serenity-commands 0.8.0

#![cfg_attr(docsrs, feature(doc_auto_cfg))]
//! A library for creating/parsing [`serenity`] slash commands.
//!
//! # Examples
//!
//! ```rust
//! use serenity::all::{
//!     async_trait, Client, Context, CreateInteractionResponse, CreateInteractionResponseMessage,
//!     EventHandler, GatewayIntents, GuildId, Interaction,
//! };
//! use serenity_commands::{Command, Commands, SubCommand};
//!
//! #[derive(Debug, Commands)]
//! enum AllCommands {
//!     /// Ping the bot.
//!     Ping,
//!
//!     /// Echo a message.
//!     Echo {
//!         /// The message to echo.
//!         message: String,
//!     },
//!
//!     /// Perform math operations.
//!     Math(MathCommand),
//! }
//!
//! impl AllCommands {
//!     fn run(self) -> String {
//!         match self {
//!             Self::Ping => "Pong!".to_string(),
//!             Self::Echo { message } => message,
//!             Self::Math(math) => math.run().to_string(),
//!         }
//!     }
//! }
//!
//! #[derive(Debug, Command)]
//! enum MathCommand {
//!     /// Add two numbers.
//!     Add(BinaryOperation),
//!
//!     /// Subtract two numbers.
//!     Subtract(BinaryOperation),
//!
//!     /// Multiply two numbers.
//!     Multiply(BinaryOperation),
//!
//!     /// Divide two numbers.
//!     Divide(BinaryOperation),
//!
//!     /// Negate a number.
//!     Negate {
//!         /// The number to negate.
//!         a: f64,
//!     },
//! }
//!
//! impl MathCommand {
//!     fn run(self) -> f64 {
//!         match self {
//!             Self::Add(BinaryOperation { a, b }) => a + b,
//!             Self::Subtract(BinaryOperation { a, b }) => a - b,
//!             Self::Multiply(BinaryOperation { a, b }) => a * b,
//!             Self::Divide(BinaryOperation { a, b }) => a / b,
//!             Self::Negate { a } => -a,
//!         }
//!     }
//! }
//!
//! #[derive(Debug, SubCommand)]
//! struct BinaryOperation {
//!     /// The first number.
//!     a: f64,
//!
//!     /// The second number.
//!     b: f64,
//! }
//!
//! struct Handler {
//!     guild_id: GuildId,
//! }
//!
//! #[async_trait]
//! impl EventHandler for Handler {
//!     async fn ready(&self, ctx: Context, _: serenity::all::Ready) {
//!         self.guild_id
//!             .set_commands(&ctx, AllCommands::create_commands())
//!             .await
//!             .unwrap();
//!     }
//!
//!     async fn interaction_create(&self, ctx: Context, interaction: Interaction) {
//!         if let Interaction::Command(command) = interaction {
//!             let command_data = AllCommands::from_command_data(&command.data).unwrap();
//!             command
//!                 .create_response(
//!                     ctx,
//!                     CreateInteractionResponse::Message(
//!                         CreateInteractionResponseMessage::new().content(command_data.run()),
//!                     ),
//!                 )
//!                 .await
//!                 .unwrap();
//!         }
//!     }
//! }
//! ```

use std::fmt::Debug;

