// 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 super::EnvInstance;
use crate::{
    call::{
        Call,
        CallParams,
        CallV1,
        ConstructorReturnType,
        CreateParams,
        DelegateCall,
        FromAccountId,
        LimitParamsV1,
        LimitParamsV2,
    },
    event::{
        Event,
        TopicsBuilderBackend,
    },
    hash::{
        Blake2x128,
        Blake2x256,
        CryptoHash,
        HashOutput,
        Keccak256,
        Sha2x256,
    },
    Clear,
    EnvBackend,
    Environment,
    Result,
    TypedEnvBackend,
};
use ink_engine::ext::Engine;
use ink_storage_traits::{
    decode_all,
    Storable,
};
use pallet_contracts_uapi::{
    ReturnErrorCode,
    ReturnFlags,
};
use schnorrkel::{
    PublicKey,
    Signature,
};

/// The capacity of the static buffer.
/// This is the same size as the ink! on-chain environment. We chose to use the same size
/// to be as close to the on-chain behavior as possible.
const BUFFER_SIZE: usize = crate::BUFFER_SIZE;

impl CryptoHash for Blake2x128 {
    fn hash(input: &[u8], output: &mut <Self as HashOutput>::Type) {
        type OutputType = [u8; 16];
        static_assertions::assert_type_eq_all!(
            <Blake2x128 as HashOutput>::Type,
            OutputType
        );
        let output: &mut OutputType = array_mut_ref!(output, 0, 16);
        Engine::hash_blake2_128(input, output);
    }
}

impl CryptoHash for Blake2x256 {
    fn hash(input: &[u8], output: &mut <Self as HashOutput>::Type) {
        type OutputType = [u8; 32];
        static_assertions::assert_type_eq_all!(
            <Blake2x256 as HashOutput>::Type,
            OutputType
        );
        let output: &mut OutputType = array_mut_ref!(output, 0, 32);
        Engine::hash_blake2_256(input, output);
    }
}

impl CryptoHash for Sha2x256 {
    fn hash(input: &[u8], output: &mut <Self as HashOutput>::Type) {
        type OutputType = [u8; 32];
        static_assertions::assert_type_eq_all!(
            <Sha2x256 as HashOutput>::Type,
            OutputType
        );
        let output: &mut OutputType = array_mut_ref!(output, 0, 32);
        Engine::hash_sha2_256(input, output);
    }
}

impl CryptoHash for Keccak256 {
    fn hash(input: &[u8], output: &mut <Self as HashOutput>::Type) {
        type OutputType = [u8; 32];
        static_assertions::assert_type_eq_all!(
            <Keccak256 as HashOutput>::Type,
            OutputType
        );
        let output: &mut OutputType = array_mut_ref!(output, 0, 32);
        Engine::hash_keccak_256(input, output);
    }
}

#[derive(Default)]
pub struct TopicsBuilder {
    pub topics: Vec<Vec<u8>>,
}

impl<E> TopicsBuilderBackend<E> for TopicsBuilder
where
    E: Environment,
{
    type Output = Vec<u8>;

    fn expect(&mut self, _expected_topics: usize) {}

    fn push_topic<T>(&mut self, topic_value: &T)
    where
        T: scale::Encode,
    {
        let encoded = topic_value.encode();
        let len_encoded = encoded.len();
        let mut result = <E as Environment>::Hash::CLEAR_HASH;
        let len_result = result.as_ref().len();
        if len_encoded <= len_result {
            result.as_mut()[..len_encoded].copy_from_slice(&encoded[..]);
        } else {
            let mut hash_output = <Blake2x256 as HashOutput>::Type::default();
            <Blake2x256 as CryptoHash>::hash(&encoded[..], &mut hash_output);
            let copy_len = core::cmp::min(hash_output.len(), len_result);
            result.as_mut()[0..copy_len].copy_from_slice(&hash_output[0..copy_len]);
        }
        let off_hash = result.as_ref();
        let off_hash = off_hash.to_vec();
        self.topics.push(off_hash);
    }

    fn output(self) -> Self::Output {
        let mut all: Vec<u8> = Vec::new();

        let topics_len_compact = &scale::Compact(self.topics.len() as u32);
        let topics_encoded = &scale::Encode::encode(&topics_len_compact)[..];
        all.append(&mut topics_encoded.to_vec());

        self.topics.into_iter().for_each(|mut v| all.append(&mut v));
        all
    }
}

impl EnvInstance {
    /// Returns the contract property value.
    fn get_property<T>(
        &mut self,
        ext_fn: fn(engine: &Engine, output: &mut &mut [u8]),
    ) -> Result<T>
    where
        T: scale::Decode,
    {
        let mut full_scope: [u8; BUFFER_SIZE] = [0; BUFFER_SIZE];
        let full_scope = &mut &mut full_scope[..];
        ext_fn(&self.engine, full_scope);
        scale::Decode::decode(&mut &full_scope[..]).map_err(Into::into)
    }
}

