import { useMemo } from "react";
import { useHive } from "../store";
import { fmtCost, fmtNum } from "../lib/format";
import { hhmmss, statusColorVar, statusKey } from "../lib/agents";
import { bundleEvents, itemAgent, mergeThinking, type ActivityItem as LiveItem } from "../lib/activity";
import type { ScopeAgent } from "../store";
import type { AgentRuntime, HiveEvent } from "../types";

type Kind = "DELEGATE" | "TOOL" | "MSG" | "DONE" | "ERROR" | "THINK";

const KIND_COLOR: Record<Kind, string> = {
  DELEGATE: "var(--run)",
  TOOL: "var(--ink-dim)",
  MSG: "var(--ink-dim)",
  DONE: "var(--done)",
  ERROR: "var(--crit)",
  THINK: "var(--brand)",
};

// Map a bundled activity item onto the spec's five-kind vocabulary.
function kindOf(item: LiveItem): Kind {
  if (item.kind === "thinking") return "THINK";
  if (item.kind === "tool") {
    return item.end?.payload?.isError ? "ERROR" : "TOOL";
  }
  const e = item.event;
  const p = e.payload || {};
  switch (e.type) {
    case "delegation_start": return "DELEGATE";
    case "delegation_end": return p.type === "error" || p.isError ? "ERROR" : "DONE";
    case "error": return "ERROR";
    case "worker_retry": return "ERROR";
    case "assistant_message":
    case "user_message": return "MSG";
    default: return p.isError ? "ERROR" : "MSG";
  }
}

// Line-2 message text.
function messageOf(item: LiveItem): string {
  if (item.kind === "thinking") return item.text.replace(/\*\*/g, "").replace(/\s+/g, " ").trim();
  if (item.kind === "tool") {
    const p = (item.end || item.start)?.payload || {};
    const args = typeof p.args === "string" ? p.args : "";
    return [p.toolName, args].filter(Boolean).join(" ") || p.toolName || "tool call";
  }
  const e = item.event;
  const p = e.payload || {};
  switch (e.type) {
    case "delegation_start": return p.task || `spawned ${p.to || "worker"}`;
    case "delegation_end": return p.message || "task complete";
    case "assistant_message":
    case "user_message": return p.text || "";
    case "error": return p.message || "error";
    // worker_retry carries attempt/maxAttempts/errorMessage (K6). The "start"
    // phase is the informative one; the "end" phase just reports success.
    case "worker_retry":
      return p.phase === "end"
        ? (p.success ? "retry succeeded" : "retry failed")
        : `retry ${p.attempt ?? "?"}/${p.maxAttempts ?? "?"}${p.errorMessage ? ` — ${p.errorMessage}` : ""}`;
    default: return typeof p.text === "string" ? p.text : e.type;
  }
}

// Whether an item's payload was clipped at source (J6) — drives a "… truncated"
// affordance so a reader knows the preview is partial.
function isTruncated(item: LiveItem): boolean {
  if (item.kind === "tool") return (item.end || item.start)?.payload?.truncated === true;
  if (item.kind === "event") return item.event?.payload?.truncated === true;
  return false;
}

// Right-aligned line-2 metadata: delegation target, token delta, duration, retry.
function metaOf(item: LiveItem): string {
  if (item.kind === "thinking") return item.tokens ? `+${fmtNum(item.tokens)} tok` : "";
  if (item.kind === "tool") {
    if (item.start && item.end) {
      const ms = new Date(item.end.ts).getTime() - new Date(item.start.ts).getTime();
      return ms < 1000 ? `${ms}ms` : `${(ms / 1000).toFixed(1)}s`;
    }
    return "running";
  }
  const e = item.event;
  const p = e.payload || {};
  switch (e.type) {
    case "delegation_start": return p.to ? `→ ${p.to}` : "";
    case "delegation_end": {
      const rt = p.runtime || {};
      const tok = Number(rt.inputTokens || 0) + Number(rt.outputTokens || 0);
      if (tok) return `+${fmtNum(tok)} tok`;
      if (p.costUsd) return fmtCost(p.costUsd);
      return p.elapsedMs ? `${Math.round(p.elapsedMs / 1000)}s` : "";
    }
    // worker_retry meta shows the attempt counter (K6). The dead `p.retry` read
    // on `error` events is gone — retries arrive as their own worker_retry event.
    case "worker_retry": return p.attempt != null ? `attempt ${p.attempt}/${p.maxAttempts ?? "?"}` : "";
    default: return "";
  }
}

