index.ts

"use strict";

import { checkResultErrors, EventFragment, Fragment, FunctionFragment, Indexed, Interface, JsonFragment, LogDescription, ParamType, Result } from "@ethersproject/abi";
import { Block, BlockTag, Filter, FilterByBlockHash, Listener, Log, Provider, TransactionReceipt, TransactionRequest, TransactionResponse } from "@ethersproject/abstract-provider";
import { Signer, VoidSigner } from "@ethersproject/abstract-signer";
import { getAddress, getContractAddress } from "@ethersproject/address";
import { BigNumber, BigNumberish } from "@ethersproject/bignumber";
import { arrayify, BytesLike, concat, hexlify, isBytes, isHexString } from "@ethersproject/bytes";
import { Deferrable, defineReadOnly, deepCopy, getStatic, resolveProperties, shallowCopy } from "@ethersproject/properties";
import { AccessList, accessListify, AccessListish } from "@ethersproject/transactions";

import { Logger } from "@ethersproject/logger";
import { version } from "./_version";

const logger = new Logger(version);

export interface Overrides {
    gasLimit?: BigNumberish | Promise<BigNumberish>;
    gasPrice?: BigNumberish | Promise<BigNumberish>;
    nonce?: BigNumberish | Promise<BigNumberish>;
    type?: number;
    accessList?: AccessListish;
};

export interface PayableOverrides extends Overrides {
    value?: BigNumberish | Promise<BigNumberish>;
}

export interface CallOverrides extends PayableOverrides {
    blockTag?: BlockTag | Promise<BlockTag>;
    from?: string | Promise<string>;
}

// @TODO: Better hierarchy with: (in v6)
//  - abstract-provider:TransactionRequest
//  - transactions:Transaction
//  - transaction:UnsignedTransaction

export interface PopulatedTransaction {
    to?: string;
    from?: string;
    nonce?: number;

    gasLimit?: BigNumber;
    gasPrice?: BigNumber;

    data?: string;
    value?: BigNumber;
    chainId?: number;

    type?: number;
    accessList?: AccessList;
};

export type EventFilter = {
    address?: string;
    topics?: Array<string|Array<string>>;
};


export type ContractFunction<T = any> = (...args: Array<any>) => Promise<T>;


// The (n + 1)th parameter passed to contract event callbacks
export interface Event extends Log {

    // The event name
    event?: string;

    // The event signature
    eventSignature?: string;

    // The parsed arguments to the event
    args?: Result;

    // If parsing the arguments failed, this is the error
    decodeError?: Error;

    // A function that can be used to decode event data and topics
    decode?: (data: string, topics?: Array<string>) => any;

    // A function that will remove the listener responsible for this event (if any)
    removeListener: () => void;

    // Get blockchain details about this event's block and transaction
    getBlock: () => Promise<Block>;
    getTransaction: () => Promise<TransactionResponse>;
    getTransactionReceipt: () => Promise<TransactionReceipt>;
}

export interface ContractReceipt extends TransactionReceipt {
    events?: Array<Event>;
}

export interface ContractTransaction extends TransactionResponse {
    wait(confirmations?: number): Promise<ContractReceipt>;
}

///////////////////////////////

const allowedTransactionKeys: { [ key: string ]: boolean } = {
    chainId: true, data: true, from: true, gasLimit: true, gasPrice:true, nonce: true, to: true, value: true,
    type: true, accessList: true,
}

async function resolveName(resolver: Signer | Provider, nameOrPromise: string | Promise<string>): Promise<string> {
    const name = await nameOrPromise;

