//! # Actions Block
//!
//! [slack api docs 🔗]
//!
//! A block that is used to hold interactive [elements 🔗]
//!
//! [slack api docs 🔗]: https://api.slack.com/reference/block-kit/blocks#actions
//! [elements 🔗]: https://api.slack.com/reference/messaging/block-elements

use std::{borrow::Cow, convert::TryFrom};

use serde::{Deserialize, Serialize};
use validator::Validate;

use crate::{convert,
            elems::{select,
                    BlockElement,
                    Button,
                    Checkboxes,
                    DatePicker,
                    Overflow,
                    Radio,
                    TextInput},
            val_helpr::*};

/// # Actions Block
///
/// [slack api docs 🔗]
///
/// A block that is used to hold interactive [elements 🔗]
///
/// [slack api docs 🔗]: https://api.slack.com/reference/block-kit/blocks#actions
/// [elements 🔗]: https://api.slack.com/reference/messaging/block-elements
#[derive(Clone,
           Debug,
           Default,
           Deserialize,
           Hash,
           PartialEq,
           Serialize,
           Validate)]
pub struct Actions<'a> {
  #[validate(length(max = 5))]
  elements: Vec<SupportedElement<'a>>,

  #[serde(skip_serializing_if = "Option::is_none")]
  #[validate(custom = "super::validate_block_id")]
  block_id: Option<Cow<'a, str>>,
}

impl<'a> Actions<'a> {
  /// Build a new Actions block.
  ///
  /// For example, see docs for ActionsBuilder.
  pub fn builder() -> build::ActionsBuilderInit<'a> {
    build::ActionsBuilderInit::new()
  }

  /// Validate that this Section block agrees with Slack's model requirements
  ///
  /// # Errors
  /// - If `with_block_id` was called with a block id longer
  ///     than 255 chars
  /// - If `from_elements` or `from_action_elements` was
  ///     called with more than 5 elements.
  ///
  /// # Example
  /// ```
  /// use slack_blocks::{blocks, compose, elems::Button};
  ///
  /// let long_string = std::iter::repeat(' ').take(256).collect::<String>();
  ///
  /// let block =
  ///   blocks::Actions::builder().element(Button::builder().text("Click me")
  ///                                                       .action_id("btn")
  ///                                                       .build())
  ///                             .block_id(long_string)
  ///                             .build();
  ///
  /// assert!(matches!(block.validate(), Err(_)));
  /// ```
  pub fn validate(&self) -> ValidationResult {
    Validate::validate(self)
  }
}

/// Actions block builder
pub mod build {
  use std::marker::PhantomData;

  use super::*;
  use crate::build::*;

  /// Compile-time markers for builder methods
  #[allow(non_camel_case_types)]
  pub mod method {
    /// ActionsBuilder.elements
    #[derive(Clone, Copy, Debug)]
    pub struct elements;
  }

  /// Initial state for `ActionsBuilder`
  pub type ActionsBuilderInit<'a> =
    ActionsBuilder<'a, RequiredMethodNotCalled<method::elements>>;

  /// Build an Actions block
  ///
  /// Allows you to construct safely, with compile-time checks
  /// on required setter methods.
  ///
  /// # Required Methods
  /// `ActionsBuilder::build()` is only available if these methods have been called:
  ///  - `element`
  ///
  /// # Example
  /// ```
  /// use slack_blocks::{blocks::Actions, elems::Button};
  ///
  /// let block = Actions::builder().element(Button::builder().text("Click me!")
  ///                                                         .action_id("clicked")
  ///                                                         .build())
  ///                               .build();
  /// ```
  #[derive(Debug)]
  pub struct ActionsBuilder<'a, Elements> {
    elements: Option<Vec<SupportedElement<'a>>>,
    block_id: Option<Cow<'a, str>>,
    state: PhantomData<Elements>,
  }

  impl<'a, E> ActionsBuilder<'a, E> {
    /// Create a new ActionsBuilder
    pub fn new() -> Self {
      Self { elements: None,
             block_id: None,
             state: PhantomData::<_> }
    }

    /// Add an `element` (**Required**, can be called many times)
    ///
    /// Add an interactive [element object 🔗]
    ///
    /// For a list of `BlockElement` types that are supported, see `slack_blocks::blocks::actions::SupportedElement`.
    ///
    /// There is a maximum of 5 elements in each action block.
    ///
    /// [element object 🔗]: https://api.slack.com/reference/messaging/block-elements
    pub fn element<El>(self,
                       element: El)
                       -> ActionsBuilder<'a, Set<method::elements>>
      where El: Into<SupportedElement<'a>>
    {
      let mut elements = self.elements.unwrap_or_default();
      elements.push(element.into());

      ActionsBuilder { block_id: self.block_id,
                       elements: Some(elements),
                       state: PhantomData::<_> }
    }

