[10px] text-muted-foreground">convoy {ev.convoyId.slice(0, 8)}</p>
              </li>
            ))}
          </ul>
        )}
      </div>
    </div>
  );
}