// Copyright (C) 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::{CallFlags, Result, ReturnFlags, StorageFlags};
use pezpallet_revive_proc_macro::unstable_hostfn;

#[cfg(target_arch = "riscv64")]
mod riscv64;

/// Implements [`HostFn`] when compiled on supported architectures (RISC-V).
pub enum HostFnImpl {}

/// Defines all the host apis available to contracts.
pub trait HostFn: private::Sealed {
	/// Stores the address of the current contract into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the address.
	fn address(output: &mut [u8; 20]);

	/// Get the contract immutable data.
	///
	/// Traps if:
	/// - Called from within the deploy export.
	/// - Called by contracts that didn't set immutable data by calling `set_immutable_data` during
	///   their constructor execution.
	///
	/// # Parameters
	/// - `output`: A reference to the output buffer to write the immutable bytes.
	fn get_immutable_data(output: &mut &mut [u8]);

	/// Set the contract immutable data.
	///
	/// It is only valid to set non-empty immutable data in the constructor once.
	///
	/// Traps if:
	/// - Called from within the call export.
	/// - Called more than once.
	/// - The provided data was empty.
	///
	/// # Parameters
	/// - `data`: A reference to the data to be stored as immutable bytes.
	fn set_immutable_data(data: &[u8]);

	/// Stores the **reducible** balance of the current account into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the balance.
	fn balance(output: &mut [u8; 32]);

	/// Stores the **reducible** balance of the supplied address into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `addr`: The target address of which to retreive the free balance.
	/// - `output`: A reference to the output data buffer to write the balance.
	fn balance_of(addr: &[u8; 20], output: &mut [u8; 32]);

	/// Returns the [EIP-155](https://eips.ethereum.org/EIPS/eip-155) chain ID.
	fn chain_id(output: &mut [u8; 32]);

	/// Returns the price per ref_time, akin to the EVM
	/// [GASPRICE](https://www.evm.codes/?fork=cancun#3a) opcode.
	fn gas_price() -> u64;

	/// Returns the base fee, akin to the EVM
	/// [BASEFEE](https://www.evm.codes/?fork=cancun#48) opcode.
	fn base_fee(output: &mut [u8; 32]);

	/// Returns the call data size.
	fn call_data_size() -> u64;

	/// Call (possibly transferring some amount of funds) into the specified account.
	///
	/// # Parameters
	///
	/// - `flags`: See [`CallFlags`] for a documentation of the supported flags.
	/// - `callee`: The address of the callee. Should be decodable as an `T::AccountId`. Traps
	///   otherwise.
	/// - `ref_time_limit`: how much *ref_time* Weight to devote to the execution.
	/// - `proof_size_limit`: how much *proof_size* Weight to devote to the execution.
	/// - `deposit`: The storage deposit limit for instantiation. Passing `None` means setting no
	///   specific limit for the call, which implies storage usage up to the limit of the parent
	///   call.
	/// - `value`: The value to transfer into the contract.
	/// - `input`: The input data buffer used to call the contract.
	/// - `output`: A reference to the output data buffer to write the call output buffer. If `None`
	///   is provided then the output buffer is not copied.
	///
	/// # Errors
	///
	/// An error means that the call wasn't successful output buffer is returned unless
	/// stated otherwise.
	///
	/// - [CalleeReverted][`crate::ReturnErrorCode::CalleeReverted]: Output buffer is returned.
	/// - [CalleeTrapped][`crate::ReturnErrorCode::CalleeTrapped]
	/// - [TransferFailed][`crate::ReturnErrorCode::TransferFailed]
	/// - [OutOfResources][`crate::ReturnErrorCode::OutOfResources]
	fn call(
		flags: CallFlags,
		callee: &[u8; 20],
		ref_time_limit: u64,
		proof_size_limit: u64,
		deposit: &[u8; 32],
		value: &[u8; 32],
		input_data: &[u8],
		output: Option<&mut &mut [u8]>,
	) -> Result;

	/// Stores the address of the caller into the supplied buffer.
	///
	/// If this is a top-level call (i.e. initiated by an extrinsic) the origin address of the
	/// extrinsic will be returned. Otherwise, if this call is initiated by another contract then
	/// the address of the contract will be returned.
	///
	/// If there is no address associated with the caller (e.g. because the caller is root) then
	/// it traps with `BadOrigin`.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the caller address.
	fn caller(output: &mut [u8; 20]);

	/// Stores the origin address (initator of the call stack) into the supplied buffer.
	///
	/// If there is no address associated with the origin (e.g. because the origin is root) then
	/// it traps with `BadOrigin`. This can only happen through on-chain governance actions or
	/// customized runtimes.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the origin's address.
	fn origin(output: &mut [u8; 20]);

