Fix Member methods due to variant joined_at values

Fix an issue where the library would check the Id of the guild that a
member is in by checking the Member's ID and joined_at value with those
of the members of guilds present in the cache.

Performing this check would have the issue of where a joined_at
for a member received over websocket would potentially have a varying
value than that of the same member retrieved over REST.

To fix this, attach the relevant guild's Id to the member on creation,
where the Id is available.

Fixes #68.

3 files changed, 42 insertions, 20 deletions

diff --git a/src/model/event.rs b/src/model/event.rs
index b9801dc..5ae6629 100644
--- a/src/model/event.rs
+++ b/src/model/event.rs
@@ -312,9 +312,11 @@ impl GuildMemberAddEvent {
     #[doc(hidden)]
     #[inline]
     pub fn decode(mut map: Map) -> Result<Self> {
+        let guild_id = remove(&mut map, "guild_id").and_then(GuildId::decode)?;
+
         Ok(GuildMemberAddEvent {
-            guild_id: remove(&mut map, "guild_id").and_then(GuildId::decode)?,
-            member: Member::decode(Value::Object(map))?,
+            guild_id: guild_id,
+            member: Member::decode_guild(guild_id, Value::Object(map))?,
         })
     }
 }
@@ -367,9 +369,11 @@ impl GuildMembersChunkEvent {
     #[doc(hidden)]
     #[inline]
     pub fn decode(mut map: Map) -> Result<Self> {
+        let guild_id = remove(&mut map, "guild_id").and_then(GuildId::decode)?;
+
         Ok(GuildMembersChunkEvent {
-            guild_id: remove(&mut map, "guild_id").and_then(GuildId::decode)?,
-            members: remove(&mut map, "members").and_then(decode_members)?,
+            guild_id: guild_id,
+            members: remove(&mut map, "members").and_then(|x| decode_guild_members(guild_id, x))?,
         })
     }
 }
diff --git a/src/model/guild.rs b/src/model/guild.rs
index 8fa6d0e..b3879b1 100644
--- a/src/model/guild.rs
+++ b/src/model/guild.rs
@@ -1734,6 +1734,15 @@ impl Member {
         roles.iter().find(|r| r.colour.0 != default.0).map(|r| r.colour)
     }
 
+    #[doc(hidden)]
+    pub fn decode_guild(guild_id: GuildId, mut value: Value) -> Result<Member> {
+        if let Some(v) = value.as_object_mut() {
+            v.insert("guild_id".to_owned(), Value::U64(guild_id.0));
+        }
+
+        Self::decode(value)
+    }
+
     /// Calculates the member's display name.
     ///
     /// The nickname takes priority over the member's username if it exists.
@@ -1768,6 +1777,8 @@ impl Member {
 
     /// Finds the Id of the [`Guild`] that the member is in.
     ///
+    /// If some value is present in [`guild_id`], then that value is returned.
+    ///
     /// # Errors
     ///
     /// Returns a [`ClientError::GuildNotFound`] if the guild could not be
@@ -1775,8 +1786,13 @@ impl Member {
     ///
     /// [`ClientError::GuildNotFound`]: ../client/enum.ClientError.html#variant.GuildNotFound
     /// [`Guild`]: struct.Guild.html
+    /// [`guild_id`]: #structfield.guild_id
     #[cfg(feature="cache")]
     pub fn find_guild(&self) -> Result<GuildId> {
+        if let Some(guild_id) = self.guild_id {
+            return Ok(guild_id);
+        }
+
         for guild in CACHE.read().unwrap().guilds.values() {
             let guild = guild.read().unwrap();
 
diff --git a/src/model/utils.rs b/src/model/utils.rs
index 8de7dd2..17f91f1 100644
--- a/src/model/utils.rs
+++ b/src/model/utils.rs
@@ -1,21 +1,6 @@
 use std::collections::{BTreeMap, HashMap};
 use std::sync::{Arc, RwLock};
-use super::{
-    Channel,
-    ChannelId,
-    Emoji,
-    EmojiId,
-    Member,
-    Message,
-    Presence,
-    ReadState,
-    Relationship,
-    Role,
-    RoleId,
-    User,
-    UserId,
-    VoiceState,
-};
+use super::*;
 use ::internal::prelude::*;
 use ::utils::{decode_array, into_array};
 
@@ -100,6 +85,23 @@ pub fn decode_members(value: Value) -> Result<HashMap<UserId, Member>> {
     Ok(members)
 }
 
+pub fn decode_guild_members(guild_id: GuildId, value: Value) -> Result<HashMap<UserId, Member>> {
+    let mut members = HashMap::new();
+    let member_vec = into_array(value).map(|x| x
+        .into_iter()
+        .map(|v| Member::decode_guild(guild_id, v))
+        .filter_map(Result::ok)
+        .collect::<Vec<_>>())?;
+
+    for member in member_vec {
+        let user_id = member.user.read().unwrap().id;
+
+        members.insert(user_id, member);
+    }
+
+    Ok(members)
+}
+
 // Clippy's lint is incorrect here and will result in invalid code.
 //
 // Bit more detaul: `result_unwrap_or_default` is not yet stable as of rustc