From ac1c1114898fe3160d76bbb7e34fe5d64b367337 Mon Sep 17 00:00:00 2001
From: Keegan McAllister <keegan@humbughq.com>
Date: Wed, 27 Feb 2013 13:24:56 -0500
Subject: [PATCH] Fill in default recipient when composing while narrowed

Fixes #977.

(imported from commit 1abe26d94d5179a3dd1e970224a36c63bba9ff48)
---
 zephyr/static/js/compose.js | 16 +++++++++++-----
 zephyr/static/js/narrow.js  | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/zephyr/static/js/compose.js b/zephyr/static/js/compose.js
index ef46b22c92..9af683611c 100644
--- a/zephyr/static/js/compose.js
+++ b/zephyr/static/js/compose.js
@@ -129,11 +129,17 @@ exports.start = function (msg_type, opts) {
 
     compose.clear();
 
-    opts = $.extend({ message_type:     msg_type,
-                      stream:           '',
-                      subject:          '',
-                      private_message_recipient: ''
-                    }, opts);
+    var default_opts = {
+        message_type:     msg_type,
+        stream:           '',
+        subject:          '',
+        private_message_recipient: ''
+    };
+
+    // Set default parameters based on the current narrowed view.
+    narrow.set_compose_defaults(default_opts);
+
+    opts = $.extend(default_opts, opts);
 
     compose.stream_name(opts.stream);
     compose.subject(opts.subject);
diff --git a/zephyr/static/js/narrow.js b/zephyr/static/js/narrow.js
index 77c41b8f9e..944e773063 100644
--- a/zephyr/static/js/narrow.js
+++ b/zephyr/static/js/narrow.js
@@ -99,6 +99,43 @@ exports.describe = function (operators) {
     }).join(', ');
 };
 
+// Collect operators which appear only once into an object,
+// and discard those which appear more than once.
+function collect_single(operators) {
+    var seen   = {};
+    var result = {};
+    $.each(operators, function (index, elem) {
+        var key = elem[0];
+        if (seen.hasOwnProperty(key)) {
+            delete result[key];
+        } else {
+            result[key] = elem[1];
+            seen  [key] = true;
+        }
+    });
+    return result;
+}
+
+// Modify default compose parameters (stream etc.) based on
+// the current narrowed view.
+//
+// This logic is here and not in the 'compose' module because
+// it will get more complicated as we add things to the narrow
+// operator language.
+exports.set_compose_defaults = function (opts) {
+    var single = collect_single(exports.operators());
+
+    // Set the stream, subject, and/or PM recipient if they are
+    // uniquely specified in the narrow view.
+    $.each(['stream', 'subject'], function (idx, key) {
+        if (single[key] !== undefined)
+            opts[key] = single[key];
+    });
+
+    if (single['pm-with'] !== undefined)
+        opts.private_message_recipient = single['pm-with'];
+};
+
 // Parse a string into a list of operators (see below).
 exports.parse = function (str) {
     var operators   = [];