[IMP] hr_holidays: Add leave stats widget

When approving a leave, to make an informed decision, it might
be needed to check leaves already taken by the employee or leaves
of its collaborators. This commit adds a widget displaying some stats
in a leave form view. Stats displayed are:
   - the number of days taken
   by the employee this year, grouped by leave type
   - Leaves taken by employees in the same department in the month
   of the leave.
This widget is only displayed in the context of the action leading
to leaves to approve.

2 files changed, 216 insertions, 0 deletions

diff --git a/addons/hr_holidays/static/src/js/leave_stats_widget.js b/addons/hr_holidays/static/src/js/leave_stats_widget.js
new file mode 100644
index 00000000000..d224fe6ddca
--- /dev/null
+++ b/addons/hr_holidays/static/src/js/leave_stats_widget.js
@@ -0,0 +1,152 @@
+odoo.define('hr_holidays.LeaveStatsWidget', function (require) {
+    "use strict";
+
+    var time = require('web.time');
+    var Widget = require('web.Widget');
+    var widget_registry = require('web.widget_registry');
+
+    var LeaveStatsWidget = Widget.extend({
+        template: 'hr_holidays.leave_stats',
+
+        /**
+         * @override
+         * @param {Widget|null} parent
+         * @param {Object} params
+         */
+        init: function (parent, params) {
+            this._setState(params);
+            this._super(parent);
+        },
+
+        //--------------------------------------------------------------------------
+        // Public
+        //--------------------------------------------------------------------------
+
+        /**
+         * @override to fetch data before rendering.
+         */
+        willStart: function () {
+            return Promise.all([this._super(), this._fetchLeaveTypesData(), this._fetchDepartmentLeaves()]);
+        },
+
+        /**
+         * Fetch new data if needed (according to updated fields) and re-render the widget.
+         * Called by the basic renderer when the view changes.
+         * @param {Object} state
+         * @returns {Promise}
+         */
+        updateState: function (state) {
+            var self = this;
+            var to_await = [];
+            var updatedFields = this._setState(state);
+
+            if (_.intersection(updatedFields, ['employee', 'date']).length) {
+                to_await.push(this._fetchLeaveTypesData());
+            }
+            if (_.intersection(updatedFields, ['department', 'date']).length) {
+                to_await.push(this._fetchDepartmentLeaves());
+            }
+            return Promise.all(to_await).then(function () {
+                self.renderElement();
+            });
+        },
+
+        //--------------------------------------------------------------------------
+        // Private
+        //--------------------------------------------------------------------------
+
+        /**
+         * Update the state
+         * @param {Object} state
+         * @returns {String[]} list of updated fields
+         */
+        _setState(state) {
+            var updatedFields = [];
+            if (state.data.employee_id.res_id !== (this.employee && this.employee.res_id)) {
+                updatedFields.push('employee');
+                this.employee = state.data.employee_id;
+            }
+            if (state.data.department_id.res_id !== (this.department && this.department.res_id)) {
+                updatedFields.push('department');
+                this.department = state.data.department_id;
+            }
+            if (state.data.date_from !== this.date) {
+                updatedFields.push('date');
+                this.date = state.data.date_from;
+            }
+            return updatedFields;
+        },
+
+        /**
+         * Fetch leaves taken by members of ``this.department`` in the
+         * month of ``this.date``.
+         * Three fields are fetched for each leave, namely: employee_id, date_from
+         * and date_to.
+         * The resulting data is assigned to ``this.departmentLeaves``
+         * @private
+         * @returns {Promise}
+         */
+        _fetchDepartmentLeaves: function () {
+            if (!this.date || !this.department) {
+                this.departmentLeaves = null;
+                return Promise.resolve();
+            }
+            var self = this;
+            var month_date_from = this.date.clone().startOf('month');
+            var month_date_to = this.date.clone().endOf('month');
+            return this._rpc({
+                model: 'hr.leave',
+                method: 'search_read',
+                args: [
+                    [['department_id', '=', this.department.res_id],
+                    ['state', '=', 'validate'],
