# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1411423419 -7200
# Node ID 72b7602bf5315f318ef4d6ce039e0ac16590afeb
# Parent  b62b34a78ad02693dc838a17ac4170aa6b905685
Return fragments from handlers so that they may be combined into single calendar
objects, converted into message parts, and such parts then combined into single
messages.

diff -r b62b34a78ad0 -r 72b7602bf531 imip_agent.py
--- a/imip_agent.py	Mon Sep 22 22:51:29 2014 +0200
+++ b/imip_agent.py	Tue Sep 23 00:03:39 2014 +0200
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 
 from email import message_from_file
+from email.mime.multipart import MIMEMultipart
 from email.mime.text import MIMEText
 from smtplib import SMTP
 from vCalendar import parse, iterwrite, ParseError, SECTION_TYPES
@@ -12,6 +13,8 @@
 except ImportError:
     from StringIO import StringIO
 
+OWNER = "resource+manager@example.com"
+
 # Postfix exit codes.
 
 EX_USAGE        = 64
@@ -54,19 +57,31 @@
     """
 
     msg = message_from_file(f)
-    print >>open("/tmp/imip.txt", "a"), "----"
-    print >>open("/tmp/imip.txt", "a"), original_recipients, recipients
-    print >>open("/tmp/imip.txt", "a"), "----"
-    print >>open("/tmp/imip.txt", "a"), msg.as_string()
-    print >>open("/tmp/imip.txt", "a")
+    sender = msg.get("Reply-To") or msg["From"]
 
     # Handle messages with iTIP parts.
 
+    all_parts = []
+
     for part in msg.walk():
         if part.get_content_type() in itip_content_types and \
             part.get_param("method"):
 
-            handle_itip_part(part, original_recipients)
+            all_parts += handle_itip_part(part, original_recipients)
+
+    # Pack the parts into a single message.
+
+    if all_parts:
+        if len(all_parts) > 1:
+            message = MIMEMultipart("alternative", _subparts=all_parts)
+        else:
+            message = all_parts[0]
+
+        message["From"] = OWNER
+        message["To"] = sender
+
+        if "-d" in sys.argv:
+            print message
 
 def get_itip_elements(elements):
     d = {}
@@ -118,7 +133,23 @@
 def get_uri(value):
     return value.startswith("mailto:") and value or "mailto:%s" % value
 
+def to_part(method, calendar):
+    out = StringIO()
+    try:
+        w = iterwrite(out, encoding="utf-8")
+        calendar[:0] = [
+            ("METHOD", {}, method),
+            ("VERSION", {}, "2.0")
+            ]
+        w.write("VCALENDAR", {}, calendar)
+        return MIMEText(out.getvalue(), "calendar", "utf-8")
+    finally:
+        out.close()
+
 def handle_itip_part(part, recipients):
+
+    "Handle the given iTIP 'part' for the given 'recipients'."
+
     method = part.get_param("method")
 
     # Decode the data and parse it.
@@ -132,6 +163,8 @@
 
     # Only handle calendar information.
 
+    all_parts = []
+
     if doctype == "VCALENDAR":
         itip = get_itip_elements(elements)
 
@@ -141,16 +174,27 @@
 
             # Look for different kinds of sections.
 
+            all_objects = []
+
             for name, cls in handlers:
                 for details in get_values(itip, name) or []:
 
                     # Dispatch to a handler and obtain any response.
 
                     handler = cls(details, recipients)
-                    part = methods[method](handler)()
+                    object = methods[method](handler)()
+
+                    # Concatenate responses for a single calendar object.
+
+                    if object:
+                        all_objects += object
 
-                    if part:
-                        print >>open("/tmp/imip.txt", "a"), part.as_string()
+            # Obtain a message part for the objects.
+
+            if all_objects:
+                all_parts.append(to_part(method, all_objects))
+
+    return all_parts
 
 class Handler:
 
@@ -235,8 +279,8 @@
     def request(self):
 
         """
-        Respond to a request by sending a reply containing free/busy information
-        for each indicated attendee.
+        Respond to a request by preparing a reply containing free/busy
+        information for each indicated attendee.
         """
 
         attendee_map = self.get_value_map("ATTENDEE")
@@ -251,39 +295,32 @@
 
         organiser, organiser_attr = organiser
 
-        # Get the details for the attendee.
+        # Construct an appropriate fragment.
+
+        calendar = []
+        cwrite = calendar.append
 
-        out = StringIO()
-        try:
-            w = iterwrite(out, encoding="utf-8")
+        # Get the details for each attendee.
 
-            calendar = []
-            cwrite = calendar.append
-            cwrite(("METHOD", {}, "REPLY"))
-            cwrite(("VERSION", {}, "2.0"))
+        for attendee in attendees:
+            freebusy = self.store.get_freebusy(attendee)
 
-            for attendee in attendees:
-                freebusy = self.store.get_freebusy(attendee)
-                if freebusy:
-                    record = []
-                    rwrite = record.append
-                    rwrite(("ORGANIZER", organiser_attr, organiser))
-                    rwrite(("ATTENDEE", attendee_map[attendee], attendee))
-                    rwrite(("UID", {}, self.uid))
+            if freebusy:
+                record = []
+                rwrite = record.append
+
+                rwrite(("ORGANIZER", organiser_attr, organiser))
+                rwrite(("ATTENDEE", attendee_map[attendee], attendee))
+                rwrite(("UID", {}, self.uid))
 
-                    for start, end in freebusy:
-                        rwrite(("FREEBUSY", {}, [start, end]))
-
-                    cwrite(("VFREEBUSY", {}, record))
-
-            # Send a reply with the information.
+                for start, end in freebusy:
+                    rwrite(("FREEBUSY", {}, [start, end]))
 
-            w.write("VCALENDAR", {}, calendar)
+                cwrite(("VFREEBUSY", {}, record))
 
-            return MIMEText(out.getvalue(), "calendar", "utf-8")
+        # Return the reply.
 
-        finally:
-            out.close()
+        return calendar
 
 class Journal(Handler):