import { useEffect, useMemo, useRef, useState, type MutableRefObject } from "react";
import { Link } from "react-router-dom";
import { useQuery } from "@tanstack/react-query";
import type { Issue, LiveEvent } from "@paperclip/shared";
import { heartbeatsApi, type LiveRunForIssue } from "../api/heartbeats";
import { issuesApi } from "../api/issues";
import { getUIAdapter } from "../adapters";
import type { TranscriptEntry } from "../adapters";
import { queryKeys } from "../lib/queryKeys";
import { cn, relativeTime } from "../lib/utils";
import { ExternalLink } from "lucide-react";
import { Identity } from "./Identity";

type FeedTone = "info" | "warn" | "error" | "assistant" | "tool";

interface FeedItem {
  id: string;
  ts: string;
  runId: string;
  agentId: string;
  agentName: string;
  text: string;
  tone: FeedTone;
}

const MAX_FEED_ITEMS = 40;

function readString(value: unknown): string | null {
  return typeof value === "string" && value.trim().length > 0 ? value : null;
}

function summarizeEntry(entry: TranscriptEntry): { text: string; tone: FeedTone } | null {
  if (entry.kind === "assistant") {
    const text = entry.text.trim();
    return text ? { text, tone: "assistant" } : null;
  }
  if (entry.kind === "thinking") {
    const text = entry.text.trim();
    return text ? { text: `[thinking] ${text}`, tone: "info" } : null;
  }
  if (entry.kind === "tool_call") {
    return { text: `tool ${entry.name}`, tone: "tool" };
  }
  if (entry.kind === "tool_result") {
    const base = entry.content.trim();
    return {
      text: entry.isError ? `tool error: ${base}` : `tool result: ${base}`,
      tone: entry.isError ? "error" : "tool",
    };
  }
  if (entry.kind === "stderr") {
    const text = entry.text.trim();
    return text ? { text, tone: "error" } : null;
  }
  if (entry.kind === "system") {
    const text = entry.text.trim();
    return text ? { text, tone: "warn" } : null;
  }
  if (entry.kind === "stdout") {
    const text = entry.text.trim();
    return text ? { text, tone: "info" } : null;
  }
  return null;
}

function createFeedItem(
  run: LiveRunForIssue,
  ts: string,
  text: string,
  tone: FeedTone,
  nextId: number,
): FeedItem | null {
  const trimmed = text.trim();
  if (!trimmed) return null;
  return {
    id: `${run.id}:${nextId}`,
    ts,
    runId: run.id,
    agentId: run.agentId,
    agentName: run.agentName,
    text: trimmed.slice(0, 220),
    tone,
  };
}

function parseStdoutChunk(
  run: LiveRunForIssue,
  chunk: string,
  ts: string,
  pendingByRun: Map<string, string>,
  nextIdRef: MutableRefObject<number>,
): FeedItem[] {
  const pendingKey = `${run.id}:stdout`;
  const combined = `${pendingByRun.get(pendingKey) ?? ""}${chunk}`;
  const split = combined.split(/\r?\n/);
  pendingByRun.set(pendingKey, split.pop() ?? "");
  const adapter = getUIAdapter(run.adapterType);

  const items: FeedItem[] = [];
  for (const line of split.slice(-8)) {
    const trimmed = line.trim();
    if (!trimmed) continue;
    const parsed = adapter.parseStdoutLine(trimmed, ts);
    if (parsed.length === 0) {
      const fallback = createFeedItem(run, ts, trimmed, "info", nextIdRef.current++);
      if (fallback) items.push(fallback);
      continue;
    }
    for (const entry of parsed) {
      const summary = summarizeEntry(entry);
      if (!summary) continue;
      const item = createFeedItem(run, ts, summary.text, summary.tone, nextIdRef.current++);
      if (item) items.push(item);
    }
  }

  return items;
}

function parseStderrChunk(
  run: LiveRunForIssue,
  chunk: string,
  ts: string,
  pendingByRun: Map<string, string>,
  nextIdRef: MutableRefObject<number>,
): FeedItem[] {
  const pendingKey = `${run.id}:stderr`;
  const combined = `${pendingByRun.get(pendingKey) ?? ""}${chunk}`;
  const split = combined.split(/\r?\n/);
  pendingByRun.set(pendingKey, split.pop() ?? "");

  const items: FeedItem[] = [];
  for (const line of split.slice(-8)) {
    const item = createFeedItem(run, ts, line, "error", nextIdRef.current++);
    if (item) items.push(item);
  }
  return items;
}