impl EnvBackend for EnvInstance {
    fn set_contract_storage<K, V>(&mut self, key: &K, value: &V) -> Option<u32>
    where
        K: scale::Encode,
        V: Storable,
    {
        let mut v = vec![];
        Storable::encode(value, &mut v);
        self.engine.set_storage(&key.encode(), &v[..])
    }

    fn get_contract_storage<K, R>(&mut self, key: &K) -> Result<Option<R>>
    where
        K: scale::Encode,
        R: Storable,
    {
        match self.engine.get_storage(&key.encode()) {
            Ok(res) => {
                let decoded = decode_all(&mut &res[..])?;
                Ok(Some(decoded))
            }
            Err(ReturnErrorCode::KeyNotFound) => Ok(None),
            Err(_) => panic!("encountered unexpected error"),
        }
    }

    fn take_contract_storage<K, R>(&mut self, key: &K) -> Result<Option<R>>
    where
        K: scale::Encode,
        R: Storable,
    {
        match self.engine.take_storage(&key.encode()) {
            Ok(output) => {
                let decoded = decode_all(&mut &output[..])?;
                Ok(Some(decoded))
            }
            Err(ReturnErrorCode::KeyNotFound) => Ok(None),
            Err(_) => panic!("encountered unexpected error"),
        }
    }

    fn contains_contract_storage<K>(&mut self, key: &K) -> Option<u32>
    where
        K: scale::Encode,
    {
        self.engine.contains_storage(&key.encode())
    }

    fn clear_contract_storage<K>(&mut self, key: &K) -> Option<u32>
    where
        K: scale::Encode,
    {
        self.engine.clear_storage(&key.encode())
    }

    fn decode_input<T>(&mut self) -> Result<T>
    where
        T: scale::Decode,
    {
        unimplemented!("the off-chain env does not implement `input`")
    }

    fn return_value<R>(&mut self, _flags: ReturnFlags, _return_value: &R) -> !
    where
        R: scale::Encode,
    {
        unimplemented!("the off-chain env does not implement `return_value`")
    }

    fn debug_message(&mut self, message: &str) {
        self.engine.debug_message(message)
    }

    fn hash_bytes<H>(&mut self, input: &[u8], output: &mut <H as HashOutput>::Type)
    where
        H: CryptoHash,
    {
        <H as CryptoHash>::hash(input, output)
    }

    fn hash_encoded<H, T>(&mut self, input: &T, output: &mut <H as HashOutput>::Type)
    where
        H: CryptoHash,
        T: scale::Encode,
    {
        let enc_input = &scale::Encode::encode(input)[..];
        <H as CryptoHash>::hash(enc_input, output)
    }

    fn ecdsa_recover(
        &mut self,
        signature: &[u8; 65],
        message_hash: &[u8; 32],
        output: &mut [u8; 33],
    ) -> Result<()> {
        use secp256k1::{
            ecdsa::{
                RecoverableSignature,
                RecoveryId,
            },
            Message,
            SECP256K1,
        };

        // In most implementations, the v is just 0 or 1 internally, but 27 was added
        // as an arbitrary number for signing Bitcoin messages and Ethereum adopted that
        // as well.
        let recovery_byte = if signature[64] > 26 {
            signature[64] - 27
        } else {
            signature[64]
        };
        let recovery_id = RecoveryId::from_i32(recovery_byte as i32)
            .unwrap_or_else(|error| panic!("Unable to parse the recovery id: {error}"));
        let message = Message::from_digest_slice(message_hash).unwrap_or_else(|error| {
            panic!("Unable to create the message from hash: {error}")
        });
        let signature =
            RecoverableSignature::from_compact(&signature[0..64], recovery_id)
                .unwrap_or_else(|error| panic!("Unable to parse the signature: {error}"));

        let pub_key = SECP256K1.recover_ecdsa(&message, &signature);
        match pub_key {
            Ok(pub_key) => {
                *output = pub_key.serialize();
                Ok(())
            }
            Err(_) => Err(ReturnErrorCode::EcdsaRecoveryFailed.into()),
        }
    }

    fn ecdsa_to_eth_address(
        &mut self,
        pubkey: &[u8; 33],
        output: &mut [u8; 20],
    ) -> Result<()> {
        let pk = secp256k1::PublicKey::from_slice(pubkey)
            .map_err(|_| ReturnErrorCode::EcdsaRecoveryFailed)?;
        let uncompressed = pk.serialize_uncompressed();
        let mut hash = <Keccak256 as HashOutput>::Type::default();
        <Keccak256>::hash(&uncompressed[1..], &mut hash);
        output.as_mut().copy_from_slice(&hash[12..]);
        Ok(())
    }

