/*!
 * NY 问卷考试系统数据平台 - 随机抽取页逻辑
 */
(function () {
  'use strict';

  const $  = s => document.querySelector(s);
  const $$ = s => Array.prototype.slice.call(document.querySelectorAll(s));

  function esc(s) {
    return String(s == null ? '' : s).replace(/[&<>"']/g, c =>
      ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]));
  }
  const sleep = ms => new Promise(r => setTimeout(r, ms));

  const LS_RESULT   = 'ny_draw_result';   // 最近一次抽取结果（刷新后仍可下载）
  const LS_HISTORY  = 'ny_draw_history';  // 累计抽中的学号（用于"排除已抽中"）
  const LS_SETTINGS = 'ny_draw_settings'; // 来源 / 项目 / 班级 / 组别 / 人数

  const state = {
    roster:   [],
    projects: [],
    answers:  [],
    source:   'roster',
    picked:   [],
    history:  new Set(),
    drawing:  false,
  };

  /* ---------------- 接口 ---------------- */
  async function api(action, params) {
    const q = new URLSearchParams(Object.assign({ action: action }, params || {}));
    const r = await fetch('api.php?' + q.toString(), { credentials: 'same-origin' });
    let j;
    try {
      j = await r.json();
    } catch (e) {
      throw new Error('接口返回异常（HTTP ' + r.status + '）');
    }
    if (r.status === 401 || (j && j.ok === false && /未登录/.test(j.msg || ''))) {
      location.href = 'login.php';
      throw new Error('未登录');
    }
    if (!j || !j.ok) {
      throw new Error((j && j.msg) || '请求失败');
    }
    return j.data;
  }

  function showAlert(msg, type) {
    const el = $('#alert');
    if (!el) return;
    if (!msg) { el.classList.add('hidden'); return; }
    el.textContent = msg;
    el.className = 'alert' + (type === 'info' ? ' info' : '');
  }

  /* ---------------- 数据加载 ---------------- */
  async function loadRoster() {
    const d = await api('roster');
    state.roster = (d && d.students ? d.students : []).map(s => ({
      sid: String(s.sid || ''),
      name: String(s.name || ''),
      cls: String(s.cls || ''),
      grp: String(s.grp || ''),
    }));
    const badge = $('#rosterBadge');
    if (badge) badge.textContent = state.roster.length;
  }

  async function loadProjects() {
    try {
      state.projects = (await api('projects')) || [];
    } catch (e) {
      state.projects = [];
    }
    const sel = $('#projectSel');
    if (!sel) return;

    const isFolder = p => (p.mode || '').toLowerCase().indexOf('folder') >= 0;
    const parentIds = new Set();
    state.projects.forEach(p => {
      const pid = String(p.parent_id || '0');
      if (pid !== '0' && pid !== '') parentIds.add(pid);
    });
    const folderSet = new Set();
    state.projects.forEach(p => { if (isFolder(p) || parentIds.has(p.id)) folderSet.add(p.id); });

    const nameOf = id => {
      const f = state.projects.filter(p => p.id === id)[0];
      return f ? String(f.name || '') : '';
    };

    const items = state.projects.filter(p => !folderSet.has(p.id));
    if (!items.length) {
      sel.innerHTML = '<option value="">（无可用的问卷 / 考试）</option>';
      return;
    }
    sel.innerHTML = items.map(p => {
      const pid = String(p.parent_id || '0');
      const fn = (pid !== '0' && pid !== '' && folderSet.has(pid)) ? nameOf(pid) : '';
      const label = fn ? fn + ' / ' + p.name : p.name;
      return '<option value="' + esc(p.id) + '">' + esc(label) + '</option>';
    }).join('');
  }

  async function loadAnswers(pid) {
    const d = await api('data', { projectId: pid });
    state.answers = ((d && d.rows) ? d.rows : []).map(r => ({
      sid: String(r.sid || ''),
      name: String(r.name || ''),
      cls: String(r.cls || ''),
      grp: String(r.grp || ''),
    }));
  }

