diff --git a/discord.py b/discord.py
index f8bbae4..92020bc 100644
--- a/discord.py
+++ b/discord.py
@@ -1,16 +1,21 @@
-import httpx
 from typing import Dict, Any
+import httpx
+
+DISCORD_INVITE_HACK_URL = "https://discord.com/api/v9/invites/{invite_code}?with_counts=true&with_expiration=true"
 
-DISCORD_INVITE_HACK_URL = 'https://discord.com/api/v9/invites/{invite_code}?with_counts=true&with_expiration=true'
 
 def get_discord_stats(invite_code: str) -> Dict[str, Any]:
-    discord_stats = {}
+    """Get discord stats from invite code"""
+
+    discord_stats: Dict[str, Any] = {}
     res = httpx.get(DISCORD_INVITE_HACK_URL.format(invite_code=invite_code))
     if res.status_code == 200:
         res_json = res.json()
-        discord_stats['discordTotalMembers'] = res_json.get('approximate_member_count')
-        discord_stats['discordTotalActiveMembers'] = res_json.get(
-            'approximate_presence_count'
+        discord_stats["discordTotalMembers"] = res_json.get(
+            "approximate_member_count", 0
+        )
+        discord_stats["discordTotalActiveMembers"] = res_json.get(
+            "approximate_presence_count", 0
         )
 
     return discord_stats
diff --git a/main.py b/main.py
index 88872b2..9e6ada7 100644
--- a/main.py
+++ b/main.py
@@ -1,26 +1,43 @@
-'''
-    This script is used for generating developersIndia subreddit traffic stats
-'''
-import praw
-import os
+"""
+This script is used for generating developersIndia subreddit traffic stats
+"""
+
 import json
-from datetime import datetime, timedelta
+import os
+from typing import Any, Dict, List
+
+import praw
+
 from discord import get_discord_stats
-from utils import *
+from utils import get_last_day, get_last_month, get_readable_day, get_readable_month
 
-client_id = os.environ["REDDIT_CLIENT_ID"]
-client_secret = os.environ["REDDIT_CLIENT_SECRET"]
-reddit_pass = os.environ["REDDIT_PASSWORD"]
-reddit_user = os.environ["REDDIT_USER"]
 
-discord_invite_code = os.environ["DISCORD_INVITE_CODE"]
+# Get credentials from env
+client_id = os.getenv("REDDIT_CLIENT_ID")
+client_secret = os.getenv("REDDIT_CLIENT_SECRET")
+reddit_pass = os.getenv("REDDIT_PASSWORD")
+reddit_user = os.getenv("REDDIT_USER")
+discord_invite_code = os.getenv("DISCORD_INVITE_CODE")
 
-REPORT_PATH="data/index.json"
+# validate that all credentials are present
+if not client_id or not client_secret or not reddit_pass or not reddit_user:
+    raise RuntimeError("Missing reddit credentials")
+
+if not discord_invite_code:
+    raise RuntimeError("Missing DISCORD_INVITE_CODE")
+
+
+REPORT_PATH = "data/index.json"
 
 last_month = get_last_month()
 last_day = get_last_day()
 
-def generate_data(members, stats, discord_stats):
+
+def generate_data(
+    members: int | None,
+    stats: Dict[str, List[List[int]]],
+    discord_stats: Dict[str, Any],
+):
     subreddit_stats = {}
 
     if members is not None:
@@ -40,9 +57,10 @@ def generate_data(members, stats, discord_stats):
 
     # populate discord data to the stats.
     combined_stats = {**subreddit_stats, **discord_stats}
-    with open(REPORT_PATH, 'w') as report:
+    with open(REPORT_PATH, "w", encoding="utf-8") as report:
         json.dump(combined_stats, report, indent=4)
 
+
 def find_traffic():
     reddit = praw.Reddit(
         client_id=client_id,
@@ -51,12 +69,13 @@ def find_traffic():
         user_agent="testscript",
         username=reddit_user,
     )
-    stats = reddit.subreddit("developersIndia").traffic()
-    members = reddit.subreddit("developersIndia").subscribers
+    stats: Dict[str, List[List[int]]] = reddit.subreddit("developersIndia").traffic()
+    members: int = reddit.subreddit("developersIndia").subscribers
 
     # Discord server data
-    discord_stats = get_discord_stats(discord_invite_code)
+    discord_stats: Dict[str, Any] = get_discord_stats(discord_invite_code)
     generate_data(members, stats, discord_stats)
 
-if __name__ == '__main__':
+
+if __name__ == "__main__":
     find_traffic()
diff --git a/utils.py b/utils.py
index 3a79192..ab1f01b 100644
--- a/utils.py
+++ b/utils.py
@@ -12,25 +12,25 @@ def non_zero_padded_prefix():
     return prefix
 
 
-def get_last_month():
+def get_last_month() -> str:
     now = datetime.now()
     last_month = now - timedelta(weeks=4)
     return last_month.strftime(f"%{non_zero_padded_prefix()}m %Y")
 
 
-def get_last_day():
+def get_last_day() -> str:
     now = datetime.now()
     last_day = now - timedelta(days=1)
     return last_day.strftime(f"%d/%{non_zero_padded_prefix()}m/%Y")
 
 
-def get_readable_month(unix_t):
+def get_readable_month(unix_t: float) -> str:
     t = time.localtime(unix_t)
     # Format: '9, 2021'
     return time.strftime(f"%{non_zero_padded_prefix()}m %Y", t)
 
 
-def get_readable_day(unix_t):
+def get_readable_day(unix_t: float) -> str:
     t = time.localtime(unix_t)
     # Format: '03/12/2021'
     return time.strftime(f"%d/%{non_zero_padded_prefix()}m/%Y", t)