"use client";

// Messenger data layer. Serves EITHER a local mock (when the Shell isn't configured — the demo
// keeps working) OR the live be-crm data door (crm.messenger.*), behind one interface so the UI is
// mode-agnostic. DM-vs-group + who-can-chat are enforced server-side by IIOS/OPA; this is just glue.
//
// Live contract (be-crm):
//   query crm.messenger.directory        { kind, query?, limit } -> DirectoryEntry[]
//   query crm.messenger.conversation.list {}                     -> ConversationSummary[]
//   cmd   crm.messenger.conversation.open { participantIds[], membership?, subject? } -> { threadId, ... }
//   query crm.messenger.history          { threadId }            -> MessengerMessage[]
//   cmd   crm.messenger.send             { threadId, content }   -> MessengerMessage
//   cmd   crm.messenger.participant.add  { threadId, userId }
//
// v1 uses REST + polling for the live stream; v2 layers the IIOS MessageSocket (messenger-socket.tsx)
// on top for live messages, typing, read receipts, and reactions.

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { useAppShell, useAuth, useQuery } from "@abe-kap/appshell-sdk/react";
import type { AnnotationEvent, AnnotationGroup } from "@insignia/iios-kernel-client";
import { isShellConfigured } from "./appshell";
import { useMessengerSocket } from "./messenger-socket";

export type Membership = "dm" | "group";
export interface UiPerson { id: string; name: string; kind: "staff" | "customer" }
export interface UiConversation {
  threadId: string; title: string; subject: string | null; membership: Membership | null;
  participants: string[]; unread: number; lastMessage?: string; lastAt?: string;
}
export interface UiReaction { emoji: string; count: number; mine: boolean }
export interface UiMessage {
  id: string; actorId: string | null; senderId?: string | null; text: string; at: string; mine: boolean;
  parentInteractionId?: string | null;
  reactions?: UiReaction[];
}

interface DirectoryDTO { id: string; displayName: string; kind: "staff" | "customer" }
interface ConversationDTO {
  threadId: string; subject: string | null; membership: Membership | null;
  participants: string[]; unread: number; lastMessage?: string; lastAt?: string;
}
interface MessageDTO { interactionId: string; actorId: string | null; kind: string; occurredAt: string; text: string | null }

const SHELL = isShellConfigured();
const POLL_MS = 4000;
const TYPING_TTL_MS = 3500;

const shortId = (id: string) => id.replace(/^(pp_|cust_)/, "").slice(0, 6);

/** Turn the kernel's generic annotation aggregates into reaction chips. `users` may hold user or
 *  actor ids depending on the source, so `mine` is best-effort; a fresh annotation event corrects it. */
export function toReactions(annotations: AnnotationGroup[] | undefined, myId?: string): UiReaction[] {
  if (!annotations) return [];
  return annotations
    .filter((a) => a.type === "reaction" && a.users.length > 0)
    .map((a) => ({ emoji: a.value, count: a.users.length, mine: !!myId && a.users.includes(myId) }));
}

function applyAnnotation(prev: UiReaction[] | undefined, e: AnnotationEvent, myId?: string): UiReaction[] {
  const base = (prev ?? []).filter((r) => r.emoji !== e.value);
  if (e.type !== "reaction" || e.users.length === 0) return base;
  return [...base, { emoji: e.value, count: e.users.length, mine: !!myId && e.users.includes(myId) }];
}

/* ======================================================================== */
/* Public hooks                                                             */
/* ======================================================================== */

export interface MessengerData {
  live: boolean; loading: boolean; error: string | null;
  directory: UiPerson[];
  conversations: UiConversation[];
  nameOf: (id: string) => string;
  openConversation: (participantIds: string[], opts?: { membership?: Membership; subject?: string }) => Promise<string>;
  refetch: () => void;
}

export interface ThreadData {
  loading: boolean; error: string | null;
  messages: UiMessage[];
  send: (content: string, opts?: { parentInteractionId?: string }) => Promise<void>;
  react: (interactionId: string, emoji: string) => void;
  typingUserIds: string[];
  seenIds: Set<string>;
  refetch: () => void;
}

export function useMessengerData(): MessengerData {
  return SHELL ? useLiveMessenger() : useMockMessenger();
}
export function useThread(threadId: string): ThreadData {
  return SHELL ? useLiveThread(threadId) : useMockThread(threadId);
}

