// Copyright 2017-2019 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Dispatch system. Contains a macro for defining runtime modules and
//! generating values representing lazy module function calls.

pub use crate::rstd::prelude::{Vec, Clone, Eq, PartialEq};
#[cfg(feature = "std")]
pub use std::fmt;
pub use crate::rstd::result;
pub use crate::codec::{Codec, Decode, Encode, Input, Output, HasCompact, EncodeAsRef};
pub use srml_metadata::{FunctionMetadata, DecodeDifferent, DecodeDifferentArray, FunctionArgumentMetadata};

/// A type that cannot be instantiated.
pub enum Never {}

/// Result of a module function call; either nothing (functions are only called for "side effects")
/// or an error message.
pub type Result = result::Result<(), &'static str>;

/// A lazy call (module function and argument values) that can be executed via its `dispatch`
/// method.
pub trait Dispatchable {
	/// Every function call from your runtime has an origin, which specifies where the extrinsic was
	/// generated from. In the case of a signed extrinsic (transaction), the origin contains an
	/// identifier for the caller. The origin can be empty in the case of an inherent extrinsic.
	type Origin;
	type Trait;
	fn dispatch(self, origin: Self::Origin) -> Result;
}

/// Serializable version of Dispatchable.
/// This value can be used as a "function" in an extrinsic.
pub trait Callable {
	type Call: Dispatchable + Codec + Clone + PartialEq + Eq;
}

// dirty hack to work around serde_derive issue
// https://github.com/rust-lang/rust/issues/51331
pub type CallableCallFor<A> = <A as Callable>::Call;

#[cfg(feature = "std")]
pub trait Parameter: Codec + Clone + Eq + fmt::Debug {}

#[cfg(feature = "std")]
impl<T> Parameter for T where T: Codec + Clone + Eq + fmt::Debug {}

#[cfg(not(feature = "std"))]
pub trait Parameter: Codec + Clone + Eq {}

#[cfg(not(feature = "std"))]
impl<T> Parameter for T where T: Codec + Clone + Eq {}

