Handle message type 7 (member join)

When message type 7 is received from the gateway, transform the content
if the type is 7 to a proper greeting.

Additionally, when the type is 6, provide a proper content notifying that a
user has pinned a message to the channel.

These transformations are not done at REST-level when retrieving messages, and
are instead done in `ChannelId::message` and `ChannelId::messages`.

2 files changed, 37 insertions, 0 deletions

diff --git a/src/model/channel/channel_id.rs b/src/model/channel/channel_id.rs
index 66bbbf3..46b00c6 100644
--- a/src/model/channel/channel_id.rs
+++ b/src/model/channel/channel_id.rs
@@ -255,6 +255,11 @@ impl ChannelId {
     #[inline]
     pub fn message<M: Into<MessageId>>(&self, message_id: M) -> Result<Message> {
         rest::get_message(self.0, message_id.into().0)
+            .map(|mut msg| {
+                msg.transform_content();
+
+                msg
+            })
     }
 
     /// Gets messages from the channel.
@@ -279,6 +284,13 @@ impl ChannelId {
         }
 
         rest::get_messages(self.0, &query)
+            .map(|msgs| msgs
+                .into_iter()
+                .map(|mut msg| {
+                    msg.transform_content();
+
+                    msg
+                }).collect::<Vec<Message>>())
     }
 
     /// Pins a [`Message`] to the channel.
diff --git a/src/model/channel/message.rs b/src/model/channel/message.rs
index d360975..593aa48 100644
--- a/src/model/channel/message.rs
+++ b/src/model/channel/message.rs
@@ -1,4 +1,5 @@
 use std::mem;
+use time;
 use ::constants;
 use ::client::rest;
 use ::model::*;
@@ -189,6 +190,28 @@ impl Message {
         }
     }
 
+    #[doc(hidden)]
+    pub fn transform_content(&mut self) {
+        match self.kind {
+            MessageType::PinsAdd => {
+                self.content = format!("{} pinned a message to this channel. See all the pins.", self.author);
+            },
+            MessageType::MemberJoin => {
+                if let Ok(tm) = time::strptime(&self.timestamp, "%Y-%m-%dT%H:%M:%S") {
+                    let sec = tm.to_timespec().sec as usize;
+                    let chosen = constants::JOIN_MESSAGES[sec % constants::JOIN_MESSAGES.len()];
+
+                    self.content = if chosen.contains("$user") {
+                        chosen.replace("$user", &self.author.mention())
+                    } else {
+                        chosen.to_owned()
+                    };
+                }
+            },
+            _ => {},
+        }
+    }
+
     /// Returns message content, but with user and role mentions replaced with
     /// names and everyone/here mentions cancelled.
     #[cfg(feature="cache")]
@@ -550,6 +573,8 @@ enum_number!(
         GroupIconUpdate = 5,
         /// An indicator that a message was pinned by the author.
         PinsAdd = 6,
+        /// An indicator that a member joined the guild.
+        MemberJoin = 7,
     }
 );