[fix] fix date period selector limits in tx history

src/sakia/gui/navigation/txhistory/controller.py

 import logging
 
-from PyQt5.QtCore import QTime, pyqtSignal, QObject
+from PyQt5.QtCore import QTime, pyqtSignal, QObject, QDateTime
 from PyQt5.QtGui import QCursor
 
 from sakia.decorators import asyncify
@@ -125,14 +125,50 @@ class TxHistoryController(QObject):
     def dates_changed(self):
         self._logger.debug("Changed dates")
         if self.view.table_history.model():
-            qdate_from = self.view.date_from
+            # capture datetimes from calendar widget
+            qdate_from = self.view.date_from.dateTime()  # type: QDateTime
+            qdate_to = self.view.date_to.dateTime()  # type: QDateTime
+            # time is midnight
             qdate_from.setTime(QTime(0, 0, 0))
-            qdate_to = self.view.date_to
             qdate_to.setTime(QTime(0, 0, 0))
-            ts_from = qdate_from.dateTime().toTime_t()
-            ts_to = qdate_to.dateTime().toTime_t()
 
+            # calculate dates
+            qdate_from_plus_one_year = qdate_from.addYears(1)
+            qdate_to_minus_one_month = qdate_to.addMonths(-1)
+            qone_month_ago = QDateTime.currentDateTime().addMonths(-1)
+            qtomorrow = QDateTime.currentDateTime().addDays(1)
+            qtomorrow.setTime(QTime(0, 0, 0))
+
+            # if start later than one month ago...
+            if qdate_from > qone_month_ago:
+                # start = now - 1 month
+                qdate_from = qone_month_ago
+
+            # if start > end minus one month...
+            if qdate_from > qdate_to_minus_one_month:
+                # end = start + 1 month
+                qdate_to = qdate_from.addMonths(1)
+
+            # if period is more than one year long...
+            if qdate_to > qdate_from_plus_one_year:
+                # end = start + 1 year
+                qdate_to.setDate(qdate_from_plus_one_year.date())
+
+            # if end > tomorrow...
+            if qdate_to > qtomorrow:
+                # end = tomorrow
+                qdate_to = qtomorrow
+
+            # todo: update minimum and maximum of the calendar to forbid bad dates
+            # update calendar
+            self.view.date_from.setDateTime(qdate_from)
+            self.view.date_to.setDateTime(qdate_to)
+
+            # update model in table
+            ts_from = qdate_from.toTime_t()
+            ts_to = qdate_to.toTime_t()
             self.view.table_history.model().set_period(ts_from, ts_to)
 
+            # refresh
             self.refresh_balance()
             self.refresh_pages()