    // If it is already an address, just use it (after adding checksum)
    try {
        return getAddress(name);
    } catch (error) { }

    if (!resolver) {
        logger.throwError("a provider or signer is needed to resolve ENS names", Logger.errors.UNSUPPORTED_OPERATION, {
            operation: "resolveName"
        });
    }

    const address = await resolver.resolveName(name);

    if (address == null) {
        logger.throwArgumentError("resolver or addr is not configured for ENS name", "name", name);
    }

    return address;
}

// Recursively replaces ENS names with promises to resolve the name and resolves all properties
async function resolveAddresses(resolver: Signer | Provider, value: any, paramType: ParamType | Array<ParamType>): Promise<any> {
    if (Array.isArray(paramType)) {
        return await Promise.all(paramType.map((paramType, index) => {
            return resolveAddresses(
                resolver,
                ((Array.isArray(value)) ? value[index]: value[paramType.name]),
                paramType
            );
        }));
    }

    if (paramType.type === "address") {
        return await resolveName(resolver, value);
    }

    if (paramType.type === "tuple") {
        return await resolveAddresses(resolver, value, paramType.components);
    }

    if (paramType.baseType === "array") {
        if (!Array.isArray(value)) { return Promise.reject(new Error("invalid value for array")); }
        return await Promise.all(value.map((v) => resolveAddresses(resolver, v, paramType.arrayChildren)));
    }

    return value;
}

async function populateTransaction(contract: Contract, fragment: FunctionFragment, args: Array<any>): Promise<PopulatedTransaction> {
    // If an extra argument is given, it is overrides
    let overrides: CallOverrides = { };
    if (args.length === fragment.inputs.length + 1 && typeof(args[args.length - 1]) === "object") {
        overrides = shallowCopy(args.pop());
    }

    // Make sure the parameter count matches
    logger.checkArgumentCount(args.length, fragment.inputs.length, "passed to contract");

    // Populate "from" override (allow promises)
    if (contract.signer) {
        if (overrides.from) {
            // Contracts with a Signer are from the Signer's frame-of-reference;
            // but we allow overriding "from" if it matches the signer
            overrides.from = resolveProperties({
                override: resolveName(contract.signer, overrides.from),
                signer: contract.signer.getAddress()
            }).then(async (check) => {
                if (getAddress(check.signer) !== check.override) {
                    logger.throwError("Contract with a Signer cannot override from", Logger.errors.UNSUPPORTED_OPERATION, {
                        operation: "overrides.from"
                    });
                }

                return check.override;
            });

        } else {
            overrides.from = contract.signer.getAddress();
        }

    } else if (overrides.from) {
        overrides.from = resolveName(contract.provider, overrides.from);

    //} else {
        // Contracts without a signer can override "from", and if
        // unspecified the zero address is used
        //overrides.from = AddressZero;
    }

    // Wait for all dependencies to be resolved (prefer the signer over the provider)
    const resolved = await resolveProperties({
        args: resolveAddresses(contract.signer || contract.provider, args, fragment.inputs),
        address: contract.resolvedAddress,
        overrides: (resolveProperties(overrides) || { })
    });

    // The ABI coded transaction
    const data = contract.interface.encodeFunctionData(fragment, resolved.args);
    const tx: PopulatedTransaction = {
      data: data,
      to: resolved.address
    };

    // Resolved Overrides
    const ro = resolved.overrides;

    // Populate simple overrides
    if (ro.nonce != null) { tx.nonce = BigNumber.from(ro.nonce).toNumber(); }
    if (ro.gasLimit != null) { tx.gasLimit = BigNumber.from(ro.gasLimit); }
    if (ro.gasPrice != null) { tx.gasPrice = BigNumber.from(ro.gasPrice); }
    if (ro.from != null) { tx.from = ro.from; }

    if (ro.type != null) { tx.type = ro.type; }
    if (ro.accessList != null) { tx.accessList = accessListify(ro.accessList); }

    // If there was no "gasLimit" override, but the ABI specifies a default, use it
    if (tx.gasLimit == null && fragment.gas != null) {
        // Conmpute the intrinisic gas cost for this transaction
        // @TODO: This is based on the yellow paper as of Petersburg; this is something
        // we may wish to parameterize in v6 as part of the Network object. Since this
        // is always a non-nil to address, we can ignore G_create, but may wish to add
        // similar logic to the ContractFactory.
        let intrinsic = 21000;
        const bytes = arrayify(data);
        for (let i = 0; i < bytes.length; i++) {
            intrinsic += 4;
            if (bytes[i]) { intrinsic += 64; }
        }
        tx.gasLimit = BigNumber.from(fragment.gas).add(intrinsic);
    }