	/// Retrieve the code hash for a specified contract address.
	///
	/// # Parameters
	///
	/// - `addr`: The address of the contract.
	/// - `output`: A reference to the output data buffer to write the code hash.
	///
	/// # Note
	///
	/// If `addr` is not a contract but the account exists then the hash of empty data
	/// `0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470` is written,
	/// otherwise `zero`.
	fn code_hash(addr: &[u8; 20], output: &mut [u8; 32]);

	/// Returns the code size for a specified contract address.
	///
	/// # Parameters
	///
	/// - `addr`: The address of the contract.
	///
	/// # Note
	///
	/// If `addr` is not a contract the `output` will be zero.
	fn code_size(addr: &[u8; 20]) -> u64;

	/// Execute code in the context (storage, caller, value) of the current contract.
	///
	/// Reentrancy protection is always disabled since the callee is allowed
	/// to modify the callers storage. This makes going through a reentrancy attack
	/// unnecessary for the callee when it wants to exploit the caller.
	///
	/// # Parameters
	///
	/// - `flags`: See [`CallFlags`] for a documentation of the supported flags.
	/// - `address`: The address of the code to be executed. Should be decodable as an
	///   `T::AccountId`. Traps otherwise.
	/// - `ref_time_limit`: how much *ref_time* Weight to devote to the execution.
	/// - `proof_size_limit`: how much *proof_size* Weight to devote to the execution.
	/// - `deposit_limit`: The storage deposit limit for delegate call. Passing `None` means setting
	///   no specific limit for the call, which implies storage usage up to the limit of the parent
	///   call.
	/// - `input`: The input data buffer used to call the contract.
	/// - `output`: A reference to the output data buffer to write the call output buffer. If `None`
	///   is provided then the output buffer is not copied.
	///
	/// # Errors
	///
	/// An error means that the call wasn't successful and no output buffer is returned unless
	/// stated otherwise.
	///
	/// - [CalleeReverted][`crate::ReturnErrorCode::CalleeReverted]: Output buffer is returned.
	/// - [CalleeTrapped][`crate::ReturnErrorCode::CalleeTrapped]
	/// - [OutOfResources][`crate::ReturnErrorCode::OutOfResources]
	fn delegate_call(
		flags: CallFlags,
		address: &[u8; 20],
		ref_time_limit: u64,
		proof_size_limit: u64,
		deposit_limit: &[u8; 32],
		input_data: &[u8],
		output: Option<&mut &mut [u8]>,
	) -> Result;

	/// Deposit a contract event with the data buffer and optional list of topics. There is a limit
	/// on the maximum number of topics specified by `event_topics`.
	///
	/// There should not be any duplicates in `topics`.
	///
	/// # Parameters
	///
	/// - `topics`: The topics list. It can't contain duplicates.
	fn deposit_event(topics: &[[u8; 32]], data: &[u8]);

	/// Retrieve the value under the given key from storage.
	///
	/// The key length must not exceed the maximum defined by the `pezpallet-revive` parameter.
	///
	/// # Parameters
	/// - `key`: The storage key.
	/// - `output`: A reference to the output data buffer to write the storage entry.
	///
	/// # Errors
	///
	/// [KeyNotFound][`crate::ReturnErrorCode::KeyNotFound]
	fn get_storage(flags: StorageFlags, key: &[u8], output: &mut &mut [u8]) -> Result;

	/// Computes the keccak_256 32-bit hash on the given input buffer.
	///
	/// - The `input` and `output` buffer may overlap.
	/// - The output buffer is expected to hold at least 32 bits.
	/// - It is the callers responsibility to provide an output buffer that is large enough to hold
	///   the expected amount of bytes returned by the hash function.
	///
	/// # Parameters
	///
	/// - `input`: The input data buffer.
	/// - `output`: The output buffer to write the hash result to.
	fn hash_keccak_256(input: &[u8], output: &mut [u8; 32]);

	/// Stores the input data passed by the caller into the supplied `output` buffer,
	/// starting from the given input data `offset`.
	///
	/// The `output` buffer is guaranteed to always be fully populated:
	/// - If the call data (starting from the given `offset`) is larger than the `output` buffer,
	///   only what fits into the `output` buffer is written.
	/// - If the `output` buffer size exceeds the call data size (starting from `offset`), remaining
	///   bytes in the `output` buffer are zeroed out.
	/// - If the provided call data `offset` is out-of-bounds, the whole `output` buffer is zeroed
	///   out.
	///
	/// # Note
	///
	/// This function traps if:
	/// - the input was previously forwarded by a [`call()`][`Self::call()`].
	/// - the `output` buffer is located in an PolkaVM invalid memory range.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the call data.
	/// - `offset`: The offset index into the call data from where to start copying.
	fn call_data_copy(output: &mut [u8], offset: u32);

