import React, { useEffect, useMemo, useState } from 'react';
import { apiExam, type ExamRoomItem } from '../api';
import { openExam } from './NavHistoryBar';
import { useAuth } from '../auth/AuthContext';

function fmtTime(iso: string) {
  try {
    return new Date(iso).toLocaleString('vi-VN');
  } catch {
    return iso;
  }
}

function statusMeta(st: string) {
  if (st === 'draft') return { text: 'Tạm thời', tone: 'muted' };
  if (st === 'ready') return { text: 'Sẵn sàng', tone: 'info' };
  if (st === 'active') return { text: 'Đang thi', tone: 'active' };
  if (st === 'cancelled') return { text: 'Đã hủy', tone: 'warn' };
  if (st === 'ended') return { text: 'Đã kết thúc', tone: 'muted' };
  return { text: st, tone: 'muted' };
}

function toLocalInput(iso?: string) {
  if (!iso) return '';
  const d = new Date(iso);
  const pad = (n: number) => String(n).padStart(2, '0');
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}T${pad(d.getHours())}:${pad(d.getMinutes())}`;
}

function localInputToISO(v: string) {
  if (!v) return '';
  return new Date(v).toISOString();
}

type RoomScope = 'mine' | 'all';
type IconProps = { size?: number; filled?: boolean };

const IconClipboard = ({ size = 22 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="1.75" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <path d="M9 5H7a2 2 0 0 0-2 2v12a2 2 0 0 0 2 2h10a2 2 0 0 0 2-2V7a2 2 0 0 0-2-2h-2" />
    <rect x="9" y="3" width="6" height="4" rx="1" />
    <path d="M9 12h6M9 16h4" />
  </svg>
);

const IconPlus = ({ size = 16 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="2.25" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <path d="M12 5v14M5 12h14" />
  </svg>
);

const IconStar = ({ size = 14, filled }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill={filled ? 'currentColor' : 'none'} stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <path d="m12 3.5 2.6 5.3 5.8.8-4.2 4.1 1 5.8L12 16.8l-5.2 2.7 1-5.8-4.2-4.1 5.8-.8L12 3.5z" />
  </svg>
);

const IconSearch = ({ size = 16 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <circle cx="11" cy="11" r="7" />
    <line x1="21" y1="21" x2="16.65" y2="16.65" />
  </svg>
);

const IconCalendar = ({ size = 13 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <rect x="3" y="5" width="18" height="16" rx="2" />
    <path d="M16 3v4M8 3v4M3 11h18" />
  </svg>
);

const IconUsers = ({ size = 12 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <path d="M16 21v-2a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v2" />
    <circle cx="9" cy="7" r="3.5" />
    <path d="M22 21v-2a3.5 3.5 0 0 0-2.5-3.35" />
    <path d="M16 3.5a3.5 3.5 0 0 1 0 7" />
  </svg>
);

const IconOpen = ({ size = 14 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <path d="M5 12h14" />
    <path d="m13 6 6 6-6 6" />
  </svg>
);

const IconInbox = ({ size = 36 }: IconProps) => (
  <svg viewBox="0 0 24 24" width={size} height={size} fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden>
    <polyline points="22 12 16 12 14 15 10 15 8 12 2 12" />
    <path d="M5.45 5.11 2 12v6a2 2 0 0 0 2 2h16a2 2 0 0 0 2-2v-6l-3.45-6.89A2 2 0 0 0 16.76 4H7.24a2 2 0 0 0-1.79 1.11z" />
  </svg>
);

export const ExamsTab: React.FC = () => {
  const { staff } = useAuth();
  const isSuperAdmin = staff?.email === 'phuocntb@rikkeiacademy.com';
  const myStaffId = staff?.id ?? 0;

  const [rooms, setRooms] = useState<ExamRoomItem[]>([]);
  const [loading, setLoading] = useState(true);
  const [showCreate, setShowCreate] = useState(false);
  const [name, setName] = useState('');
  const [start, setStart] = useState('');
  const [end, setEnd] = useState('');
  const [busy, setBusy] = useState(false);
  const [search, setSearch] = useState('');
  const [roomScope, setRoomScope] = useState<RoomScope>('mine');

  const load = async () => {
    setLoading(true);
    try {
      const res = await apiExam.list();
      setRooms(res.data);
    } catch (e) {
      console.error(e);
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    load();
  }, []);

  const scopedRooms = useMemo(() => {
    if (roomScope === 'all' || !myStaffId) return rooms;
    return rooms.filter((r) => Number(r.createdByStaffId) === myStaffId);
  }, [rooms, roomScope, myStaffId]);

