(function () {
  'use strict';

  var SIZE_OPTIONS = [10, 20, 50, 100];

  function pagesCount(total, size) {
    return Math.max(1, Math.ceil((total || 0) / (size || 20)));
  }

  function html(opts) {
    opts = opts || {};
    var page = opts.page || 1;
    var size = opts.size || 20;
    var total = opts.total || 0;
    var pages = pagesCount(total, size);
    var sizes = opts.sizeOptions || SIZE_OPTIONS;
    if (total === 0) {
      return '<div class="soon-admin-pager soon-admin-pager--empty"><span class="soon-admin-pager__info">共 0 条</span></div>';
    }
    var sizeOpts = sizes.map(function (n) {
      return '<option value="' + n + '"' + (n === size ? ' selected' : '') + '>' + n + ' 条/页</option>';
    }).join('');
    return '<div class="soon-admin-pager" data-page="' + page + '" data-size="' + size + '" data-total="' + total + '">' +
      '<div class="soon-admin-pager__left">' +
      '<button type="button" class="soon-btn soon-btn--sm soon-btn--ghost soon-pager-first"' +
      (page <= 1 ? ' disabled' : '') + ' title="首页">«</button>' +
      '<button type="button" class="soon-btn soon-btn--sm soon-btn--ghost soon-pager-prev"' +
      (page <= 1 ? ' disabled' : '') + ' title="上一页">‹</button>' +
      '<span class="soon-admin-pager__info">第 <strong>' + page + '</strong> / ' + pages + ' 页，共 ' + total + ' 条</span>' +
      '<button type="button" class="soon-btn soon-btn--sm soon-btn--ghost soon-pager-next"' +
      (page >= pages ? ' disabled' : '') + ' title="下一页">›</button>' +
      '<button type="button" class="soon-btn soon-btn--sm soon-btn--ghost soon-pager-last"' +
      (page >= pages ? ' disabled' : '') + ' title="末页">»</button>' +
      '</div>' +
      '<div class="soon-admin-pager__right">' +
      '<label class="soon-admin-pager__size-label">每页<select class="soon-input soon-input--sm soon-pager-size">' +
      sizeOpts + '</select></label>' +
      '<label class="soon-admin-pager__jump-label">跳至<input type="number" class="soon-input soon-input--sm soon-pager-jump" min="1" max="' +
      pages + '" value="' + page + '">页<button type="button" class="soon-btn soon-btn--sm soon-btn--ghost soon-pager-go">GO</button></label>' +
      '</div></div>';
  }

  function bind(container, state, onChange) {
    if (!container) return;
    var page = state.page || 1;
    var size = state.size || 20;
    var total = state.total || 0;
    var pages = pagesCount(total, size);

    function go(p) {
      p = Math.max(1, Math.min(pages, p));
      if (p !== page) onChange({ page: p });
    }

    var first = container.querySelector('.soon-pager-first');
    var prev = container.querySelector('.soon-pager-prev');
    var next = container.querySelector('.soon-pager-next');
    var last = container.querySelector('.soon-pager-last');
    var sizeSel = container.querySelector('.soon-pager-size');
    var jump = container.querySelector('.soon-pager-jump');
    var goBtn = container.querySelector('.soon-pager-go');

    if (first && !first.disabled) first.onclick = function () { go(1); };
    if (prev && !prev.disabled) prev.onclick = function () { go(page - 1); };
    if (next && !next.disabled) next.onclick = function () { go(page + 1); };
    if (last && !last.disabled) last.onclick = function () { go(pages); };
    if (sizeSel) {
      sizeSel.onchange = function () {
        onChange({ page: 1, size: parseInt(sizeSel.value, 10) || size });
      };
    }
    if (goBtn && jump) {
      goBtn.onclick = function () {
        go(parseInt(jump.value, 10) || page);
      };
      jump.onkeydown = function (e) {
        if (e.key === 'Enter') go(parseInt(jump.value, 10) || page);
      };
    }
  }

  window.AdminPager = { html: html, bind: bind, pagesCount: pagesCount };
})();