/// Utilities for launching a ganache-cli testnet instance
#[cfg(not(target_arch = "wasm32"))]
mod ganache;
#[cfg(not(target_arch = "wasm32"))]
pub use ganache::{Ganache, GanacheInstance};

/// Utilities for launching a go-ethereum dev-mode instance
#[cfg(not(target_arch = "wasm32"))]
mod geth;
#[cfg(not(target_arch = "wasm32"))]
pub use geth::{Geth, GethInstance};

/// Solidity compiler bindings
#[cfg(not(target_arch = "wasm32"))]
mod solc;

#[cfg(not(target_arch = "wasm32"))]
pub use solc::{CompiledContract, Solc};

#[cfg(not(target_arch = "wasm32"))]
#[cfg(feature = "setup")]
mod setup;
#[cfg(not(target_arch = "wasm32"))]
#[cfg(feature = "setup")]
pub use setup::*;

mod hash;
pub use hash::{hash_message, id, keccak256, serialize};

mod units;
pub use units::Units;

/// Re-export RLP
pub use rlp;

use crate::types::{Address, Bytes, U256};
use k256::{ecdsa::SigningKey, EncodedPoint as K256PublicKey};
use std::convert::TryInto;
use std::ops::Neg;
use thiserror::Error;

#[derive(Debug, Error)]
pub enum FormatBytes32StringError {
    #[error("bytes32 strings must not exceed 32 bytes in length")]
    TextTooLong,
}

/// 1 Ether = 1e18 Wei == 0x0de0b6b3a7640000 Wei
pub const WEI_IN_ETHER: U256 = U256([0x0de0b6b3a7640000, 0x0, 0x0, 0x0]);

/// The number of blocks from the past for which the fee rewards are fetched for fee estimation.
pub const EIP1559_FEE_ESTIMATION_PAST_BLOCKS: u64 = 10;
/// The default percentile of gas premiums that are fetched for fee estimation.
pub const EIP1559_FEE_ESTIMATION_REWARD_PERCENTILE: f64 = 5.0;
/// The default max priority fee per gas, used in case the base fee is within a threshold.
pub const EIP1559_FEE_ESTIMATION_DEFAULT_PRIORITY_FEE: u64 = 3_000_000_000;
/// The threshold for base fee below which we use the default priority fee, and beyond which we
/// estimate an appropriate value for priority fee.
pub const EIP1559_FEE_ESTIMATION_PRIORITY_FEE_TRIGGER: u64 = 100_000_000_000;
/// The threshold max change/difference (in %) at which we will ignore the fee history values
/// under it.
pub const EIP1559_FEE_ESTIMATION_THRESHOLD_MAX_CHANGE: i64 = 200;

/// Format the output for the user which prefer to see values
/// in ether (instead of wei)
///
/// Divides the input by 1e18
pub fn format_ether<T: Into<U256>>(amount: T) -> U256 {
    amount.into() / WEI_IN_ETHER
}

/// Divides the provided amount with 10^{units} provided.
pub fn format_units<T: Into<U256>, K: Into<Units>>(amount: T, units: K) -> U256 {
    let units = units.into();
    let amount = amount.into();
    amount / 10u64.pow(units.as_num())
}

/// Converts the input to a U256 and converts from Ether to Wei.
///
/// ```
/// use ethers_core::{types::U256, utils::{parse_ether, WEI_IN_ETHER}};
///
/// let eth = U256::from(WEI_IN_ETHER);
/// assert_eq!(eth, parse_ether(1u8).unwrap());
/// assert_eq!(eth, parse_ether(1usize).unwrap());
/// assert_eq!(eth, parse_ether("1").unwrap());
pub fn parse_ether<S>(eth: S) -> Result<U256, S::Error>
where
    S: TryInto<U256>,
{
    Ok(eth.try_into()? * WEI_IN_ETHER)
}

/// Multiplies the provided amount with 10^{units} provided.
pub fn parse_units<S, K>(amount: S, units: K) -> Result<U256, S::Error>
where
    S: TryInto<U256>,
    K: Into<Units>,
{
    Ok(amount.try_into()? * 10u64.pow(units.into().as_num()))
}

