// 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.

//! Pallets used in the `your_first_pallet` guide.

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

#[docify::export]
#[frame::pallet(dev_mode)]
pub mod shell_pallet {
	use frame::prelude::*;

	#[pallet::config]
	pub trait Config: frame_system::Config {}

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

#[frame::pallet(dev_mode)]
pub mod pallet {
	use frame::prelude::*;

	#[docify::export]
	pub type Balance = u128;

	#[pallet::config]
	pub trait Config: frame_system::Config {}

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

	#[docify::export]
	/// Single storage item, of type `Balance`.
	#[pallet::storage]
	pub type TotalIssuance<T: Config> = StorageValue<_, Balance>;

	#[docify::export]
	/// A mapping from `T::AccountId` to `Balance`
	#[pallet::storage]
	pub type Balances<T: Config> = StorageMap<_, _, T::AccountId, Balance>;

	#[docify::export(impl_pallet)]
	#[pallet::call]
	impl<T: Config> Pallet<T> {
		/// An unsafe mint that can be called by anyone. Not a great idea.
		pub fn mint_unsafe(
			origin: T::RuntimeOrigin,
			dest: T::AccountId,
			amount: Balance,
		) -> DispatchResult {
			// ensure that this is a signed account, but we don't really check `_anyone`.
			let _anyone = ensure_signed(origin)?;

			// update the balances map. Notice how all `<T: Config>` remains as `<T>`.
			Balances::<T>::mutate(dest, |b| *b = Some(b.unwrap_or(0) + amount));
			// update total issuance.
			TotalIssuance::<T>::mutate(|t| *t = Some(t.unwrap_or(0) + amount));

			Ok(())
		}

		/// Transfer `amount` from `origin` to `dest`.
		pub fn transfer(
			origin: T::RuntimeOrigin,
			dest: T::AccountId,
			amount: Balance,
		) -> DispatchResult {
			let sender = ensure_signed(origin)?;

			// ensure sender has enough balance, and if so, calculate what is left after `amount`.
			let sender_balance = Balances::<T>::get(&sender).ok_or("NonExistentAccount")?;
			if sender_balance < amount {
				return Err("InsufficientBalance".into())
			}
			let remainder = sender_balance - amount;

			// update sender and dest balances.
			Balances::<T>::mutate(dest, |b| *b = Some(b.unwrap_or(0) + amount));
			Balances::<T>::insert(&sender, remainder);

			Ok(())
		}
	}

	#[allow(unused)]
	impl<T: Config> Pallet<T> {
		#[docify::export]
		pub fn transfer_better(
			origin: T::RuntimeOrigin,
			dest: T::AccountId,
			amount: Balance,
		) -> DispatchResult {
			let sender = ensure_signed(origin)?;

			let sender_balance = Balances::<T>::get(&sender).ok_or("NonExistentAccount")?;
			ensure!(sender_balance >= amount, "InsufficientBalance");
			let remainder = sender_balance - amount;

			// .. snip
			Ok(())
		}

		#[docify::export]
		/// Transfer `amount` from `origin` to `dest`.
		pub fn transfer_better_checked(
			origin: T::RuntimeOrigin,
			dest: T::AccountId,
			amount: Balance,
		) -> DispatchResult {
			let sender = ensure_signed(origin)?;

			let sender_balance = Balances::<T>::get(&sender).ok_or("NonExistentAccount")?;
			let remainder = sender_balance.checked_sub(amount).ok_or("InsufficientBalance")?;

			// .. snip
			Ok(())
		}
	}

	#[cfg(any(test, doc))]
	pub(crate) mod tests {
		use crate::pallet::*;

		#[docify::export(testing_prelude)]
		use frame::testing_prelude::*;

		pub(crate) const ALICE: u64 = 1;
		pub(crate) const BOB: u64 = 2;
		pub(crate) const CHARLIE: u64 = 3;

		#[docify::export]
		// This runtime is only used for testing, so it should be somewhere like `#[cfg(test)] mod
		// tests { .. }`
		mod runtime {
			use super::*;
			// we need to reference our `mod pallet` as an identifier to pass to
			// `construct_runtime`.
			// YOU HAVE TO CHANGE THIS LINE BASED ON YOUR TEMPLATE
			use crate::pallet as pallet_currency;

			construct_runtime!(
				pub enum Runtime {
					// ---^^^^^^ This is where `enum Runtime` is defined.
					System: frame_system,
					Currency: pallet_currency,
				}
			);

