feat: multi select channels (#140)

* feat: public channels multi-select

* fix multi-select validation comments

* fix tests

src/block_elements/select/multi/conversation.rs

@@ -70,15 +70,16 @@ impl<'a> Conversation<'a> {
   /// ```
   /// use slack_blocks::block_elements::select;
   ///
-  /// let select = select::Conversation::from_placeholder_and_action_id(
-  ///         r#"Hey I really would appreciate it if you chose
+  /// let select = select::multi::Conversation::builder().placeholder(
+  ///                           r#"Hey I really would appreciate it if you chose
   ///         a channel relatively soon, so that we can figure out
   ///         where we need to send this poll, ok? it's kind of
   ///         important that you specify where this poll should be
   ///         sent, in case we haven't made that super clear.
   ///         If you understand, could you pick a channel, already??"#,
-  ///         "ABC123"
-  ///     );
+  /// )
+  ///              .action_id("ABC123")
+  ///              .build();
   ///
   /// assert!(matches!(select.validate(), Err(_)))
   /// ```

src/block_elements/select/multi/external.rs

@@ -76,15 +76,16 @@ impl<'a> External<'a> {
   /// ```
   /// use slack_blocks::block_elements::select;
   ///
-  /// let select = select::External::from_placeholder_and_action_id(
-  ///         r#"Hey I really would appreciate it if you chose
+  /// let placeholder = r#"Hey I really would appreciate it if you chose
   ///         a channel relatively soon, so that we can figure out
   ///         where we need to send this poll, ok? it's kind of
   ///         important that you specify where this poll should be
   ///         sent, in case we haven't made that super clear.
-  ///         If you understand, could you pick a channel, already??"#,
-  ///         "ABC123"
-  ///     );
+  ///         If you understand, could you pick a channel, already??"#;
+  ///
+  /// let select = select::multi::External::builder().placeholder(placeholder)
+  ///                                                .action_id("ABC123")
+  ///                                                .build();
   ///
   /// assert!(matches!(select.validate(), Err(_)))
   /// ```

src/block_elements/select/multi/mod.rs

@@ -11,19 +11,18 @@
 //! [select menus 🔗]: https://api.slack.com/reference/block-kit/block-elements#select
 //! [guide to enabling interactivity 🔗]: https://api.slack.com/interactivity/handling
 
-// mod builder;
 pub mod conversation;
 pub mod external;
-// pub mod public_channel;
+pub mod public_channel;
 pub mod static_;
 pub mod user;
 
 #[doc(inline)]
 pub use conversation::Conversation;
 #[doc(inline)]
 pub use external::External;
-// #[doc(inline)]
-// pub use public_channel::PublicChannel;
+#[doc(inline)]
+pub use public_channel::PublicChannel;
 #[doc(inline)]
 pub use static_::Static;
 #[doc(inline)]

src/block_elements/select/multi/public_channel.rs

@@ -0,0 +1,75 @@
+use std::borrow::Cow;
+
+use serde::{Deserialize, Serialize};
+use validator::Validate;
+
+use crate::{compose::Confirm,
+            elems::select::public_channel::build,
+            text,
+            val_helpr::ValidationResult};
+
+/// # Public Channel Select
+/// [slack api docs 🔗](https://api.slack.com/reference/block-kit/block-elements#channel_select)
+///
+/// This select menu will populate its options with a list of
+/// public channels visible to the current user in the active workspace.
+#[derive(Clone, Debug, Deserialize, Hash, PartialEq, Serialize, Validate)]
+pub struct PublicChannel<'a> {
+  #[validate(custom = "crate::elems::select::validate::placeholder")]
+  pub(in crate::elems::select) placeholder: text::Text,
+
+  #[validate(length(max = 255))]
+  pub(in crate::elems::select) action_id: Cow<'a, str>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  #[validate]
+  pub(in crate::elems::select) confirm: Option<Confirm>,
+
+  #[serde(skip_serializing_if = "Option::is_none")]
+  pub(in crate::elems::select) initial_channels: Option<Cow<'a, [String]>>,
+
+  #[validate(range(min = 1))]
+  pub(in crate::elems::select) max_selected_items: Option<u32>,
+}
+
+impl<'a> PublicChannel<'a> {
+  /// Build a new conversation multi-select element
+  ///
+  /// # Examples
+  /// ```
+  /// // TODO(#130)
+  /// ```
+  pub fn builder() -> build::MultiPublicChannelBuilderInit<'a> {
+    build::MultiPublicChannelBuilderInit::new()
+  }
+
+  /// Validate that this Public Channel Select element
+  /// agrees with Slack's model requirements
+  ///
+  /// # Errors
+  /// - If `from_placeholder_and_action_id` was called with
+  ///     `placeholder` longer than 150 chars
+  /// - If `from_placeholder_and_action_id` was called with
+  ///     `action_id` longer than 255 chars
+  ///
+  /// # Example
+  /// ```
+  /// use slack_blocks::block_elements::select;
+  ///
+  /// let select = select::multi::PublicChannel::builder().placeholder(
+  ///                           r#"Hey I really would appreciate it if you chose
+  ///         a channel relatively soon, so that we can figure out
+  ///         where we need to send this poll, ok? it's kind of
+  ///         important that you specify where this poll should be
+  ///         sent, in case we haven't made that super clear.
+  ///         If you understand, could you pick a channel, already??"#,
+  /// )
+  ///              .action_id("ABC123")
+  ///              .build();
+  ///
+  /// assert!(matches!(select.validate(), Err(_)))
+  /// ```
+  pub fn validate(&self) -> ValidationResult {
+    Validate::validate(&self)
+  }
+}

src/block_elements/select/multi/static_.rs

@@ -81,10 +81,10 @@ impl<'a> Static<'a> {
   /// sent, in case we haven't made that super clear.
   /// If you understand, could you pick a channel, already??"#;
   ///
-  /// let select = select::Static::builder().placeholder(placeholder)
-  ///                                       .action_id("abc123")
-  ///                                       .options(std::iter::empty())
-  ///                                       .build();
+  /// let select = select::multi::Static::builder().placeholder(placeholder)
+  ///                                              .action_id("abc123")
+  ///                                              .options(std::iter::empty())
+  ///                                              .build();
   ///
   /// assert!(matches!(select.validate(), Err(_)))
   /// ```

src/block_elements/select/multi/user.rs

@@ -63,15 +63,16 @@ impl<'a> User<'a> {
   /// ```
   /// use slack_blocks::elems::select;
   ///
-  /// let select = select::User::from_placeholder_and_action_id(
-  ///         r#"Hey I really would appreciate it if you chose
+  /// let select = select::multi::User::builder().placeholder(
+  ///                           r#"Hey I really would appreciate it if you chose
   ///         a channel relatively soon, so that we can figure out
   ///         where we need to send this poll, ok? it's kind of
   ///         important that you specify where this poll should be
   ///         sent, in case we haven't made that super clear.
   ///         If you understand, could you pick a channel, already??"#,
-  ///         "ABC123"
-  ///     );
+  /// )
+  ///              .action_id("ABC123")
+  ///              .build();
   ///
   /// assert!(matches!(select.validate(), Err(_)))
   /// ```