/// Declares a `Module` struct and a `Call` enum, which implements the dispatch logic.
///
/// ## Declaration
///
/// ```
/// # #[macro_use]
/// # extern crate srml_support;
/// # use srml_support::dispatch::Result;
/// # use srml_system::{self as system, Trait, ensure_signed};
/// decl_module! {
/// 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
///
/// 		// Private functions are dispatchable, but not available to other
/// 		// SRML modules.
/// 		fn my_function(origin, var: u64) -> Result {
///				// Your implementation
///				Ok(())
/// 		}
///
///			// Public functions are both dispatchable and available to other
/// 		// SRML modules.
///			pub fn my_public_function(origin) -> Result {
/// 			// Your implementation
///				Ok(())
/// 		}
///		}
/// }
/// # fn main() {}
/// ```
///
/// The declaration is set with the header where:
///
/// * `Module`: The struct generated by the macro, with type `Trait`.
/// * `Call`: The enum generated for every module, which implements [`Callable`](./dispatch/trait.Callable.html).
/// * `origin`: Alias of `T::Origin`, declared by the [`impl_outer_origin!`](./macro.impl_outer_origin.html) macro.
/// * `Result`: The expected return type from module functions.
///
/// ### Shorthand Example
///
/// The macro automatically expands a shorthand function declaration to return the `Result` type.
/// These functions are the same:
///
/// ```
/// # #[macro_use]
/// # extern crate srml_support;
/// # use srml_support::dispatch::Result;
/// # use srml_system::{self as system, Trait, ensure_signed};
/// decl_module! {
/// 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
///
/// 		fn my_long_function(origin) -> Result {
///				// Your implementation
/// 			Ok(())
/// 		}
///
/// 		fn my_short_function(origin) {
///				// Your implementation
/// 		}
///		}
/// }
/// # fn main() {}
/// ```
///
/// ### Privileged Function Example
///
/// If the `origin` param is omitted, the macro adds it as the first parameter and adds `ensure_root(origin)`
/// as the first line of the function. These functions are the same:
///
/// ```
/// # #[macro_use]
/// # extern crate srml_support;
/// # use srml_support::dispatch::Result;
/// # use srml_system::{self as system, Trait, ensure_signed, ensure_root};
/// decl_module! {
/// 	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
///
///			fn my_privileged_function() -> Result {
///				// Your implementation
/// 			Ok(())
/// 		}
///
///			fn my_function(origin) -> Result {
/// 			ensure_root(origin);
///				// Your implementation
/// 			Ok(())
/// 		}
///		}
/// }
/// # fn main() {}
/// ```
///
/// ## Multiple Module Instances Example
///
/// A Substrate module can be built such that multiple instances of the same module can be used within a single
/// runtime. For example, the [Balances module](../srml_balances/index.html) can be added multiple times to your
/// runtime in order to support multiple, independent currencies for your blockchain. Here is an example of how
/// you would declare such a module using the `decl_module!` macro:
///
/// ```
/// # #[macro_use]
/// # extern crate srml_support;
/// # use srml_support::dispatch::Result;
/// # use srml_system::{self as system, ensure_signed};
/// # pub struct DefaultInstance;
/// # pub trait Instance {}
/// # impl Instance for DefaultInstance {}
/// pub trait Trait<I: Instance=DefaultInstance>: system::Trait {}
///
/// decl_module! {
/// 	pub struct Module<T: Trait<I>, I: Instance = DefaultInstance> for enum Call where origin: T::Origin {
/// 		// Your implementation
/// 	}
/// }
/// # fn main() {}
/// ```
///
/// ## Reserved Functions
///
/// The following are reserved function signatures:
///
/// * `deposit_event`: Helper function for depositing an [event](https://docs.substrate.dev/docs/event-enum).
/// The default behavior is to call `deposit_event` from the [System module](../srml_system/index.html).
/// However, you can write your own implementation for events in your runtime. To use the default behavior,
/// add `fn deposit_event<T>() = default;` to your `Module`.
///
/// The following reserved functions also take the block number (with type `T::BlockNumber`) as an optional input:
///
/// * `on_initialize`: Executes at the beginning of a block. Using this function will
/// implement the [`OnInitialize`](../sr_primitives/traits/trait.OnInitialize.html) trait.
/// * `on_finalize`: Executes at the end of a block. Using this function will
/// implement the [`OnFinalize`](../sr_primitives/traits/trait.OnFinalize.html) trait.
/// * `offchain_worker`: Executes at the beginning of a block and produces extrinsics for a future block
/// upon completion. Using this function will implement the
/// [`OffchainWorker`](../sr_primitives/traits/trait.OffchainWorker.html) trait.
#[macro_export]
macro_rules! decl_module {
	// Macro transformations (to convert invocations with incomplete parameters to the canonical
	// form)
	(
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty {
			$($t:tt)*
		}
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = system
			{}
			{}
			{}
			{}
			[]
			$($t)*
		);
	};
	(
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident {
			$($t:tt)*
		}
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{}
			{}
			{}
			{}
			[]
			$($t)*
		);
	};