			#[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
			impl frame_system::Config for Runtime {
				type Block = MockBlock<Runtime>;
				// within pallet we just said `<T as frame_system::Config>::AccountId`, now we
				// finally specified it.
				type AccountId = u64;
			}

			// our simple pallet has nothing to be configured.
			impl pallet_currency::Config for Runtime {}
		}

		pub(crate) use runtime::*;

		#[allow(unused)]
		#[docify::export]
		fn new_test_state_basic() -> TestState {
			let mut state = TestState::new_empty();
			let accounts = vec![(ALICE, 100), (BOB, 100)];
			state.execute_with(|| {
				for (who, amount) in &accounts {
					Balances::<Runtime>::insert(who, amount);
					TotalIssuance::<Runtime>::mutate(|b| *b = Some(b.unwrap_or(0) + amount));
				}
			});

			state
		}

		#[docify::export]
		pub(crate) struct StateBuilder {
			balances: Vec<(<Runtime as frame_system::Config>::AccountId, Balance)>,
		}

		#[docify::export(default_state_builder)]
		impl Default for StateBuilder {
			fn default() -> Self {
				Self { balances: vec![(ALICE, 100), (BOB, 100)] }
			}
		}

		#[docify::export(impl_state_builder_add)]
		impl StateBuilder {
			fn add_balance(
				mut self,
				who: <Runtime as frame_system::Config>::AccountId,
				amount: Balance,
			) -> Self {
				self.balances.push((who, amount));
				self
			}
		}

		#[docify::export(impl_state_builder_build)]
		impl StateBuilder {
			pub(crate) fn build_and_execute(self, test: impl FnOnce() -> ()) {
				let mut ext = TestState::new_empty();
				ext.execute_with(|| {
					for (who, amount) in &self.balances {
						Balances::<Runtime>::insert(who, amount);
						TotalIssuance::<Runtime>::mutate(|b| *b = Some(b.unwrap_or(0) + amount));
					}
				});

				ext.execute_with(test);

				// assertions that must always hold
				ext.execute_with(|| {
					assert_eq!(
						Balances::<Runtime>::iter().map(|(_, x)| x).sum::<u128>(),
						TotalIssuance::<Runtime>::get().unwrap_or_default()
					);
				})
			}
		}

		#[docify::export]
		#[test]
		fn first_test() {
			TestState::new_empty().execute_with(|| {
				// We expect Alice's account to have no funds.
				assert_eq!(Balances::<Runtime>::get(&ALICE), None);
				assert_eq!(TotalIssuance::<Runtime>::get(), None);

				// mint some funds into Alice's account.
				assert_ok!(Pallet::<Runtime>::mint_unsafe(
					RuntimeOrigin::signed(ALICE),
					ALICE,
					100
				));

				// re-check the above
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(100));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(100));
			})
		}

		#[docify::export]
		#[test]
		fn state_builder_works() {
			StateBuilder::default().build_and_execute(|| {
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(100));
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(100));
				assert_eq!(Balances::<Runtime>::get(&CHARLIE), None);
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(200));
			});
		}

		#[docify::export]
		#[test]
		fn state_builder_add_balance() {
			StateBuilder::default().add_balance(CHARLIE, 42).build_and_execute(|| {
				assert_eq!(Balances::<Runtime>::get(&CHARLIE), Some(42));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(242));
			})
		}

		#[test]
		#[should_panic]
		fn state_builder_duplicate_genesis_fails() {
			StateBuilder::default()
				.add_balance(CHARLIE, 42)
				.add_balance(CHARLIE, 43)
				.build_and_execute(|| {
					assert_eq!(Balances::<Runtime>::get(&CHARLIE), None);
					assert_eq!(TotalIssuance::<Runtime>::get(), Some(242));
				})
		}

		#[docify::export]
		#[test]
		fn mint_works() {
			StateBuilder::default().build_and_execute(|| {
				// given the initial state, when:
				assert_ok!(Pallet::<Runtime>::mint_unsafe(RuntimeOrigin::signed(ALICE), BOB, 100));

				// then:
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(200));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(300));

				// given:
				assert_ok!(Pallet::<Runtime>::mint_unsafe(
					RuntimeOrigin::signed(ALICE),
					CHARLIE,
					100
				));

				// then:
				assert_eq!(Balances::<Runtime>::get(&CHARLIE), Some(100));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(400));
			});
		}

		#[docify::export]
		#[test]
		fn transfer_works() {
			StateBuilder::default().build_and_execute(|| {
				// given the initial state, when:
				assert_ok!(Pallet::<Runtime>::transfer(RuntimeOrigin::signed(ALICE), BOB, 50));