	/// Stores the U256 value at given `offset` from the input passed by the caller
	/// into the supplied buffer.
	///
	/// # Note
	/// - If `offset` is out of bounds, a value of zero will be returned.
	/// - If `offset` is in bounds but there is not enough call data, the available data
	/// is right-padded in order to fill a whole U256 value.
	/// - The data written to `output` is a little endian U256 integer value.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the fixed output data buffer to write the value.
	/// - `offset`: The offset (index) into the call data.
	fn call_data_load(output: &mut [u8; 32], offset: u32);

	/// Instantiate a contract with the specified code hash.
	///
	/// This function creates an account and executes the constructor defined in the code specified
	/// by the code hash.
	///
	/// # Parameters
	///
	/// - `ref_time_limit`: how much *ref_time* Weight to devote to the execution.
	/// - `proof_size_limit`: how much *proof_size* Weight to devote to the execution.
	/// - `deposit`: The storage deposit limit for instantiation. Passing `None` means setting no
	///   specific limit for the call, which implies storage usage up to the limit of the parent
	///   call.
	/// - `value`: The value to transfer into the contract.
	/// - `input`: The code hash and constructor input data buffer. The first 32 bytes are the code
	///   hash of the code to be instantiated. The remaining bytes are the constructor call data.
	/// - `address`: A reference to the address buffer to write the address of the contract. If
	///   `None` is provided then the output buffer is not copied.
	/// - `output`: A reference to the return value buffer to write the constructor output buffer.
	///   If `None` is provided then the output buffer is not copied.
	/// - `salt`: The salt bytes to use for this instantiation.
	///
	/// # Errors
	///
	/// Please consult the [ReturnErrorCode][`crate::ReturnErrorCode`] enum declaration for more
	/// information on those errors. Here we only note things specific to this function.
	///
	/// An error means that the account wasn't created and no address or output buffer
	/// is returned unless stated otherwise.
	///
	/// - [CalleeReverted][`crate::ReturnErrorCode::CalleeReverted]: Output buffer is returned.
	/// - [CalleeTrapped][`crate::ReturnErrorCode::CalleeTrapped]
	/// - [TransferFailed][`crate::ReturnErrorCode::TransferFailed]
	/// - [OutOfResources][`crate::ReturnErrorCode::OutOfResources]
	fn instantiate(
		ref_time_limit: u64,
		proof_size_limit: u64,
		deposit: &[u8; 32],
		value: &[u8; 32],
		input: &[u8],
		address: Option<&mut [u8; 20]>,
		output: Option<&mut &mut [u8]>,
		salt: Option<&[u8; 32]>,
	) -> Result;

	/// Load the latest block timestamp in seconds into the supplied buffer
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the timestamp.
	fn now(output: &mut [u8; 32]);

	/// Returns the block ref_time limit.
	fn gas_limit() -> u64;

	/// Cease contract execution and save a data buffer as a result of the execution.
	///
	/// This function never returns as it stops execution of the caller.
	/// This is the only way to return a data buffer to the caller. Returning from
	/// execution without calling this function is equivalent to calling:
	/// ```nocompile
	/// return_value(ReturnFlags::empty(), &[])
	/// ```
	///
	/// Using an unnamed non empty `ReturnFlags` triggers a trap.
	///
	/// # Parameters
	///
	/// - `flags`: Flag used to signal special return conditions to the supervisor. See
	///   [`ReturnFlags`] for a documentation of the supported flags.
	/// - `return_value`: The return value buffer.
	fn return_value(flags: ReturnFlags, return_value: &[u8]) -> !;

	/// Set the value at the given key in the contract storage.
	///
	/// The key and value lengths must not exceed the maximums defined by the `pezpallet-revive`
	/// parameters.
	///
	/// # Parameters
	///
	/// - `key`: The storage key.
	/// - `encoded_value`: The storage value.
	///
	/// # Return
	///
	/// Returns the size of the pre-existing value at the specified key if any.
	fn set_storage(flags: StorageFlags, key: &[u8], value: &[u8]) -> Option<u32>;

	/// Sets the storage entry for a fixed 256‑bit key with a fixed 256‑bit value.
	///
	/// If the provided 32‑byte value is all zeros then the key is cleared (i.e. deleted),
	/// mimicking Ethereum’s SSTORE behavior.
	///
	/// # Parameters
	/// - `key`: The fixed 256‑bit storage key (32 bytes).
	/// - `value`: The fixed 256‑bit storage value (32 bytes).
	///
	/// # Return
	/// Returns the size (in bytes) of the pre‑existing value at the specified key, if any.
	fn set_storage_or_clear(flags: StorageFlags, key: &[u8; 32], value: &[u8; 32]) -> Option<u32>;