/* ======================================================================== */
/* Live implementation (be-crm data door + IIOS socket)                     */
/* ======================================================================== */

function useLiveMessenger(): MessengerData {
  const { sdk } = useAppShell();
  const { user } = useAuth();
  const socket = useMessengerSocket();
  const myId = user?.id;
  const dirQ = useQuery<DirectoryDTO[]>("crm.messenger.directory", { kind: "all", limit: 100 });
  const convQ = useQuery<ConversationDTO[]>("crm.messenger.conversation.list", {});

  const directory: UiPerson[] = useMemo(
    () => (dirQ.data ?? []).map((d) => ({ id: d.id, name: d.displayName, kind: d.kind })),
    [dirQ.data],
  );
  const nameById = useMemo(() => Object.fromEntries(directory.map((p) => [p.id, p.name])), [directory]);
  const nameOf = useCallback((id: string) => nameById[id] ?? `User ${shortId(id)}`, [nameById]);

  // Live sidebar previews: patch lastMessage/lastAt the instant a message arrives on any thread,
  // then reconcile authoritative unread/order with a debounced refetch.
  const [previews, setPreviews] = useState<Record<string, { lastMessage: string; lastAt: string }>>({});
  const refetchRef = useRef(convQ.refetch);
  refetchRef.current = convQ.refetch;
  useEffect(() => {
    if (!socket) return;
    let timer: ReturnType<typeof setTimeout> | null = null;
    const off = socket.onAnyMessage((threadId, m) => {
      setPreviews((p) => ({ ...p, [threadId]: { lastMessage: m.text, lastAt: m.at } }));
      if (timer) clearTimeout(timer);
      timer = setTimeout(() => refetchRef.current(), 600);
    });
    return () => { off(); if (timer) clearTimeout(timer); };
  }, [socket]);

  const conversations: UiConversation[] = useMemo(
    () => (convQ.data ?? []).map((c) => shape(c, nameOf, myId, previews[c.threadId])),
    [convQ.data, nameOf, myId, previews],
  );

  const refetch = useCallback(() => { dirQ.refetch(); convQ.refetch(); }, [dirQ, convQ]);
  const openConversation = useCallback(async (participantIds: string[], opts?: { membership?: Membership; subject?: string }) => {
    const res = (await sdk.command("crm.messenger.conversation.open", {
      participantIds, ...(opts?.membership ? { membership: opts.membership } : {}), ...(opts?.subject ? { subject: opts.subject } : {}),
    })) as { threadId: string };
    convQ.refetch();
    return res.threadId;
  }, [sdk, convQ]);

  return {
    live: true,
    loading: dirQ.loading || convQ.loading,
    error: (dirQ.error ?? convQ.error)?.message ?? null,
    directory, conversations, nameOf, openConversation, refetch,
  };
}

function useLiveThread(threadId: string): ThreadData {
  const { sdk } = useAppShell();
  const socket = useMessengerSocket();
  const socketReady = socket?.ready ?? false;
  const q = useQuery<MessageDTO[]>("crm.messenger.history", { threadId });
  const [socketMsgs, setSocketMsgs] = useState<UiMessage[]>([]);
  const [myActorId, setMyActorId] = useState<string | null>(null);
  const myActorIdRef = useRef<string | null>(null);
  myActorIdRef.current = myActorId;
  const [typing, setTyping] = useState<Record<string, number>>({}); // userId -> expiry ts
  const [seenIds, setSeenIds] = useState<Set<string>>(new Set());
  const myId = socket?.myUserId;

  // REST poll — the fallback whenever the live socket isn't connected.
  const refetchRef = useRef(q.refetch);
  refetchRef.current = q.refetch;
  useEffect(() => {
    if (socketReady) return;
    const t = setInterval(() => refetchRef.current(), POLL_MS);
    return () => clearInterval(t);
  }, [socketReady, threadId]);

  // Socket (primary): load history + subscribe to live messages, typing, receipts, reactions.
  useEffect(() => {
    if (!socket || !socketReady) return;
    let alive = true;
    setSocketMsgs([]); setSeenIds(new Set()); setTyping({});
    void socket.openThread(threadId).then((hist) => { if (alive) setSocketMsgs(hist); }).catch(() => {});