	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{}
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn deposit_event $(<$dpeg:ident $(, $dpeg_instance:ident)?>)* () = default;
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $vis fn deposit_event $(<$dpeg $(, $dpeg_instance)?>)* () = default; }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
			[ $($t)* ]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{}
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn deposit_event $(<$dpeg:ident $(, $dpeg_instance:ident)?>)* (
			$($param_name:ident : $param:ty),*
		) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $vis fn deposit_event $(<$dpeg $(, $dpeg_instance)?>)* ($( $param_name: $param ),* ) { $( $impl )* } }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
			[ $($t)* ]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{}
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		fn on_finalize($($param_name:ident : $param:ty),* ) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $( $deposit_event )* }
			{ $( $on_initialize )* }
			{ fn on_finalize( $( $param_name : $param ),* ) { $( $impl )* } }
			{ $( $offchain )* }
			[ $($t)* ]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{}
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		fn on_finalise($($param_name:ident : $param:ty),* ) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		compile_error!(
			"`on_finalise` was renamed to `on_finalize`. Please rename your function accordingly."
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{}
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		fn on_initialize($($param_name:ident : $param:ty),* ) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $( $deposit_event )* }
			{ fn on_initialize( $( $param_name : $param ),* ) { $( $impl )* } }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
			[ $($t)* ]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{}
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		fn on_initialise($($param_name:ident : $param:ty),* ) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		compile_error!(
			"`on_initialise` was renamed to `on_initialize`. Please rename your function accordingly."
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		fn offchain_worker($($param_name:ident : $param:ty),* ) { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name>
			for enum $call_type where origin: $origin_type, system = $system
			{ $( $deposit_event )* }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ fn offchain_worker( $( $param_name : $param ),* ) { $( $impl )* } }
			[ $($t)* ]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$fn_vis:vis fn $fn_name:ident(
			$origin:ident $(, $(#[$codec_attr:ident])* $param_name:ident : $param:ty)*
		) $( -> $result:ty )* { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, $instance: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $( $deposit_event )* }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
			[
				$($t)*
				$(#[doc = $doc_attr])*
				$fn_vis fn $fn_name(
					$origin $( , $(#[$codec_attr])* $param_name : $param )*
				) $( -> $result )* { $( $impl )* }
				{ $($instance: $instantiable)? }
			]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$fn_vis:vis fn $fn_name:ident(
			$origin:ident : T::Origin $(, $(#[$codec_attr:ident])* $param_name:ident : $param:ty)*
		) $( -> $result:ty )* { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		compile_error!(
			"First parameter of dispatch should be marked `origin` only, with no type specified \
			(a bit like `self`). (For root-matching dispatches, ensure the first parameter does \
			not use the `T::Origin` type.)"
		)
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$fn_vis:vis fn $fn_name:ident(
			origin : $origin:ty $(, $(#[$codec_attr:ident])* $param_name:ident : $param:ty)*
		) $( -> $result:ty )* { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		compile_error!(
			"First parameter of dispatch should be marked `origin` only, with no type specified \
			(a bit like `self`). (For root-matching dispatches, ensure the first parameter does \
			not use the `T::Origin` type.)"
		)
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
		$(#[doc = $doc_attr:tt])*
		$fn_vis:vis fn $fn_name:ident(
			$( $(#[$codec_attr:ident])* $param_name:ident : $param:ty),*
		) $( -> $result:ty )* { $( $impl:tt )* }
		$($rest:tt)*
	) => {
		$crate::decl_module!(@normalize
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, $instance: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system
			{ $( $deposit_event )* }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
			[
				$($t)*
				$(#[doc = $doc_attr])*
				$fn_vis fn $fn_name(
					root $( , $(#[$codec_attr])* $param_name : $param )*
				) $( -> $result )* { $( $impl )* }
				{ $($instance: $instantiable)? }
			]
			$($rest)*
		);
	};
	(@normalize
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
		[ $($t:tt)* ]
	) => {
		$crate::decl_module!(@imp
			$(#[$attr])*
			pub struct $mod_type<$trait_instance: $trait_name$(<I>, I: $instantiable $(= $module_default_instance)?)?>
			for enum $call_type where origin: $origin_type, system = $system {
				$($t)*
			}
			{ $( $deposit_event )* }
			{ $( $on_initialize )* }
			{ $( $on_finalize )* }
			{ $( $offchain )* }
		);
	};

	// Implementation of Call enum's .dispatch() method.
	// TODO: this probably should be a different macro?

	(@call
		root
		$mod_type:ident<$trait_instance:ident $(, $instance:ident)?>  $fn_name:ident  $origin:ident $system:ident [ $( $param_name:ident),* ]
	) => {
		{
			$system::ensure_root($origin)?;
			<$mod_type<$trait_instance $(, $instance)?>>::$fn_name( $( $param_name ),* )
		}
	};
	(@call
		$ingore:ident
		$mod_type:ident<$trait_instance:ident $(, $instance:ident)?> $fn_name:ident $origin:ident $system:ident [ $( $param_name:ident),* ]
	) => {
		<$mod_type<$trait_instance $(, $instance)?>>::$fn_name( $origin $(, $param_name )* )
	};

	// no `deposit_event` function wanted
	(@impl_deposit_event
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, I: $instantiable:path)?>;
		$system:ident;
	) => {};

	(@impl_deposit_event
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$system:ident;
		$vis:vis fn deposit_event$(<$event_trait_instance:ident $(, $event_instance:ident)?>)?() = default;
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?> $module<$trait_instance $(, $instance)?> {
			$vis fn deposit_event(event: Event$(<$event_trait_instance $(, $event_instance)?>)?) {
				<$system::Module<$trait_instance>>::deposit_event(
					<$trait_instance as $trait_name$(<$instance>)?>::Event::from(event).into()
				);
			}
		}
	};

	(@impl_deposit_event
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$system:ident;
		$vis:vis fn deposit_event($param:ident : $param_ty:ty) { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?> $module<$trait_instance $(, $instance)?> {
			$vis fn deposit_event($param: $param_ty) {
				$( $impl )*
			}
		}
	};

	(@impl_on_initialize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn on_initialize() { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnInitialize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn on_initialize(_block_number_not_used: $trait_instance::BlockNumber) { $( $impl )* }
		}
	};

	(@impl_on_initialize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn on_initialize($param:ident : $param_ty:ty) { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnInitialize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn on_initialize($param: $param_ty) { $( $impl )* }
		}
	};

	(@impl_on_initialize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnInitialize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{}
	};

