// Copyright 2018-2022 Parity Technologies (UK) Ltd.
//
// 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.

use crate::{
    call::{
        utils::{
            EmptyArgumentList,
            ReturnType,
            Set,
            Unset,
            Unwrap,
        },
        ExecutionInput,
        Selector,
    },
    ContractEnv,
    Environment,
    Error,
};
use core::marker::PhantomData;

pub mod state {
    //! Type states that tell what state of a instantiation argument has not
    //! yet been set properly for a valid construction.

    /// Type state for the salt used for contract instantiation.
    pub enum Salt {}
}

/// Contracts that can be constructed from an `AccountId`.
///
/// # Note
///
/// This is needed because of conflicting implementations of `From<T> for T`
/// in the generated code of `ink`.
pub trait FromAccountId<T>
where
    T: Environment,
{
    /// Creates the contract instance from the account ID of the already instantiated contract.
    fn from_account_id(account_id: <T as Environment>::AccountId) -> Self;
}

/// Represents any type that can be returned from an `ink!` constructor. The following contract
/// implements the four different return type signatures implementing this trait:
///
/// - `Self`
/// - `Result<Self, Error>`
/// - `Contract`
/// - `Result<Contract, Error>`
///
/// ```rust
/// #[ink::contract]
/// mod contract {
///     #[ink(storage)]
///     pub struct Contract {}
///
///     #[derive(Debug, PartialEq, Eq, scale::Encode, scale::Decode)]
///     #[cfg_attr(feature = "std", derive(::scale_info::TypeInfo))]
///     pub enum Error {
///         Foo,
///     }
///
///     impl Contract {
///         #[ink(constructor)]
///         pub fn new_self() -> Self {
///             Self {}
///         }
///
///         #[ink(constructor)]
///         pub fn new_storage_name() -> Contract {
///             Contract {}
///         }
///
///         #[ink(constructor)]
///         pub fn new_result_self() -> Result<Self, Error> {
///             Ok(Self {})
///         }
///
///         #[ink(constructor)]
///         pub fn new_result_storage_name() -> Result<Contract, Error> {
///             Ok(Contract {})
///         }
///
///         #[ink(message)]
///         pub fn message(&self) {}
///     }
/// }
/// ```
///
/// These constructor return signatures are then used by the `ContractRef` codegen for the
/// [`CreateBuilder::returns`] type parameter.
pub trait ConstructorReturnType<C> {
    /// Is `true` if `Self` is `Result<C, E>`.
    const IS_RESULT: bool = false;

    /// The actual return type of the constructor.
    /// - If a constructor returns `Self`, then `Output = Self`
    /// - If a constructor returns a `Result<Self, E>`, then `Output = Result<Self, E>`
    type Output;

    /// The error type of the constructor return type.
    type Error: scale::Decode;

    /// Construct a success value of the `Output` type.
    fn ok(value: C) -> Self::Output;

    /// Construct an error value of the `Output` type.
    ///
    /// `Result` implementations should return `Some(Err(err))`, otherwise default to `None`.
    fn err(_err: Self::Error) -> Option<Self::Output> {
        None
    }
}

/// Blanket implementation for `ContractRef` types, generated for cross-contract calls.
///
/// In the context of a `ContractRef` inherent, `Self` from a constructor return
/// type will become the type of the `ContractRef`'s type.
impl<C> ConstructorReturnType<C> for C
where
    C: ContractEnv + FromAccountId<<C as ContractEnv>::Env>,
{
    type Output = C;
    type Error = ();

    fn ok(value: C) -> Self::Output {
        value
    }
}

/// Blanket implementation for a `Result<Self>` return type. `Self` in the context
/// of a `ContractRef` inherent becomes the `ContractRef`s type.
impl<C, E> ConstructorReturnType<C> for core::result::Result<C, E>
where
    C: ContractEnv + FromAccountId<<C as ContractEnv>::Env>,
    E: scale::Decode,
{
    const IS_RESULT: bool = true;

    type Output = core::result::Result<C, E>;
    type Error = E;

    fn ok(value: C) -> Self::Output {
        Ok(value)
    }

    fn err(err: Self::Error) -> Option<Self::Output> {
        Some(Err(err))
    }
}