    const offMsg = socket.subscribe(threadId, (m) =>
      setSocketMsgs((l) => (l.some((x) => x.id === m.id) ? l : [...l, m])),
    );
    const offTyping = socket.onTyping(threadId, (userId) =>
      setTyping((t) => ({ ...t, [userId]: Date.now() + TYPING_TTL_MS })),
    );
    // Receipts are a global stream (no threadId). Count only reads by the OTHER side; seenMine then
    // narrows to my messages in this thread.
    const offReceipt = socket.onReceipt((e) => {
      if (e.actorId === myActorIdRef.current) return;
      setSeenIds((s) => (s.has(e.interactionId) ? s : new Set(s).add(e.interactionId)));
    });
    const offAnn = socket.onAnnotation(threadId, (e) =>
      setSocketMsgs((l) => l.map((m) => (m.id === e.interactionId ? { ...m, reactions: applyAnnotation(m.reactions, e, myId) } : m))),
    );
    return () => { alive = false; offMsg(); offTyping(); offReceipt(); offAnn(); };
  }, [socket, socketReady, threadId, myId]);

  // Learn my own actor id from a message I sent, so receipts from OTHER actors read as "seen".
  useEffect(() => {
    const mine = socketMsgs.find((m) => m.mine && m.actorId);
    if (mine?.actorId && mine.actorId !== myActorId) setMyActorId(mine.actorId);
  }, [socketMsgs, myActorId]);

  // Tell the server I've read the latest message (drives the other side's "seen" tick).
  useEffect(() => {
    if (!socket || !socketReady || socketMsgs.length === 0) return;
    socket.markRead(threadId, socketMsgs[socketMsgs.length - 1].id);
  }, [socket, socketReady, threadId, socketMsgs]);

  // Expire stale typing entries.
  const typingUserIds = useMemo(() => {
    const now = Date.now();
    return Object.entries(typing).filter(([, exp]) => exp > now).map(([u]) => u);
  }, [typing]);
  useEffect(() => {
    if (typingUserIds.length === 0) return;
    const t = setTimeout(() => setTyping((p) => ({ ...p })), TYPING_TTL_MS);
    return () => clearTimeout(t);
  }, [typingUserIds.length, typing]);

  const restMsgs: UiMessage[] = useMemo(
    () => (q.data ?? []).map((m) => ({
      id: m.interactionId, actorId: m.actorId, senderId: null, text: m.text ?? "", at: m.occurredAt,
      mine: !!myActorId && m.actorId === myActorId, reactions: [],
    })),
    [q.data, myActorId],
  );

  const messages = socketReady ? socketMsgs : restMsgs;

  // My messages the other side has read (receipts carry the other actor's id).
  const seenMine = useMemo(() => {
    const out = new Set<string>();
    for (const id of seenIds) if (messages.some((m) => m.id === id && m.mine)) out.add(id);
    return out;
  }, [seenIds, messages]);

  const send = useCallback(async (content: string, opts?: { parentInteractionId?: string }) => {
    if (socket && socketReady) {
      await socket.send(threadId, content, opts); // echoes back over the socket as a 'message' event
    } else {
      const m = (await sdk.command("crm.messenger.send", { threadId, content })) as MessageDTO;
      if (m.actorId) setMyActorId(m.actorId);
      q.refetch();
    }
  }, [socket, socketReady, threadId, sdk, q]);

  const react = useCallback((interactionId: string, emoji: string) => {
    if (socket && socketReady) socket.react(threadId, interactionId, emoji);
  }, [socket, socketReady, threadId]);

  return {
    loading: q.loading && !socketReady, error: q.error?.message ?? null,
    messages, send, react, typingUserIds, seenIds: seenMine, refetch: q.refetch,
  };
}

function shape(
  c: ConversationDTO,
  nameOf: (id: string) => string,
  myId: string | undefined,
  overlay?: { lastMessage: string; lastAt: string },
): UiConversation {
  // A DM's title is the OTHER person — never yourself, and never the raw unknown-id fallback for both.
  const others = myId ? c.participants.filter((p) => p !== myId) : c.participants;
  const title = c.subject?.trim()
    || (c.membership === "group"
      ? `Group · ${c.participants.length}`
      : (others.map(nameOf).join(", ") || nameOf(c.participants[0] ?? "") || "Conversation"));
  const lastMessage = overlay?.lastMessage ?? c.lastMessage;
  const lastAt = overlay?.lastAt ?? c.lastAt;
  return {
    threadId: c.threadId, title, subject: c.subject, membership: c.membership,
    participants: c.participants, unread: c.unread,
    ...(lastMessage ? { lastMessage } : {}), ...(lastAt ? { lastAt } : {}),
  };
}