	/// Retrieves the storage entry for a fixed 256‑bit key.
	///
	/// If the key does not exist, the output buffer is filled with 32 zero bytes.
	///
	/// # Parameters
	/// - `key`: The fixed 256‑bit storage key (32 bytes).
	/// - `output`: A mutable output buffer (32 bytes) where the storage entry is written.
	fn get_storage_or_zero(flags: StorageFlags, key: &[u8; 32], output: &mut [u8; 32]);

	/// Stores the value transferred along with this call/instantiate into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the transferred value.
	fn value_transferred(output: &mut [u8; 32]);

	/// Returns the size of the returned data of the last contract call or instantiation.
	fn return_data_size() -> u64;

	/// Stores the returned data of the last contract call or contract instantiation.
	///
	/// # Parameters
	/// - `output`: A reference to the output buffer to write the data.
	/// - `offset`: Byte offset into the returned data
	fn return_data_copy(output: &mut &mut [u8], offset: u32);

	/// Returns the amount of ethereum gas left.
	fn gas_left() -> u64;

	/// Stores the current block author of into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the block author.
	fn block_author(output: &mut [u8; 20]);

	/// Stores the current block number of the current contract into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `output`: A reference to the output data buffer to write the block number.
	fn block_number(output: &mut [u8; 32]);

	/// Stores the block hash of the given block number into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `block_number`: A reference to the block number buffer.
	/// - `output`: A reference to the output data buffer to write the block number.
	fn block_hash(block_number: &[u8; 32], output: &mut [u8; 32]);

	/// Reverts the execution and cedes all supplied gas,
	/// akin to the `INVALID` EVM opcode.
	fn consume_all_gas() -> !;

	/// Calculates Ethereum address from the ECDSA compressed public key and stores
	/// it into the supplied buffer.
	///
	/// # Parameters
	///
	/// - `pubkey`: The public key bytes.
	/// - `output`: A reference to the output data buffer to write the address.
	///
	/// # Errors
	///
	/// - [EcdsaRecoveryFailed][`crate::ReturnErrorCode::EcdsaRecoveryFailed]
	#[unstable_hostfn]
	fn ecdsa_to_eth_address(pubkey: &[u8; 33], output: &mut [u8; 20]) -> Result;

	/// Replace the contract code at the specified address with new code.
	///
	/// # Note
	///
	/// There are a couple of important considerations which must be taken into account when
	/// using this API:
	///
	/// 1. The storage at the code address will remain untouched. This means that contract
	/// developers must ensure that the storage layout of the new code is compatible with that of
	/// the old code.
	///
	/// 2. Contracts using this API can't be assumed as having deterministic addresses. Said another
	/// way, when using this API you lose the guarantee that an address always identifies a specific
	/// code hash.
	///
	/// 3. If a contract calls into itself after changing its code the new call would use
	/// the new code. However, if the original caller panics after returning from the sub call it
	/// would revert the changes made by [`set_code_hash()`][`Self::set_code_hash`] and the next
	/// caller would use the old code.
	///
	/// # Parameters
	///
	/// - `code_hash`: The hash of the new code. Should be decodable as an `T::Hash`. Traps
	///   otherwise.
	///
	/// # Panics
	///
	/// Panics if there is no code on-chain with the specified hash.
	#[unstable_hostfn]
	fn set_code_hash(code_hash: &[u8; 32]);

	/// Verify a sr25519 signature
	///
	/// # Parameters
	///
	/// - `signature`: The signature bytes.
	/// - `message`: The message bytes.
	///
	/// # Errors
	///
	/// - [Sr25519VerifyFailed][`crate::ReturnErrorCode::Sr25519VerifyFailed]
	#[unstable_hostfn]
	fn sr25519_verify(signature: &[u8; 64], message: &[u8], pub_key: &[u8; 32]) -> Result;

	/// Remove the calling account and transfer remaining **free** balance.
	///
	/// This function never returns. Either the termination was successful and the
	/// execution of the destroyed contract is halted. Or it failed during the termination
	/// which is considered fatal and results in a trap + rollback.
	///
	/// # Parameters
	///
	/// - `beneficiary`: The address of the beneficiary account
	///
	/// # Traps
	///
	/// - The contract is live i.e is already on the call stack.
	/// - Failed to send the balance to the beneficiary.
	/// - The deletion queue is full.
	#[unstable_hostfn]
	fn terminate(beneficiary: &[u8; 20]) -> !;
}

mod private {
	pub trait Sealed {}
	impl Sealed for super::HostFnImpl {}
}