+                    ['holiday_type', '=', 'employee'],
+                    ['date_from', '<=', month_date_to],
+                    ['date_to', '>=', month_date_from]],
+                    ['employee_id', 'date_from', 'date_to'],
+                ],
+            }).then(function (data) {
+                var dateFormat = time.getLangDateFormat();
+                self.departmentLeaves = data.map(function (leave) {
+                    // Format datetimes to date (in the user's format)
+                    return _.extend(leave, {
+                        date_from: moment(leave.date_from).format(dateFormat),
+                        date_to: moment(leave.date_to).format(dateFormat),
+                    });
+                });
+            });
+        },
+
+        /**
+         * Fetch the number of leaves, grouped by leave type, taken by ``this.employee``
+         * in the year of ``this.date``.
+         * The resulting data is assigned to ``this.leavesPerType``
+         * @private
+         * @returns {Promise}
+         */
+        _fetchLeaveTypesData: function () {
+            if (!this.date || !this.employee) {
+                this.leavesPerType = null;
+                return Promise.resolve();
+            }
+            var self = this;
+            var year_date_from = this.date.clone().startOf('year');
+            var year_date_to = this.date.clone().endOf('year');
+            return this._rpc({
+                model: 'hr.leave',
+                method: 'read_group',
+                kwargs: {
+                    domain: [['employee_id', '=', this.employee.res_id], ['state', '=', 'validate'], ['date_from', '<=', year_date_to], ['date_to', '>=', year_date_from]],
+                    fields: ['holiday_status_id', 'number_of_days:sum'],
+                    groupby: ['holiday_status_id'],
+                },
+            }).then(function (data) {
+                self.leavesPerType = data;
+            });
+        }
+    });
+
+    widget_registry.add('hr_leave_stats', LeaveStatsWidget);
+
+    return LeaveStatsWidget;
+});
diff --git a/addons/hr_holidays/static/src/xml/leave_stats_templates.xml b/addons/hr_holidays/static/src/xml/leave_stats_templates.xml
new file mode 100644
index 00000000000..594ff0e6b61
--- /dev/null
+++ b/addons/hr_holidays/static/src/xml/leave_stats_templates.xml
@@ -0,0 +1,64 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<templates id="template" xml:space="preserve">
+    <t t-name="hr_holidays.leave_per_type">
+        <table class="o_group o_inner_group table-striped">
+        <thead>
+            <tr>
+                <td colspan="2">
+                    <div class="o_horizontal_separator">Time Off taken by <t t-esc="widget.employee.data.display_name"/> in <t t-esc="widget.date.format('YYYY')"/></div>
+                </td>
+            </tr>
+        </thead>
+        <tbody>
+            <t t-if="widget.leavesPerType.length === 0">
+                <tr>
+                    <td>None</td>
+                </tr>
+            </t>
+            <t t-foreach="widget.leavesPerType" t-as="leave_type">
+                <tr>
+                    <td><t t-esc="leave_type.holiday_status_id[1]"/></td>
+                    <td  class="w-50"><t t-esc="leave_type.number_of_days"/></td>
+                </tr>
+            </t>
+        </tbody>
+        </table>
+    </t>
+
+    <t t-name="hr_holidays.department_leave">
+        <table class="o_group o_inner_group table-striped">
+        <thead>
+            <tr>
+                <td colspan="2">
+                    <div class="o_horizontal_separator">In <t t-esc="widget.date.format('MMMM')"/> for <t t-esc="widget.department.data.display_name"/> Department
+                    </div>
+                </td>
+            </tr>
+        </thead>
+        <tbody>
+            <t t-if="widget.departmentLeaves.length === 0">
+                <tr>
+                    <td>None</td>
+                </tr>
+            </t>
+            <t t-foreach="widget.departmentLeaves" t-as="leave">
+                <tr t-attf-class="{{leave.employee_id[0] === widget.employee.res_id ? 'font-weight-bold' : ''}}">
+                    <td><t t-esc="leave.employee_id[1]"/></td>
+                    <td class="w-50"><t t-esc="leave.date_from"/> - <t t-esc="leave.date_to"/></td>
+                </tr>
+            </t>
+        </tbody>
+        </table>
+    </t>
+
+    <div t-name="hr_holidays.leave_stats" class="o_leave_stats">
+        <t t-if="widget.leavesPerType">
+            <t t-call="hr_holidays.leave_per_type"/>
+        </t>
+        <t t-if="widget.departmentLeaves">
+            <t t-call="hr_holidays.department_leave"/>
+        </t>
+    </div>
+
+</templates>