	(@impl_on_finalize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn on_finalize() { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnFinalize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn on_finalize(_block_number_not_used: $trait_instance::BlockNumber) { $( $impl )* }
		}
	};

	(@impl_on_finalize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn on_finalize($param:ident : $param_ty:ty) { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnFinalize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn on_finalize($param: $param_ty) { $( $impl )* }
		}
	};

	(@impl_on_finalize
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OnFinalize<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
		}
	};

	(@impl_offchain
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn offchain_worker() { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OffchainWorker<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn generate_extrinsics(_block_number_not_used: $trait_instance::BlockNumber) { $( $impl )* }
		}
	};

	(@impl_offchain
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		fn offchain_worker($param:ident : $param_ty:ty) { $( $impl:tt )* }
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OffchainWorker<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{
			fn generate_extrinsics($param: $param_ty) { $( $impl )* }
		}
	};

	(@impl_offchain
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
	) => {
		impl<$trait_instance: $trait_name$(<I>, $instance: $instantiable)?>
			$crate::runtime_primitives::traits::OffchainWorker<$trait_instance::BlockNumber>
			for $module<$trait_instance$(, $instance)?>
		{}
	};

	(@impl_function
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$origin_ty:ty;
		root;
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn $name:ident ( root $(, $param:ident : $param_ty:ty )* ) { $( $impl:tt )* }
	) => {
		$(#[doc = $doc_attr])*
		$vis fn $name($( $param: $param_ty ),* ) -> $crate::dispatch::Result {
			{ $( $impl )* }
			Ok(())
		}
	};

	(@impl_function
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$origin_ty:ty;
		root;
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn $name:ident (
			root $(, $param:ident : $param_ty:ty )*
		) -> $result:ty { $( $impl:tt )* }
	) => {
		$(#[doc = $doc_attr])*
		$vis fn $name($( $param: $param_ty ),* ) -> $result {
			$( $impl )*
		}
	};

	(@impl_function
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$origin_ty:ty;
		$ignore:ident;
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn $name:ident (
			$origin:ident $(, $param:ident : $param_ty:ty )*
		) { $( $impl:tt )* }
	) => {
		$(#[doc = $doc_attr])*
		$vis fn $name(
			$origin: $origin_ty $(, $param: $param_ty )*
		) -> $crate::dispatch::Result {
			{ $( $impl )* }
			Ok(())
		}
	};

	(@impl_function
		$module:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>;
		$origin_ty:ty;
		$ignore:ident;
		$(#[doc = $doc_attr:tt])*
		$vis:vis fn $name:ident (
			$origin:ident $(, $param:ident : $param_ty:ty )*
		) -> $result:ty { $( $impl:tt )* }
	) => {
		$(#[doc = $doc_attr])*
		$vis fn $name($origin: $origin_ty $(, $param: $param_ty )* ) -> $result {
			$( $impl )*
		}
	};

	// Declare a `Call` variant parameter that should be encoded `compact`.
	(@create_call_enum
		$( #[$attr:meta] )*
		$call_type:ident;
		<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		{ $( $generated_variants:tt )* }
		{ $( $current_params:tt )* }
		variant $fn_name:ident;
		$( #[doc = $doc_attr:tt] )*
		#[compact]
		$type:ty;
		$( $rest:tt )*
	) => {
		$crate::decl_module! {
			@create_call_enum
			$( #[$attr] )*
			$call_type;
			<$trait_instance: $trait_name $(<I>, $instance: $instantiable $(= $module_default_instance)? )?>
			{ $( $generated_variants )* }
			{
				$( $current_params )*
				#[codec(compact)]
				$type,
			}
			variant $fn_name;
			$( $rest )*
		}
	};

	// Declare a `Call` variant parameter.
	(@create_call_enum
		$( #[$attr:meta] )*
		$call_type:ident;
		<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		{ $( $generated_variants:tt )* }
		{ $( $current_params:tt )* }
		variant $fn_name:ident;
		$(#[doc = $doc_attr:tt])*
		$type:ty;
		$( $rest:tt )*
	) => {
		$crate::decl_module! {
			@create_call_enum
			$( #[$attr] )*
			$call_type;
			<$trait_instance: $trait_name $(<I>, $instance: $instantiable $(= $module_default_instance)? )?>
			{ $( $generated_variants )* }
			{
				$( $current_params )*
				$type,
			}
			variant $fn_name;
			$( $rest )*
		}
	};