use serenity::all::{
    AttachmentId, ChannelId, CommandData, CommandDataOption, CommandDataOptionValue,
    CommandOptionType, CreateCommand, CreateCommandOption, GenericId, RoleId, UserId,
};
/// Derives [`BasicOption`].
///
/// `option_type` can be `"string"`, `"integer"`, or `"number"`.
///
/// # Examples
///
/// ```rust
/// use serenity_commands::BasicOption;
///
/// #[derive(Debug, BasicOption)]
/// #[choice(option_type = "integer")]
/// enum Medal {
///     #[choice(name = "Gold", value = 1)]
///     Gold,
///
///     #[choice(name = "Silver", value = 2)]
///     Silver,
///
///     #[choice(name = "Bronze", value = 3)]
///     Bronze,
/// }
/// ```
pub use serenity_commands_macros::BasicOption;
/// Derives [`Command`].
///
/// # Examples
///
/// ## Struct
///
/// Each field must implement [`BasicOption`].
///
/// ```rust
/// use serenity_commands::Command;
///
/// #[derive(Command)]
/// struct Add {
///     /// First number.
///     a: f64,
///
///     /// Second number.
///     b: f64,
/// }
/// ```
///
/// ## Enum
///
/// Each field of named variants must implement [`BasicOption`].
///
/// The inner type of newtype variants must implement [`SubCommandGroup`] (or,
/// by extension, [`SubCommand`], as [`SubCommand`] is a sub-trait of
/// [`SubCommandGroup`]).
///
/// ```rust
/// use serenity_commands::{Command, SubCommandGroup};
///
/// #[derive(SubCommandGroup)]
/// enum ModUtilities {
///     // ...
/// }
///
/// #[derive(Command)]
/// enum Utilities {
///     /// Ping the bot.
///     Ping,
///
///     /// Add two numbers.
///     Add {
///         /// First number.
///         a: f64,
///
///         /// Second number.
///         b: f64,
///     },
///
///     /// Moderation utilities.
///     Mod(ModUtilities),
/// }
pub use serenity_commands_macros::Command;
/// Derives [`Commands`].
///
/// # Examples
///
/// Each field of named variants must implement [`Command`].
///
/// The inner type of newtype variants must implement [`Command`].
///
/// ```rust
/// use serenity_commands::{Command, Commands};
///
/// #[derive(Command)]
/// enum MathCommand {
///     // ...
/// }
///
/// #[derive(Commands)]
/// enum AllCommands {
///     /// Ping the bot.
///     Ping,
///
///     /// Echo a message.
///     Echo {
///         /// The message to echo.
///         message: String,
///     },
///
///     /// Do math operations.
///     Math(MathCommand),
/// }
pub use serenity_commands_macros::Commands;
/// Derives [`SubCommand`].
///
/// Each field must implement [`BasicOption`].
///
/// # Examples
///
/// ```rust
/// use serenity_commands::SubCommand;
///
/// #[derive(SubCommand)]
/// struct Add {
///     /// First number.
///     a: f64,
///
///     /// Second number.
///     b: f64,
/// }
/// ```
pub use serenity_commands_macros::SubCommand;
/// Derives [`SubCommandGroup`].
///
/// Each field of named variants must implement [`BasicOption`].
///
/// The inner type of newtype variants must implement [`SubCommand`].
///
/// # Examples
///
/// ```rust
/// use serenity_commands::{SubCommand, SubCommandGroup};
///
/// #[derive(SubCommand)]
/// struct AddSubCommand {
///     /// First number.
///     a: f64,
///
///     /// Second number.
///     b: f64,
/// }
///
/// #[derive(SubCommandGroup)]
/// enum Math {
///     /// Add two numbers.
///     Add(AddSubCommand),
///
///     /// Negate a number.
///     Negate {
///         /// The number to negate.
///         a: f64,
///     },
/// }
pub use serenity_commands_macros::SubCommandGroup;
use thiserror::Error;

/// A type alias for [`std::result::Result`]s which use [`Error`] as the error
/// type.
///
/// [`Error`]: enum@Error
pub type Result<T> = std::result::Result<T, Error>;

/// An error which can occur when extracting data from a command interaction.
#[derive(Debug, Error)]
pub enum Error {
    /// An unknown command was provided.
    #[error("unknown command: {0}")]
    UnknownCommand(String),

    /// An incorrect command option type was provided.
    #[error("incorrect command option type: got {got:?}, expected {expected:?}")]
    IncorrectCommandOptionType {
        /// The type of command option that was provided.
        got: CommandOptionType,

        /// The type of command option that was expected.
        expected: CommandOptionType,
    },

    /// An incorrect number of command options were provided.
    #[error("incorrect command option count: got {got}, expected {expected}")]
    IncorrectCommandOptionCount {
        /// The number of command options that were provided.
        got: usize,

        /// The number of command options that were expected.
        expected: usize,
    },

    /// An unknown command option was provided.
    #[error("unknown command option: {0}")]
    UnknownCommandOption(String),

    /// An unknown autocomplete option was provided.
    #[error("unknown autocomplete option: {0}")]
    UnknownAutocompleteOption(String),

    /// A required command option was not provided.
    #[error("required command option not provided")]
    MissingRequiredCommandOption,

    /// An unexpected autocomplete option was provided.
    #[error("unexpected autocomplete option")]
    UnexpectedAutocompleteOption,

    /// An autocomplete option was not provided.
    #[error("autocomplete option not provided")]
    MissingAutocompleteOption,

    /// An unknown choice was provided.
    #[error("unknown choice: {0}")]
    UnknownChoice(String),

    /// An error occurred within a custom implementation.
    #[error(transparent)]
    Custom(#[from] Box<dyn std::error::Error + Send + Sync>),
}

/// A utility for creating commands and extracting their data from application
/// commands.
pub trait Commands: Sized {
    /// List of top-level commands.
    fn create_commands() -> Vec<CreateCommand>;

    /// Extract data from [`CommandData`].
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_command_data(data: &CommandData) -> Result<Self>;
}

/// A top-level command for use with [`Commands`].
pub trait Command: Sized {
    /// Create the command.
    fn create_command(name: impl Into<String>, description: impl Into<String>) -> CreateCommand;

    /// Extract data from a list of [`CommandDataOption`]s.
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_options(options: &[CommandDataOption]) -> Result<Self>;
}

/// A sub-command group which can be nested inside of a [`Command`] and contains
/// [`SubCommand`]s.
///
/// This is a super-trait of [`SubCommand`], as a [`SubCommand`] can be used
/// anywhere a [`SubCommandGroup`] can.
pub trait SubCommandGroup: Sized {
    /// Create the command option.
    fn create_option(
        name: impl Into<String>,
        description: impl Into<String>,
    ) -> CreateCommandOption;

    /// Extract data from a [`CommandDataOptionValue`].
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_value(value: &CommandDataOptionValue) -> Result<Self>;
}

/// A sub-command which can be nested inside of a [`Command`] or
/// [`SubCommandGroup`].
///
/// This is a sub-trait of [`SubCommandGroup`], as a [`SubCommand`] can be used
/// anywhere a [`SubCommandGroup`] can.
pub trait SubCommand: SubCommandGroup {}

/// A basic option which can be nested inside of [`Command`]s or
/// [`SubCommand`]s.
///
/// This trait is implemented already for most primitive types.
pub trait BasicOption: Sized {
    /// The type of this option when it may not be fully parseable.
    ///
    /// This will usually occur when this field is part of an autocomplete
    /// interaction. This will usually be [`String`] or an integer type, and is
    /// present so an autocomplete interaction can still be handled if a field
    /// is not yet parseable to the type of the option.
    ///
    /// As this should be a type that can reliably be parsed from a
    /// [`CommandDataOptionValue`], it's [`BasicOption::from_value`]
    /// implementation should ideally be infallible.
    type Partial: BasicOption;

    /// Create the command option.
    fn create_option(
        name: impl Into<String>,
        description: impl Into<String>,
    ) -> CreateCommandOption;

    /// Extract data from a [`CommandDataOptionValue`].
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self>;
}

impl<T: BasicOption> BasicOption for Option<T> {
    /// Delegates to `T`'s [`BasicOption::Partial`] type.
    type Partial = T::Partial;

    /// Delegates to `T`'s [`BasicOption::create_option`] implementation, but
    /// sets [`CreateCommandOption::required`] to `false` afterwards.
    fn create_option(
        name: impl Into<String>,
        description: impl Into<String>,
    ) -> CreateCommandOption {
        T::create_option(name, description).required(false)
    }

    /// Only delegates to `T`'s [`BasicOption::from_value`] implementation if
    /// `value` is [`Some`].
    fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
        value.map(|option| T::from_value(Some(option))).transpose()
    }
}

macro_rules! impl_command_option {
    ($($Variant:ident($($Ty:ty),* $(,)?)),* $(,)?) => {
        $($(
            impl BasicOption for $Ty {
                type Partial = Self;

                fn create_option(name: impl Into<String>, description: impl Into<String>) -> CreateCommandOption {
                    CreateCommandOption::new(CommandOptionType::$Variant, name, description)
                        .required(true)
                }

                fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
                    let value = value.ok_or(Error::MissingRequiredCommandOption)?;