interface ActiveAgentsPanelProps {
  companyId: string;
}

export function ActiveAgentsPanel({ companyId }: ActiveAgentsPanelProps) {
  const [feedByRun, setFeedByRun] = useState<Map<string, FeedItem[]>>(new Map());
  const seenKeysRef = useRef(new Set<string>());
  const pendingByRunRef = useRef(new Map<string, string>());
  const nextIdRef = useRef(1);

  const { data: liveRuns } = useQuery({
    queryKey: queryKeys.liveRuns(companyId),
    queryFn: () => heartbeatsApi.liveRunsForCompany(companyId),
  });

  const runs = liveRuns ?? [];
  const { data: issues } = useQuery({
    queryKey: queryKeys.issues.list(companyId),
    queryFn: () => issuesApi.list(companyId),
    enabled: runs.length > 0,
  });

  const issueById = useMemo(() => {
    const map = new Map<string, Issue>();
    for (const issue of issues ?? []) {
      map.set(issue.id, issue);
    }
    return map;
  }, [issues]);

  const runById = useMemo(() => new Map(runs.map((r) => [r.id, r])), [runs]);
  const activeRunIds = useMemo(() => new Set(runs.map((r) => r.id)), [runs]);

  // Clean up pending buffers for runs that ended
  useEffect(() => {
    const stillActive = new Set<string>();
    for (const runId of activeRunIds) {
      stillActive.add(`${runId}:stdout`);
      stillActive.add(`${runId}:stderr`);
    }
    for (const key of pendingByRunRef.current.keys()) {
      if (!stillActive.has(key)) {
        pendingByRunRef.current.delete(key);
      }
    }
  }, [activeRunIds]);

  // WebSocket connection for streaming
  useEffect(() => {
    if (activeRunIds.size === 0) return;

    let closed = false;
    let reconnectTimer: number | null = null;
    let socket: WebSocket | null = null;

    const appendItems = (runId: string, items: FeedItem[]) => {
      if (items.length === 0) return;
      setFeedByRun((prev) => {
        const next = new Map(prev);
        const existing = next.get(runId) ?? [];
        next.set(runId, [...existing, ...items].slice(-MAX_FEED_ITEMS));
        return next;
      });
    };

    const scheduleReconnect = () => {
      if (closed) return;
      reconnectTimer = window.setTimeout(connect, 1500);
    };

    const connect = () => {
      if (closed) return;
      const protocol = window.location.protocol === "https:" ? "wss" : "ws";
      const url = `${protocol}://${window.location.host}/api/companies/${encodeURIComponent(companyId)}/events/ws`;
      socket = new WebSocket(url);

      socket.onmessage = (message) => {
        const raw = typeof message.data === "string" ? message.data : "";
        if (!raw) return;

        let event: LiveEvent;
        try {
          event = JSON.parse(raw) as LiveEvent;
        } catch {
          return;
        }

        if (event.companyId !== companyId) return;
        const payload = event.payload ?? {};
        const runId = readString(payload["runId"]);
        if (!runId || !activeRunIds.has(runId)) return;

        const run = runById.get(runId);
        if (!run) return;

        if (event.type === "heartbeat.run.event") {
          const seq = typeof payload["seq"] === "number" ? payload["seq"] : null;
          const eventType = readString(payload["eventType"]) ?? "event";
          const messageText = readString(payload["message"]) ?? eventType;
          const dedupeKey = `${runId}:event:${seq ?? `${eventType}:${messageText}:${event.createdAt}`}`;
          if (seenKeysRef.current.has(dedupeKey)) return;
          seenKeysRef.current.add(dedupeKey);
          if (seenKeysRef.current.size > 2000) seenKeysRef.current.clear();
          const tone = eventType === "error" ? "error" : eventType === "lifecycle" ? "warn" : "info";
          const item = createFeedItem(run, event.createdAt, messageText, tone, nextIdRef.current++);
          if (item) appendItems(run.id, [item]);
          return;
        }

        if (event.type === "heartbeat.run.status") {
          const status = readString(payload["status"]) ?? "updated";
          const dedupeKey = `${runId}:status:${status}:${readString(payload["finishedAt"]) ?? ""}`;
          if (seenKeysRef.current.has(dedupeKey)) return;
          seenKeysRef.current.add(dedupeKey);
          if (seenKeysRef.current.size > 2000) seenKeysRef.current.clear();
          const tone = status === "failed" || status === "timed_out" ? "error" : "warn";
          const item = createFeedItem(run, event.createdAt, `run ${status}`, tone, nextIdRef.current++);
          if (item) appendItems(run.id, [item]);
          return;
        }

