/* @flow */
import Web3 from 'web3';
import BigNumber from 'bignumber.js';

import EthereumjsUnits from 'ethereumjs-units';
// import InputDataDecoder from 'ethereum-input-data-decoder';
import type { EstimateGasOptions } from 'web3';
import * as WEB3 from 'actions/constants/web3';
import * as PENDING from 'actions/constants/pendingTx';
import * as ethUtils from 'utils/ethUtils';

import type { Dispatch, GetState, ThunkAction, PromiseAction } from 'flowtype';

import type { Account } from 'reducers/AccountsReducer';
import type { Web3Instance } from 'reducers/Web3Reducer';
import type { Token } from 'reducers/TokensReducer';
import type { NetworkToken } from 'reducers/LocalStorageReducer';
import * as TokenActions from './TokenActions';

export type Web3UpdateBlockAction = {
    type: typeof WEB3.BLOCK_UPDATED,
    network: string,
    blockHash: string,
};

export type Web3UpdateGasPriceAction = {
    type: typeof WEB3.GAS_PRICE_UPDATED,
    network: string,
    gasPrice: string,
};

export type Web3Action =
    | {
          type: typeof WEB3.READY,
      }
    | {
          type: typeof WEB3.START,
      }
    | {
          type: typeof WEB3.CREATE | typeof WEB3.DISCONNECT,
          instance: Web3Instance,
      }
    | Web3UpdateBlockAction
    | Web3UpdateGasPriceAction;

export const initWeb3 = (
    network: string,
    urlIndex: number = 0
): PromiseAction<Web3Instance> => async (
    dispatch: Dispatch,
    getState: GetState
): Promise<Web3Instance> =>
    new Promise(async (resolve, reject) => {
        // check if requested web was initialized before
        const instance = getState().web3.find(w3 => w3.network === network);
        if (instance && instance.web3.currentProvider.connected) {
            resolve(instance);
            return;
        }

        // requested web3 wasn't initialized or is disconnected
        // initialize again
        const { config, ERC20Abi } = getState().localStorage;
        const networkData = config.networks.find(c => c.shortcut === network);
        if (!networkData) {
            // network not found
            reject(new Error(`Network ${network} not found in application config.`));
            return;
        }

        // get first url
        const url = networkData.web3[urlIndex];
        if (!url) {
            reject(new Error('Web3 backend is not responding'));
            return;
        }

        const web3 = new Web3(new Web3.providers.WebsocketProvider(url));

        const onConnect = async () => {
            const latestBlock = await web3.eth.getBlockNumber();
            const gasPrice = await web3.eth.getGasPrice();

            const newInstance = {
                network,
                web3,
                chainId: networkData.chainId,
                erc20: new web3.eth.Contract(ERC20Abi),
                latestBlock,
                gasPrice,
            };

            dispatch({
                type: WEB3.CREATE,
                instance: newInstance,
            });

            resolve(newInstance);
        };

        const onEnd = async () => {
            web3.currentProvider.reset();
            const oldInstance = getState().web3.find(w3 => w3.network === network);

            if (oldInstance && oldInstance.web3.currentProvider.connected) {
                // backend disconnects
                // dispatch({
                //     type: 'WEB3.DISCONNECT',
                //     network
                // });
            } else {
                // backend initialization error for given url, try next one
                try {
                    const otherWeb3 = await dispatch(initWeb3(network, urlIndex + 1));
                    resolve(otherWeb3);
                } catch (error) {
                    console.error(error);
                    reject(error);
                }
            }
        };

        web3.currentProvider.on('connect', onConnect);
        web3.currentProvider.on('end', onEnd);
        web3.currentProvider.on('error', onEnd);
    });

// not used since connect@8
// export const discoverAccount = (descriptor: string, network: string): PromiseAction<any> => async (
//     dispatch: Dispatch
// ): Promise<any> => {
//     const instance: Web3Instance = await dispatch(initWeb3(network));
//     const balance = await instance.web3.eth.getBalance(descriptor);
//     const nonce = await instance.web3.eth.getTransactionCount(descriptor);
//     return {
//         descriptor,
//         transactions: 0,
//         block: 0,
//         balance: EthereumjsUnits.convert(balance, 'wei', 'ether'),
//         availableBalance: EthereumjsUnits.convert(balance, 'wei', 'ether'),
//         nonce,
//     };
// };

export const resolvePendingTransactions = (network: string): PromiseAction<void> => async (
    dispatch: Dispatch,
    getState: GetState
): Promise<void> => {
    const instance: Web3Instance = await dispatch(initWeb3(network));
    const pending = getState().pending.filter(p => p.network === network);
    pending.forEach(async tx => {
        const status = await instance.web3.eth.getTransaction(tx.txid);
        if (!status) {
            dispatch({
                type: PENDING.TX_REJECTED,
                hash: tx.txid,
            });
        } else {
            const receipt = await instance.web3.eth.getTransactionReceipt(tx.txid);
            if (receipt) {
                if (status.gas !== receipt.gasUsed) {
                    dispatch({
                        type: PENDING.TX_TOKEN_ERROR,
                        hash: tx.txid,
                    });
                }
                dispatch({
                    type: PENDING.TX_RESOLVED,
                    hash: tx.txid,
                });
            }
        }
    });
};

/*
export const getPendingInfo = (network: string, txid: string): PromiseAction<void> => async (dispatch: Dispatch): Promise<void> => {
    const instance: Web3Instance = await dispatch(initWeb3(network));
    const tx = await instance.web3.eth.getTransaction(txid);


    if (tx.input !== "0x") {
        // find token:
        // tx.to <= smart contract address

