Implemented alarm clock function

cogs/alarm.py

@@ -1,7 +1,12 @@
 from discord.ext import commands
+import asyncio
+import datetime
+import time
+
+ALLOWED_TIME_FORMAT = "%H:%M"
 
-class alarm(commands.Cog):
 
+class alarm(commands.Cog):
     def __init__(self, client):
         self.client = client
 
@@ -13,10 +18,27 @@ async def alarm(self, ctx, time):
             time ([type]): time in 24 hour format
         """
         # Take user input (time in 24-hour format), for example 23:00
-        # Check if it is a valid 24-hour format, and return an apppropriate message
-        # Parse the user input using time.split(":")
-        # Remind the user as soon as it's time
-        pass
+        # Check if it is a valid 24-hour format, and return an apppropriate
+        # message
+
+        try:
+            alarm_time = datetime.datetime.strptime(time, ALLOWED_TIME_FORMAT)
+        except ValueError:
+            await ctx.send(
+                ctx.message.author.mention
+                + " Please input the alarm time in 24-hour format (e.g. 14:00)"
+            )
+
+        while True:
+            now = datetime.now()
+            if now >= alarm_time:
+                await ctx.send(
+                    ctx.message.author.mention
+                    + f" Ding dong, it is {alarm_time}, your alarm went off!"
+                )
+                break
+            await asyncio.sleep(1)
+
 
 def setup(client):
-    client.add_cog(alarm(client))
+    client.add_cog(alarm(client))