1 files changed, 244 insertions, 0 deletions
diff --git a/toolkit/content/widgets/datekeeper.js b/toolkit/content/widgets/datekeeper.js
new file mode 100644
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+++ b/toolkit/content/widgets/datekeeper.js
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/**
+ * DateKeeper keeps track of the date states.
+ *
+ * @param {Object} date parts
+ *        {
+ *          {Number} year
+ *          {Number} month
+ *          {Number} date
+ *        }
+ *        {Object} options
+ *        {
+ *          {Number} firstDayOfWeek [optional]
+ *          {Array<Number>} weekends [optional]
+ *          {Number} calViewSize [optional]
+ *        }
+ */
+function DateKeeper({ year, month, date }, { firstDayOfWeek = 0, weekends = [0], calViewSize = 42 }) {
+  this.state = {
+    firstDayOfWeek, weekends, calViewSize,
+    dateObj: new Date(0),
+    years: [],
+    months: [],
+    days: []
+  };
+  this.state.weekHeaders = this._getWeekHeaders(firstDayOfWeek);
+  this._update(year, month, date);
+}
+
+{
+  const DAYS_IN_A_WEEK = 7,
+        MONTHS_IN_A_YEAR = 12,
+        YEAR_VIEW_SIZE = 200,
+        YEAR_BUFFER_SIZE = 10;
+
+  DateKeeper.prototype = {
+    /**
+     * Set new date
+     * @param {Object} date parts
+     *        {
+     *          {Number} year [optional]
+     *          {Number} month [optional]
+     *          {Number} date [optional]
+     *        }
+     */
+    set({ year = this.state.year, month = this.state.month, date = this.state.date }) {
+      this._update(year, month, date);
+    },
+
+    /**
+     * Set date with value
+     * @param {Number} value: Date value
+     */
+    setValue(value) {
+      const dateObj = new Date(value);
+      this._update(dateObj.getUTCFullYear(), dateObj.getUTCMonth(), dateObj.getUTCDate());
+    },
+
+    /**
+     * Set month. Makes sure the date is <= the last day of the month
+     * @param {Number} month
+     */
+    setMonth(month) {
+      const lastDayOfMonth = this._newUTCDate(this.state.year, month + 1, 0).getUTCDate();
+      this._update(this.state.year, month, Math.min(this.state.date, lastDayOfMonth));
+    },
+
+    /**
+     * Set year. Makes sure the date is <= the last day of the month
+     * @param {Number} year
+     */
+    setYear(year) {
+      const lastDayOfMonth = this._newUTCDate(year, this.state.month + 1, 0).getUTCDate();
+      this._update(year, this.state.month, Math.min(this.state.date, lastDayOfMonth));
+    },
+
+    /**
+     * Set month by offset. Makes sure the date is <= the last day of the month
+     * @param {Number} offset
+     */
+    setMonthByOffset(offset) {
+      const lastDayOfMonth = this._newUTCDate(this.state.year, this.state.month + offset + 1, 0).getUTCDate();
+      this._update(this.state.year, this.state.month + offset, Math.min(this.state.date, lastDayOfMonth));
+    },
+
+    /**
+     * Update the states.
+     * @param  {Number} year  [description]
+     * @param  {Number} month [description]
+     * @param  {Number} date  [description]
+     */
+    _update(year, month, date) {
+      // Use setUTCFullYear so that year 99 doesn't get parsed as 1999
+      this.state.dateObj.setUTCFullYear(year, month, date);
+      this.state.year = this.state.dateObj.getUTCFullYear();
+      this.state.month = this.state.dateObj.getUTCMonth();
+      this.state.date = this.state.dateObj.getUTCDate();
+    },
+
+    /**
+     * Generate the array of months
+     * @return {Array<Object>}
+     *         {
+     *           {Number} value: Month in int
+     *           {Boolean} enabled
+     *         }
+     */
+    getMonths() {
+      // TODO: add min/max and step support
+      let months = [];
+
+      for (let i = 0; i < MONTHS_IN_A_YEAR; i++) {
+        months.push({
+          value: i,
+          enabled: true
+        });
+      }
+
+      return months;
+    },
+
+    /**
+     * Generate the array of years
+     * @return {Array<Object>}
+     *         {
+     *           {Number} value: Year in int
+     *           {Boolean} enabled
+     *         }
+     */
+    getYears() {
+      // TODO: add min/max and step support
+      let years = [];
+
+      const firstItem = this.state.years[0];
+      const lastItem = this.state.years[this.state.years.length - 1];
+      const currentYear = this.state.dateObj.getUTCFullYear();
+
+      // Generate new years array when the year is outside of the first &
+      // last item range. If not, return the cached result.