    fn sr25519_verify(
        &mut self,
        signature: &[u8; 64],
        message: &[u8],
        pub_key: &[u8; 32],
    ) -> Result<()> {
        // the context associated with the signing (specific to the sr25519 algorithm)
        // defaults to "substrate" in substrate, but could be different elsewhere
        // https://github.com/paritytech/substrate/blob/c32f5ed2ae6746d6f791f08cecbfc22fa188f5f9/primitives/core/src/sr25519.rs#L60
        let context = b"substrate";
        // attempt to parse a signature from bytes
        let signature: Signature = Signature::from_bytes(signature)
            .map_err(|_| ReturnErrorCode::Sr25519VerifyFailed)?;
        // attempt to parse a public key from bytes
        let public_key: PublicKey = PublicKey::from_bytes(pub_key)
            .map_err(|_| ReturnErrorCode::Sr25519VerifyFailed)?;
        // verify the signature
        public_key
            .verify_simple(context, message, &signature)
            .map_err(|_| ReturnErrorCode::Sr25519VerifyFailed.into())
    }

    fn call_chain_extension<I, T, E, ErrorCode, F, D>(
        &mut self,
        id: u32,
        input: &I,
        status_to_result: F,
        decode_to_result: D,
    ) -> ::core::result::Result<T, E>
    where
        I: scale::Encode,
        T: scale::Decode,
        E: From<ErrorCode>,
        F: FnOnce(u32) -> ::core::result::Result<(), ErrorCode>,
        D: FnOnce(&[u8]) -> ::core::result::Result<T, E>,
    {
        let enc_input = &scale::Encode::encode(input)[..];
        let mut output: [u8; BUFFER_SIZE] = [0; BUFFER_SIZE];

        self.engine
            .call_chain_extension(id, enc_input, &mut &mut output[..]);
        let (status, out): (u32, Vec<u8>) = scale::Decode::decode(&mut &output[..])
            .unwrap_or_else(|error| {
                panic!("could not decode `call_chain_extension` output: {error:?}")
            });

        status_to_result(status)?;
        let decoded = decode_to_result(&out[..])?;
        Ok(decoded)
    }

    fn set_code_hash(&mut self, _code_hash: &[u8]) -> Result<()> {
        unimplemented!("off-chain environment does not support `set_code_hash`")
    }
}

impl TypedEnvBackend for EnvInstance {
    fn caller<E: Environment>(&mut self) -> E::AccountId {
        self.get_property::<E::AccountId>(Engine::caller)
            .unwrap_or_else(|error| panic!("could not read `caller` property: {error:?}"))
    }

    fn transferred_value<E: Environment>(&mut self) -> E::Balance {
        self.get_property::<E::Balance>(Engine::value_transferred)
            .unwrap_or_else(|error| {
                panic!("could not read `transferred_value` property: {error:?}")
            })
    }

    fn gas_left<E: Environment>(&mut self) -> u64 {
        self.get_property::<u64>(Engine::gas_left)
            .unwrap_or_else(|error| {
                panic!("could not read `gas_left` property: {error:?}")
            })
    }

    fn block_timestamp<E: Environment>(&mut self) -> E::Timestamp {
        self.get_property::<E::Timestamp>(Engine::block_timestamp)
            .unwrap_or_else(|error| {
                panic!("could not read `block_timestamp` property: {error:?}")
            })
    }

    fn account_id<E: Environment>(&mut self) -> E::AccountId {
        self.get_property::<E::AccountId>(Engine::address)
            .unwrap_or_else(|error| {
                panic!("could not read `account_id` property: {error:?}")
            })
    }

    fn balance<E: Environment>(&mut self) -> E::Balance {
        self.get_property::<E::Balance>(Engine::balance)
            .unwrap_or_else(|error| {
                panic!("could not read `balance` property: {error:?}")
            })
    }

    fn block_number<E: Environment>(&mut self) -> E::BlockNumber {
        self.get_property::<E::BlockNumber>(Engine::block_number)
            .unwrap_or_else(|error| {
                panic!("could not read `block_number` property: {error:?}")
            })
    }

    fn minimum_balance<E: Environment>(&mut self) -> E::Balance {
        self.get_property::<E::Balance>(Engine::minimum_balance)
            .unwrap_or_else(|error| {
                panic!("could not read `minimum_balance` property: {error:?}")
            })
    }

    fn emit_event<E, Evt>(&mut self, event: Evt)
    where
        E: Environment,
        Evt: Event,
    {
        let builder = TopicsBuilder::default();
        let enc_topics = event.topics::<E, _>(builder.into());
        let enc_data = &scale::Encode::encode(&event)[..];
        self.engine.deposit_event(&enc_topics[..], enc_data);
    }

