[FIX] calendar: add timezone info to avoid DST issue on recurrent events

As original timezone is not taken into account when computing recurrent event
time of a given recurrency change depending on the DST. This commit fixes that
behavior by correctly storing the event timezone and using it when computing
recurrency datetimes.

Related to task 30388

closes odoo/odoo#32950

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/calendar/models/calendar.py

@@ -17,6 +17,7 @@ import uuid
 
 from odoo import api, fields, models
 from odoo import tools
+from odoo.addons.base.models.res_partner import _tz_get
 from odoo.osv import expression
 from odoo.tools.translate import _
 from odoo.tools import DEFAULT_SERVER_DATE_FORMAT, DEFAULT_SERVER_DATETIME_FORMAT, pycompat
@@ -599,7 +600,7 @@ class Meeting(models.Model):
         else:
             reference_date = self.start
 
-        timezone = pytz.timezone(self._context.get('tz') or 'UTC')
+        timezone = pytz.timezone(self.event_tz) if self.event_tz else pytz.timezone(self._context.get('tz') or 'UTC')
         event_date = pytz.UTC.localize(fields.Datetime.from_string(reference_date))  # Add "+hh:mm" timezone
         if not event_date:
             event_date = datetime.datetime.now()
@@ -637,7 +638,7 @@ class Meeting(models.Model):
             invalidate = True
 
         def naive_tz_to_utc(d):
-            return timezone.localize(d).astimezone(pytz.UTC)
+            return timezone.localize(d.replace(tzinfo=None), is_dst=True).astimezone(pytz.UTC)
         return [naive_tz_to_utc(d) if not use_naive_datetime else d for d in rset1 if d.year < MAXYEAR]
 
     @api.multi
@@ -780,6 +781,7 @@ class Meeting(models.Model):
     start_datetime = fields.Datetime('Start DateTime', compute='_compute_dates', inverse='_inverse_dates', store=True, states={'done': [('readonly', True)]}, tracking=True)
     stop_date = fields.Date('End Date', compute='_compute_dates', inverse='_inverse_dates', store=True, states={'done': [('readonly', True)]}, tracking=True)
     stop_datetime = fields.Datetime('End Datetime', compute='_compute_dates', inverse='_inverse_dates', store=True, states={'done': [('readonly', True)]}, tracking=True)  # old date_deadline
+    event_tz = fields.Selection('_event_tz_get', string='Timezone', default=lambda self: self.env.context.get('tz') or self.user_id.tz)
     duration = fields.Float('Duration', states={'done': [('readonly', True)]})
     description = fields.Text('Description', states={'done': [('readonly', True)]})
     privacy = fields.Selection([('public', 'Everyone'), ('private', 'Only me'), ('confidential', 'Only internal users')], 'Privacy', default='public', states={'done': [('readonly', True)]}, oldname="class")
@@ -935,6 +937,10 @@ class Meeting(models.Model):
                 data.update(self._rrule_parse(meeting.rrule, data, meeting.start))
                 meeting.update(data)
 
+    @api.model
+    def _event_tz_get(self):
+        return _tz_get(self)
+
     @api.constrains('start_datetime', 'stop_datetime', 'start_date', 'stop_date')
     def _check_closing_date(self):
         for meeting in self:

addons/calendar/views/calendar_views.xml

@@ -139,6 +139,7 @@
                                     {'no_create_edit': True}"/>
                                     <field name="alarm_ids" widget="many2many_tags" />
                                     <field name="location" />
+                                    <field name="event_tz" attrs="{'invisible': [('recurrency', '=', False)]}"/>
                                 </group>
 
                             </group>

addons/hr_holidays/models/hr_leave.py

@@ -618,7 +618,8 @@ class HolidaysRequest(models.Model):
             'stop': self.date_to,
             'allday': False,
             'state': 'open',  # to block that meeting date in the calendar
-            'privacy': 'confidential'
+            'privacy': 'confidential',
+            'event_tz': self.user_id.tz,
         }
         # Add the partner_id (if exist) as an attendee
         if self.user_id and self.user_id.partner_id: