use anyhow::Result;
use async_trait::async_trait;
use backoff::{backoff::Constant as ConstantBackoff, future::FutureOperation as _};
use futures::TryFutureExt;
use monero::{Address, Network, PrivateKey};
use monero_harness::rpc::wallet;
use std::{str::FromStr, time::Duration};
use xmr_btc::monero::{
    Address, Amount, CreateWalletForOutput, InsufficientFunds, Network, PrivateKey, PrivateViewKey,
    PublicKey, PublicViewKey, Transfer, TransferProof, TxHash, WatchForTransfer, WatchForTransferImproved,
};

pub struct Wallet {
    pub inner: wallet::Client,
    /// Secondary wallet which is only used to watch for the Monero lock
    /// transaction without needing a transfer proof.
    pub watch_only: wallet::Client,
}

impl Wallet {
    /// Get the balance of the primary account.
    pub async fn get_balance(&self) -> Result<Amount> {
        let amount = self.inner.get_balance(0).await?;

        Ok(Amount::from_piconero(amount))
    }
}

#[async_trait]
impl Transfer for Wallet {
    async fn transfer(
        &self,
        public_spend_key: PublicKey,
        public_view_key: PublicViewKey,
        amount: Amount,
    ) -> Result<(TransferProof, Amount)> {
        let destination_address =
            Address::standard(Network::Mainnet, public_spend_key, public_view_key.into());

        let res = self
            .inner
            .transfer(0, amount.as_piconero(), &destination_address.to_string())
            .await?;

        let tx_hash = TxHash(res.tx_hash);
        let tx_key = PrivateKey::from_str(&res.tx_key)?;

        let fee = Amount::from_piconero(res.fee);

        Ok((TransferProof::new(tx_hash, tx_key), fee))
    }
}

#[async_trait]
impl CreateWalletForOutput for Wallet {
    async fn create_and_load_wallet_for_output(
        &self,
        private_spend_key: PrivateKey,
        private_view_key: PrivateViewKey,
    ) -> Result<()> {
        let public_spend_key = PublicKey::from_private_key(&private_spend_key);
        let public_view_key = PublicKey::from_private_key(&private_view_key.into());

        let address = Address::standard(Network::Mainnet, public_spend_key, public_view_key);

        let _ = self
            .inner
            .generate_from_keys(
                &address.to_string(),
                Some(&private_spend_key.to_string()),
                &PrivateKey::from(private_view_key).to_string(),
            )
            .await?;

        Ok(())
    }
}

#[async_trait]
impl WatchForTransfer for Wallet {
    async fn watch_for_transfer(
        &self,
        public_spend_key: PublicKey,
        public_view_key: PublicViewKey,
        transfer_proof: TransferProof,
        expected_amount: Amount,
        expected_confirmations: u32,
    ) -> Result<(), InsufficientFunds> {
        enum Error {
            TxNotFound,
            InsufficientConfirmations,
            InsufficientFunds { expected: Amount, actual: Amount },
        }

        let address = Address::standard(Network::Mainnet, public_spend_key, public_view_key.into());

        let res = (|| async {
            // NOTE: Currently, this is conflating IO errors with the transaction not being
            // in the blockchain yet, or not having enough confirmations on it. All these
            // errors warrant a retry, but the strategy should probably differ per case
            let proof = self
                .inner
                .check_tx_key(
                    &String::from(transfer_proof.tx_hash()),
                    &transfer_proof.tx_key().to_string(),
                    &address.to_string(),
                )
                .await
                .map_err(|_| backoff::Error::Transient(Error::TxNotFound))?;

            if proof.received != expected_amount.as_piconero() {
                return Err(backoff::Error::Permanent(Error::InsufficientFunds {
                    expected: expected_amount,
                    actual: Amount::from_piconero(proof.received),
                }));
            }

            if proof.confirmations < expected_confirmations {
                return Err(backoff::Error::Transient(Error::InsufficientConfirmations));
            }

            Ok(proof)
        })
        .retry(ConstantBackoff::new(Duration::from_secs(1)))
        .await;

        if let Err(Error::InsufficientFunds { expected, actual }) = res {
            return Err(InsufficientFunds { expected, actual });
        };

        Ok(())
    }
}

#[async_trait]
impl WatchForTransferImproved for Wallet {
    async fn watch_for_transfer_improved(
        &self,
        address: Address,
        expected_amount: Amount,
        private_view_key: PrivateViewKey,
    ) -> Result<(), InsufficientFunds> {
        let address = address.to_string();
        let private_view_key = PrivateKey::from(private_view_key).to_string();
        let load_address = || {
            self.watch_only
                .generate_from_keys(&address, None, &private_view_key)
                .map_err(backoff::Error::Transient)
        };

        load_address
            .retry(ConstantBackoff::new(Duration::from_secs(1)))
            .await
            .expect("transient error is never returned");

        let refresh = || self.watch_only.refresh().map_err(backoff::Error::Transient);

        refresh
            .retry(ConstantBackoff::new(Duration::from_secs(1)))
            .await
            .expect("transient error is never returned");

        let get_balance = || {
            self.watch_only
                .get_balance(0)
                .map_err(backoff::Error::Transient)
        };

        let balance = get_balance
            .retry(ConstantBackoff::new(Duration::from_secs(1)))
            .await
            .expect("transient error is never returned");
        let balance = Amount::from_piconero(balance);

        if balance != expected_amount {
            return Err(InsufficientFunds {
                expected: expected_amount,
                actual: balance,
            });
        }

        Ok(())
    }
}