zedr · June 14, 2019 11:16 · Jun 8, 2017 · Jun 7, 2017
diff --git a/lambda_echobot.py b/lambda_echobot.py
@@ -17,10 +17,6 @@
 def lambda_handler(data, context):
     """Handle an incoming HTTP request from a Slack chat-bot.
     """
-    logging.warn(data)
-    if "challenge" in data:
-        return data["challenge"]
-
     # Grab the Slack event data.
     slack_event = data['event']
 

diff --git a/lambda_echobot.py b/lambda_echobot.py
@@ -0,0 +1,73 @@
+"""
+Slack chat-bot Lambda handler.
+"""
+
+import os
+import logging
+import urllib
+
+# Grab the Bot OAuth token from the environment.
+BOT_TOKEN = os.environ["BOT_TOKEN"]
+
+# Define the URL of the targeted Slack API resource.
+# We'll send our replies there.
+SLACK_URL = "https://slack.com/api/chat.postMessage"
+
+
+def lambda_handler(data, context):
+    """Handle an incoming HTTP request from a Slack chat-bot.
+    """
+    logging.warn(data)
+    if "challenge" in data:
+        return data["challenge"]
+
+    # Grab the Slack event data.
+    slack_event = data['event']
+
+    # We need to discriminate between events generated by 
+    # the users, which we want to process and handle, 
+    # and those generated by the bot.
+    if "bot_id" in slack_event:
+        logging.warn("Ignore bot event")
+    else:
+        # Get the text of the message the user sent to the bot,
+        # and reverse it.
+        text = slack_event["text"]
+        reversed_text = text[::-1]
+
+        # Get the ID of the channel where the message was posted.
+        channel_id = slack_event["channel"]
+
+        # We need to send back three pieces of information:
+        #     1. The reversed text (text)
+        #     2. The channel id of the private, direct chat (channel)
+        #     3. The OAuth token required to communicate with 
+        #        the API (token)
+        # Then, create an associative array and URL-encode it, 
+        # since the Slack API doesn't not handle JSON (bummer).
+        data = urllib.parse.urlencode(
+            (
+                ("token", BOT_TOKEN),
+                ("channel", channel_id),
+                ("text", reversed_text)
+            )
+        )
+        data = data.encode("ascii")
+
+        # Construct the HTTP request that will be sent to the Slack API.
+        request = urllib.request.Request(
+            SLACK_URL, 
+            data=data, 
+            method="POST"
+        )
+        # Add a header mentioning that the text is URL-encoded.
+        request.add_header(
+            "Content-Type", 
+            "application/x-www-form-urlencoded"
+        )
+
+        # Fire off the request!
+        urllib.request.urlopen(request).read()
+
+    # Everything went fine.
+    return "200 OK"