/* ======================================================================== */
/* Mock implementation (no Shell configured — the demo keeps working)       */
/* ======================================================================== */

const MOCK_PEOPLE: UiPerson[] = [
  { id: "pp_sofia", name: "Sofia Ramirez", kind: "staff" },
  { id: "pp_dan", name: "Dan Whitaker", kind: "staff" },
  { id: "pp_priya", name: "Priya Nair", kind: "staff" },
  { id: "cust_acme", name: "Acme Roofing (Client)", kind: "customer" },
  { id: "cust_globex", name: "Globex Homes (Client)", kind: "customer" },
];

interface MockThread { threadId: string; membership: Membership; subject: string | null; participants: string[]; messages: UiMessage[] }
const now = () => new Date().toISOString();
let MOCK_SEQ = 100;

// A tiny module-level store both mock hooks share, with a subscribe-on-change so the
// conversation list and the open thread stay in sync (no globalThis, no render writes).
const MOCK_STORE = new Map<string, MockThread>([
  ["th_mock_1", { threadId: "th_mock_1", membership: "dm", subject: null, participants: ["me", "pp_sofia"],
    messages: [{ id: "m1", actorId: "pp_sofia", text: "Can you review the Henderson estimate?", at: now(), mine: false, reactions: [] }] }],
  ["th_mock_2", { threadId: "th_mock_2", membership: "group", subject: "Storm response — East side", participants: ["me", "pp_dan", "pp_priya"],
    messages: [{ id: "m2", actorId: "pp_dan", text: "Crew is rolling out at 7.", at: now(), mine: false, reactions: [] }] }],
]);
const mockListeners = new Set<() => void>();
const notifyMock = () => mockListeners.forEach((l) => l());
function useMockSubscription(): void {
  const [, setV] = useState(0);
  useEffect(() => {
    const l = () => setV((n) => n + 1);
    mockListeners.add(l);
    return () => { mockListeners.delete(l); };
  }, []);
}

function useMockMessenger(): MessengerData {
  useMockSubscription();
  const nameById = useMemo(() => Object.fromEntries(MOCK_PEOPLE.map((p) => [p.id, p.name])), []);
  const nameOf = useCallback((id: string) => nameById[id] ?? `User ${shortId(id)}`, [nameById]);

  const conversations: UiConversation[] = [...MOCK_STORE.values()].map((t) => {
    const last = t.messages[t.messages.length - 1];
    return {
      threadId: t.threadId,
      title: t.subject || t.participants.filter((p) => p !== "me").map(nameOf).join(", ") || "Conversation",
      subject: t.subject, membership: t.membership, participants: t.participants, unread: 0,
      ...(last ? { lastMessage: last.text, lastAt: last.at } : {}),
    };
  });

  const openConversation = useCallback(async (participantIds: string[], opts?: { membership?: Membership; subject?: string }) => {
    const membership = opts?.membership ?? (participantIds.length === 1 ? "dm" : "group");
    const threadId = `th_mock_${MOCK_SEQ++}`;
    MOCK_STORE.set(threadId, { threadId, membership, subject: opts?.subject ?? null, participants: ["me", ...participantIds], messages: [] });
    notifyMock();
    return threadId;
  }, []);

  return { live: false, loading: false, error: null, directory: MOCK_PEOPLE, conversations, nameOf, openConversation, refetch: () => {} };
}

function useMockThread(threadId: string): ThreadData {
  useMockSubscription();
  const thread = MOCK_STORE.get(threadId);
  const send = useCallback(async (content: string, opts?: { parentInteractionId?: string }) => {
    const t = MOCK_STORE.get(threadId);
    if (t) {
      t.messages = [...t.messages, {
        id: `m_${MOCK_SEQ++}`, actorId: "me", text: content, at: now(), mine: true, reactions: [],
        ...(opts?.parentInteractionId ? { parentInteractionId: opts.parentInteractionId } : {}),
      }];
      notifyMock();
    }
  }, [threadId]);
  const react = useCallback((interactionId: string, emoji: string) => {
    const t = MOCK_STORE.get(threadId);
    if (!t) return;
    t.messages = t.messages.map((m) => {
      if (m.id !== interactionId) return m;
      const has = (m.reactions ?? []).find((r) => r.emoji === emoji);
      const reactions = has
        ? (m.reactions ?? []).filter((r) => r.emoji !== emoji)
        : [...(m.reactions ?? []), { emoji, count: 1, mine: true }];
      return { ...m, reactions };
    });
    notifyMock();
  }, [threadId]);
  return {
    loading: false, error: null, messages: thread?.messages ?? [], send, react,
    typingUserIds: [], seenIds: new Set(), refetch: notifyMock,
  };
}