import { useEffect, useMemo, useRef, useState, useCallback } from 'react';
import { useSession } from '../context/SessionContext.jsx';
import { useSettingsNamespace } from '../settings/index.js';
import { useSocket } from '../context/SocketContext.jsx';
import NicknameForm from './NicknameForm.jsx';
import DiscordInviteButton from './DiscordInviteButton.jsx';
import KoFiButton from './KoFiButton.jsx';

function roleColors(role) {
  switch (role) {
    case 'admin':
    case 'lockdown':
    case 'lockdown-admin':
      return 'text-amber-300';
    case 'spectator':
      return 'text-slate-400';
    default:
      return 'text-sky-300';
  }
}

function formatLabel(user, selfId) {
  if (!user) return '';
  const base = user.nickname || user.socketId?.slice(0, 6) || 'unknown';
  if (user.socketId && user.socketId === selfId) {
    return `${base} (you)`;
  }
  return base;
}

export default function UserListPanel({ hideNicknameForm = false, hideHeader = false, className = '', fillHeight = false }) {
  const { session, setNickname } = useSession();
  const { value } = useSettingsNamespace('profile', { nickname: '' });
  const lastSyncedSocketRef = useRef(null);
  const socket = useSocket();
  const canSetNickname = session?.role !== 'spectator';
  const users = session?.users ?? [];
  const selfId = session?.socketId || null;
  const isTurnsMode = session?.mode === 'turns';
  const turnQueues = session?.turnQueues || {};
  const roster = session?.roster || [];

  useEffect(() => {
    if (!canSetNickname) return;
    if (!session?.socketId) return;
    const nicknameInput = value.nickname || '';
    if (!nicknameInput) return;
    if (session.socketId === lastSyncedSocketRef.current) return;
    const currentId = session.socketId;
    setNickname(nicknameInput).then(() => {
      lastSyncedSocketRef.current = currentId;
    }).catch(() => {});
  }, [canSetNickname, session?.socketId, setNickname, value.nickname]);

  useEffect(() => {
    if (!socket) return undefined;
    const handleConnect = () => {
      if (!canSetNickname) return;
      const nick = (value.nickname || '').trim();
      if (!nick) return;
      setNickname(nick).then(() => {
        lastSyncedSocketRef.current = session?.socketId || null;
      }).catch(() => {});
    };
    socket.on('connect', handleConnect);
    return () => socket.off('connect', handleConnect);
  }, [canSetNickname, setNickname, socket, value.nickname, session?.socketId]);

  const sorted = useMemo(
    () =>
      [...users].sort((a, b) => {
        if (a.socketId === selfId) return -1;
        if (b.socketId === selfId) return 1;
        return (a.nickname || '').localeCompare(b.nickname || '');
      }),
    [selfId, users],
  );

  const rosterName = useCallback(
    (roverId) => roster.find((r) => String(r.id) === String(roverId))?.name || roverId,
    [roster],
  );

  const lookupUser = useCallback(
    (socketId) => users.find((u) => u.socketId === socketId) || { socketId, nickname: null, role: null },
    [users],
  );

  const secondsRemaining = useCallback((deadline) => {
    if (!deadline) return null;
    const ms = deadline - Date.now();
    if (ms <= 0) return 0;
    return Math.ceil(ms / 1000);
  }, []);

  const baseListClass = fillHeight ? 'flex-1 min-h-0 overflow-y-auto' : 'h-48 overflow-y-auto';
  const turnsListClass = isTurnsMode && fillHeight ? 'max-h-40 overflow-y-auto' : baseListClass;
  const usersListClass = isTurnsMode && fillHeight ? 'flex-1 min-h-0 overflow-y-auto' : baseListClass;

  const renderUserList = () =>
    sorted.length === 0 ? (
      <p className="text-sm text-slate-500">Waiting for users…</p>
    ) : (
      sorted.map((user) => {
        const isAdmin =
          user.role === 'admin' || user.role === 'lockdown' || user.role === 'lockdown-admin';
        return (
          <div
            key={user.socketId}
            className="surface-muted flex items-center gap-1 text-sm"
          >
            <p className={`font-semibold ${roleColors(user.role)}`}>{formatLabel(user, selfId)}</p>
            {user.roverId ? (
              <span className="rounded bg-slate-800 px-1 text-[0.7rem]">rover {user.roverId}</span>
            ) : (
              <span className="text-[0.7rem] text-slate-500">no rover</span>
            )}
            {isAdmin && (
              <span className="rounded bg-amber-500/30 px-1 text-[0.7rem] text-amber-200">
                Admin
              </span>
            )}
          </div>
        );
      })
    );