	(@create_call_enum
		$( #[$attr:meta] )*
		$call_type:ident;
		<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		{ $( $generated_variants:tt )* }
		{ $( $current_params:tt )* }
		variant $fn_name:ident;
		$(#[doc = $doc_attr:tt])*
		$(
			variant $next_fn_name:ident;
			$( $rest:tt )*
		)?
	) => {
		$crate::decl_module! {
			@create_call_enum
			$( #[$attr] )*
			$call_type;
			<$trait_instance: $trait_name $(<I>, $instance: $instantiable $(= $module_default_instance)? )?>
			{
				$( $generated_variants )*
				#[allow(non_camel_case_types)]
				$(#[doc = $doc_attr])*
				$fn_name (
					$( $current_params )*
				),
			}
			{}
			$(
				variant $next_fn_name;
				$( $rest )*
			)?
		}
	};

	(@create_call_enum
		$( #[$attr:meta] )*
		$call_type:ident;
		<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		{ $( $generated_variants:tt )* }
		{}
	) => {
		#[derive($crate::codec::Encode, $crate::codec::Decode)]
		$( #[$attr] )*
		pub enum $call_type<$trait_instance: $trait_name$(<I>, $instance: $instantiable $( = $module_default_instance)?)?> {
			#[doc(hidden)]
			#[codec(skip)]
			__PhantomItem($crate::rstd::marker::PhantomData<($trait_instance $(, $instance)?)>, $crate::dispatch::Never),
			$( $generated_variants )*
		}
	};

	// The main macro expansion that actually renders the module code.

	(@imp
		$(#[$attr:meta])*
		pub struct $mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path $(= $module_default_instance:path)?)?>
		for enum $call_type:ident where origin: $origin_type:ty, system = $system:ident {
			$(
				$(#[doc = $doc_attr:tt])*
				$fn_vis:vis fn $fn_name:ident(
					$from:ident $( , $(#[$codec_attr:ident])* $param_name:ident : $param:ty)*
				) $( -> $result:ty )* { $( $impl:tt )* }
				{ $($fn_instance:ident: $fn_instantiable:path)? }
			)*
		}
		{ $( $deposit_event:tt )* }
		{ $( $on_initialize:tt )* }
		{ $( $on_finalize:tt )* }
		{ $( $offchain:tt )* }
	) => {
		$crate::__check_reserved_fn_name! {
			$($fn_name)*
		}

		// Workaround for https://github.com/rust-lang/rust/issues/26925 . Remove when sorted.
		#[derive(Clone, Copy, PartialEq, Eq)]
		#[cfg_attr(feature = "std", derive(Debug))]
		pub struct $mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable $( = $module_default_instance)?)?>($crate::rstd::marker::PhantomData<($trait_instance $(, $instance)?)>);

		$crate::decl_module! {
			@impl_on_initialize
			$mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?>;
			$( $on_initialize )*
		}

		$crate::decl_module! {
			@impl_on_finalize
			$mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?>;
			$( $on_finalize )*
		}

		$crate::decl_module! {
			@impl_offchain
			$mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?>;
			$( $offchain )*
		}

		$crate::decl_module! {
			@impl_deposit_event
			$mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?>;
			$system;
			$( $deposit_event )*
		}

		/// Can also be called using [`Call`].
		///
		/// [`Call`]: enum.Call.html
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $mod_type<$trait_instance $(, $instance)?> {
			$(
				$crate::decl_module! {
					@impl_function
					$mod_type<$trait_instance: $trait_name $(<I>, $fn_instance: $fn_instantiable)?>;
					$origin_type;
					$from;
					$(#[doc = $doc_attr])*
					$fn_vis fn $fn_name (
						$from $(, $param_name : $param )*
					) $( -> $result )* { $( $impl )* }
				}
			)*
		}

		$crate::decl_module! {
			@create_call_enum
			$( #[$attr] )*
			$call_type;
			<$trait_instance: $trait_name $(<I>, $instance: $instantiable $(= $module_default_instance)? )?>
			{}
			{}
			$(
				variant $fn_name;
				$(#[doc = $doc_attr])*
				$(
					$(#[$codec_attr])*
					$param;
				)*
			)*
		}