/// The address for an Ethereum contract is deterministically computed from the
/// address of its creator (sender) and how many transactions the creator has
/// sent (nonce). The sender and nonce are RLP encoded and then hashed with Keccak-256.
pub fn get_contract_address(sender: impl Into<Address>, nonce: impl Into<U256>) -> Address {
    let mut stream = rlp::RlpStream::new();
    stream.begin_list(2);
    stream.append(&sender.into());
    stream.append(&nonce.into());

    let hash = keccak256(&stream.out());

    let mut bytes = [0u8; 20];
    bytes.copy_from_slice(&hash[12..]);
    Address::from(bytes)
}

/// Returns the CREATE2 of a smart contract as specified in
/// [EIP1014](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1014.md)
///
/// keccak256( 0xff ++ senderAddress ++ salt ++ keccak256(init_code))[12..]
pub fn get_create2_address(
    from: impl Into<Address>,
    salt: impl Into<Bytes>,
    init_code: impl Into<Bytes>,
) -> Address {
    let bytes = [
        &[0xff],
        from.into().as_bytes(),
        salt.into().as_ref(),
        &keccak256(init_code.into().as_ref()),
    ]
    .concat();

    let hash = keccak256(&bytes);

    let mut bytes = [0u8; 20];
    bytes.copy_from_slice(&hash[12..]);
    Address::from(bytes)
}

/// Converts a K256 SigningKey to an Ethereum Address
pub fn secret_key_to_address(secret_key: &SigningKey) -> Address {
    // TODO: Can we do this in a better way?
    let uncompressed_pub_key = K256PublicKey::from(&secret_key.verifying_key()).decompress();
    let public_key = uncompressed_pub_key.unwrap().to_bytes();
    debug_assert_eq!(public_key[0], 0x04);
    let hash = keccak256(&public_key[1..]);
    Address::from_slice(&hash[12..])
}

/// Converts an Ethereum address to the checksum encoding
/// Ref: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-55.md
pub fn to_checksum(addr: &Address, chain_id: Option<u8>) -> String {
    let prefixed_addr = match chain_id {
        Some(chain_id) => format!("{}0x{:x}", chain_id, addr),
        None => format!("{:x}", addr),
    };
    let hash = hex::encode(keccak256(&prefixed_addr));
    let hash = hash.as_bytes();

    let addr_hex = hex::encode(addr.as_bytes());
    let addr_hex = addr_hex.as_bytes();

    addr_hex
        .iter()
        .zip(hash)
        .fold("0x".to_owned(), |mut encoded, (addr, hash)| {
            encoded.push(if *hash >= 56 {
                addr.to_ascii_uppercase() as char
            } else {
                addr.to_ascii_lowercase() as char
            });
            encoded
        })
}

/// Returns a bytes32 string representation of text. If the length of text exceeds 32 bytes,
/// an error is returned.
pub fn format_bytes32_string(text: &str) -> Result<[u8; 32], FormatBytes32StringError> {
    let str_bytes: &[u8] = text.as_bytes();
    if str_bytes.len() > 32 {
        return Err(FormatBytes32StringError::TextTooLong);
    }

    let mut bytes32: [u8; 32] = [0u8; 32];
    bytes32[..str_bytes.len()].copy_from_slice(str_bytes);

    Ok(bytes32)
}

/// Returns the decoded string represented by the bytes32 encoded data.
pub fn parse_bytes32_string(bytes: &[u8; 32]) -> Result<&str, std::str::Utf8Error> {
    let mut length = 0;
    while length < 32 && bytes[length] != 0 {
        length += 1;
    }

    std::str::from_utf8(&bytes[..length])
}

/// The default EIP-1559 fee estimator which is based on the work by [MyCrypto](https://github.com/MyCryptoHQ/MyCrypto/blob/master/src/services/ApiService/Gas/eip1559.ts)
pub fn eip1559_default_estimator(base_fee_per_gas: U256, rewards: Vec<Vec<U256>>) -> (U256, U256) {
    let max_priority_fee_per_gas =
        if base_fee_per_gas < U256::from(EIP1559_FEE_ESTIMATION_PRIORITY_FEE_TRIGGER) {
            U256::from(EIP1559_FEE_ESTIMATION_DEFAULT_PRIORITY_FEE)
        } else {
            std::cmp::max(
                estimate_priority_fee(rewards),
                U256::from(EIP1559_FEE_ESTIMATION_DEFAULT_PRIORITY_FEE),
            )
        };
    let potential_max_fee = base_fee_surged(base_fee_per_gas);
    let max_fee_per_gas = if max_priority_fee_per_gas > potential_max_fee {
        max_priority_fee_per_gas + potential_max_fee
    } else {
        potential_max_fee
    };
    (max_fee_per_gas, max_priority_fee_per_gas)
}