/// Builds up contract instantiations.
#[derive(Debug)]
pub struct CreateParams<E, ContractRef, Args, Salt, R>
where
    E: Environment,
{
    /// The code hash of the created contract.
    code_hash: E::Hash,
    /// The maximum gas costs allowed for the instantiation.
    gas_limit: u64,
    /// The endowment for the instantiated contract.
    endowment: E::Balance,
    /// The input data for the instantiation.
    exec_input: ExecutionInput<Args>,
    /// The salt for determining the hash for the contract account ID.
    salt_bytes: Salt,
    /// The return type of the target contract's constructor method.
    _return_type: ReturnType<R>,
    /// The type of the reference to the contract returned from the constructor.
    _phantom: PhantomData<fn() -> ContractRef>,
}

impl<E, ContractRef, Args, Salt, R> CreateParams<E, ContractRef, Args, Salt, R>
where
    E: Environment,
{
    /// The code hash of the contract.
    #[inline]
    pub fn code_hash(&self) -> &E::Hash {
        &self.code_hash
    }

    /// The gas limit for the contract instantiation.
    #[inline]
    pub fn gas_limit(&self) -> u64 {
        self.gas_limit
    }

    /// The endowment for the instantiated contract.
    #[inline]
    pub fn endowment(&self) -> &E::Balance {
        &self.endowment
    }

    /// The raw encoded input data.
    #[inline]
    pub fn exec_input(&self) -> &ExecutionInput<Args> {
        &self.exec_input
    }

    /// Modify the selector.
    ///
    /// Useful when using the [`CreateParams`] generated as part of the
    /// `ContractRef`, but using a custom selector.
    pub fn update_selector(&mut self, selector: Selector) {
        self.exec_input.update_selector(selector)
    }
}

impl<E, ContractRef, Args, Salt, R> CreateParams<E, ContractRef, Args, Salt, R>
where
    E: Environment,
    Salt: AsRef<[u8]>,
{
    /// The salt for determining the hash for the contract account ID.
    #[inline]
    pub fn salt_bytes(&self) -> &Salt {
        &self.salt_bytes
    }
}

impl<E, ContractRef, Args, Salt, R> CreateParams<E, ContractRef, Args, Salt, R>
where
    E: Environment,
    ContractRef: FromAccountId<E>,
    Args: scale::Encode,
    Salt: AsRef<[u8]>,
    R: ConstructorReturnType<ContractRef>,
{
    /// Instantiates the contract and returns its account ID back to the caller.
    ///
    /// # Panics
    ///
    /// This method panics if it encounters an [`ink::env::Error`][`crate::Error`] or an
    /// [`ink::primitives::LangError`][`ink_primitives::LangError`]. If you want to handle those
    /// use the [`try_instantiate`][`CreateParams::try_instantiate`] method instead.
    #[inline]
    pub fn instantiate(&self) -> <R as ConstructorReturnType<ContractRef>>::Output {
        crate::instantiate_contract(self)
            .unwrap_or_else(|env_error| {
                panic!("Cross-contract instantiation failed with {env_error:?}")
            })
            .unwrap_or_else(|lang_error| {
                panic!("Received a `LangError` while instantiating: {lang_error:?}")
            })
    }

    /// Instantiates the contract and returns its account ID back to the caller.
    ///
    /// # Note
    ///
    /// On failure this returns an outer [`ink::env::Error`][`crate::Error`] or inner
    /// [`ink::primitives::LangError`][`ink_primitives::LangError`], both of which can be handled
    /// by the caller.
    #[inline]
    pub fn try_instantiate(
        &self,
    ) -> Result<
        ink_primitives::ConstructorResult<
            <R as ConstructorReturnType<ContractRef>>::Output,
        >,
        crate::Error,
    > {
        crate::instantiate_contract(self)
    }
}