  const stats = useMemo(() => {
    const active = scopedRooms.filter((r) => (r.displayStatus || r.status) === 'active').length;
    const upcoming = scopedRooms.filter((r) => {
      const st = r.displayStatus || r.status;
      return st === 'ready' || st === 'draft';
    }).length;
    return { total: scopedRooms.length, active, upcoming };
  }, [scopedRooms]);

  const filtered = useMemo(() => {
    const q = search.trim().toLowerCase();
    if (!q) return scopedRooms;
    return scopedRooms.filter((r) => r.name.toLowerCase().includes(q));
  }, [scopedRooms, search]);

  const canDeleteRoom = (r: ExamRoomItem) =>
    isSuperAdmin || (myStaffId > 0 && Number(r.createdByStaffId) === myStaffId);

  const create = async () => {
    if (!name.trim() || !start || !end) return;
    setBusy(true);
    try {
      const room = await apiExam.create({
        name: name.trim(),
        startTime: localInputToISO(start),
        endTime: localInputToISO(end),
      });
      setShowCreate(false);
      setName('');
      setStart('');
      setEnd('');
      await load();
      openExam(room.id, room.name);
    } catch (e: any) {
      alert(e?.message || 'Lỗi');
    } finally {
      setBusy(false);
    }
  };

  const handleDeleteRoom = async (roomId: number, roomName: string) => {
    if (
      window.confirm(
        `Bạn có chắc chắn muốn xóa hoàn toàn phòng thi "${roomName}" không? Hành động này sẽ xóa sạch dữ liệu phòng thi, các bài nộp, và không thể khôi phục.`
      )
    ) {
      try {
        await apiExam.remove(roomId);
        alert('Đã xóa phòng thi thành công!');
        await load();
      } catch (err: any) {
        alert(err.message || 'Xóa phòng thi thất bại');
      }
    }
  };

  return (
    <div className="tab-page exams-page">
      <div className="tab-page-toolbar">
        <div className="page-header">
          <div className="page-title">
            <h1 className="page-title-heading">
              <span className="page-title-icon" aria-hidden>
                <IconClipboard />
              </span>
              Danh sách phòng thi
            </h1>
            <p>
              {roomScope === 'mine'
                ? 'Mặc định chỉ hiện phòng thi do bạn tạo — chuyển sang xem tất cả khi cần'
                : 'Đang xem toàn bộ phòng thi trong hệ thống'}
            </p>
          </div>
          <div className="exams-header-actions">
            <button type="button" className="btn btn-primary" onClick={() => setShowCreate(true)}>
              <IconPlus />
              Tạo phòng thi
            </button>
          </div>
        </div>
      </div>

      <div className="tab-page-body" style={{ gap: '0.85rem' }}>
        <div className="exams-stats-row">
          <div className="learning-stat">
            <span className="learning-stat-value">{stats.total}</span>
            <span className="learning-stat-label">
              {roomScope === 'mine' ? 'Phòng của tôi' : 'Tổng phòng'}
            </span>
          </div>
          <div className="learning-stat learning-stat--accent">
            <span className="learning-stat-value">{stats.active}</span>
            <span className="learning-stat-label">Đang thi</span>
          </div>
          <div className="learning-stat">
            <span className="learning-stat-value">{stats.upcoming}</span>
            <span className="learning-stat-label">Sắp / tạm</span>
          </div>
        </div>

        <div className="content-card learning-toolbar-card exams-toolbar-card">
          <div className="learning-toolbar exams-toolbar-inner">
            <div className="learning-seg" role="group" aria-label="Phạm vi phòng thi">
              <button
                type="button"
                className={`learning-seg-btn${roomScope === 'mine' ? ' learning-seg-btn--active' : ''}`}
                onClick={() => setRoomScope('mine')}
              >
                <IconStar size={13} filled={roomScope === 'mine'} />
                <span>Phòng của tôi</span>
              </button>
              <button
                type="button"
                className={`learning-seg-btn${roomScope === 'all' ? ' learning-seg-btn--active' : ''}`}
                onClick={() => setRoomScope('all')}
              >
                <span>Xem tất cả</span>
              </button>
            </div>
            <input
              type="search"
              className="app-pool-search learning-search exams-search"
              placeholder="Tìm theo tên phòng thi..."
              value={search}
              onChange={(e) => setSearch(e.target.value)}
            />
          </div>
        </div>