fn estimate_priority_fee(rewards: Vec<Vec<U256>>) -> U256 {
    let mut rewards: Vec<U256> = rewards
        .iter()
        .map(|r| r[0])
        .filter(|r| *r > U256::zero())
        .collect();
    if rewards.is_empty() {
        return U256::zero();
    }
    if rewards.len() == 1 {
        return rewards[0];
    }
    // Sort the rewards as we will eventually take the median.
    rewards.sort();

    // A copy of the same vector is created for convenience to calculate percentage change
    // between subsequent fee values.
    let mut rewards_copy = rewards.clone();
    rewards_copy.rotate_left(1);

    let mut percentage_change: Vec<i64> = rewards
        .iter()
        .zip(rewards_copy.iter())
        .map(|(a, b)| {
            if b > a {
                ((b - a).low_u32() as i64 * 100) / (a.low_u32() as i64)
            } else {
                (((a - b).low_u32() as i64 * 100) / (a.low_u32() as i64)).neg()
            }
        })
        .collect();
    percentage_change.pop();

    // Fetch the max of the percentage change, and that element's index.
    let max_change = percentage_change.iter().max().unwrap();
    let max_change_index = percentage_change
        .iter()
        .position(|&c| c == *max_change)
        .unwrap();

    // If we encountered a big change in fees at a certain position, then consider only
    // the values >= it.
    let values = if *max_change >= EIP1559_FEE_ESTIMATION_THRESHOLD_MAX_CHANGE
        && (max_change_index >= (rewards.len() / 2))
    {
        rewards[max_change_index..].to_vec()
    } else {
        rewards
    };

    // Return the median.
    values[values.len() / 2]
}

fn base_fee_surged(base_fee_per_gas: U256) -> U256 {
    if base_fee_per_gas <= U256::from(40_000_000_000u64) {
        base_fee_per_gas * 2
    } else if base_fee_per_gas <= U256::from(100_000_000_000u64) {
        base_fee_per_gas * 16 / 10
    } else if base_fee_per_gas <= U256::from(200_000_000_000u64) {
        base_fee_per_gas * 14 / 10
    } else {
        base_fee_per_gas * 12 / 10
    }
}

/// A bit of hack to find an unused TCP port.
///
/// Does not guarantee that the given port is unused after the function exists, just that it was
/// unused before the function started (i.e., it does not reserve a port).
#[cfg(not(target_arch = "wasm32"))]
pub(crate) fn unused_port() -> u16 {
    let listener = std::net::TcpListener::bind("127.0.0.1:0")
        .expect("Failed to create TCP listener to find unused port");

    let local_addr = listener
        .local_addr()
        .expect("Failed to read TCP listener local_addr to find unused port");
    local_addr.port()
}

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

    #[test]
    fn wei_in_ether() {
        assert_eq!(WEI_IN_ETHER.as_u64(), 1e18 as u64);
    }

    #[test]
    fn test_format_units() {
        let gwei_in_ether = format_units(WEI_IN_ETHER, 9);
        assert_eq!(gwei_in_ether.as_u64(), 1e9 as u64);

        let eth = format_units(WEI_IN_ETHER, "ether");
        assert_eq!(eth.as_u64(), 1);
    }

    #[test]
    fn test_parse_units() {
        let gwei = parse_units(1, 9).unwrap();
        assert_eq!(gwei.as_u64(), 1e9 as u64);

        let eth = parse_units(1, "ether").unwrap();
        assert_eq!(eth, WEI_IN_ETHER);
    }