+      if (!firstItem || !lastItem ||
+          currentYear <= firstItem.value + YEAR_BUFFER_SIZE ||
+          currentYear >= lastItem.value - YEAR_BUFFER_SIZE) {
+        // The year is set in the middle with items on both directions
+        for (let i = -(YEAR_VIEW_SIZE / 2); i < YEAR_VIEW_SIZE / 2; i++) {
+          years.push({
+            value: currentYear + i,
+            enabled: true
+          });
+        }
+        this.state.years = years;
+      }
+      return this.state.years;
+    },
+
+    /**
+     * Get days for calendar
+     * @return {Array<Object>}
+     *         {
+     *           {Number} dateValue
+     *           {Number} textContent
+     *           {Array<String>} classNames
+     *         }
+     */
+    getDays() {
+      // TODO: add min/max and step support
+      let firstDayOfMonth = this._getFirstCalendarDate(this.state.dateObj, this.state.firstDayOfWeek);
+      let days = [];
+      let month = this.state.dateObj.getUTCMonth();
+
+      for (let i = 0; i < this.state.calViewSize; i++) {
+        let dateObj = this._newUTCDate(firstDayOfMonth.getUTCFullYear(), firstDayOfMonth.getUTCMonth(), firstDayOfMonth.getUTCDate() + i);
+        let classNames = [];
+        if (this.state.weekends.includes(dateObj.getUTCDay())) {
+          classNames.push("weekend");
+        }
+        if (month != dateObj.getUTCMonth()) {
+          classNames.push("outside");
+        }
+        days.push({
+          dateValue: dateObj.getTime(),
+          textContent: dateObj.getUTCDate(),
+          classNames
+        });
+      }
+      return days;
+    },
+
+    /**
+     * Get week headers for calendar
+     * @param  {Number} firstDayOfWeek
+     * @return {Array<Object>}
+     *         {
+     *           {Number} textContent
+     *           {Array<String>} classNames
+     *         }
+     */
+    _getWeekHeaders(firstDayOfWeek) {
+      let headers = [];
+      let day = firstDayOfWeek;
+
+      for (let i = 0; i < DAYS_IN_A_WEEK; i++) {
+        headers.push({
+          textContent: day % DAYS_IN_A_WEEK,
+          classNames: this.state.weekends.includes(day % DAYS_IN_A_WEEK) ? ["weekend"] : []
+        });
+        day++;
+      }
+      return headers;
+    },
+
+    /**
+     * Get the first day on a calendar month
+     * @param  {Date} dateObj
+     * @param  {Number} firstDayOfWeek
+     * @return {Date}
+     */
+    _getFirstCalendarDate(dateObj, firstDayOfWeek) {
+      const daysOffset = 1 - DAYS_IN_A_WEEK;
+      let firstDayOfMonth = this._newUTCDate(dateObj.getUTCFullYear(), dateObj.getUTCMonth());
+      let dayOfWeek = firstDayOfMonth.getUTCDay();
+
+      return this._newUTCDate(
+        firstDayOfMonth.getUTCFullYear(),
+        firstDayOfMonth.getUTCMonth(),
+        // When first calendar date is the same as first day of the week, add
+        // another row on top of it.
+        firstDayOfWeek == dayOfWeek ? daysOffset : (firstDayOfWeek - dayOfWeek + daysOffset) % DAYS_IN_A_WEEK);
+    },
+
+    /**
+     * Helper function for creating UTC dates
+     * @param  {...[Number]} parts
+     * @return {Date}
+     */
+    _newUTCDate(...parts) {
+      return new Date(Date.UTC(...parts));
+    }
+  };
+}