/// Builds up contract instantiations.
pub struct CreateBuilder<
    E,
    ContractRef,
    CodeHash,
    GasLimit,
    Endowment,
    Args,
    Salt,
    RetType,
> where
    E: Environment,
{
    code_hash: CodeHash,
    gas_limit: GasLimit,
    endowment: Endowment,
    exec_input: Args,
    salt: Salt,
    return_type: RetType,
    _phantom: PhantomData<fn() -> (E, ContractRef)>,
}

/// Returns a new [`CreateBuilder`] to build up the parameters to a cross-contract instantiation.
///
/// # Example
///
/// **Note:** The shown examples panic because there is currently no cross-calling
///           support in the off-chain testing environment. However, this code
///           should work fine in on-chain environments.
///
/// ## Example 1: Returns Address of Instantiated Contract
///
/// The below example shows instantiation of contract of type `MyContract`.
///
/// The used constructor:
///
/// - has a selector equal to `0xDEADBEEF`
/// - is provided with 4000 units of gas for its execution
/// - is provided with 25 units of transferred value for the new contract instance
/// - receives the following arguments in order
///    1. an `i32` with value `42`
///    2. a `bool` with value `true`
///    3. an array of 32 `u8` with value `0x10`
///
/// ```should_panic
/// # use ::ink_env::{
/// #     Environment,
/// #     DefaultEnvironment,
/// #     call::{build_create, Selector, ExecutionInput, FromAccountId}
/// # };
/// # type Hash = <DefaultEnvironment as Environment>::Hash;
/// #
/// # #[ink::contract]
/// # pub mod contract {
/// #     #[ink(storage)]
/// #     pub struct MyContract {}
/// #
/// #     impl MyContract {
/// #         #[ink(constructor)]
/// #         pub fn my_constructor() -> Self { Self {} }
/// #
/// #         #[ink(message)]
/// #         pub fn message(&self) {}
/// #     }
/// # }
/// # use contract::MyContractRef;
/// let my_contract: MyContractRef = build_create::<MyContractRef>()
///     .code_hash(Hash::from([0x42; 32]))
///     .gas_limit(4000)
///     .endowment(25)
///     .exec_input(
///         ExecutionInput::new(Selector::new(ink::selector_bytes!("my_constructor")))
///             .push_arg(42)
///             .push_arg(true)
///             .push_arg(&[0x10u8; 32])
///     )
///     .salt_bytes(&[0xDE, 0xAD, 0xBE, 0xEF])
///     .returns::<MyContractRef>()
///     .instantiate();
/// ```
///
/// ## Example 2: Handles Result from Fallible Constructor
///
/// ```should_panic
/// # use ::ink_env::{
/// #     Environment,
/// #     DefaultEnvironment,
/// #     call::{build_create, Selector, ExecutionInput, FromAccountId}
/// # };
/// # type Hash = <DefaultEnvironment as Environment>::Hash;
/// #
/// # #[ink::contract]
/// # pub mod contract {
/// #     #[derive(scale::Encode, scale::Decode, Debug)]
/// #     #[cfg_attr(feature = "std", derive(scale_info::TypeInfo))]
/// #     pub struct ConstructorError;
/// #
/// #     #[ink(storage)]
/// #     pub struct MyContract {}
/// #
/// #     impl MyContract {
/// #         #[ink(constructor)]
/// #         pub fn my_constructor() -> Result<Self, ConstructorError> {
/// #             Ok(Self {})
/// #         }
/// #
/// #         #[ink(message)]
/// #         pub fn message(&self) {}
/// #     }
/// # }
/// # use contract::{MyContractRef, ConstructorError};
/// let my_contract: MyContractRef = build_create::<MyContractRef>()
///     .code_hash(Hash::from([0x42; 32]))
///     .gas_limit(4000)
///     .endowment(25)
///     .exec_input(
///         ExecutionInput::new(Selector::new(ink::selector_bytes!("my_constructor")))
///             .push_arg(42)
///             .push_arg(true)
///             .push_arg(&[0x10u8; 32])
///     )
///     .salt_bytes(&[0xDE, 0xAD, 0xBE, 0xEF])
///     .returns::<Result<MyContractRef, ConstructorError>>()
///     .instantiate()
///     .expect("Constructor should have executed succesfully.");
/// ```
#[allow(clippy::type_complexity)]
pub fn build_create<ContractRef>() -> CreateBuilder<
    <ContractRef as ContractEnv>::Env,
    ContractRef,
    Unset<<<ContractRef as ContractEnv>::Env as Environment>::Hash>,
    Unset<u64>,
    Unset<<<ContractRef as ContractEnv>::Env as Environment>::Balance>,
    Unset<ExecutionInput<EmptyArgumentList>>,
    Unset<state::Salt>,
    Unset<ReturnType<()>>,
>
where
    ContractRef: ContractEnv,
{
    CreateBuilder {
        code_hash: Default::default(),
        gas_limit: Default::default(),
        endowment: Default::default(),
        exec_input: Default::default(),
        salt: Default::default(),
        return_type: Default::default(),
        _phantom: Default::default(),
    }
}