  /* ---------------- 候选池 ---------------- */
  function baseList() {
    return state.source === 'project' ? state.answers : state.roster;
  }

  function currentPool() {
    let list = baseList().slice();
    const cls = $('#clsSel').value;
    const grp = $('#grpSel').value;
    if (cls) list = list.filter(x => (x.cls || '') === cls);
    if (grp) list = list.filter(x => (x.grp || '') === grp);
    if ($('#excludePicked').checked) {
      list = list.filter(x => !state.history.has(String(x.sid)));
    }
    return list;
  }

  function uniqSorted(arr) {
    const seen = {};
    const out = [];
    arr.forEach(v => { if (v && !seen[v]) { seen[v] = 1; out.push(v); } });
    out.sort((a, b) => String(a).localeCompare(String(b), 'zh', { numeric: true }));
    return out;
  }

  function fillSel(sel, values, allLabel) {
    if (!sel) return;
    const cur = sel.value;
    sel.innerHTML = '<option value="">' + esc(allLabel) + '</option>' +
      values.map(v => '<option value="' + esc(v) + '">' + esc(v) + '</option>').join('');
    sel.value = (values.indexOf(cur) >= 0) ? cur : '';
  }

  function populateFilters() {
    const list = baseList();
    fillSel($('#clsSel'), uniqSorted(list.map(x => x.cls || '')), '全部班级');
    fillSel($('#grpSel'), uniqSorted(list.map(x => x.grp || '')), '全部组别');
  }

  function renderStats() {
    const pool = currentPool();
    $('#dPool').textContent = pool.length;
    $('#dPicked').textContent = state.picked.length;
    $('#dHistory').textContent = state.history.size;
    $('#dSource').textContent = state.source === 'project' ? '已提交人员' : '学号名单';

    const cls = $('#clsSel').value, grp = $('#grpSel').value;
    const parts = [];
    if (cls) parts.push(cls);
    if (grp) parts.push(grp + '组');
    $('#drawHint').textContent = '候选 ' + pool.length + ' 人' +
      (parts.length ? '（' + parts.join(' / ') + '）' : '');
  }

  /* ---------------- 抽取 ---------------- */
  function shuffle(arr) {
    const a = arr.slice();
    for (let i = a.length - 1; i > 0; i--) {
      const j = Math.floor(Math.random() * (i + 1));
      const t = a[i]; a[i] = a[j]; a[j] = t;
    }
    return a;
  }

  async function doDraw() {
    if (state.drawing) return;
    const pool = currentPool();
    if (!pool.length) {
      showAlert('当前筛选下没有可抽取的人员（可关闭「排除已抽中」或调整班级 / 组别）');
      return;
    }
    let n = parseInt($('#numInput').value, 10);
    if (!n || n < 1) n = 1;
    if (n > pool.length) n = pool.length;

    state.drawing = true;
    const stage = $('#drawStage');
    const btn = $('#btnDraw');
    btn.disabled = true;
    showAlert('');

    // 滚动动画：先快速闪动若干次
    stage.className = 'draw-stage rolling';
    const rounds = Math.min(24, 10 + n);
    for (let i = 0; i < rounds; i++) {
      const p = pool[Math.floor(Math.random() * pool.length)];
      stage.textContent = p.name || p.sid || '—';
      await sleep(40 + i * 7);
    }

    const picked = shuffle(pool).slice(0, n);
    state.picked = picked;
    picked.forEach(m => state.history.add(String(m.sid)));

    stage.className = 'draw-stage done';
    stage.textContent = n === 1
      ? (picked[0].name || picked[0].sid)
      : ('🎉 已抽取 ' + n + ' 人');

    renderResult();
    renderStats();
    saveState();

    state.drawing = false;
    btn.disabled = false;
    showAlert('已抽取 ' + n + ' 人' + (n > 1 ? '，可点击右侧按钮下载白名单' : ''), 'info');
  }

  function renderResult() {
    const tb = $('#drawBody');
    if (!state.picked.length) {
      tb.innerHTML = '<tr><td colspan="5" class="empty">尚未抽取</td></tr>';
      return;
    }
    tb.innerHTML = state.picked.map((m, i) =>
      '<tr>' +
      '<td class="num">' + (i + 1) + '</td>' +
      '<td class="sid">' + esc(m.sid) + '</td>' +
      '<td class="name">' + esc(m.name) + '</td>' +
      '<td>' + esc(m.cls || '') + '</td>' +
      '<td>' + esc(m.grp || '') + '</td>' +
      '</tr>').join('');
  }

  /* ---------------- 下载 ---------------- */
  async function download(type) {
    if (!state.picked.length) {
      showAlert('请先点击「🎲 开始抽取」');
      return;
    }
    const fname = type === 'import' ? '白名单导入模板.xlsx' : '白名单列表.xlsx';
    try {
      const r = await fetch('api.php?action=draw_export', {
        method: 'POST',
        credentials: 'same-origin',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          type: type,
          members: state.picked.map(m => ({ name: m.name, sid: m.sid })),
        }),
      });
      if (!r.ok) throw new Error('HTTP ' + r.status);
      const blob = await r.blob();
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = fname;
      document.body.appendChild(a);
      a.click();
      a.remove();
      setTimeout(() => URL.revokeObjectURL(url), 3000);
      showAlert('已下载 ' + fname, 'info');
    } catch (e) {
      showAlert('导出失败：' + e.message);
    }
  }

