import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
import { useNostrLogin } from '@nostrify/react/login';
import type { NostrSigner } from '@contextvm/sdk/core';
import type { JoinRequest } from '@cordn/core';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useCoordinator } from '@/hooks/useCoordinator';
import { SKATESPOTS_COORDINATOR } from '@/lib/coordinator';
import { resolveCordnEndpoint } from '@/lib/cordn/endpoint';
// Dexie-only (light); the heavy MLS/ContextVM module is imported lazily so it
// loads only when the private-chat tab is opened, and stays out of the crew-page
// chunk.
import { createCordnStore, cordnGroupExists, cordnGroupGids } from '@/lib/cordn/native/idbStore';
import type {
  CordnChatMessage,
  CordnGroupInfo,
  CordnSession,
} from '@/lib/cordn/native';
import { isInteractiveSigner } from '@/lib/signerCapabilities';
import type { SkateCrew } from '@/lib/types';

/** Resolved coordinator endpoint for the native (ContextVM) client. */
export interface NativeCoordinator {
  serverPubkey: string;
  relays: string[];
}

/**
 * Resolve the coordinator a crew's native MLS chat should use: the crew's own
 * `coordinator` tag when it names a service pubkey, otherwise the viewer's
 * Settings → Coordinator, otherwise SkateSpots' provided coordinator.
 */
export function resolveNativeCoordinator(
  crew: SkateCrew,
  fallback: { pubkey: string; relays: string[] } | null,
): NativeCoordinator | null {
  const endpoint = resolveCordnEndpoint(crew);
  const serverPubkey =
    endpoint?.coordinatorPubkey ?? fallback?.pubkey ?? SKATESPOTS_COORDINATOR.pubkey;
  if (!serverPubkey) return null;
  const relays = endpoint
    ? [endpoint.relayUrl]
    : fallback?.relays?.length
      ? fallback.relays
      : SKATESPOTS_COORDINATOR.relays;
  return { serverPubkey, relays };
}

export interface UseCordnNativeResult {
  ready: boolean;
  coordinator: NativeCoordinator | null;
  /** The crew's MLS group id — the crew coordinate (deterministic for everyone). */
  groupId: string;
  group: CordnGroupInfo | null;
  messages: CordnChatMessage[];
  busy: boolean;
  error: string | null;
  /** Send a group message (optionally an image URL, encrypted in the payload). */
  send: (text: string, imageUrl?: string) => Promise<void>;
  /** Re-fetch messages (and adopt any new commits). */
  refresh: () => Promise<void>;
  /** Founder/admin: create the crew's MLS group. */
  createChat: () => Promise<void>;
  /** Non-admin: ask the coordinator to be added. */
  requestJoin: () => Promise<void>;
  /** Non-admin: collect a waiting welcome and join. */
  checkInvite: () => Promise<boolean>;
  /** Founder/admin: pending join requests for this group. */
  requests: JoinRequest[];
  loadRequests: () => Promise<void>;
  /** Founder/admin: add a requester (by pubkey) and deliver a welcome. */
  approve: (identifier: string) => Promise<void>;
  /** True for interactive signers (Amber) — manual refresh/send, no polling. */
  interactiveHintVisible: boolean;
  /** Shareable `cordn1…` reference for the crew's group (once known). */
  groupRef: string | null;
}

const POLL_MS = 6000;

/**
 * Drives a {@link CordnSession} for one crew: real MLS over the crew's Cordn
 * coordinator, keyed to the viewer's own Nostr identity (the transport signs
 * with the viewer's signer). State is persisted per account (IndexedDB), so a
 * reload resumes the same MLS group.
 */
export function useCordnNative({
  crew,
  enabled,
}: {
  crew: SkateCrew | null;
  enabled: boolean;
}): UseCordnNativeResult {
  const { user } = useCurrentUser();
  const { logins } = useNostrLogin();
  const { coordinator: userCoordinator } = useCoordinator();

  const coordinator = useMemo(
    () =>
      crew
        ? resolveNativeCoordinator(
            crew,
            userCoordinator ? { pubkey: userCoordinator.pubkey, relays: userCoordinator.relays } : null,
          )
        : null,
    [crew, userCoordinator],
  );

  const groupId = crew ? `35006:${crew.pubkey}:${crew.identifier}` : '';

  const sessionRef = useRef<CordnSession | null>(null);
  const [ready, setReady] = useState(false);
  const [group, setGroup] = useState<CordnGroupInfo | null>(null);
  const [messages, setMessages] = useState<CordnChatMessage[]>([]);
  const [requests, setRequests] = useState<JoinRequest[]>([]);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [groupRef, setGroupRef] = useState<string | null>(null);

  const interactive = isInteractiveSigner(user, logins);

  // Stable primitives for the session effect — depending on the `user` object
  // itself would re-open the session on every render if its identity churns.
  const pubkey = user?.pubkey ?? null;
  const signer = user?.signer;