        <div className="tab-page-scroll">
          <div className="content-card" style={{ padding: 0 }}>
            {loading ? (
              <div className="exams-empty-panel">
                <div className="sync-spinner" style={{ width: 36, height: 36, borderWidth: 3 }} />
                <p>Đang tải danh sách phòng thi...</p>
              </div>
            ) : filtered.length === 0 ? (
              <div className="exams-empty-panel">
                <div className="exams-empty-icon">
                  {search.trim() ? <IconSearch size={32} /> : <IconInbox />}
                </div>
                <p>
                  {search.trim()
                    ? 'Không tìm thấy phòng thi phù hợp.'
                    : roomScope === 'mine'
                      ? 'Bạn chưa tạo phòng thi nào.'
                      : 'Chưa có phòng thi — bấm Tạo phòng thi để bắt đầu.'}
                </p>
                {!search.trim() && (
                  <div className="exams-empty-actions">
                    <button type="button" className="btn btn-primary" onClick={() => setShowCreate(true)}>
                      <IconPlus />
                      Tạo phòng thi
                    </button>
                    {roomScope === 'mine' && (
                      <button type="button" className="btn btn-secondary" onClick={() => setRoomScope('all')}>
                        Xem tất cả
                      </button>
                    )}
                  </div>
                )}
              </div>
            ) : (
              <div className="exams-card-grid">
                {filtered.map((r) => {
                  const st = statusMeta(r.displayStatus || r.status);
                  const mine = myStaffId > 0 && Number(r.createdByStaffId) === myStaffId;
                  const isActive = (r.displayStatus || r.status) === 'active';
                  return (
                    <article
                      key={r.id}
                      className={`exam-list-card${isActive ? ' exam-list-card--active' : ''}`}
                    >
                      <header className="exam-list-card-head">
                        <div className="exam-list-card-info">
                          <h3 className="exam-list-card-title" title={r.name}>{r.name}</h3>
                          <div className="exam-list-card-meta-block">
                            <div className="exam-meta-row">
                              <IconCalendar />
                              <span>{fmtTime(r.startTime)}</span>
                              <span className="exam-list-card-sep">→</span>
                              <span>{fmtTime(r.endTime)}</span>
                            </div>
                            <div className="exam-meta-row exam-meta-row--secondary">
                              <IconUsers />
                              <span>
                                {r.studentCount} SV · {r.paperCount} đề
                              </span>
                            </div>
                          </div>
                        </div>
                        <div className="exam-list-card-badges">
                          {mine && <span className="exam-tag exam-tag--mine">Của tôi</span>}
                          <span className={`exam-tag exam-tag--${st.tone}`}>{st.text}</span>
                        </div>
                      </header>

                      <footer className="exam-list-card-actions">
                        <button
                          type="button"
                          className="btn btn-primary btn-sm"
                          onClick={() => openExam(r.id, r.name)}
                        >
                          Mở phòng thi
                          <IconOpen />
                        </button>
                        {canDeleteRoom(r) && (
                          <button
                            type="button"
                            className="btn btn-secondary btn-sm exam-btn-danger"
                            onClick={(e) => {
                              e.stopPropagation();
                              handleDeleteRoom(r.id, r.name);
                            }}
                          >
                            Xóa
                          </button>
                        )}
                      </footer>
                    </article>
                  );
                })}
              </div>
            )}
          </div>
        </div>
      </div>

      {showCreate && (
        <div className="modal-overlay" onClick={() => setShowCreate(false)}>
          <div className="modal-container class-picker-modal exam-create-modal" onClick={(e) => e.stopPropagation()}>
            <div className="modal-header class-picker-header">
              <div>
                <h2 className="modal-title">Tạo phòng thi mới</h2>
                <p className="class-picker-subtitle">
                  Đặt tên và khung giờ thi. Sau khi tạo sẽ mở workspace để cấu hình đề và sinh viên.
                </p>
              </div>
              <button className="modal-close-btn" onClick={() => setShowCreate(false)} aria-label="Đóng">
                &times;
              </button>
            </div>
            <div className="modal-body class-picker-body exam-create-body">
              <label className="exam-field">
                <span className="exam-field-label">Tên phòng thi</span>
                <input
                  className="search-input"
                  value={name}
                  onChange={(e) => setName(e.target.value)}
                  placeholder="VD: Thi cuối kỳ Java"
                  autoFocus
                />
              </label>
              <div className="exam-field-grid">
                <label className="exam-field">
                  <span className="exam-field-label">Bắt đầu</span>
                  <input
                    type="datetime-local"
                    className="search-input exam-datetime"
                    value={start}
                    onChange={(e) => setStart(e.target.value)}
                  />
                </label>
                <label className="exam-field">
                  <span className="exam-field-label">Kết thúc</span>
                  <input
                    type="datetime-local"
                    className="search-input exam-datetime"
                    value={end}
                    onChange={(e) => setEnd(e.target.value)}
                  />
                </label>
              </div>
            </div>
            <div className="modal-footer" style={{ gap: '0.65rem' }}>
              <button type="button" className="btn btn-secondary" onClick={() => setShowCreate(false)}>
                Hủy
              </button>
              <button
                type="button"
                className="btn btn-primary"
                disabled={busy || !name.trim() || !start || !end}
                onClick={create}
              >
                {busy ? 'Đang tạo...' : 'Tạo & mở phòng'}
              </button>
            </div>
          </div>
        </div>
      )}

