Add SMTP email support

1 files changed, 104 insertions, 0 deletions

diff --git a/email_client.py b/email_client.py
new file mode 100644
index 0000000..0f0802f
--- /dev/null
+++ b/email_client.py
@@ -0,0 +1,104 @@
+import os
+import sys
+import traceback
+import smtplib
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+
+import db
+
+BASE_URL = os.environ["BASE_URL"]
+
+def send_email(subject: str, body: str, recipient: str):
+  pass
+
+email_env_vars = [
+  "EMAIL_HOST",
+  "EMAIL_PORT",
+  "EMAIL_HOST_USER",
+  "EMAIL_HOST_PASSWORD",
+  "EMAIL_USE_TLS",
+  "EMAIL_MESSAGE_FROM",
+]
+
+email_enabled = any(var in os.environ for var in email_env_vars)
+if email_enabled:
+  for var in email_env_vars:
+    if var not in os.environ:
+      raise Exception(f"Some EMAIL_ variables are set but {var} is not set")
+
+  email_host = os.environ["EMAIL_HOST"]
+  email_port = int(os.environ["EMAIL_PORT"])
+  email_host_user = os.environ["EMAIL_HOST_USER"]
+  email_host_password = os.environ["EMAIL_HOST_PASSWORD"]
+  email_use_tls = os.environ["EMAIL_USE_TLS"].lower() in ["true", "1", "yes"]
+  email_message_from = os.environ["EMAIL_MESSAGE_FROM"]
+
+  print(f"SMTP email client enabled using email host {email_host}")
+
+  def _actual_send_email(subject: str, body: str, recipient: str):
+    if not email_enabled:
+      return
+    
+    print("debug: subject:", subject)
+    print("debug: body:", body)
+    print("debug: recipient:", recipient)
+    print("debug: email_host:", email_host)
+    print("debug: email_port:", email_port)
+    print("debug: email_host_user:", email_host_user)
+    print("debug: email_host_password:", email_host_password)
+    print("debug: email_use_tls:", email_use_tls)
+    print("debug: email_message_from:", email_message_from)
+
+    msg = MIMEMultipart()
+    msg['From'] = email_host_user
+    msg['To'] = recipient
+    msg['Subject'] = subject
+    msg.attach(MIMEText(body, 'plain'))
+
+    with smtplib.SMTP(email_host, email_port) as server:
+      if email_use_tls:
+        server.starttls()
+
+      server.login(email_host_user, email_host_password)
+      server.send_message(msg)
+
+  send_email = _actual_send_email
+else:
+  print("SMTP email client not enabled")
+
+def send_participation_email_if_enabled(poll_id: str, voter_name: str):
+  if email_enabled:
+    poll = db.get_poll(poll_id)
+    if not poll or poll.author_email is None:
+      return
+
+    try:
+      send_email(
+        subject=f"{voter_name} participated in your poll \"{poll.title}\"",
+        body=f"{voter_name} participated in your diddle \"{poll.title}\".\n\n"
+             f"View the results at {BASE_URL}/poll/{poll.id}\n"
+             f"Manage your diddle at {BASE_URL}/manage/{poll.manage_code}\n"
+              "You will be notified by email when someone participates.",
+        recipient=poll.author_email,
+      )
+    except Exception as e:
+      traceback.print_exc(file=sys.stderr)
+      print(f"Failed to send participation email to {poll.author_email}", file=sys.stderr)
+
+def send_poll_created_email_if_enabled(poll_id: str):
+  if email_enabled:
+    poll = db.get_poll(poll_id)
+    if not poll or poll.author_email is None:
+      return
+
+    try:
+      send_email(
+        subject=f"You created a new diddle \"{poll.title}\"",
+        body=f"Manage your diddle at {BASE_URL}/manage/{poll.manage_code}\n"
+              "You will be notified by email when someone participates.",
+        recipient=poll.author_email,
+      )
+    except Exception as e:
+      traceback.print_exc(file=sys.stderr)
+      print(f"Failed to send poll created email to {poll.author_email}", file=sys.stderr)
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