				// then:
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(50));
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(150));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(200));

				// when:
				assert_ok!(Pallet::<Runtime>::transfer(RuntimeOrigin::signed(BOB), ALICE, 50));

				// then:
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(100));
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(100));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(200));
			});
		}

		#[docify::export]
		#[test]
		fn transfer_from_non_existent_fails() {
			StateBuilder::default().build_and_execute(|| {
				// given the initial state, when:
				assert_err!(
					Pallet::<Runtime>::transfer(RuntimeOrigin::signed(CHARLIE), ALICE, 10),
					"NonExistentAccount"
				);

				// then nothing has changed.
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(100));
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(100));
				assert_eq!(Balances::<Runtime>::get(&CHARLIE), None);
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(200));
			});
		}
	}
}

#[frame::pallet(dev_mode)]
pub mod pallet_v2 {
	use super::pallet::Balance;
	use frame::prelude::*;

	#[docify::export(config_v2)]
	#[pallet::config]
	pub trait Config: frame_system::Config {
		/// The overarching event type of the runtime.
		type RuntimeEvent: From<Event<Self>>
			+ IsType<<Self as frame_system::Config>::RuntimeEvent>
			+ TryInto<Event<Self>>;
	}

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

	#[pallet::storage]
	pub type Balances<T: Config> = StorageMap<_, _, T::AccountId, Balance>;

	#[pallet::storage]
	pub type TotalIssuance<T: Config> = StorageValue<_, Balance>;

	#[docify::export]
	#[pallet::error]
	pub enum Error<T> {
		/// Account does not exist.
		NonExistentAccount,
		/// Account does not have enough balance.
		InsufficientBalance,
	}

	#[docify::export]
	#[pallet::event]
	#[pallet::generate_deposit(pub(super) fn deposit_event)]
	pub enum Event<T: Config> {
		/// A transfer succeeded.
		Transferred { from: T::AccountId, to: T::AccountId, amount: Balance },
	}

	#[pallet::call]
	impl<T: Config> Pallet<T> {
		#[docify::export(transfer_v2)]
		pub fn transfer(
			origin: T::RuntimeOrigin,
			dest: T::AccountId,
			amount: Balance,
		) -> DispatchResult {
			let sender = ensure_signed(origin)?;

			// ensure sender has enough balance, and if so, calculate what is left after `amount`.
			let sender_balance =
				Balances::<T>::get(&sender).ok_or(Error::<T>::NonExistentAccount)?;
			let remainder =
				sender_balance.checked_sub(amount).ok_or(Error::<T>::InsufficientBalance)?;

			Balances::<T>::mutate(&dest, |b| *b = Some(b.unwrap_or(0) + amount));
			Balances::<T>::insert(&sender, remainder);

			Self::deposit_event(Event::<T>::Transferred { from: sender, to: dest, amount });

			Ok(())
		}
	}

	#[cfg(any(test, doc))]
	pub mod tests {
		use super::{super::pallet::tests::StateBuilder, *};
		use frame::testing_prelude::*;
		const ALICE: u64 = 1;
		const BOB: u64 = 2;

		#[docify::export]
		pub mod runtime_v2 {
			use super::*;
			use crate::pallet_v2 as pallet_currency;

			construct_runtime!(
				pub enum Runtime {
					System: frame_system,
					Currency: pallet_currency,
				}
			);

			#[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
			impl frame_system::Config for Runtime {
				type Block = MockBlock<Runtime>;
				type AccountId = u64;
			}

			impl pallet_currency::Config for Runtime {
				type RuntimeEvent = RuntimeEvent;
			}
		}

		pub(crate) use runtime_v2::*;

		#[docify::export(transfer_works_v2)]
		#[test]
		fn transfer_works() {
			StateBuilder::default().build_and_execute(|| {
				// skip the genesis block, as events are not deposited there and we need them for
				// the final assertion.
				System::set_block_number(ALICE);

				// given the initial state, when:
				assert_ok!(Pallet::<Runtime>::transfer(RuntimeOrigin::signed(ALICE), BOB, 50));

				// then:
				assert_eq!(Balances::<Runtime>::get(&ALICE), Some(50));
				assert_eq!(Balances::<Runtime>::get(&BOB), Some(150));
				assert_eq!(TotalIssuance::<Runtime>::get(), Some(200));

				// now we can also check that an event has been deposited:
				assert_eq!(
					System::read_events_for_pallet::<Event<Runtime>>(),
					vec![Event::Transferred { from: ALICE, to: BOB, amount: 50 }]
				);
			});
		}
	}
}