      <style>{`
        .page-title-heading {
          display: flex;
          align-items: center;
          gap: 0.55rem;
        }
        .page-title-icon {
          display: inline-flex;
          align-items: center;
          justify-content: center;
          color: var(--accent);
          flex-shrink: 0;
        }

        .exams-header-actions {
          display: flex;
          gap: 0.5rem;
          flex-wrap: wrap;
          justify-content: flex-end;
        }
        .exams-header-actions .btn {
          display: inline-flex;
          align-items: center;
          gap: 0.4rem;
        }

        .exams-toolbar-card {
          margin-bottom: 0 !important;
        }
        .exams-toolbar-inner {
          margin: 0;
        }
        .exams-search {
          max-width: none !important;
        }

        .exams-empty-panel {
          display: flex;
          flex-direction: column;
          align-items: center;
          justify-content: center;
          gap: 0.65rem;
          padding: 2.75rem 1.25rem;
          text-align: center;
        }
        .exams-empty-panel p {
          margin: 0;
          color: var(--text-secondary);
          font-size: 0.9rem;
          font-weight: 500;
          max-width: 36ch;
          line-height: 1.45;
        }
        .exams-empty-icon {
          color: var(--text-muted);
          display: flex;
        }
        .exams-empty-actions {
          display: flex;
          gap: 0.5rem;
          flex-wrap: wrap;
          justify-content: center;
          margin-top: 0.25rem;
        }
        .exams-empty-actions .btn {
          display: inline-flex;
          align-items: center;
          gap: 0.35rem;
        }

        .exams-card-grid {
          display: grid;
          grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
          gap: 0.75rem;
          padding: 0.85rem;
          padding-bottom: 4.75rem;
        }

        .exam-list-card {
          background: #fff;
          border: 1px solid var(--border-color);
          border-radius: 10px;
          padding: 0.85rem;
          display: flex;
          flex-direction: column;
          gap: 0.55rem;
          box-shadow: var(--shadow-sm);
          transition: border-color 0.15s, box-shadow 0.15s;
          min-height: 0;
        }
        .exam-list-card:hover {
          border-color: #c5cdd8;
          box-shadow: 0 3px 12px rgba(26, 35, 50, 0.08);
        }
        .exam-list-card--active {
          border-left: 3px solid var(--accent);
          background: rgba(187, 33, 38, 0.03);
        }

        .exam-list-card-head {
          display: flex;
          align-items: flex-start;
          justify-content: space-between;
          gap: 0.5rem;
          flex: 1;
        }
        .exam-list-card-info {
          min-width: 0;
          flex: 1;
        }
        .exam-list-card-title {
          margin: 0 0 0.4rem;
          font-size: 0.88rem;
          font-weight: 700;
          color: var(--text-primary);
          line-height: 1.35;
          display: -webkit-box;
          -webkit-line-clamp: 2;
          -webkit-box-orient: vertical;
          overflow: hidden;
        }
        .exam-list-card-meta-block {
          display: flex;
          flex-direction: column;
          gap: 0.2rem;
        }
        .exam-meta-row {
          display: flex;
          align-items: flex-start;
          gap: 0.35rem;
          font-size: 0.7rem;
          color: var(--text-secondary);
          line-height: 1.4;
          flex-wrap: wrap;
        }
        .exam-meta-row svg {
          flex-shrink: 0;
          color: var(--text-muted);
          margin-top: 0.1rem;
        }
        .exam-meta-row--secondary {
          color: var(--text-muted);
          font-size: 0.68rem;
        }
        .exam-list-card-sep {
          color: var(--text-muted);
          opacity: 0.7;
        }