		// manual implementation of clone/eq/partialeq because using derive erroneously requires
		// clone/eq/partialeq from T.
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::Clone
			for $call_type<$trait_instance $(, $instance)?>
		{
			fn clone(&self) -> Self {
				match *self {
					$(
						$call_type::$fn_name( $( ref $param_name ),* ) =>
							$call_type::$fn_name( $( (*$param_name).clone() ),* )
					,)*
					_ => unreachable!(),
				}
			}
		}
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::PartialEq
			for $call_type<$trait_instance $(, $instance)?>
		{
			fn eq(&self, _other: &Self) -> bool {
				match *self {
					$(
						$call_type::$fn_name( $( ref $param_name ),* ) => {
							let self_params = ( $( $param_name, )* );
							if let $call_type::$fn_name( $( ref $param_name ),* ) = *_other {
								self_params == ( $( $param_name, )* )
							} else {
								match *_other {
									$call_type::__PhantomItem(_, _) => unreachable!(),
									_ => false,
								}
							}
						}
					)*
					_ => unreachable!(),
				}
			}
		}
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::Eq
			for $call_type<$trait_instance $(, $instance)?>
		{}

		#[cfg(feature = "std")]
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::fmt::Debug
			for $call_type<$trait_instance $(, $instance)?>
		{
			fn fmt(&self, _f: &mut $crate::dispatch::fmt::Formatter) -> $crate::dispatch::result::Result<(), $crate::dispatch::fmt::Error> {
				match *self {
					$(
						$call_type::$fn_name( $( ref $param_name ),* ) =>
							write!(_f, "{}{:?}",
								stringify!($fn_name),
								( $( $param_name.clone(), )* )
							)
					,)*
					_ => unreachable!(),
				}
			}
		}

		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::Dispatchable
			for $call_type<$trait_instance $(, $instance)?>
		{
			type Trait = $trait_instance;
			type Origin = $origin_type;
			fn dispatch(self, _origin: Self::Origin) -> $crate::dispatch::Result {
				match self {
					$(
						$call_type::$fn_name( $( $param_name ),* ) => {
							$crate::decl_module!(
								@call
								$from
								$mod_type<$trait_instance $(, $fn_instance)?> $fn_name _origin $system [ $( $param_name ),* ]
							)
						},
					)*
					$call_type::__PhantomItem(_, _) => { unreachable!("__PhantomItem should never be used.") },
				}
			}
		}
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $crate::dispatch::Callable
			for $mod_type<$trait_instance $(, $instance)?>
		{
			type Call = $call_type<$trait_instance $(, $instance)?>;
		}

		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $mod_type<$trait_instance $(, $instance)?> {
			#[doc(hidden)]
			pub fn dispatch<D: $crate::dispatch::Dispatchable<Trait = $trait_instance>>(d: D, origin: D::Origin) -> $crate::dispatch::Result {
				d.dispatch(origin)
			}
		}
		$crate::__dispatch_impl_metadata! {
			$mod_type<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $call_type $origin_type
			{$( $(#[doc = $doc_attr])* fn $fn_name($from $(, $(#[$codec_attr])* $param_name : $param )*); )*}
		}
	}
}

pub trait IsSubType<T: Callable> {
	fn is_aux_sub_type(&self) -> Option<&<T as Callable>::Call>;
}

/// Implement a meta-dispatch module to dispatch to other dispatchers.
#[macro_export]
macro_rules! impl_outer_dispatch {
	(
		$(#[$attr:meta])*
		pub enum $call_type:ident for $runtime:ident where origin: $origin:ty {
			$(
				$module:ident::$camelcase:ident,
			)*
		}
	) => {
		$(#[$attr])*
		#[derive(Clone, PartialEq, Eq, $crate::codec::Encode, $crate::codec::Decode)]
		#[cfg_attr(feature = "std", derive(Debug))]
		pub enum $call_type {
			$(
				$camelcase ( $crate::dispatch::CallableCallFor<$camelcase> )
			,)*
		}
		impl $crate::dispatch::Dispatchable for $call_type {
			type Origin = $origin;
			type Trait = $call_type;
			fn dispatch(self, origin: $origin) -> $crate::dispatch::Result {
				match self {
					$(
						$call_type::$camelcase(call) => call.dispatch(origin),
					)*
				}
			}
		}
		$(
			impl $crate::dispatch::IsSubType<$camelcase> for $call_type {
				fn is_aux_sub_type(&self) -> Option<&<$camelcase as $crate::dispatch::Callable>::Call> {
					if let $call_type::$camelcase ( ref r ) = *self {
						Some(r)
					} else {
						None
					}
				}
			}
		)*
	}
}

/// Implement metadata for dispatch.
#[macro_export]
#[doc(hidden)]
macro_rules! __dispatch_impl_metadata {
	(
		$mod_type:ident<$trait_instance:ident: $trait_name:ident$(<I>, $instance:ident: $instantiable:path)?>
		$($rest:tt)*
	) => {
		impl<$trait_instance: $trait_name $(<I>, $instance: $instantiable)?> $mod_type<$trait_instance $(, $instance)?> {
			#[doc(hidden)]
			pub fn call_functions() -> &'static [$crate::dispatch::FunctionMetadata] {
				$crate::__call_to_functions!($($rest)*)
			}
		}
	}
}

