Move the builders to the utils

The builders aren't a large enough portion of the library to deserve
their own root-level module, so move them to the `utils` module.

Additionally, split them into separate files, as the library will be
receiving more builders and the single-file pattern was getting rather
large.

1 files changed, 71 insertions, 0 deletions

diff --git a/src/utils/builder/create_invite.rs b/src/utils/builder/create_invite.rs
new file mode 100644
index 0000000..55cc1bd
--- /dev/null
+++ b/src/utils/builder/create_invite.rs
@@ -0,0 +1,71 @@
+use serde_json::builder::ObjectBuilder;
+use serde_json::Value;
+use std::default::Default;
+
+/// A builder to create a [`RichInvite`] for use via [`Context::create_invite`].
+///
+/// This is a structured and cleaner way of creating an invite, as all
+/// parameters are optional.
+///
+/// # Examples
+///
+/// Create an invite with a max age of 3600 seconds and 10 max uses:
+///
+/// ```rust,ignore
+/// use serenity::Client;
+/// use std::env;
+///
+/// let mut client = Client::login_bot(&env::var("DISCORD_BOT_TOKEN").unwrap());
+///
+/// client.on_message(|context, message| {
+///     if message.content == "!invite" {
+///         let invite = context.create_invite(message.channel_id, |i| i
+///             .max_age(3600)
+///             .max_uses(10));
+///     }
+/// });
+/// ```
+///
+/// [`Context::create_invite`]: ../client/struct.Context.html#method.create_invite
+/// [`RichInvite`]: ../model/struct.Invite.html
+pub struct CreateInvite(pub ObjectBuilder);
+
+impl CreateInvite {
+    /// The duration that the invite will be valid for.
+    ///
+    /// Set to `0` for an invite which does not expire after an amount of time.
+    ///
+    /// Defaults to `86400`, or 24 hours.
+    pub fn max_age(self, max_age: u64) -> Self {
+        CreateInvite(self.0.insert("max_age", max_age))
+    }
+
+    /// The number of uses that the invite will be valid for.
+    ///
+    /// Set to `0` for an invite which does not expire after a number of uses.
+    ///
+    /// Defaults to `0`.
+    pub fn max_uses(self, max_uses: u64) -> Self {
+        CreateInvite(self.0.insert("max_uses", max_uses))
+    }
+
+    /// Whether an invite grants a temporary membership.
+    ///
+    /// Defaults to `false`.
+    pub fn temporary(self, temporary: bool) -> Self {
+        CreateInvite(self.0.insert("temporary", temporary))
+    }
+
+    /// Whether or not to try to reuse a similar invite.
+    ///
+    /// Defaults to `false`.
+    pub fn unique(self, unique: bool) -> Self {
+        CreateInvite(self.0.insert("unique", unique))
+    }
+}
+
+impl Default for CreateInvite {
+    fn default() -> CreateInvite {
+        CreateInvite(ObjectBuilder::new().insert("validate", Value::Null))
+    }
+}