reminder: save reminders in storage

edmond/plugins/reminder.py

@@ -1,6 +1,7 @@
 import datetime
 import re
 import string
+import uuid
 from typing import Optional
 
 from apscheduler.triggers.date import DateTrigger
@@ -9,13 +10,52 @@ from edmond.plugin import Plugin
 
 
 class ReminderPlugin(Plugin):
-    """Reminders using an async scheduler."""
+    """Reminders using an async scheduler.
+
+    Reminders can be set in a given amount of time or to a given hour. They are
+    kept between restarts.
+    """
 
     REQUIRED_CONFIGS = [
         "commands", "at_word", "in_word", "day_letter", "hour_letter",
         "minute_letter", "second_letter", "reminder_format", "done"
     ]
 
+    def on_join(self, event):
+        """Reschedule undelivered reminders."""
+        nick = event.source.nick
+        if nick != self.bot.nick:
+            return
+
+        joined_channel = event.target
+        reminder_format = self.config["reminder_format"]
+        saved_reminders = self.get_storage_value("reminders", [])
+        self.set_storage_value("reminders", [])
+
+        for reminder in saved_reminders:
+            # Ignore reminders for other targets than this channel.
+            if reminder["target"] != joined_channel:
+                continue
+
+            when = datetime.datetime.fromisoformat(reminder["when"])
+            # If the timer passed, deliver it now and forget it.
+            if when <= datetime.datetime.now():
+                message = reminder_format.format(
+                    username=reminder["sender"],
+                    reminder=reminder["message"]
+                )
+                self.bot.say(reminder["target"], message)
+                continue
+
+            # Else schedule it properly (but skip storage backup, we're on it).
+            self.schedule(
+                when,
+                reminder["message"],
+                reminder["sender"],
+                reminder["target"],
+            )
+
+
     def on_pubmsg(self, event):
         if not self.should_handle_command(event.arguments[0]):
             return False
@@ -43,7 +83,6 @@ class ReminderPlugin(Plugin):
         reminder = " ".join(words[2:])
         self.setup_reminder(mode, time, reminder, sender, target)
         return True
-        # self.bot.scheduler.add_job(, 'cron', hour='1', minute='52')
 
     def parse_time(self, time: str) -> Optional[dict[str, int]]:
         """Parse a time request string.
@@ -72,11 +111,20 @@ class ReminderPlugin(Plugin):
         self,
         mode: str,
         time: dict[str, int],
-        reminder: str,
+        message: str,
         sender: str,
         target: str
     ) -> None:
-        """Remind something at a given time."""
+        """Remind something at a given time.
+
+        There are two possible modes, "at" for a given time and "in" for a
+        given delay. In both cases, it should result to a datetime in the
+        future, or it will be discarded.
+
+        Reminders are saved in the bot's storage to prevent losing reminders
+        between restarts. Only when a reminder is delivered it is removed from
+        the storage.
+        """
         now = datetime.datetime.now()
         if mode == self.config["at_word"]:
             if "day" in time: # "day" is not supported in at mode.
@@ -100,15 +148,53 @@ class ReminderPlugin(Plugin):
             self.signal_failure(target)
             return
 
+        self.schedule(when, message, sender, target)
+        self.bot.say(target, self.config["done"])
+
+    def schedule(
+        self,
+        when: datetime.datetime,
+        message: str,
+        sender: str,
+        target: str,
+    ) -> None:
+        """Schedule the reminder to be delivered at the given datetime."""
+        identifier = str(uuid.uuid4())
+        # Store the reminder in case the bot shuts down before delivery.
+        reminder = {
+            "id": identifier,
+            "when": when.isoformat(),
+            "message": message,
+            "sender": sender,
+            "target": target,
+        }
+        self.append_storage_list_value("reminders", reminder)
+
         self.bot.scheduler.add_job(
             self.remind,
             trigger=DateTrigger(when),
-            args=(reminder, sender, target)
+            args=(identifier, message, sender, target)
         )
-        self.bot.log_d(f"Scheduled for {when}, time was {time}.")
-        self.bot.say(target, self.config["done"])
+        self.bot.log_d(f"Scheduled {identifier} for {when}.")
 
-    async def remind(self, reminder: str, username: str, target: str) -> None:
+    async def remind(
+        self,
+        identifier: str,
+        reminder: str,
+        username: str,
+        target: str
+    ) -> None:
+        self.bot.log_d(
+            f"Delivering reminder {identifier} in {target} for {username}…"
+        )
         reminder_format = self.config["reminder_format"]
         message = reminder_format.format(username=username, reminder=reminder)
         self.bot.say(target, message)
+
+        # Remove the reminder from the saved reminder list.
+        saved_reminders = self.get_storage_value("reminders", [])
+        for reminder in saved_reminders.copy():
+            if reminder["id"] == identifier:
+                saved_reminders.remove(reminder)
+                break
+        self.set_storage_value("reminders", saved_reminders)