        // smart contract data
        const decoder = new InputDataDecoder(instance.erc20.options.jsonInterface);
        const data = decoder.decodeData(tx.input);
        if (data.name === 'transfer') {
            console.warn("DATA!", data.inputs[0], data.inputs[1].toString(10));
        }


    }

    // return tx;
};

export const getTxInput = (): PromiseAction<void> => async (dispatch: Dispatch): Promise<void> => {
    const instance: Web3Instance = await dispatch(initWeb3('ropsten'));
    // const inputData = instance.web3.utils.hexToAscii("0xa9059cbb00000000000000000000000073d0385f4d8e00c5e6504c6030f47bf6212736a80000000000000000000000000000000000000000000000000000000000000001");
    // console.warn("input data!", inputData);
};
*/

// not used since connect@8
// export const updateAccount = (
//     account: Account,
//     newAccount: any,
//     network: string
// ): PromiseAction<void> => async (dispatch: Dispatch): Promise<void> => {
//     const instance: Web3Instance = await dispatch(initWeb3(network));
//     const balance = await instance.web3.eth.getBalance(account.descriptor);
//     const nonce = await instance.web3.eth.getTransactionCount(account.descriptor);
//     const empty = nonce <= 0 && balance === '0';
//     dispatch(
//         AccountsActions.update({
//             networkType: 'ethereum',
//             ...account,
//             ...newAccount,
//             empty,
//             nonce,
//             balance: EthereumjsUnits.convert(balance, 'wei', 'ether'),
//             availableBalance: EthereumjsUnits.convert(balance, 'wei', 'ether'),
//         })
//     );

//     // update tokens for this account
//     dispatch(updateAccountTokens(account));
// };

export const updateAccountTokens = (account: Account): PromiseAction<void> => async (
    dispatch: Dispatch,
    getState: GetState
): Promise<void> => {
    const tokens = getState().tokens.filter(
        t => t.network === account.network && t.ethAddress === account.descriptor
    );
    tokens.forEach(async token => {
        const balance = await dispatch(getTokenBalance(token));
        // const newBalance: string = balance.dividedBy(Math.pow(10, token.decimals)).toString(10);
        if (balance !== token.balance) {
            dispatch(TokenActions.setBalance(token.address, token.ethAddress, balance));
        }
    });
};

export const getTokenInfo = (
    address: string,
    network: string
): PromiseAction<NetworkToken> => async (dispatch: Dispatch): Promise<NetworkToken> => {
    const instance: Web3Instance = await dispatch(initWeb3(network));
    const contract = instance.erc20.clone();
    contract.options.address = address;

    const name = await contract.methods.name().call();
    const symbol = await contract.methods.symbol().call();
    const decimals = await contract.methods.decimals().call();

    return {
        address,
        name,
        symbol,
        decimals,
    };
};

export const getTokenBalance = (token: Token): PromiseAction<string> => async (
    dispatch: Dispatch
): Promise<string> => {
    const instance = await dispatch(initWeb3(token.network));
    const contract = instance.erc20.clone();
    contract.options.address = token.address;

    const balance = await contract.methods.balanceOf(token.ethAddress).call();
    return new BigNumber(balance).dividedBy(10 ** token.decimals).toString(10);
};

export const getCurrentGasPrice = (network: string): PromiseAction<string> => async (
    dispatch: Dispatch,
    getState: GetState
): Promise<string> => {
    const instance = getState().web3.find(w3 => w3.network === network);
    if (instance) {
        return EthereumjsUnits.convert(instance.gasPrice, 'wei', 'gwei');
    }
    return '0';
};

export const updateGasPrice = (network: string): PromiseAction<void> => async (
    dispatch: Dispatch
): Promise<void> => {
    try {
        const instance = await dispatch(initWeb3(network));
        const gasPrice = await instance.web3.eth.getGasPrice();
        if (instance.gasPrice !== gasPrice) {
            dispatch({
                type: WEB3.GAS_PRICE_UPDATED,
                network,
                gasPrice,
            });
        }
    } catch (e) {
        // silent action
        // nothing happens if this fails
    }
};

export const estimateGasLimit = (
    network: string,
    $options: EstimateGasOptions
): PromiseAction<string> => async (dispatch: Dispatch): Promise<string> => {
    const instance = await dispatch(initWeb3(network));
    const data = ethUtils.sanitizeHex($options.data);
    const options = {
        ...$options,
        to: '0x0000000000000000000000000000000000000000',
        data,
        value: instance.web3.utils.toHex(
            EthereumjsUnits.convert($options.value || '0', 'ether', 'wei')
        ),
        gasPrice: instance.web3.utils.toHex(
            EthereumjsUnits.convert($options.gasPrice, 'gwei', 'wei')
        ),
    };

    const limit = await instance.web3.eth.estimateGas(options);
    return limit.toString();
};

export const disconnect = (network: string): ThunkAction => (
    dispatch: Dispatch,
    getState: GetState
): void => {
    // check if Web3 was already initialized
    const instance = getState().web3.find(w3 => w3.network === network);
    if (instance) {
        // reset current connection
        instance.web3.currentProvider.reset();
        instance.web3.currentProvider.connection.close();

        // remove instance from reducer
        dispatch({
            type: WEB3.DISCONNECT,
            instance,
        });
    }
};