    #[test]
    fn addr_checksum() {
        let addr_list = vec![
            // mainnet
            (
                None,
                "27b1fdb04752bbc536007a920d24acb045561c26",
                "0x27b1fdb04752bbc536007a920d24acb045561c26",
            ),
            (
                None,
                "3599689e6292b81b2d85451025146515070129bb",
                "0x3599689E6292b81B2d85451025146515070129Bb",
            ),
            (
                None,
                "42712d45473476b98452f434e72461577d686318",
                "0x42712D45473476b98452f434e72461577D686318",
            ),
            (
                None,
                "52908400098527886e0f7030069857d2e4169ee7",
                "0x52908400098527886E0F7030069857D2E4169EE7",
            ),
            (
                None,
                "5aaeb6053f3e94c9b9a09f33669435e7ef1beaed",
                "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed",
            ),
            (
                None,
                "6549f4939460de12611948b3f82b88c3c8975323",
                "0x6549f4939460DE12611948b3f82b88C3C8975323",
            ),
            (
                None,
                "66f9664f97f2b50f62d13ea064982f936de76657",
                "0x66f9664f97F2b50F62D13eA064982f936dE76657",
            ),
            (
                None,
                "88021160c5c792225e4e5452585947470010289d",
                "0x88021160C5C792225E4E5452585947470010289D",
            ),
            // rsk mainnet
            (
                Some(30),
                "27b1fdb04752bbc536007a920d24acb045561c26",
                "0x27b1FdB04752BBc536007A920D24ACB045561c26",
            ),
            (
                Some(30),
                "3599689e6292b81b2d85451025146515070129bb",
                "0x3599689E6292B81B2D85451025146515070129Bb",
            ),
            (
                Some(30),
                "42712d45473476b98452f434e72461577d686318",
                "0x42712D45473476B98452f434E72461577d686318",
            ),
            (
                Some(30),
                "52908400098527886e0f7030069857d2e4169ee7",
                "0x52908400098527886E0F7030069857D2E4169ee7",
            ),
            (
                Some(30),
                "5aaeb6053f3e94c9b9a09f33669435e7ef1beaed",
                "0x5aaEB6053f3e94c9b9a09f33669435E7ef1bEAeD",
            ),
            (
                Some(30),
                "6549f4939460de12611948b3f82b88c3c8975323",
                "0x6549F4939460DE12611948B3F82B88C3C8975323",
            ),
            (
                Some(30),
                "66f9664f97f2b50f62d13ea064982f936de76657",
                "0x66F9664f97f2B50F62d13EA064982F936de76657",
            ),
        ];

        for (chain_id, addr, checksummed_addr) in addr_list {
            let addr = addr.parse::<Address>().unwrap();
            assert_eq!(to_checksum(&addr, chain_id), String::from(checksummed_addr));
        }
    }

    #[test]
    fn contract_address() {
        // http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
        let from = "6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0"
            .parse::<Address>()
            .unwrap();
        for (nonce, expected) in [
            "cd234a471b72ba2f1ccf0a70fcaba648a5eecd8d",
            "343c43a37d37dff08ae8c4a11544c718abb4fcf8",
            "f778b86fa74e846c4f0a1fbd1335fe81c00a0c91",
            "fffd933a0bc612844eaf0c6fe3e5b8e9b6c1d19c",
        ]
        .iter()
        .enumerate()
        {
            let address = get_contract_address(from, nonce);
            assert_eq!(address, expected.parse::<Address>().unwrap());
        }
    }

    #[test]
    // Test vectors from https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1014.md#examples
    fn create2_address() {
        for (from, salt, init_code, expected) in &[
            (
                "0000000000000000000000000000000000000000",
                "0000000000000000000000000000000000000000000000000000000000000000",
                "00",
                "4D1A2e2bB4F88F0250f26Ffff098B0b30B26BF38",
            ),
            (
                "deadbeef00000000000000000000000000000000",
                "0000000000000000000000000000000000000000000000000000000000000000",
                "00",
                "B928f69Bb1D91Cd65274e3c79d8986362984fDA3",
            ),
            (
                "deadbeef00000000000000000000000000000000",
                "000000000000000000000000feed000000000000000000000000000000000000",
                "00",
                "D04116cDd17beBE565EB2422F2497E06cC1C9833",
            ),
            (
                "0000000000000000000000000000000000000000",
                "0000000000000000000000000000000000000000000000000000000000000000",
                "deadbeef",
                "70f2b2914A2a4b783FaEFb75f459A580616Fcb5e",
            ),
            (
                "00000000000000000000000000000000deadbeef",
                "00000000000000000000000000000000000000000000000000000000cafebabe",
                "deadbeef",
                "60f3f640a8508fC6a86d45DF051962668E1e8AC7",
            ),
            (
                "00000000000000000000000000000000deadbeef",
                "00000000000000000000000000000000000000000000000000000000cafebabe",
                "deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef",
                "1d8bfDC5D46DC4f61D6b6115972536eBE6A8854C",
            ),
            (
                "0000000000000000000000000000000000000000",
                "0000000000000000000000000000000000000000000000000000000000000000",
                "",
                "E33C0C7F7df4809055C3ebA6c09CFe4BaF1BD9e0",
            ),
        ] {
            let from = from.parse::<Address>().unwrap();
            let salt = hex::decode(salt).unwrap();
            let init_code = hex::decode(init_code).unwrap();
            let expected = expected.parse::<Address>().unwrap();
            assert_eq!(expected, get_create2_address(from, salt, init_code))
        }
    }

