//! # Input Block
//!
//! [slack api docs 🔗]
//!
//! A block that collects information from users -
//!
//! Read [slack's guide to using modals 🔗]
//! to learn how input blocks pass information to your app.
//!
//! [slack api docs 🔗]: https://api.slack.com/reference/block-kit/blocks#input
//! [slack's guide to using modals 🔗]: https://api.slack.com/surfaces/modals/using#gathering_input

use std::borrow::Cow;

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

use crate::{compose::text,
            convert,
            elems,
            elems::{select, BlockElement},
            val_helpr::ValidationResult};

/// # Input Block
///
/// [slack api docs 🔗]
///
/// A block that collects information from users -
///
/// Read [slack's guide to using modals 🔗]
/// to learn how input blocks pass information to your app.
///
/// [slack api docs 🔗]: https://api.slack.com/reference/block-kit/blocks#input
/// [slack's guide to using modals 🔗]: https://api.slack.com/surfaces/modals/using#gathering_input
#[derive(Clone, Debug, Deserialize, Hash, PartialEq, Serialize, Validate)]
pub struct Input<'a> {
  #[validate(custom = "validate::label")]
  label: text::Text,

  element: SupportedElement<'a>,

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

  #[serde(skip_serializing_if = "Option::is_none")]
  #[validate(custom = "validate::hint")]
  hint: Option<text::Text>,

  #[serde(skip_serializing_if = "Option::is_none")]
  dispatch_action: Option<bool>,

  #[serde(skip_serializing_if = "Option::is_none")]
  optional: Option<bool>,
}

impl<'a> Input<'a> {
  /// Build a new input block
  ///
  /// For example, see `blocks::input::build::InputBuilder`.
  pub fn builder() -> build::InputBuilderInit<'a> {
    build::InputBuilderInit::new()
  }
  /// Create an Input Block from a text Label and interactive element.
  ///
  /// # Arguments
  ///
  /// - `label` - A label that appears above an input element in the form of
  ///     a [text object 🔗] that must have type of `plain_text`.
  ///     Maximum length for the text in this field is 2000 characters.
  ///
  /// - `element` - An interactive `block_element` that will be used to gather
  ///     the input for this block.
  ///     For the kinds of Elements supported by
  ///     Input blocks, see the `SupportedElement` enum.
  ///     For info about Block Elements in general,
  ///     see the `elems` module.
  ///
  /// [text object 🔗]: https://api.slack.com/reference/messaging/composition-objects#text
  ///
  /// # Example
  /// ```
  /// use slack_blocks::elems::Select;
  /// use slack_blocks::blocks;
  ///
  /// let label = "On a scale from 1 - 5, how angsty are you?";
  /// let input = Select::from_placeholder_and_action_id("Pick a channel...", "ABC123")
  ///     .choose_from_public_channels();
  ///
  /// let block = blocks::Input::from_label_and_element(label, input);
  ///
  /// // < send to slack API >
  /// ```
  pub fn from_label_and_element(label: impl Into<text::Plain>,
                                element: impl Into<SupportedElement<'a>>)
                                -> Self {
    Input { label: label.into().into(),
            element: element.into(),
            block_id: None,
            hint: None,
            dispatch_action: None,
            optional: None }
  }

  /// Set a unique `block_id` to identify this instance of an Input Block.
  ///
  /// # Arguments
  ///
  /// - `block_id` - 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, one will be generated.
  ///     Maximum length for this field is 255 characters.
  ///     `block_id` should be unique for each message and each iteration of a message.
  ///     If a message is updated, use a new `block_id`.
  ///
  /// [identify the source of the action 🔗]: https://api.slack.com/interactivity/handling#payloads
  ///
  /// # Example
  /// ```
  /// use slack_blocks::elems::Select;
  /// use slack_blocks::blocks;
  ///
  /// let label = "On a scale from 1 - 5, how angsty are you?";
  /// let input = Select::from_placeholder_and_action_id("Pick a channel...", "ABC123")
  ///     .choose_from_public_channels();
  ///
  /// let block = blocks::Input
  ///     ::from_label_and_element(label, input)
  ///     .with_block_id("angst_rating_12345");
  ///
  /// // < send to slack API >
  /// ```
  pub fn with_block_id(mut self, block_id: impl Into<Cow<'a, str>>) -> Self {
    self.block_id = Some(block_id.into());
    self
  }