    /// Invoked by `blox!` when a child element is passed to `<actions_block>`.
    ///
    /// Alias of `ActionsBuilder.element`.
    #[cfg(feature = "blox")]
    #[cfg_attr(docsrs, doc(cfg(feature = "blox")))]
    pub fn child<El>(self,
                     element: El)
                     -> ActionsBuilder<'a, Set<method::elements>>
      where El: Into<SupportedElement<'a>>
    {
      self.element(element)
    }

    /// Set `block_id` (Optional)
    ///
    /// A string acting as a unique identifier for a block.
    ///
    /// You can use this `block_id` when you receive an interaction payload
    /// to [identify the source of the action 🔗].
    ///
    /// If not specified, a `block_id` will be generated.
    ///
    /// Maximum length for this field is 255 characters.
    ///
    /// [identify the source of the action 🔗]: https://api.slack.com/interactivity/handling#payloads
    pub fn block_id<S>(mut self, block_id: S) -> Self
      where S: Into<Cow<'a, str>>
    {
      self.block_id = Some(block_id.into());
      self
    }
  }

  impl<'a> ActionsBuilder<'a, Set<method::elements>> {
    /// All done building, now give me a darn actions block!
    ///
    /// > `no method name 'build' found for struct 'ActionsBuilder<...>'`?
    /// Make sure all required setter methods have been called. See docs for `ActionsBuilder`.
    ///
    /// ```compile_fail
    /// use slack_blocks::blocks::Actions;
    ///
    /// let foo = Actions::builder().build(); // Won't compile!
    /// ```
    ///
    /// ```
    /// use slack_blocks::{blocks::Actions, elems::Button};
    ///
    /// let block = Actions::builder().element(Button::builder().text("Click me!")
    ///                                                         .action_id("clicked")
    ///                                                         .build())
    ///                               .build();
    /// ```
    pub fn build(self) -> Actions<'a> {
      Actions { elements: self.elements.unwrap(),
                block_id: self.block_id }
    }
  }
}

/// The Block Elements supported in an Action Block.
///
/// Supports:
/// - Overflow
/// - RadioButtons
/// - Button
/// - TextInput
/// - Checkboxes
/// - DatePicker
/// - Select Menus:
///   - PublicChannel
///   - Conversation
///   - External
///   - Static
///   - User
#[derive(Clone, Debug, Deserialize, Hash, PartialEq, Serialize)]
pub struct SupportedElement<'a>(BlockElement<'a>);

impl<'a> TryFrom<BlockElement<'a>> for self::SupportedElement<'a> {
  type Error = ();
  fn try_from(el: BlockElement<'a>) -> Result<Self, Self::Error> {
    use BlockElement as El;

    match el {
      | El::SelectPublicChannel(_)
      | El::SelectConversation(_)
      | El::SelectExternal(_)
      | El::SelectStatic(_)
      | El::SelectUser(_)
      | El::Overflow(_)
      | El::RadioButtons(_)
      | El::Button(_)
      | El::TextInput(_)
      | El::Checkboxes(_)
      | El::DatePicker(_) => Ok(SupportedElement(el)),
      | _ => Err(()),
    }
  }
}

convert!(impl<'a> From<select::PublicChannel<'a>> for self::SupportedElement<'a> => |s| self::SupportedElement(BlockElement::from(s)));
convert!(impl<'a> From<select::Conversation<'a>>  for self::SupportedElement<'a> => |s| self::SupportedElement(BlockElement::from(s)));
convert!(impl<'a> From<select::User<'a>>          for self::SupportedElement<'a> => |s| self::SupportedElement(BlockElement::from(s)));
convert!(impl<'a> From<select::External<'a>>      for self::SupportedElement<'a> => |s| self::SupportedElement(BlockElement::from(s)));
convert!(impl<'a> From<select::Static<'a>>        for self::SupportedElement<'a> => |s| self::SupportedElement(BlockElement::from(s)));
convert!(impl<'a> From<Button<'a>>                for self::SupportedElement<'a> => |b| self::SupportedElement(BlockElement::from(b)));
convert!(impl<'a> From<Radio<'a>>                 for self::SupportedElement<'a> => |b| self::SupportedElement(BlockElement::from(b)));
convert!(impl<'a> From<TextInput<'a>>             for self::SupportedElement<'a> => |t| self::SupportedElement(BlockElement::from(t)));
convert!(impl<'a> From<DatePicker<'a>>            for self::SupportedElement<'a> => |t| self::SupportedElement(BlockElement::from(t)));
convert!(impl<'a> From<Checkboxes<'a>>            for self::SupportedElement<'a> => |t| self::SupportedElement(BlockElement::from(t)));
convert!(impl<'a> From<Overflow<'a>>              for self::SupportedElement<'a> => |t| self::SupportedElement(BlockElement::from(t)));