Initial commit

2020-06-15 10:58:47 +08:00
commit 4f1dfe7564
8590 changed files with 1516878 additions and 0 deletions
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+var Backbone = require('backbone');
+var _ = require('underscore');
+
+/**
+ * View model intended to be responsible for pagination logic, and to be used in conjunction with a Pagination view.
+ */
+module.exports = Backbone.Model.extend({
+  defaults: {
+    total_count: 0,
+    per_page: 10,
+    current_page: 1,
+    display_count: 5,
+    extras_display_count: 1,
+    url_to: undefined
+  },
+
+  pagesCount: function () {
+    return Math.max(
+      Math.ceil(
+        this.get('total_count') / this.get('per_page')
+      ), 1);
+  },
+
+  isCurrentPage: function (page) {
+    return this.get('current_page') === page;
+  },
+
+  shouldBeVisible: function () {
+    var pagesCount = this.pagesCount();
+    return this.get('total_count') > 0 && pagesCount > 1 && this.get('current_page') <= pagesCount;
+  },
+
+  urlTo: function (page) {
+    if (this.hasUrl()) {
+      return this.get('url_to')(page);
+    }
+  },
+
+  hasUrl: function () {
+    return typeof this.get('url_to') === 'function';
+  },
+
+  /**
+   * Get the pages that are expected to be displayed.
+   * The current page will be in the middle of the returned sequence.
+   *
+   * @returns {number[]} a sequence of Numbers
+   */
+  pagesToDisplay: function () {
+    var rangeStart;
+
+    if (this._inLowRange()) {
+      rangeStart = 1;
+    } else if (this._inHighRange()) {
+      rangeStart = this.get('current_page') - this._startOffset();
+    } else {
+      // Somewhere between the low and high boundary
+      rangeStart = this.pagesCount() - this.get('display_count') + 1;
+    }
+    rangeStart = Math.max(rangeStart, 1);
+
+    return this._withExtraPages(
+      _.range(rangeStart, this._rangeEnd(rangeStart))
+    );
+  },
+
+  _withExtraPages: function (pagesRelativeToCurrentPage) {
+    var lastPage = this.pagesCount();
+    var extraCount = this.get('extras_display_count');
+    var extraStartPages = _.range(1, extraCount + 1);
+    var extraEndPages = _.range(lastPage - extraCount + 1, lastPage + 1);
+
+    var startPagesDiff = pagesRelativeToCurrentPage[0] - extraStartPages.slice(-1)[0];
+    if (startPagesDiff === 2) {
+      // There is only one missing page in the gap, so add it
+      extraStartPages.push(pagesRelativeToCurrentPage[0] - 1);
+    } else if (startPagesDiff > 2) {
+      // There are more hidden pages at low range, add padding at end
+      extraStartPages.push(-1);
+    }
+
+    var endPagesDiff = extraEndPages[0] - pagesRelativeToCurrentPage.slice(-1);
+    if (endPagesDiff === 2) {
+      // There is only one missing page in the gap, so add it
+      extraEndPages.unshift(extraEndPages[0] - 1);
+    } if (endPagesDiff > 2) {
+      // There are more hidden pages at high range, add padding at beginning
+      extraEndPages.unshift(-2);
+    }
+
+    return _.union(extraStartPages, pagesRelativeToCurrentPage, extraEndPages);
+  },
+
+  _inLowRange: function () {
+    return this.get('current_page') < this._startOffset();
+  },
+
+  _inHighRange: function () {
+    return this.get('current_page') < this._highBoundary();
+  },
+
+  _highBoundary: function () {
+    return this.pagesCount() - this._startOffset();
+  },
+
+  _startOffset: function () {
+    return Math.floor(this.get('display_count') / 2);
+  },
+
+  _rangeEnd: function (rangeStart) {
+    // If we are too close to the range end then cap to the pages count.
+    return Math.min(rangeStart + this.get('display_count'), this.pagesCount() + 1);
+  }
+});