  return (
    <section
      className={`panel-section space-y-0.5 text-base ${fillHeight ? 'flex h-full min-h-0 flex-col overflow-hidden' : ''} ${className}`}
    >
      {!hideNicknameForm && (
        <div className="space-y-0.5">
          <div className="flex items-stretch gap-0.5">
            <div className="flex min-w-0 flex-1">
              <div className="surface flex w-full items-center">
                <NicknameForm />
              </div>
            </div>
            <div className="flex w-1/2 min-w-[8rem] flex-col gap-0.5">
              <DiscordInviteButton />
              <KoFiButton />
            </div>
          </div>
          {!canSetNickname && <p className="text-xs text-slate-500">Spectators cannot set nicknames.</p>}
        </div>
      )}

      <div className={`space-y-0.5 ${fillHeight ? 'flex flex-1 min-h-0 flex-col' : ''}`}>
        {!hideHeader && (
          <div className="flex items-center justify-between text-sm text-slate-400">
            <span>{isTurnsMode ? 'Turn queues' : 'Users'}</span>
            <span className="text-xs text-slate-500">
              {isTurnsMode ? Object.keys(turnQueues || {}).length : sorted.length}
            </span>
          </div>
        )}
        <div className={`surface space-y-0.25 ${isTurnsMode ? turnsListClass : baseListClass}`}>
          {isTurnsMode ? (
            Object.keys(turnQueues || {}).length === 0 ? (
              <p className="text-sm text-slate-500">No turn queues yet.</p>
            ) : (
              Object.entries(turnQueues).map(([roverId, info]) => {
                const queue = info?.queue || [];
                const deadline = info?.idleDeadline || info?.deadline || null;
                const remaining = secondsRemaining(deadline);
                return (
                  <div key={roverId} className="surface-muted flex flex-col gap-0.25 text-sm">
                    <div className="flex items-center gap-1">
                      <p className="font-semibold text-slate-200">{rosterName(roverId)}</p>
                      {remaining != null && (
                        <span className="rounded bg-slate-800 px-1 text-[0.7rem]">
                          {remaining}s left
                        </span>
                      )}
                    </div>
                    {queue.length === 0 ? (
                      <p className="text-[0.75rem] text-slate-500">No drivers queued.</p>
                    ) : (
                      <div className="flex flex-wrap items-center gap-1">
                        {queue.map((socketId, idx) => {
                          const user = lookupUser(socketId);
                          const isCurrent = socketId === info?.current;
                          const isAdmin =
                            user.role === 'admin' || user.role === 'lockdown' || user.role === 'lockdown-admin';
                          return (
                            <span
                              key={`${roverId}-${socketId}-${idx}`}
                              className={`flex items-center gap-0.5 rounded px-1 text-[0.8rem] ${
                                isCurrent ? 'bg-sky-700 text-white' : 'bg-slate-800 text-slate-200'
                              }`}
                            >
                              <span className={`${roleColors(user.role)} font-semibold`}>
                                {formatLabel(user, selfId)}
                              </span>
                              {isAdmin && <span className="text-[0.7rem] text-amber-200">★</span>}
                              {isCurrent && <span className="text-[0.7rem] text-slate-200">now</span>}
                            </span>
                          );
                        })}
                      </div>
                    )}
                  </div>
                );
              })
            )
          ) : (
            renderUserList()
          )}
        </div>

        {isTurnsMode ? (
          <div className={`space-y-0.25 ${fillHeight ? 'flex min-h-0 flex-1 flex-col' : ''}`}>
            <div className="flex items-center justify-between text-xs text-slate-400">
              <span>Users</span>
              <span className="text-[0.7rem] text-slate-500">{sorted.length}</span>
            </div>
            <div className={`surface space-y-0.25 ${usersListClass}`}>
              {renderUserList()}
            </div>
          </div>
        ) : null}
      </div>
    </section>
  );
}