  /// Set the `hint` on this Input Block that appears below
  /// an input element in a lighter grey.
  ///
  /// # Arguments
  ///
  /// - `hint` - An optional hint that appears below an input element
  ///     in a lighter grey.
  ///     It must be a a [text object 🔗] with a `type` of `plain_text`.
  ///     Maximum length for the `text` in this field is 2000 characters.
  ///
  /// [text object 🔗]: https://api.slack.com/reference/messaging/composition-objects#text
  ///
  /// # Example
  /// ```
  /// use slack_blocks::elems::Select;
  /// use slack_blocks::blocks;
  ///
  /// # use std::error::Error;
  /// # pub fn main() -> Result<(), Box<dyn Error>> {
  /// let label = "On a scale from 1 - 5, how angsty are you?";
  /// let input = Select::from_placeholder_and_action_id("Pick a channel...", "ABC123")
  ///     .choose_from_public_channels();
  ///
  /// let block = blocks::Input
  ///     ::from_label_and_element(label, input)
  ///     .with_hint("PSST hey! Don't let them know how angsty you are!");
  ///
  /// // < send to slack API >
  /// # Ok(())
  /// # }
  /// ```
  pub fn with_hint(mut self, hint: impl Into<text::Plain>) -> Self {
    self.hint = Some(hint.into().into());
    self
  }

  /// Set whether or not this input is Optional.
  ///
  /// # Arguments
  /// - `optionality` - A boolean that indicates whether the input
  ///     element may be empty when a user submits the modal.
  ///     Defaults to false.
  ///
  /// # Example
  /// ```
  /// use slack_blocks::elems::Select;
  /// use slack_blocks::blocks;
  ///
  /// let label = "On a scale from 1 - 5, how angsty are you?";
  /// let input = Select::from_placeholder_and_action_id("Pick a channel...", "ABC123")
  ///     .choose_from_public_channels();
  ///
  /// let block = blocks::Input
  ///     ::from_label_and_element(label, input)
  ///     .with_hint("PSST hey! Don't even answer that!")
  ///     .with_optional(true);
  ///
  /// // < send to slack API >
  /// ```
  pub fn with_optional(mut self, optionality: bool) -> Self {
    self.optional = Some(optionality);
    self
  }

  /// Will allow the elements in this block to dispatch block_actions payloads. Defaults to false.
  pub fn dispatch_block_actions(mut self) -> Self {
    self.dispatch_action = Some(true);
    self
  }

  /// Validate that this Input block agrees with Slack's model requirements
  ///
  /// # Errors
  /// - If `from_label_and_element` was passed a Text object longer
  ///     than 2000 chars
  /// - If `with_hint` was called with a block id longer
  ///     than 2000 chars
  /// - If `with_block_id` was called with a block id longer
  ///     than 256 chars
  ///
  /// # Example
  /// ```
  /// use slack_blocks::elems::Select;
  /// use slack_blocks::blocks;
  ///
  /// let label = "On a scale from 1 - 5, how angsty are you?";
  /// let input = Select::from_placeholder_and_action_id("Pick a channel...", "ABC123")
  ///     .choose_from_public_channels();
  /// let long_string = std::iter::repeat(' ').take(2001).collect::<String>();
  ///
  /// let block = blocks::Input
  ///     ::from_label_and_element(label, input)
  ///     .with_block_id(long_string);
  ///
  /// assert_eq!(true, matches!(block.validate(), Err(_)));
  ///
  /// // < send to slack API >
  /// ```
  pub fn validate(&self) -> ValidationResult {
    Validate::validate(self)
  }
}

/// Input 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 {
    /// InputBuilder.element
    #[derive(Clone, Copy, Debug)]
    pub struct element;

    /// InputBuilder.label
    #[derive(Clone, Copy, Debug)]
    pub struct label;
  }

  /// Initial state for `InputBuilder`
  pub type InputBuilderInit<'a> =
    InputBuilder<'a,
                 RequiredMethodNotCalled<method::element>,
                 RequiredMethodNotCalled<method::label>>;