        .exam-list-card-badges {
          display: flex;
          flex-direction: column;
          align-items: flex-end;
          gap: 0.25rem;
          flex-shrink: 0;
        }
        .exam-tag {
          display: inline-flex;
          align-items: center;
          padding: 0.15rem 0.45rem;
          border-radius: 999px;
          font-size: 0.62rem;
          font-weight: 700;
          line-height: 1.2;
          white-space: nowrap;
          border: 1px solid transparent;
        }
        .exam-tag--mine {
          background: rgba(234, 179, 8, 0.14);
          color: #a16207;
          border-color: rgba(234, 179, 8, 0.35);
        }
        .exam-tag--active {
          background: rgba(13, 159, 110, 0.12);
          color: #0b7a55;
          border-color: rgba(13, 159, 110, 0.28);
        }
        .exam-tag--info {
          background: rgba(37, 99, 235, 0.1);
          color: #1d4ed8;
          border-color: rgba(37, 99, 235, 0.22);
        }
        .exam-tag--warn {
          background: rgba(245, 158, 11, 0.12);
          color: #b45309;
          border-color: rgba(245, 158, 11, 0.3);
        }
        .exam-tag--muted {
          background: var(--bg-subtle);
          color: var(--text-muted);
          border-color: var(--border-color);
        }

        .exam-list-card-actions {
          display: flex;
          gap: 0.4rem;
          margin-top: auto;
          padding-top: 0.55rem;
          border-top: 1px solid var(--border-light);
        }
        .exam-list-card-actions .btn {
          flex: 1;
          justify-content: center;
          align-items: center;
          gap: 0.25rem;
          height: 30px;
          padding: 0.35rem 0.5rem;
          font-size: 0.72rem;
          border-radius: 7px;
          line-height: 1;
        }
        .exam-btn-danger {
          color: #b91c1c !important;
          border-color: #fecaca !important;
          background: #fef2f2 !important;
          flex: 0 0 auto !important;
          min-width: 52px;
        }
        .exam-btn-danger:hover {
          background: #fee2e2 !important;
          border-color: #fca5a5 !important;
        }

        .exam-create-modal {
          max-width: 520px !important;
        }
        .exam-create-modal .class-picker-header {
          align-items: flex-start !important;
          padding: 1.1rem 1.35rem !important;
        }
        .exam-create-modal .class-picker-subtitle {
          margin: 0.3rem 0 0;
          color: var(--text-muted);
          font-size: 0.78rem;
          line-height: 1.4;
          max-width: 42ch;
        }
        .exam-create-modal .class-picker-body {
          padding: 1rem 1.35rem 1.15rem !important;
          display: flex;
          flex-direction: column;
          min-height: 0;
        }
        .exam-create-body {
          gap: 0.9rem !important;
        }
        .exam-field {
          display: flex;
          flex-direction: column;
          gap: 0.35rem;
        }
        .exam-field-label {
          font-weight: 600;
          font-size: 0.75rem;
          color: var(--text-secondary);
        }
        .exam-field .search-input {
          width: 100%;
          box-sizing: border-box;
        }
        .exam-field-grid {
          display: grid;
          grid-template-columns: 1fr 1fr;
          gap: 0.75rem;
        }
        .exam-datetime {
          padding: 0.5rem 0.75rem !important;
        }

        @media (max-width: 900px) {
          .exams-header-actions {
            width: 100%;
          }
          .exams-header-actions .btn {
            flex: 1;
            justify-content: center;
          }
          .page-header {
            flex-direction: column;
            align-items: stretch;
            gap: 0.75rem;
          }
          .learning-seg {
            width: 100%;
          }
          .learning-seg-btn {
            flex: 1;
          }
          .exams-stats-row {
            grid-template-columns: repeat(3, 1fr) !important;
            gap: 0.45rem;
          }
        }

        @media (max-width: 768px) {
          .exams-card-grid {
            grid-template-columns: 1fr;
            padding: 0.75rem;
            gap: 0.65rem;
          }
          .exam-list-card-actions .btn {
            height: 32px;
            font-size: 0.75rem;
          }
        }

        @media (max-width: 560px) {
          .exams-stats-row {
            grid-template-columns: 1fr !important;
          }
          .exam-field-grid {
            grid-template-columns: 1fr;
          }
          .exam-list-card-actions {
            flex-direction: column;
          }
          .exam-btn-danger {
            width: 100%;
          }
        }
      `}</style>
    </div>
  );
};

export { toLocalInput, localInputToISO, fmtTime };