impl<E, ContractRef, GasLimit, Endowment, Args, Salt, RetType>
    CreateBuilder<
        E,
        ContractRef,
        Unset<E::Hash>,
        GasLimit,
        Endowment,
        Args,
        Salt,
        RetType,
    >
where
    E: Environment,
{
    /// Sets the used code hash for the contract instantiation.
    #[inline]
    pub fn code_hash(
        self,
        code_hash: E::Hash,
    ) -> CreateBuilder<
        E,
        ContractRef,
        Set<E::Hash>,
        GasLimit,
        Endowment,
        Args,
        Salt,
        RetType,
    > {
        CreateBuilder {
            code_hash: Set(code_hash),
            gas_limit: self.gas_limit,
            endowment: self.endowment,
            exec_input: self.exec_input,
            salt: self.salt,
            return_type: self.return_type,
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, CodeHash, Endowment, Args, Salt, RetType>
    CreateBuilder<E, ContractRef, CodeHash, Unset<u64>, Endowment, Args, Salt, RetType>
where
    E: Environment,
{
    /// Sets the maximum allowed gas costs for the contract instantiation.
    #[inline]
    pub fn gas_limit(
        self,
        gas_limit: u64,
    ) -> CreateBuilder<E, ContractRef, CodeHash, Set<u64>, Endowment, Args, Salt, RetType>
    {
        CreateBuilder {
            code_hash: self.code_hash,
            gas_limit: Set(gas_limit),
            endowment: self.endowment,
            exec_input: self.exec_input,
            salt: self.salt,
            return_type: self.return_type,
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, CodeHash, GasLimit, Args, Salt, RetType>
    CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Unset<E::Balance>,
        Args,
        Salt,
        RetType,
    >
where
    E: Environment,
{
    /// Sets the value transferred upon the execution of the call.
    #[inline]
    pub fn endowment(
        self,
        endowment: E::Balance,
    ) -> CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Set<E::Balance>,
        Args,
        Salt,
        RetType,
    > {
        CreateBuilder {
            code_hash: self.code_hash,
            gas_limit: self.gas_limit,
            endowment: Set(endowment),
            exec_input: self.exec_input,
            salt: self.salt,
            return_type: self.return_type,
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, CodeHash, GasLimit, Endowment, Salt, RetType>
    CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Unset<ExecutionInput<EmptyArgumentList>>,
        Salt,
        RetType,
    >
where
    E: Environment,
{
    /// Sets the value transferred upon the execution of the call.
    #[inline]
    pub fn exec_input<Args>(
        self,
        exec_input: ExecutionInput<Args>,
    ) -> CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Set<ExecutionInput<Args>>,
        Salt,
        RetType,
    > {
        CreateBuilder {
            code_hash: self.code_hash,
            gas_limit: self.gas_limit,
            endowment: self.endowment,
            exec_input: Set(exec_input),
            salt: self.salt,
            return_type: self.return_type,
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, CodeHash, GasLimit, Endowment, Args, RetType>
    CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Args,
        Unset<state::Salt>,
        RetType,
    >
where
    E: Environment,
{
    /// Sets the value transferred upon the execution of the call.
    #[inline]
    pub fn salt_bytes<Salt>(
        self,
        salt: Salt,
    ) -> CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Args,
        Set<Salt>,
        RetType,
    >
    where
        Salt: AsRef<[u8]>,
    {
        CreateBuilder {
            code_hash: self.code_hash,
            gas_limit: self.gas_limit,
            endowment: self.endowment,
            exec_input: self.exec_input,
            salt: Set(salt),
            return_type: self.return_type,
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, CodeHash, GasLimit, Endowment, Args, Salt>
    CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Args,
        Salt,
        Unset<ReturnType<()>>,
    >
where
    E: Environment,
{
    /// Sets the type of the returned value upon the execution of the constructor.
    ///
    /// # Note
    ///
    /// Constructors are not able to return arbitrary values. Instead a successful call to a
    /// constructor returns the address at which the contract was instantiated.
    ///
    /// Therefore this must always be a reference (i.e `ContractRef`) to the contract you're trying
    /// to instantiate.
    #[inline]
    pub fn returns<R>(
        self,
    ) -> CreateBuilder<
        E,
        ContractRef,
        CodeHash,
        GasLimit,
        Endowment,
        Args,
        Salt,
        Set<ReturnType<R>>,
    >
    where
        ContractRef: FromAccountId<E>,
        R: ConstructorReturnType<ContractRef>,
    {
        CreateBuilder {
            code_hash: self.code_hash,
            gas_limit: self.gas_limit,
            endowment: self.endowment,
            exec_input: self.exec_input,
            salt: self.salt,
            return_type: Set(Default::default()),
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, GasLimit, Args, Salt, RetType>
    CreateBuilder<
        E,
        ContractRef,
        Set<E::Hash>,
        GasLimit,
        Set<E::Balance>,
        Set<ExecutionInput<Args>>,
        Set<Salt>,
        Set<ReturnType<RetType>>,
    >
where
    E: Environment,
    GasLimit: Unwrap<Output = u64>,
{
    /// Finalizes the create builder, allowing it to instantiate a contract.
    #[inline]
    pub fn params(self) -> CreateParams<E, ContractRef, Args, Salt, RetType> {
        CreateParams {
            code_hash: self.code_hash.value(),
            gas_limit: self.gas_limit.unwrap_or_else(|| 0),
            endowment: self.endowment.value(),
            exec_input: self.exec_input.value(),
            salt_bytes: self.salt.value(),
            _return_type: Default::default(),
            _phantom: Default::default(),
        }
    }
}

