Generate email content from ninja2 templates

src/ddns_service/email.py

@@ -5,6 +5,28 @@ import smtplib
 
 from . import datetime_str
 from email.mime.text import MIMEText
+from jinja2 import Environment, BaseLoader
+
+
+def load_template(path):
+    """
+    Load template from file.
+
+    Args:
+        path: Path to template.
+    Returns:
+        Template if path was not None, None otherwise.
+    """
+    if path is None:
+        return
+
+    with open(path) as fh:
+        data = fh.read()
+
+    return Environment(
+        loader=BaseLoader(),
+        trim_blocks=True
+    ).from_string(data)
 
 
 class EmailService:
@@ -20,6 +42,13 @@ class EmailService:
         self.config = config.get("email", {})
         self.enabled = self.config.get("enabled", False)
 
+        self.change_template = load_template(self.config.get("change_notification_template", None))
+        self.expiry_template = load_template(self.config.get("expiry_notification_template", None))
+
+        if not self.change_template and not self.expiry_template and self.enabled:
+            logging.warning("No templates configured, disabling Email")
+            self.enabled = False
+
     def send(self, to, subject, body):
         """
         Send email using configured SMTP server.
@@ -65,15 +94,58 @@ class EmailService:
             logging.error(f"Email send failed: to={to} error={e}")
             return False
 
+    def send_changed_notification(
+        self,
+        email,
+        hostname,
+        ipv4_changed,
+        ipv6_changed
+    ):
+        """
+        Send hostname changed notification email.
+
+        Args:
+            email: Recipient email.
+            hostname: Changed hostname.
+            ipv4_changed: Wheter IPv4 address changed.
+            ipv6_changed: Wheter IPv6 address changed.
+
+        Returns:
+            True if sent successfully.
+        """
+        if not self.enabled:
+            logging.debug("Email disabled, skipping")
+            return False
+
+        if not self.change_template:
+            logging.debug("No change notification template configured, skipping")
+            return False
+
+        fqdn = f"{hostname.hostname}.{hostname.zone}"
+        template_variables = {
+            "hostname": hostname.hostname,
+            "zone": hostname.zone,
+            "fqdn": fqdn,
+            "ipv4_changed": ipv4_changed,
+            "ipv4": hostname.last_ipv4,
+            "last_ipv4_update": datetime_str(hostname.last_ipv4_update),
+            "ipv6_changed": ipv6_changed,
+            "ipv6": hostname.last_ipv6,
+            "last_ipv6_update": datetime_str(hostname.last_ipv6_update),
+            "expiry_ttl": hostname.expiry_ttl,
+        }
+
+        subject = f"DDNS hostname expired: {fqdn}"
+        body = self.expiry_template.render(**template_variables)
+
+        return self.send(email, subject, body)
+
     def send_expiry_notification(
         self,
         email,
         hostname,
-        last_ipv4,
-        last_ipv4_update,
-        last_ipv6,
-        last_ipv6_update,
-        expiry_ttl
+        ipv4_expired,
+        ipv6_expired
     ):
         """
         Send hostname expiry notification email.
@@ -81,27 +153,35 @@ class EmailService:
         Args:
             email: Recipient email.
             hostname: Expired hostname.
-            last_ipv4: Tuple containing last IPv4 address and last update timestamp.
-            last_ipv6: Tuple containing last IPv6 address and last update timestamp.
-            expiry_ttl: Expiry TTL in seconds.
+            ipv4_expired: Wheter IPv4 address expired.
+            ipv6_expired: Wheter IPv6 address expired.
 
         Returns:
             True if sent successfully.
         """
+        if not self.enabled:
+            logging.debug("Email disabled, skipping")
+            return False
 
-        expired = ""
-        if last_ipv4 and last_ipv4_update:
-            expired += f"IPv4 address: {last_ipv4} (last update: {last_ipv4_update})\n"
-        if last_ipv6 and last_ipv6_update:
-            expired += f"IPv6 address: {last_ipv6} (last update: {last_ipv6_update})\n"
+        if not self.expiry_template:
+            logging.debug("No expiry notification template configured, skipping")
+            return False
 
-        subject = f"DDNS hostname expired: {hostname}"
-        body = f"""Your dynamic DNS entry has expired due to inactivity.
+        fqdn = f"{hostname.hostname}.{hostname.zone}"
+        template_variables = {
+            "hostname": hostname.hostname,
+            "zone": hostname.zone,
+            "fqdn": fqdn,
+            "ipv4_expired": ipv4_expired,
+            "last_ipv4": hostname.last_ipv4,
+            "last_ipv4_update": datetime_str(hostname.last_ipv4_update),
+            "ipv6_expired": ipv6_expired,
+            "last_ipv6": hostname.last_ipv6,
+            "last_ipv6_update": datetime_str(hostname.last_ipv6_update),
+            "expiry_ttl": hostname.expiry_ttl,
+        }
 
-Hostname: {hostname}
-{expired}
-Expiry TTL: {expiry_ttl} seconds
+        subject = f"DDNS hostname expired: {fqdn}"
+        body = self.expiry_template.render(**template_variables)
 
-The DNS records have been removed. Update your client to restore them.
-"""
         return self.send(email, subject, body)