                    match value {
                        CommandDataOptionValue::$Variant(v) => Ok(v.clone() as _),
                        _ => Err(Error::IncorrectCommandOptionType {
                            got: value.kind(),
                            expected: CommandOptionType::$Variant,
                        }),
                    }
                }
            }
        )*)*
    };
}

impl_command_option! {
    String(String),
    Boolean(bool),
    User(UserId),
    Channel(ChannelId),
    Role(RoleId),
    Mentionable(GenericId),
    Attachment(AttachmentId),
}

macro_rules! impl_number_command_option {
    ($($Ty:ty),* $(,)?) => {
        $(
            impl BasicOption for $Ty {
                type Partial = Self;

                fn create_option(name: impl Into<String>, description: impl Into<String>) -> CreateCommandOption {
                    CreateCommandOption::new(CommandOptionType::Number, name, description)
                        .required(true)
                }

                fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
                    let value = value.ok_or(Error::MissingRequiredCommandOption)?;

                    #[allow(clippy::cast_possible_truncation)]
                    match value {
                        CommandDataOptionValue::Number(v) => Ok(*v as _),
                        _ => Err(Error::IncorrectCommandOptionType {
                            got: value.kind(),
                            expected: CommandOptionType::Number,
                        }),
                    }
                }
            }

        )*
    };
}

impl_number_command_option!(f32, f64);

macro_rules! impl_integer_command_option {
    ($($Ty:ty),* $(,)?) => {
        $(
            impl BasicOption for $Ty {
                type Partial = i64;

                fn create_option(name: impl Into<String>, description: impl Into<String>) -> CreateCommandOption {
                    CreateCommandOption::new(CommandOptionType::Integer, name, description)
                        .required(true)
                }

                fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
                    let value = value.ok_or(Error::MissingRequiredCommandOption)?;

                    #[allow(
                        clippy::cast_possible_truncation,
                        clippy::cast_sign_loss,
                        clippy::cast_lossless
                    )]
                    match value {
                        CommandDataOptionValue::Integer(v) => Ok(*v as _),
                        _ => Err(Error::IncorrectCommandOptionType {
                            got: value.kind(),
                            expected: CommandOptionType::Integer,
                        }),
                    }
                }
            }
        )*
    };
}

impl_integer_command_option!(u8, u16, u32, u64, u128, usize, i8, i16, i32, i64, i128, isize);

impl BasicOption for char {
    type Partial = String;

    fn create_option(
        name: impl Into<String>,
        description: impl Into<String>,
    ) -> CreateCommandOption {
        CreateCommandOption::new(CommandOptionType::String, name, description)
            .min_length(1)
            .max_length(1)
            .required(true)
    }

    fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
        let s = String::from_value(value)?;

        let mut chars = s.chars();

        match (chars.next(), chars.next()) {
            (Some(c), None) => Ok(c),
            _ => Err(Error::Custom("expected single character".into())),
        }
    }
}

/// A field which may be partially parsed.
///
/// This is used for fields which may not be fully parseable, such as when
/// handling autocomplete interactions.
pub enum PartialOption<T: BasicOption> {
    /// A successfully parsed value.
    Value(T),

    /// A partially parsed value, along with the error that occurred while
    /// attempting to parse it.
    Partial(T::Partial, Error),

    /// A value that has not been entered yet.
    None,
}

impl<T: BasicOption> PartialOption<T> {
    /// Extract the parsed value from this field.
    pub fn into_value(self) -> Option<T> {
        match self {
            Self::Value(value) => Some(value),
            Self::Partial(_, _) | Self::None => None,
        }
    }

    /// Extract the partially parsed value and the error that occurred while
    /// attempting to parse it from this field.
    pub fn into_partial(self) -> Option<(T::Partial, Error)> {
        match self {
            Self::Partial(value, error) => Some((value, error)),
            Self::Value(_) | Self::None => None,
        }
    }

    /// Get a reference to the parsed value from this field.
    pub const fn as_value(&self) -> Option<&T> {
        match self {
            Self::Value(value) => Some(value),
            Self::Partial(_, _) | Self::None => None,
        }
    }

    /// Get a reference to the partially parsed value and the error that
    /// occurred while attempting to parse it from this field.
    pub const fn as_partial(&self) -> Option<(&T::Partial, &Error)> {
        match self {
            Self::Partial(value, error) => Some((value, error)),
            Self::Value(_) | Self::None => None,
        }
    }