export default function LiveActivity(props: {
  limit?: number;
  events?: HiveEvent[];
  // Replay (M4): when replaying, `replayTs` is the cursor timestamp so we can
  // clip the live-polled thinking feed to the playhead, and `replayStatus` is
  // the replay-derived status map (from the same slice) so status dots reflect
  // the rewound state rather than the live roster.
  replayTs?: string;
  replayStatus?: Map<string, AgentRuntime>;
}) {
  const scopedEventsLive = useHive((s) => s.scopedEvents);
  const scopedAgents = useHive((s) => s.scopedAgents);
  const scopedSessions = useHive((s) => s.scopedSessions);
  const thinkingBySession = useHive((s) => s.thinkingBySession);
  // Replay (K5) passes its own event slice; live SSE never mutates it.
  const scopedEvents = props.events ?? scopedEventsLive;
  const replayTs = props.replayTs;
  const replayStatus = props.replayStatus;

  // Single roster: id → model/status, shared with the topology graph. In replay
  // mode the status dot comes from the replay-derived map (statusFor); the roster
  // still supplies identity colour.
  const roster = useMemo(() => {
    const m = new Map<string, ScopeAgent>();
    for (const a of scopedAgents) if (!m.has(a.name)) m.set(a.name, a);
    return m;
  }, [scopedAgents]);

  // Thinking entries for the sessions in scope, merged into the feed by time. In
  // replay mode, clip to the cursor timestamp so future thinking never leaks in.
  const thinking = useMemo(() => {
    const out: Array<{ agent: string; ts: string; text: string }> = [];
    for (const s of scopedSessions) for (const t of thinkingBySession.get(s.session_id) || []) {
      if (replayTs && t.ts > replayTs) continue;
      out.push(t);
    }
    return out;
  }, [scopedSessions, thinkingBySession, replayTs]);

  const items = useMemo(
    () => mergeThinking(bundleEvents(scopedEvents), thinking).slice(0, props.limit ?? 40),
    [scopedEvents, thinking, props.limit],
  );

  // The thinking feed is polled for at most 6 sessions (fan-out cap in wiring).
  // Surface that at fleet scale so a reader knows thinking is partial.
  const THINKING_SESSION_CAP = 6;
  const thinkingCapped = scopedSessions.length > THINKING_SESSION_CAP;

  if (!items.length) return <div className="tl-scroll"><div className="empty">No activity yet.</div></div>;

  return (
    <div className="tl-scroll">
      {thinkingCapped && (
        <div className="text-[10px] text-ink-dimmer italic px-2 py-1">
          Showing agent thinking for the {THINKING_SESSION_CAP} most-recent sessions in scope.
        </div>
      )}
      {items.map((item) => {
        const agentId = itemAgent(item) || "—";
        const agent = roster.get(agentId);
        const kind = kindOf(item);
        const kc = KIND_COLOR[kind];
        // Status dot: replay-derived status when rewound, else the live roster.
        const status = replayStatus ? replayStatus.get(agentId)?.status : agent?.status;
        const sk = statusKey(status);
        const dotColor = statusColorVar(status);
        const msg = messageOf(item);
        const meta = metaOf(item);
        const truncated = isTruncated(item);
        // Identity color drives the row's left border (real agents only; else neutral).
        const agentColor = agent?.color || "var(--ink-dimmer)";
        return (
          <div key={item.id} className="feed-row animate-feedin" style={{ "--agent-color": agentColor } as React.CSSProperties}>
            <div className="flex items-center gap-[7px]">
              <span className="font-mono text-[10px] text-ink-dimmer flex-none">{hhmmss(new Date(item.ts).getTime())}</span>
              {/* one dot: live agent status. Identity color is carried by the row's left border. */}
              <span className="relative w-[6px] h-[6px] flex-none" title={sk}>
                {sk === "running" && <span className="absolute -inset-[3px] rounded-full animate-halo" style={{ background: "color-mix(in srgb, var(--run) 45%, transparent)" }} />}
                <span className="absolute inset-0 rounded-full" style={{ background: dotColor }} />
              </span>
              <span className="text-[11px] font-bold text-ink flex-none">{agentId}</span>
              <span className="flex-1" />
              <span className="feed-pill flex-none" style={{ color: kc, background: `color-mix(in srgb, ${kc} 15%, transparent)` }}>{kind}</span>
            </div>
            <div className="flex gap-2 mt-1 pl-[23px]">
              <span className="text-[11.5px] text-ink leading-[1.4] flex-1 min-w-0 line-clamp-2">
                {msg}
                {truncated && <span className="text-ink-dimmer italic" title="Preview was truncated at source"> … truncated</span>}
              </span>
              {meta && <span className="font-mono text-[10px] text-ink-dim flex-none whitespace-nowrap">{meta}</span>}
            </div>
          </div>
        );
      })}
    </div>
  );
}