    fn invoke_contract_v1<E, Args, R>(
        &mut self,
        _params: &CallParams<E, CallV1<E>, Args, R>,
    ) -> Result<ink_primitives::MessageResult<R>>
    where
        E: Environment,
        Args: scale::Encode,
        R: scale::Decode,
    {
        unimplemented!("off-chain environment does not support contract invocation")
    }

    fn invoke_contract<E, Args, R>(
        &mut self,
        _params: &CallParams<E, Call<E>, Args, R>,
    ) -> Result<ink_primitives::MessageResult<R>>
    where
        E: Environment,
        Args: scale::Encode,
        R: scale::Decode,
    {
        unimplemented!("off-chain environment does not support contract invocation")
    }

    fn invoke_contract_delegate<E, Args, R>(
        &mut self,
        params: &CallParams<E, DelegateCall<E>, Args, R>,
    ) -> Result<ink_primitives::MessageResult<R>>
    where
        E: Environment,
        Args: scale::Encode,
        R: scale::Decode,
    {
        let _code_hash = params.code_hash();
        unimplemented!(
            "off-chain environment does not support delegated contract invocation"
        )
    }

    fn instantiate_contract<E, ContractRef, Args, Salt, R>(
        &mut self,
        params: &CreateParams<E, ContractRef, LimitParamsV2<E>, Args, Salt, R>,
    ) -> Result<
        ink_primitives::ConstructorResult<
            <R as ConstructorReturnType<ContractRef>>::Output,
        >,
    >
    where
        E: Environment,
        ContractRef: FromAccountId<E>,
        Args: scale::Encode,
        Salt: AsRef<[u8]>,
        R: ConstructorReturnType<ContractRef>,
    {
        let _code_hash = params.code_hash();
        let _ref_time_limit = params.ref_time_limit();
        let _proof_size_limit = params.proof_size_limit();
        let _storage_deposit_limit = params.storage_deposit_limit();
        let _endowment = params.endowment();
        let _input = params.exec_input();
        let _salt_bytes = params.salt_bytes();
        unimplemented!("off-chain environment does not support contract instantiation")
    }

    fn instantiate_contract_v1<E, ContractRef, Args, Salt, R>(
        &mut self,
        params: &CreateParams<E, ContractRef, LimitParamsV1, Args, Salt, R>,
    ) -> Result<
        ink_primitives::ConstructorResult<
            <R as ConstructorReturnType<ContractRef>>::Output,
        >,
    >
    where
        E: Environment,
        ContractRef: FromAccountId<E>,
        Args: scale::Encode,
        Salt: AsRef<[u8]>,
        R: ConstructorReturnType<ContractRef>,
    {
        let _code_hash = params.code_hash();
        let _ref_time_limit = params.gas_limit();
        let _endowment = params.endowment();
        let _input = params.exec_input();
        let _salt_bytes = params.salt_bytes();
        unimplemented!("off-chain environment does not support contract instantiation")
    }

    fn terminate_contract<E>(&mut self, beneficiary: E::AccountId) -> !
    where
        E: Environment,
    {
        let buffer = scale::Encode::encode(&beneficiary);
        self.engine.terminate(&buffer[..])
    }

    fn transfer<E>(&mut self, destination: E::AccountId, value: E::Balance) -> Result<()>
    where
        E: Environment,
    {
        let enc_destination = &scale::Encode::encode(&destination)[..];
        let enc_value = &scale::Encode::encode(&value)[..];
        self.engine
            .transfer(enc_destination, enc_value)
            .map_err(Into::into)
    }

    fn weight_to_fee<E: Environment>(&mut self, gas: u64) -> E::Balance {
        let mut output: [u8; BUFFER_SIZE] = [0; BUFFER_SIZE];
        self.engine.weight_to_fee(gas, &mut &mut output[..]);
        scale::Decode::decode(&mut &output[..]).unwrap_or_else(|error| {
            panic!("could not read `weight_to_fee` property: {error:?}")
        })
    }

    fn is_contract<E>(&mut self, account: &E::AccountId) -> bool
    where
        E: Environment,
    {
        self.engine.is_contract(scale::Encode::encode(&account))
    }

    fn caller_is_origin<E>(&mut self) -> bool
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support cross-contract calls")
    }

    fn code_hash<E>(&mut self, _account: &E::AccountId) -> Result<E::Hash>
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support `code_hash`")
    }

    fn own_code_hash<E>(&mut self) -> Result<E::Hash>
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support `own_code_hash`")
    }

    fn call_runtime<E, Call>(&mut self, _call: &Call) -> Result<()>
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support `call_runtime`")
    }

    fn lock_delegate_dependency<E>(&mut self, _code_hash: &E::Hash)
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support delegate dependencies")
    }

    fn unlock_delegate_dependency<E>(&mut self, _code_hash: &E::Hash)
    where
        E: Environment,
    {
        unimplemented!("off-chain environment does not support delegate dependencies")
    }
}