  /* ---------------- 本地缓存 ---------------- */
  function saveState() {
    try {
      localStorage.setItem(LS_RESULT, JSON.stringify(state.picked));
      localStorage.setItem(LS_HISTORY, JSON.stringify(Array.from(state.history)));
    } catch (e) { /* 忽略 */ }
  }

  function saveSettings() {
    try {
      localStorage.setItem(LS_SETTINGS, JSON.stringify({
        source: state.source,
        projectId: $('#projectSel').value,
        cls: $('#clsSel').value,
        grp: $('#grpSel').value,
        num: $('#numInput').value,
        exclude: $('#excludePicked').checked,
      }));
    } catch (e) { /* 忽略 */ }
  }

  function loadState() {
    try {
      const p = JSON.parse(localStorage.getItem(LS_RESULT) || '[]');
      if (Array.isArray(p)) state.picked = p;
      const h = JSON.parse(localStorage.getItem(LS_HISTORY) || '[]');
      if (Array.isArray(h)) state.history = new Set(h.map(String));
    } catch (e) { /* 忽略 */ }
  }

  function loadSettings() {
    try {
      const s = JSON.parse(localStorage.getItem(LS_SETTINGS) || '{}');
      if (s && typeof s === 'object') return s;
    } catch (e) { /* 忽略 */ }
    return {};
  }

  /* ---------------- 事件 ---------------- */
  function bind() {
    $('#sourceSel').addEventListener('change', async () => {
      state.source = $('#sourceSel').value;
      $('#projectField').classList.toggle('hidden', state.source !== 'project');
      state.answers = [];
      state.picked = [];
      renderResult();
      if (state.source === 'project') {
        if (!state.projects.length) await loadProjects();
        const pid = $('#projectSel').value;
        if (pid) {
          try { await loadAnswers(pid); } catch (e) { showAlert(e.message); }
        }
      }
      populateFilters();
      renderStats();
      saveSettings();
    });

    $('#projectSel').addEventListener('change', async () => {
      const pid = $('#projectSel').value;
      if (!pid) { state.answers = []; populateFilters(); renderStats(); return; }
      showAlert('正在拉取已提交人员…', 'info');
      try {
        await loadAnswers(pid);
        showAlert('');
      } catch (e) {
        showAlert(e.message);
      }
      populateFilters();
      renderStats();
      saveSettings();
    });

    ['#clsSel', '#grpSel'].forEach(id => {
      $(id).addEventListener('change', () => { renderStats(); saveSettings(); });
    });
    $('#numInput').addEventListener('change', saveSettings);
    $('#excludePicked').addEventListener('change', () => { renderStats(); saveSettings(); });

    $$('[data-num]').forEach(b => {
      b.addEventListener('click', () => {
        const v = b.dataset.num;
        if (v === 'all') {
          const pool = currentPool();
          $('#numInput').value = String(Math.max(1, pool.length));
        } else {
          $('#numInput').value = v;
        }
        saveSettings();
      });
    });

    $('#btnDraw').addEventListener('click', doDraw);
    $('#btnReset').addEventListener('click', () => {
      state.picked = [];
      renderResult();
      renderStats();
      saveState();
      const stage = $('#drawStage');
      stage.className = 'draw-stage';
      stage.textContent = '点击「🎲 开始抽取」';
      showAlert('');
    });
    $('#btnClearHistory').addEventListener('click', () => {
      state.history = new Set();
      state.picked = [];
      renderResult();
      renderStats();
      saveState();
      showAlert('已清空累计抽取记录', 'info');
    });
    $('#btnDlImport').addEventListener('click', () => download('import'));
    $('#btnDlList').addEventListener('click', () => download('list'));
  }

  /* ---------------- 启动 ---------------- */
  document.addEventListener('DOMContentLoaded', async function () {
    loadState();
    const s = loadSettings();
    if (s.exclude === false) $('#excludePicked').checked = false;
    if (s.num) $('#numInput').value = s.num;
    if (s.source === 'project') {
      state.source = 'project';
      $('#sourceSel').value = 'project';
      $('#projectField').classList.remove('hidden');
    }

    bind();
    renderResult();

    try {
      await loadRoster();
    } catch (e) {
      showAlert('名单加载失败：' + e.message);
    }
    if (state.source === 'project') {
      await loadProjects();
      const pid = s.projectId || $('#projectSel').value;
      if (pid) {
        $('#projectSel').value = pid;
        try { await loadAnswers(pid); } catch (e) { /* 静默 */ }
      }
    }
    populateFilters();
    if (s.cls) $('#clsSel').value = s.cls;
    if (s.grp) $('#grpSel').value = s.grp;
    renderStats();
  });
})();