    /// Check if this field is a parsed value.
    pub const fn is_value(&self) -> bool {
        matches!(self, Self::Value(_))
    }

    /// Check if this field is a partially parsed value.
    pub const fn is_partial(&self) -> bool {
        matches!(self, Self::Partial(_, _))
    }

    /// Check if this field is empty.
    pub const fn is_none(&self) -> bool {
        matches!(self, Self::None)
    }
}

impl<T: BasicOption<Partial = T>> PartialOption<T> {
    /// Convert this field into the parsed value, if it is present.
    pub fn into_inner(self) -> Option<T> {
        match self {
            Self::Value(value) | Self::Partial(value, _) => Some(value),
            Self::None => None,
        }
    }

    /// Get a reference to the parsed value, if it is present.
    pub const fn as_inner(&self) -> Option<&T> {
        match self {
            Self::Value(value) | Self::Partial(value, _) => Some(value),
            Self::None => None,
        }
    }
}

impl<T: BasicOption> PartialOption<Option<T>> {
    /// Flatten this field into a [`PartialOption<T>`].
    pub fn flatten(self) -> PartialOption<T> {
        match self {
            Self::Value(Some(value)) => PartialOption::Value(value),
            Self::Partial(value, error) => PartialOption::Partial(value, error),
            Self::Value(None) | Self::None => PartialOption::None,
        }
    }
}

impl<T: BasicOption> BasicOption for PartialOption<T> {
    type Partial = <T::Partial as BasicOption>::Partial;

    fn create_option(
        name: impl Into<String>,
        description: impl Into<String>,
    ) -> CreateCommandOption {
        T::create_option(name, description)
    }

    fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
        match Option::<T>::from_value(value) {
            Ok(Some(value)) => Ok(Self::Value(value)),
            Ok(None) => Ok(Self::None),
            Err(error) => Ok(Self::Partial(T::Partial::from_value(value)?, error)),
        }
    }
}

impl<T: BasicOption + Debug> Debug for PartialOption<T>
where
    T::Partial: Debug,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Value(value) => f.debug_tuple("Value").field(value).finish(),
            Self::Partial(value, error) => {
                f.debug_tuple("Partial").field(value).field(error).finish()
            }
            Self::None => f.debug_tuple("None").finish(),
        }
    }
}

/// A trait for identifying types that support autocomplete interactions.
pub trait SupportsAutocomplete {
    /// The type of the autocomplete interaction.
    type Autocomplete;
}

/// A helper type alias for extracting the autocomplete type from a type that
/// supports autocomplete.
pub type Autocomplete<T> = <T as SupportsAutocomplete>::Autocomplete;

/// A utility for extracting data from an autocomplete interaction.
pub trait AutocompleteCommands: Sized {
    /// Extract data from [`CommandData`].
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_command_data(data: &CommandData) -> Result<Self>;
}

/// A top-level command for use with [`AutocompleteCommands`].
pub trait AutocompleteCommand: Sized {
    /// Extract data from a list of [`CommandDataOption`]s.
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_options(options: &[CommandDataOption]) -> Result<Self>;
}

/// A sub-command group which can be nested inside of an [`AutocompleteCommand`]
/// and contains [`AutocompleteSubCommandOrGroup`]s.
pub trait AutocompleteSubCommandOrGroup: Sized {
    /// Extract data from a [`CommandDataOptionValue`].
    ///
    /// # Errors
    ///
    /// Returns an error if the implementation fails.
    fn from_value(value: &CommandDataOptionValue) -> Result<Self>;
}

#[cfg(feature = "time")]
mod time {
    use serenity::all::{CommandDataOptionValue, CreateCommandOption};
    use time::OffsetDateTime;

    use crate::{BasicOption, Error, Result};

    impl BasicOption for OffsetDateTime {
        type Partial = i64;

        fn create_option(
            name: impl Into<String>,
            description: impl Into<String>,
        ) -> CreateCommandOption {
            i64::create_option(name, description)
        }

        fn from_value(value: Option<&CommandDataOptionValue>) -> Result<Self> {
            let value = i64::from_value(value)?;

            Self::from_unix_timestamp(value).map_err(|e| Error::Custom(Box::new(e)))
        }
    }
}