"use client";

// Compact live event tail for a single topology_run — used inline on
// the mission phase card when a run is 'running'. Subscribes to
// /api/topology-runs/{id}/events (SSE), renders events as they arrive,
// closes when 'done' or on unmount.
//
// Reuses the same stream the mission's LIVE tab consumes; the
// difference here is scope (one run) + visual density (fits inside
// a phase card, not a full tab).

import { useEffect, useRef, useState } from "react";

const mono =
  "ui-monospace, SFMono-Regular, SF Mono, Menlo, Monaco, Consolas, monospace";

interface Event {
  key: number;
  ts: string;
  kind: string;
  text: string;
}

export function PhaseRunStream({ runId }: { runId: string }) {
  const [events, setEvents] = useState<Event[]>([]);
  const [terminal, setTerminal] = useState<string | null>(null);
  const seq = useRef(0);
  const scrollRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const es = new EventSource(`/api/topology-runs/${runId}/events`);
    const push = (kind: string, text: string) => {
      seq.current += 1;
      setEvents((prev) =>
        [
          ...prev,
          {
            key: seq.current,
            ts: new Date().toISOString(),
            kind,
            text,
          },
        ].slice(-120),
      );
    };
    es.addEventListener("step", (ev) => {
      try {
        const data = JSON.parse((ev as MessageEvent<string>).data ?? "{}");
        const kind = String(data.kind ?? data.step_type ?? "step");
        const text =
          data.summary ??
          data.text ??
          data.tool ??
          data.node ??
          data.reasoning ??
          JSON.stringify(data).slice(0, 200);
        push(kind, String(text));
      } catch {
        push("step", (ev as MessageEvent<string>).data ?? "");
      }
    });
    es.addEventListener("done", (ev) => {
      try {
        const data = JSON.parse((ev as MessageEvent<string>).data ?? "{}");
        const label = data.status === "failed" ? "failed" : "done";
        push(label, String(data.error ?? data.final_output ?? data.status ?? ""));
        setTerminal(label);
      } catch {
        push("done", (ev as MessageEvent<string>).data ?? "");
        setTerminal("done");
      }
      es.close();
    });
    es.onerror = () => {
      // Auto-retry is built into EventSource; nothing to do here.
    };
    return () => {
      es.close();
    };
  }, [runId]);

  useEffect(() => {
    const el = scrollRef.current;
    if (!el) return;
    const nearBottom = el.scrollHeight - el.scrollTop - el.clientHeight < 80;
    if (nearBottom) el.scrollTop = el.scrollHeight;
  }, [events.length]);

  return (
    <div
      ref={scrollRef}
      style={{
        marginTop: 6,
        padding: 8,
        borderRadius: 5,
        background: "rgba(0,0,0,.35)",
        color: "#cfcfd5",
        fontSize: 10.5,
        fontFamily: mono,
        maxHeight: 260,
        overflow: "auto",
        display: "flex",
        flexDirection: "column",
        gap: 3,
      }}
    >
      {events.length === 0 ? (
        <span style={{ color: "#6a6a72" }}>
          Waiting for events… (runs typically emit within a few seconds)
        </span>
      ) : (
        events.map((e) => (
          <div key={e.key} style={{ display: "flex", gap: 6 }}>
            <span style={{ color: "#6a6a72", flex: "none", width: 60 }}>
              {e.ts.slice(11, 19)}
            </span>
            <span
              style={{
                color:
                  e.kind === "failed"
                    ? "#ff8a7a"
                    : e.kind === "done"
                      ? "#5fd08a"
                      : "#c9a0ff",
                flex: "none",
                width: 74,
                textTransform: "uppercase",
                letterSpacing: ".06em",
                fontSize: 9,
              }}
            >
              {e.kind}
            </span>
            <span
              style={{
                color: "#cfcfd5",
                flex: 1,
                whiteSpace: "pre-wrap",
                wordBreak: "break-word",
              }}
            >
              {e.text}
            </span>
          </div>
        ))
      )}
      {terminal && (
        <div style={{ color: "#6a6a72", marginTop: 4 }}>
          stream closed ({terminal})
        </div>
      )}
    </div>
  );
}