// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! # Split Example Pallet
//!
//! **This pallet serves as an example and is not meant to be used in production.**
//!
//! A FRAME pallet demonstrating the ability to split sections across multiple files.
//!
//! Note that this is purely experimental at this point.

#![cfg_attr(not(feature = "std"), no_std)]

// Re-export pallet items so that they can be accessed from the crate namespace.
pub use pallet::*;

#[cfg(test)]
mod mock;

#[cfg(test)]
mod tests;

#[cfg(feature = "runtime-benchmarks")]
mod benchmarking;
mod events;

pub mod weights;
pub use weights::*;

use frame_support::pallet_macros::*;

/// Imports a [`pallet_section`] defined at [`events::events`].
/// This brings the events defined in that section into the pallet's namespace.
#[import_section(events::events)]
#[frame_support::pallet]
pub mod pallet {
	use super::*;
	use frame_support::pallet_prelude::*;
	use frame_system::pallet_prelude::*;

	#[pallet::pallet]
	pub struct Pallet<T>(_);

	/// Configure the pallet by specifying the parameters and types on which it depends.
	#[pallet::config]
	pub trait Config: frame_system::Config {
		/// Because this pallet emits events, it depends on the runtime's definition of an event.
		type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
		/// Type representing the weight of this pallet
		type WeightInfo: WeightInfo;
	}

	// The pallet's runtime storage items.
	#[pallet::storage]
	pub type Something<T> = StorageValue<_, u32>;

	// Errors inform users that something went wrong.
	#[pallet::error]
	pub enum Error<T> {
		/// Error names should be descriptive.
		NoneValue,
		/// Errors should have helpful documentation associated with them.
		StorageOverflow,
	}

	// Dispatchable functions allows users to interact with the pallet and invoke state changes.
	// These functions materialize as "extrinsics", which are often compared to transactions.
	// Dispatchable functions must be annotated with a weight and must return a DispatchResult.
	#[pallet::call]
	impl<T: Config> Pallet<T> {
		/// An example dispatchable that takes a singles value as a parameter, writes the value to
		/// storage and emits an event. This function must be dispatched by a signed extrinsic.
		#[pallet::call_index(0)]
		#[pallet::weight(T::WeightInfo::do_something())]
		pub fn do_something(origin: OriginFor<T>, something: u32) -> DispatchResult {
			// Check that the extrinsic was signed and get the signer.
			// This function will return an error if the extrinsic is not signed.
			let who = ensure_signed(origin)?;

			// Update storage.
			<Something<T>>::put(something);

			// Emit an event.
			Self::deposit_event(Event::SomethingStored { something, who });
			// Return a successful DispatchResultWithPostInfo
			Ok(())
		}

		/// An example dispatchable that may throw a custom error.
		#[pallet::call_index(1)]
		#[pallet::weight(T::WeightInfo::cause_error())]
		pub fn cause_error(origin: OriginFor<T>) -> DispatchResult {
			let _who = ensure_signed(origin)?;

			// Read a value from storage.
			match Something::<T>::get() {
				// Return an error if the value has not been set.
				None => return Err(Error::<T>::NoneValue.into()),
				Some(old) => {
					// Increment the value read from storage; will error in the event of overflow.
					let new = old.checked_add(1).ok_or(Error::<T>::StorageOverflow)?;
					// Update the value in storage with the incremented result.
					<Something<T>>::put(new);
					Ok(())
				},
			}
		}
	}
}