  /// Build an Input block
  ///
  /// Allows you to construct safely, with compile-time checks
  /// on required setter methods.
  ///
  /// # Required Methods
  /// `InputBuilder::build()` is only available if these methods have been called:
  ///  - `element`
  ///
  /// # Example
  /// ```
  /// use slack_blocks::{blocks::Input,
  ///                    compose::text::ToSlackPlaintext,
  ///                    elems::TextInput};
  ///
  /// let block =
  ///   Input::builder().label("foo".plaintext())
  ///                   .element(TextInput::builder().action_id("foo").build())
  ///                   .build();
  /// ```
  #[derive(Debug)]
  pub struct InputBuilder<'a, Element, Label> {
    label: Option<text::Text>,
    element: Option<SupportedElement<'a>>,
    hint: Option<text::Text>,
    block_id: Option<Cow<'a, str>>,
    optional: Option<bool>,
    dispatch_action: Option<bool>,
    state: PhantomData<(Element, Label)>,
  }

  impl<'a, E, L> InputBuilder<'a, E, L> {
    /// Create a new InputBuilder
    pub fn new() -> Self {
      Self { label: None,
             element: None,
             hint: None,
             block_id: None,
             optional: None,
             dispatch_action: None,
             state: PhantomData::<_> }
    }

    /// Set `element` (**Required**)
    ///
    /// An interactive `block_element` that will be used to gather
    /// the input for this block.
    ///
    /// For the kinds of Elements supported by
    /// Input blocks, see the `SupportedElement` enum.
    pub fn element<El>(self,
                       element: El)
                       -> InputBuilder<'a, Set<method::element>, L>
      where El: Into<SupportedElement<'a>>
    {
      InputBuilder { label: self.label,
                     element: Some(element.into()),
                     hint: self.hint,
                     block_id: self.block_id,
                     optional: self.optional,
                     dispatch_action: self.dispatch_action,
                     state: PhantomData::<_> }
    }

    /// Set `label` (**Required**)
    ///
    /// A label that appears above an input element in the form of
    /// a [text object 🔗] that must have type of `plain_text`.
    ///
    /// Maximum length for the text in this field is 2000 characters.
    ///
    /// [text object 🔗]: https://api.slack.com/reference/messaging/composition-objects#text
    pub fn label<T>(self, label: T) -> InputBuilder<'a, E, Set<method::label>>
      where T: Into<text::Plain>
    {
      InputBuilder { label: Some(label.into().into()),
                     element: self.element,
                     hint: self.hint,
                     block_id: self.block_id,
                     optional: self.optional,
                     dispatch_action: self.dispatch_action,
                     state: PhantomData::<_> }
    }

    /// 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> InputBuilder<'a, Set<method::element>, Set<method::label>> {
    /// All done building, now give me a darn actions block!
    ///
    /// > `no method name 'build' found for struct 'InputBuilder<...>'`?
    /// Make sure all required setter methods have been called. See docs for `InputBuilder`.
    ///
    /// ```compile_fail
    /// use slack_blocks::blocks::Input;
    ///
    /// let foo = Input::builder().build(); // Won't compile!
    /// ```
    ///
    /// ```
    /// use slack_blocks::{blocks::Input,
    ///                    compose::text::ToSlackPlaintext,
    ///                    elems::TextInput};
    ///
    /// let block =
    ///   Input::builder().label("foo".plaintext())
    ///                   .element(TextInput::builder().action_id("foo").build())
    ///                   .build();
    /// ```
    pub fn build(self) -> Input<'a> {
      Input { element: self.element.unwrap(),
              label: self.label.unwrap(),
              hint: self.hint,
              dispatch_action: self.dispatch_action,
              optional: self.optional,
              block_id: self.block_id }
    }
  }
}

/// The Block Elements supported in an Input Block.
///
/// Supports:
/// - Radio Buttons
/// - Text Input
/// - Checkboxes
/// - Date Picker
/// - All Select Menus
/// - All Multi-Select Menus
#[derive(Clone, Debug, Deserialize, Hash, PartialEq, Serialize)]
pub struct SupportedElement<'a>(BlockElement<'a>);

convert!(impl<'a> From<elems::Radio<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<elems::TextInput<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<elems::Checkboxes<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<elems::DatePicker<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));

convert!(impl<'a> From<select::Static<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::External<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::User<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::Conversation<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::PublicChannel<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));

convert!(impl<'a> From<select::multi::Static<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::multi::External<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::multi::User<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::multi::Conversation<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));
convert!(impl<'a> From<select::multi::PublicChannel<'a>> for SupportedElement<'a> => |r| SupportedElement(BlockElement::from(r)));

mod validate {
  use crate::{compose::text,
              val_helpr::{below_len, ValidatorResult}};

  pub(super) fn label(text: &text::Text) -> ValidatorResult {
    below_len("Input Label", 2000, text.as_ref())
  }

  pub(super) fn hint(text: &text::Text) -> ValidatorResult {
    below_len("Input Hint", 2000, text.as_ref())
  }
}