  // Open the session when the crew, coordinator and identity are available.
  useEffect(() => {
    if (!enabled || !pubkey || !signer || !coordinator || !groupId) return;
    let cancelled = false;
    const session = import('@/lib/cordn/native').then((mod) => {
      if (!cancelled) {
        try {
          setGroupRef(
            mod.encodeGroupRef({
              gid: groupId,
              coordinatorPubkey: coordinator.serverPubkey,
              relays: coordinator.relays,
            }),
          );
        } catch {
          setGroupRef(null);
        }
      }
      return mod.CordnSession.open({
        coordinator: { serverPubkey: coordinator.serverPubkey, relays: coordinator.relays },
        pubkey,
        signer: signer as unknown as NostrSigner,
        store: createCordnStore(pubkey),
      });
    });
    session
      .then((opened) => {
        if (cancelled) {
          void opened.disconnect();
          return;
        }
        sessionRef.current = opened;
        const found = opened.listGroups().find((g) => g.gid === groupId) ?? null;
        setGroup(found);
        setMessages(found ? opened.messages(found.gid) : []);
        setReady(true);
      })
      .catch((err) => {
        if (!cancelled) setError(err instanceof Error ? err.message : String(err));
      });
    return () => {
      cancelled = true;
      const s = sessionRef.current;
      sessionRef.current = null;
      setReady(false);
      setGroupRef(null);
      if (s) void s.disconnect();
    };
  }, [enabled, pubkey, signer, coordinator, groupId]);

  const refresh = useCallback(async () => {
    const session = sessionRef.current;
    if (!session || !group) return;
    try {
      await session.fetch(group.gid);
      const next = session.messages(group.gid);
      setMessages(next);
      setGroup(session.listGroups().find((g) => g.gid === group.gid) ?? group);
      setError(null);
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }, [group]);

  // Live polling for silent signers only — an interactive signer would pop for
  // every request, so those users refresh/send manually (same rule as the DM
  // and sealed-relay chat hooks).
  useEffect(() => {
    if (!ready || !group || interactive) return;
    const id = setInterval(() => void refresh(), POLL_MS);
    return () => clearInterval(id);
  }, [ready, group, interactive, refresh]);

  const run = useCallback(async <T,>(fn: () => Promise<T>): Promise<T | undefined> => {
    setBusy(true);
    setError(null);
    try {
      return await fn();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
      return undefined;
    } finally {
      setBusy(false);
    }
  }, []);

  const send = useCallback(
    async (text: string, imageUrl?: string) => {
      const body = text.trim();
      const session = sessionRef.current;
      if ((!body && !imageUrl) || !session || !group) return;
      await run(async () => {
        await session.send(group.gid, body, imageUrl);
        setMessages(session.messages(group.gid));
      });
    },
    [group, run],
  );

  const createChat = useCallback(async () => {
    const session = sessionRef.current;
    if (!session || !crew || !groupId) return;
    await run(async () => {
      const created = await session.createGroup({ groupId, name: crew.name });
      setGroup(created);
      setMessages(session.messages(created.gid));
    });
  }, [crew, groupId, run]);

  const requestJoin = useCallback(async () => {
    const session = sessionRef.current;
    if (!session || !groupId) return;
    await run(async () => {
      await session.requestJoin(groupId);
    });
  }, [groupId, run]);

  const checkInvite = useCallback(async () => {
    const session = sessionRef.current;
    if (!session || !crew || !groupId) return false;
    const joined = await run(async () => {
      const welcomes = await session.fetchWelcomes();
      if (welcomes.length === 0) return false;
      const joinedGroup = await session.acceptWelcome(welcomes[0], crew.name);
      setGroup(joinedGroup);
      setMessages(session.messages(joinedGroup.gid));
      return true;
    });
    return joined ?? false;
  }, [crew, groupId, run]);

  const loadRequests = useCallback(async () => {
    const session = sessionRef.current;
    if (!session || !groupId) return;
    await run(async () => {
      const pending = await session.fetchJoinRequests(groupId);
      setRequests(pending);
    });
  }, [groupId, run]);

  const approve = useCallback(
    async (identifier: string) => {
      const session = sessionRef.current;
      if (!session || !group) return;
      await run(async () => {
        await session.addMemberByIdentifier(group.gid, identifier);
        const pending = await session.fetchJoinRequests(group.gid);
        setRequests(pending);
      });
    },
    [group, run],
  );

  return {
    ready,
    coordinator,
    groupId,
    group,
    messages,
    busy,
    error,
    send,
    refresh,
    createChat,
    requestJoin,
    checkInvite,
    requests,
    loadRequests,
    approve,
    interactiveHintVisible: interactive,
    groupRef,
  };
}

/**
 * Purely local check: does this account already have a saved MLS group for
 * `gid`? No coordinator request and no signer prompt — it reads the IndexedDB
 * snapshot. Re-runs when `refreshKey` changes. `undefined` until known.
 */
export function useCordnGroupExists(
  accountPubkey: string | undefined,
  gid: string,
  refreshKey?: unknown,
): boolean | undefined {
  const [exists, setExists] = useState<boolean | undefined>(undefined);
  useEffect(() => {
    let cancelled = false;
    if (!accountPubkey || !gid) {
      setExists(undefined);
      return;
    }
    cordnGroupExists(accountPubkey, gid)
      .then((value) => {
        if (!cancelled) setExists(value);
      })
      .catch(() => {
        if (!cancelled) setExists(false);
      });
    return () => {
      cancelled = true;
    };
  }, [accountPubkey, gid, refreshKey]);
  return exists;
}

/**
 * All MLS group ids this account holds (one IndexedDB read). Lets a list page
 * mark which crews already have a private chat without a per-crew read.
 */
export function useCordnGroupGids(
  accountPubkey: string | undefined,
  refreshKey?: unknown,
): Set<string> | undefined {
  const [gids, setGids] = useState<Set<string> | undefined>(undefined);
  useEffect(() => {
    let cancelled = false;
    if (!accountPubkey) {
      setGids(undefined);
      return;
    }
    cordnGroupGids(accountPubkey)
      .then((value) => {
        if (!cancelled) setGids(value);
      })
      .catch(() => {
        if (!cancelled) setGids(new Set());
      });
    return () => {
      cancelled = true;
    };
  }, [accountPubkey, refreshKey]);
  return gids;
}