    #[test]
    fn bytes32_string_parsing() {
        let text_bytes_list = vec![
            (
                "",
                hex!("0000000000000000000000000000000000000000000000000000000000000000"),
            ),
            (
                "A",
                hex!("4100000000000000000000000000000000000000000000000000000000000000"),
            ),
            (
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ012345",
                hex!("4142434445464748494a4b4c4d4e4f505152535455565758595a303132333435"),
            ),
            (
                "!@#$%^&*(),./;'[]",
                hex!("21402324255e262a28292c2e2f3b275b5d000000000000000000000000000000"),
            ),
        ];

        for (text, bytes) in text_bytes_list {
            assert_eq!(text, parse_bytes32_string(&bytes).unwrap());
        }
    }

    #[test]
    fn bytes32_string_formatting() {
        let text_bytes_list = vec![
            (
                "",
                hex!("0000000000000000000000000000000000000000000000000000000000000000"),
            ),
            (
                "A",
                hex!("4100000000000000000000000000000000000000000000000000000000000000"),
            ),
            (
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ012345",
                hex!("4142434445464748494a4b4c4d4e4f505152535455565758595a303132333435"),
            ),
            (
                "!@#$%^&*(),./;'[]",
                hex!("21402324255e262a28292c2e2f3b275b5d000000000000000000000000000000"),
            ),
        ];

        for (text, bytes) in text_bytes_list {
            assert_eq!(bytes, format_bytes32_string(text).unwrap());
        }
    }

    #[test]
    fn bytes32_string_formatting_too_long() {
        assert!(matches!(
            format_bytes32_string("ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456").unwrap_err(),
            FormatBytes32StringError::TextTooLong
        ));
    }

    #[test]
    fn test_eip1559_default_estimator() {
        // If the base fee is below the triggering base fee, we should get the default priority fee
        // with the base fee surged.
        let base_fee_per_gas = U256::from(EIP1559_FEE_ESTIMATION_PRIORITY_FEE_TRIGGER) - 1;
        let rewards: Vec<Vec<U256>> = vec![vec![]];
        let (base_fee, priority_fee) = eip1559_default_estimator(base_fee_per_gas, rewards);
        assert_eq!(
            priority_fee,
            U256::from(EIP1559_FEE_ESTIMATION_DEFAULT_PRIORITY_FEE)
        );
        assert_eq!(base_fee, base_fee_surged(base_fee_per_gas));

        // If the base fee is above the triggering base fee, we calculate the priority fee using
        // the fee history (rewards).
        let base_fee_per_gas = U256::from(EIP1559_FEE_ESTIMATION_PRIORITY_FEE_TRIGGER) + 1;
        let rewards: Vec<Vec<U256>> = vec![
            vec![100_000_000_000u64.into()],
            vec![105_000_000_000u64.into()],
            vec![102_000_000_000u64.into()],
        ]; // say, last 3 blocks
        let (base_fee, priority_fee) = eip1559_default_estimator(base_fee_per_gas, rewards.clone());
        assert_eq!(base_fee, base_fee_surged(base_fee_per_gas));
        assert_eq!(priority_fee, estimate_priority_fee(rewards.clone()));

        // The median should be taken because none of the changes are big enough to ignore values.
        assert_eq!(estimate_priority_fee(rewards), 102_000_000_000u64.into());
    }
}