        if (event.type === "heartbeat.run.log") {
          const chunk = readString(payload["chunk"]);
          if (!chunk) return;
          const stream = readString(payload["stream"]) === "stderr" ? "stderr" : "stdout";
          if (stream === "stderr") {
            appendItems(run.id, parseStderrChunk(run, chunk, event.createdAt, pendingByRunRef.current, nextIdRef));
            return;
          }
          appendItems(run.id, parseStdoutChunk(run, chunk, event.createdAt, pendingByRunRef.current, nextIdRef));
        }
      };

      socket.onerror = () => {
        socket?.close();
      };

      socket.onclose = () => {
        scheduleReconnect();
      };
    };

    connect();

    return () => {
      closed = true;
      if (reconnectTimer !== null) window.clearTimeout(reconnectTimer);
      if (socket) {
        socket.onmessage = null;
        socket.onerror = null;
        socket.onclose = null;
        socket.close(1000, "active_agents_panel_unmount");
      }
    };
  }, [activeRunIds, companyId, runById]);

  if (runs.length === 0) return null;

  return (
    <div>
      <h3 className="text-sm font-semibold text-muted-foreground uppercase tracking-wide mb-3">
        Active Agents
      </h3>
      <div className="grid md:grid-cols-2 gap-4">
        {runs.map((run) => (
          <AgentRunCard
            key={run.id}
            run={run}
            issue={run.issueId ? issueById.get(run.issueId) : undefined}
            feed={feedByRun.get(run.id) ?? []}
          />
        ))}
      </div>
    </div>
  );
}

function AgentRunCard({
  run,
  issue,
  feed,
}: {
  run: LiveRunForIssue;
  issue?: Issue;
  feed: FeedItem[];
}) {
  const bodyRef = useRef<HTMLDivElement>(null);
  const recent = feed.slice(-20);

  useEffect(() => {
    const body = bodyRef.current;
    if (!body) return;
    body.scrollTo({ top: body.scrollHeight, behavior: "smooth" });
  }, [feed.length]);

  return (
    <div className="rounded-lg border border-blue-500/30 bg-background/80 overflow-hidden shadow-[0_0_12px_rgba(59,130,246,0.08)]">
      <div className="flex items-center justify-between px-3 py-2 border-b border-border/50">
        <div className="flex items-center gap-2">
          <span className="relative flex h-2 w-2">
            <span className="animate-ping absolute inline-flex h-full w-full rounded-full bg-blue-400 opacity-75" />
            <span className="relative inline-flex rounded-full h-2 w-2 bg-blue-500" />
          </span>
          <Identity name={run.agentName} size="sm" />
          <span className="text-[11px] font-medium text-blue-400">Live</span>
          <span className="text-[10px] text-muted-foreground font-mono">
            {run.id.slice(0, 8)}
          </span>
        </div>
        <Link
          to={`/agents/${run.agentId}/runs/${run.id}`}
          className="inline-flex items-center gap-1 text-[10px] text-blue-400 hover:text-blue-300"
        >
          Open run
          <ExternalLink className="h-2.5 w-2.5" />
        </Link>
      </div>

      {run.issueId && (
        <div className="px-3 py-1.5 border-b border-border/40 text-xs flex items-center gap-1 min-w-0">
          <span className="text-muted-foreground mr-1">Working on:</span>
          <Link
            to={`/issues/${issue?.identifier ?? run.issueId}`}
            className="text-blue-400 hover:text-blue-300 hover:underline min-w-0 truncate"
            title={issue?.title ? `${issue?.identifier ?? run.issueId.slice(0, 8)} - ${issue.title}` : issue?.identifier ?? run.issueId.slice(0, 8)}
          >
            {issue?.identifier ?? run.issueId.slice(0, 8)}
            {issue?.title ? ` - ${issue.title}` : ""}
          </Link>
        </div>
      )}

      <div ref={bodyRef} className="max-h-[180px] overflow-y-auto p-2 font-mono text-[11px] space-y-1">
        {recent.length === 0 && (
          <div className="text-xs text-muted-foreground">Waiting for output...</div>
        )}
        {recent.map((item, index) => (
          <div
            key={item.id}
            className={cn(
              "flex gap-2 items-start",
              index === recent.length - 1 && "animate-in fade-in slide-in-from-bottom-1 duration-300",
            )}
          >
            <span className="text-[10px] text-muted-foreground shrink-0">{relativeTime(item.ts)}</span>
            <span className={cn(
              "min-w-0 break-words",
              item.tone === "error" && "text-red-300",
              item.tone === "warn" && "text-amber-300",
              item.tone === "assistant" && "text-emerald-200",
              item.tone === "tool" && "text-cyan-300",
              item.tone === "info" && "text-foreground/80",
            )}>
              {item.text}
            </span>
          </div>
        ))}
      </div>
    </div>
  );
}