impl<E, ContractRef, GasLimit, Args, Salt, RetType>
    CreateBuilder<
        E,
        ContractRef,
        Set<E::Hash>,
        GasLimit,
        Set<E::Balance>,
        Set<ExecutionInput<Args>>,
        Set<Salt>,
        Set<ReturnType<RetType>>,
    >
where
    E: Environment,
    ContractRef: FromAccountId<E>,
    GasLimit: Unwrap<Output = u64>,
    Args: scale::Encode,
    Salt: AsRef<[u8]>,
    RetType: ConstructorReturnType<ContractRef>,
{
    /// Instantiates the contract and returns its account ID back to the caller.
    ///
    /// # Panics
    ///
    /// This method panics if it encounters an [`ink::env::Error`][`crate::Error`] or an
    /// [`ink::primitives::LangError`][`ink_primitives::LangError`]. If you want to handle those
    /// use the [`try_instantiate`][`CreateBuilder::try_instantiate`] method instead.
    #[inline]
    pub fn instantiate(self) -> <RetType as ConstructorReturnType<ContractRef>>::Output {
        self.params().instantiate()
    }

    /// Instantiates the contract and returns its account ID back to the caller.
    ///
    /// # Note
    ///
    /// On failure this returns an outer [`ink::env::Error`][`crate::Error`] or inner
    /// [`ink::primitives::LangError`][`ink_primitives::LangError`], both of which can be handled
    /// by the caller.
    #[inline]
    pub fn try_instantiate(
        self,
    ) -> Result<
        ink_primitives::ConstructorResult<
            <RetType as ConstructorReturnType<ContractRef>>::Output,
        >,
        Error,
    > {
        self.params().try_instantiate()
    }
}