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// Copyright 2019-2020 Parity Technologies (UK) Ltd.
// This file is part of substrate-subxt.
//
// subxt 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.
//
// subxt 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-subxt.  If not, see <http://www.gnu.org/licenses/>.

//! Implements support for the pallet_contracts module.

use crate::frame::{
    balances::{
        Balances,
        BalancesEventsDecoder,
    },
    system::{
        System,
        SystemEventsDecoder,
    },
};
use codec::{
    Decode,
    Encode,
};
use core::marker::PhantomData;

/// Gas units are chosen to be represented by u64 so that gas metering
/// instructions can operate on them efficiently.
pub type Gas = u64;

/// The subset of the `pallet_contracts::Trait` that a client must implement.
#[module]
pub trait Contracts: System + Balances {}

/// Stores the given binary Wasm code into the chain's storage and returns
/// its `codehash`.
/// You can instantiate contracts only with stored code.
#[derive(Clone, Debug, Eq, PartialEq, Call, Encode)]
pub struct PutCodeCall<'a, T: Contracts> {
    /// Runtime marker.
    pub _runtime: PhantomData<T>,
    /// Wasm blob.
    pub code: &'a [u8],
}

/// Creates a new contract from the `codehash` generated by `put_code`,
/// optionally transferring some balance.
///
/// Creation is executed as follows:
///
/// - The destination address is computed based on the sender and hash of
/// the code.
/// - The smart-contract account is instantiated at the computed address.
/// - The `ctor_code` is executed in the context of the newly-instantiated
/// account. Buffer returned after the execution is saved as the `code`https://www.bbc.co.uk/
/// of the account. That code will be invoked upon any call received by
/// this account.
/// - The contract is initialized.
#[derive(Clone, Debug, Eq, PartialEq, Call, Encode)]
pub struct InstantiateCall<'a, T: Contracts> {
    /// Initial balance transfered to the contract.
    #[codec(compact)]
    pub endowment: <T as Balances>::Balance,
    /// Gas limit.
    #[codec(compact)]
    pub gas_limit: Gas,
    /// Code hash returned by the put_code call.
    pub code_hash: &'a <T as System>::Hash,
    /// Data to initialize the contract with.
    pub data: &'a [u8],
}

/// Makes a call to an account, optionally transferring some balance.
///
/// * If the account is a smart-contract account, the associated code will
///  be executed and any value will be transferred.
/// * If the account is a regular account, any value will be transferred.
/// * If no account exists and the call value is not less than
/// `existential_deposit`, a regular account will be created and any value
///  will be transferred.
#[derive(Clone, Debug, PartialEq, Call, Encode)]
pub struct CallCall<'a, T: Contracts> {
    /// Address of the contract.
    pub dest: &'a <T as System>::Address,
    /// Value to transfer to the contract.
    pub value: <T as Balances>::Balance,
    /// Gas limit.
    #[codec(compact)]
    pub gas_limit: Gas,
    /// Data to send to the contract.
    pub data: &'a [u8],
}

/// Code stored event.
#[derive(Clone, Debug, Eq, PartialEq, Event, Decode)]
pub struct CodeStoredEvent<T: Contracts> {
    /// Code hash of the contract.
    pub code_hash: T::Hash,
}

/// Instantiated event.
#[derive(Clone, Debug, Eq, PartialEq, Event, Decode)]
pub struct InstantiatedEvent<T: Contracts> {
    /// Caller that instantiated the contract.
    pub caller: <T as System>::AccountId,
    /// The address of the contract.
    pub contract: <T as System>::AccountId,
}

#[cfg(test)]
mod tests {
    use super::*;

    subxt_test!({
        name: test_put_code_and_instantiate,
        prelude: {
            const CONTRACT: &str = r#"
(module
    (func (export "call"))
    (func (export "deploy"))
)
"#;
            let wasm = wabt::wat2wasm(CONTRACT).expect("invalid wabt");
            let code_hash;
        },
        step: {
            call: PutCodeCall {
                _runtime: PhantomData,
                code: &wasm,
            },
            event: CodeStoredEvent {
                code_hash: {
                    code_hash = event.code_hash.clone();
                    event.code_hash.clone()
                },
            },
        },
        step: {
            call: InstantiateCall {
                endowment: 100_000_000_000_000,
                gas_limit: 500_000_000,
                code_hash: &code_hash,
                data: &[],
            },
            event: InstantiatedEvent {
                caller: alice.clone(),
                contract: event.contract.clone(),
            },
        },
    });
}