/// Convert the list of calls into their JSON representation, joined by ",".
#[macro_export]
#[doc(hidden)]
macro_rules! __call_to_functions {
	(
		$call_type:ident $origin_type:ty
			{$(
				$(#[doc = $doc_attr:tt])*
				fn $fn_name:ident($from:ident
					$(
						, $(#[$codec_attr:ident])* $param_name:ident : $param:ty
					)*
				);
			)*}
	) => {
		$crate::__functions_to_metadata!(0; $origin_type;; $(
			fn $fn_name( $($(#[$codec_attr])* $param_name: $param ),* );
			$( $doc_attr ),*;
		)*)
	};
}


/// Convert a list of functions into a list of `FunctionMetadata` items.
#[macro_export]
#[doc(hidden)]
macro_rules! __functions_to_metadata{
	(
		$fn_id:expr;
		$origin_type:ty;
		$( $function_metadata:expr ),*;
		fn $fn_name:ident(
			$(
				$(#[$codec_attr:ident])* $param_name:ident : $param:ty
			),*
		);
		$( $fn_doc:expr ),*;
		$( $rest:tt )*
	) => {
		$crate::__functions_to_metadata!(
			$fn_id + 1; $origin_type;
			$( $function_metadata, )* $crate::__function_to_metadata!(
				fn $fn_name($( $(#[$codec_attr])* $param_name : $param ),*); $( $fn_doc ),*; $fn_id;
			);
			$($rest)*
		)
	};
	(
		$fn_id:expr;
		$origin_type:ty;
		$( $function_metadata:expr ),*;
	) => {
		&[ $( $function_metadata ),* ]
	}
}

/// Convert a function into its metadata representation.
#[macro_export]
#[doc(hidden)]
macro_rules! __function_to_metadata {
	(
		fn $fn_name:ident(
			$( $(#[$codec_attr:ident])* $param_name:ident : $param:ty),*
		);
		$( $fn_doc:expr ),*;
		$fn_id:expr;
	) => {
		$crate::dispatch::FunctionMetadata {
			name: $crate::dispatch::DecodeDifferent::Encode(stringify!($fn_name)),
			arguments: $crate::dispatch::DecodeDifferent::Encode(&[
				$(
					$crate::dispatch::FunctionArgumentMetadata {
						name: $crate::dispatch::DecodeDifferent::Encode(stringify!($param_name)),
						ty: $crate::dispatch::DecodeDifferent::Encode(
							$crate::__function_to_metadata!(@stringify_expand_attr
								$(#[$codec_attr])* $param_name: $param
							)
						),
					}
				),*
			]),
			documentation: $crate::dispatch::DecodeDifferent::Encode(&[ $( $fn_doc ),* ]),
		}
	};

	(@stringify_expand_attr #[compact] $param_name:ident : $param:ty) => {
		concat!("Compact<", stringify!($param), ">")
	};

	(@stringify_expand_attr $param_name:ident : $param:ty) => { stringify!($param) };

	(@stringify_expand_attr $(#[codec_attr:ident])* $param_name:ident : $param:ty) => {
		compile_error!(concat!(
			"Invalid attribute for parameter `", stringify!($param_name),
			"`, the following attributes are supported: `#[compact]`"
		))
	}
}

#[macro_export]
#[doc(hidden)]
macro_rules! __check_reserved_fn_name {
	(deposit_event $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error deposit_event);
	};
	(on_initialize $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error on_initialize);
	};
	(on_initialise $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error on_initialise);
	};
	(on_finalize $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error on_finalize);
	};
	(on_finalise $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error on_finalise);
	};
	(offchain_worker $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!(@compile_error offchain_worker);
	};
	($t:ident $( $rest:ident )*) => {
		$crate::__check_reserved_fn_name!($( $rest )*);
	};
	() => {};
	(@compile_error $ident:ident) => {
		compile_error!(concat!("Invalid call fn name: `", stringify!($ident),
		"`, name is reserved and doesn't match expected signature, please refer to `decl_module!`",
		" documentation to see the appropriate usage, or rename it to an unreserved keyword."));
	};
}

#[cfg(test)]
// Do not complain about unused `dispatch` and `dispatch_aux`.
#[allow(dead_code)]
mod tests {
	use super::*;
	use crate::runtime_primitives::traits::{OnInitialize, OnFinalize};

	pub trait Trait {
		type Origin;
		type BlockNumber: Into<u32>;
	}

	pub mod system {
		use super::Result;

		pub fn ensure_root<R>(_: R) -> Result {
			Ok(())
		}
	}

	decl_module! {
		pub struct Module<T: Trait> for enum Call where origin: T::Origin {
			/// Hi, this is a comment.
			fn aux_0(_origin) -> Result { unreachable!() }
			fn aux_1(_origin, #[compact] _data: u32) -> Result { unreachable!() }
			fn aux_2(_origin, _data: i32, _data2: String) -> Result { unreachable!() }
			fn aux_3() -> Result { unreachable!() }
			fn aux_4(_data: i32) -> Result { unreachable!() }
			fn aux_5(_origin, _data: i32, #[compact] _data2: u32) -> Result { unreachable!() }

			fn on_initialize(n: T::BlockNumber) { if n.into() == 42 { panic!("on_initialize") } }
			fn on_finalize(n: T::BlockNumber) { if n.into() == 42 { panic!("on_finalize") } }
			fn offchain_worker() {}
		}
	}

	const EXPECTED_METADATA: &'static [FunctionMetadata] = &[
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_0"),
					arguments: DecodeDifferent::Encode(&[]),
					documentation: DecodeDifferent::Encode(&[
						" Hi, this is a comment."
					])
				},
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_1"),
					arguments: DecodeDifferent::Encode(&[
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data"),
							ty: DecodeDifferent::Encode("Compact<u32>")
						}
					]),
					documentation: DecodeDifferent::Encode(&[]),
				},
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_2"),
					arguments: DecodeDifferent::Encode(&[
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data"),
							ty: DecodeDifferent::Encode("i32"),
						},
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data2"),
							ty: DecodeDifferent::Encode("String"),
						}
					]),
					documentation: DecodeDifferent::Encode(&[]),
				},
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_3"),
					arguments: DecodeDifferent::Encode(&[]),
					documentation: DecodeDifferent::Encode(&[]),
				},
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_4"),
					arguments: DecodeDifferent::Encode(&[
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data"),
							ty: DecodeDifferent::Encode("i32"),
						}
					]),
					documentation: DecodeDifferent::Encode(&[]),
				},
				FunctionMetadata {
					name: DecodeDifferent::Encode("aux_5"),
					arguments: DecodeDifferent::Encode(&[
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data"),
							ty: DecodeDifferent::Encode("i32"),
						},
						FunctionArgumentMetadata {
							name: DecodeDifferent::Encode("_data2"),
							ty: DecodeDifferent::Encode("Compact<u32>")
						}
					]),
					documentation: DecodeDifferent::Encode(&[]),
				},
			];

	struct TraitImpl {}

	impl Trait for TraitImpl {
		type Origin = u32;
		type BlockNumber = u32;
	}

	#[test]
	fn module_json_metadata() {
		let metadata = Module::<TraitImpl>::call_functions();
		assert_eq!(EXPECTED_METADATA, metadata);
	}

	#[test]
	fn compact_attr() {
		let call: Call<TraitImpl> = Call::aux_1(1);
		let encoded = call.encode();
		assert_eq!(2, encoded.len());
		assert_eq!(vec![1, 4], encoded);

		let call: Call<TraitImpl> = Call::aux_5(1, 2);
		let encoded = call.encode();
		assert_eq!(6, encoded.len());
		assert_eq!(vec![5, 1, 0, 0, 0, 8], encoded);
	}

	#[test]
	fn encode_is_correct_and_decode_works() {
		let call: Call<TraitImpl> = Call::aux_0();
		let encoded = call.encode();
		assert_eq!(vec![0], encoded);
		let decoded = Call::<TraitImpl>::decode(&mut &encoded[..]).unwrap();
		assert_eq!(decoded, call);

		let call: Call<TraitImpl> = Call::aux_2(32, "hello".into());
		let encoded = call.encode();
		assert_eq!(vec![2, 32, 0, 0, 0, 20, 104, 101, 108, 108, 111], encoded);
		let decoded = Call::<TraitImpl>::decode(&mut &encoded[..]).unwrap();
		assert_eq!(decoded, call);
	}

	#[test]
	#[should_panic(expected = "on_initialize")]
	fn on_initialize_should_work() {
		<Module<TraitImpl> as OnInitialize<u32>>::on_initialize(42);
	}

	#[test]
	#[should_panic(expected = "on_finalize")]
	fn on_finalize_should_work() {
		<Module<TraitImpl> as OnFinalize<u32>>::on_finalize(42);
	}
}