    // Populate "value" override
    if (ro.value) {
        const roValue = BigNumber.from(ro.value);
        if (!roValue.isZero() && !fragment.payable) {
            logger.throwError("non-payable method cannot override value", Logger.errors.UNSUPPORTED_OPERATION, {
                operation: "overrides.value",
                value: overrides.value
            });
        }
        tx.value = roValue;
    }

    // Remvoe the overrides
    delete overrides.nonce;
    delete overrides.gasLimit;
    delete overrides.gasPrice;
    delete overrides.from;
    delete overrides.value;

    delete overrides.type;
    delete overrides.accessList;

    // Make sure there are no stray overrides, which may indicate a
    // typo or using an unsupported key.
    const leftovers = Object.keys(overrides).filter((key) => ((<any>overrides)[key] != null));
    if (leftovers.length) {
        logger.throwError(`cannot override ${ leftovers.map((l) => JSON.stringify(l)).join(",") }`, Logger.errors.UNSUPPORTED_OPERATION, {
            operation: "overrides",
            overrides: leftovers
        });
    }

    return tx;
}


function buildPopulate(contract: Contract, fragment: FunctionFragment): ContractFunction<PopulatedTransaction> {
    return function(...args: Array<any>): Promise<PopulatedTransaction> {
        return populateTransaction(contract, fragment, args);
    };
}

function buildEstimate(contract: Contract, fragment: FunctionFragment): ContractFunction<BigNumber> {
    const signerOrProvider = (contract.signer || contract.provider);
    return async function(...args: Array<any>): Promise<BigNumber> {
        if (!signerOrProvider) {
            logger.throwError("estimate require a provider or signer", Logger.errors.UNSUPPORTED_OPERATION, {
                operation: "estimateGas"
            })
        }

        const tx = await populateTransaction(contract, fragment, args);
        return await signerOrProvider.estimateGas(tx);
    };
}

function buildCall(contract: Contract, fragment: FunctionFragment, collapseSimple: boolean): ContractFunction {
    const signerOrProvider = (contract.signer || contract.provider);

    return async function(...args: Array<any>): Promise<any> {
        // Extract the "blockTag" override if present
        let blockTag = undefined;
        if (args.length === fragment.inputs.length + 1 && typeof(args[args.length - 1]) === "object") {
            const overrides = shallowCopy(args.pop());
            if (overrides.blockTag != null) {
                blockTag = await overrides.blockTag;
            }
            delete overrides.blockTag;
            args.push(overrides);
        }

        // If the contract was just deployed, wait until it is mined
        if (contract.deployTransaction != null) {
            await contract._deployed(blockTag);
        }

        // Call a node and get the result
        const tx = await populateTransaction(contract, fragment, args);
        const result = await signerOrProvider.call(tx, blockTag);

        try {
            let value = contract.interface.decodeFunctionResult(fragment, result);
            if (collapseSimple && fragment.outputs.length === 1) {
                value = value[0];
            }
            return value;

        } catch (error) {
            if (error.code === Logger.errors.CALL_EXCEPTION) {
                error.address = contract.address;
                error.args = args;
                error.transaction = tx;
            }
            throw error;
         }
    };
}

function buildSend(contract: Contract, fragment: FunctionFragment): ContractFunction<TransactionResponse> {
    return async function(...args: Array<any>): Promise<TransactionResponse> {
        if (!contract.signer) {
            logger.throwError("sending a transaction requires a signer", Logger.errors.UNSUPPORTED_OPERATION, {
                operation: "sendTransaction"
            })
        }

        // If the contract was just deployed, wait until it is minded
        if (contract.deployTransaction != null) {
            await contract._deployed();
        }

        const txRequest = await populateTransaction(contract, fragment, args);

        const tx = await contract.signer.sendTransaction(txRequest);

        // Tweak the tw.wait so the receipt has extra properties
        const wait = tx.wait.bind(tx);
        tx.wait = (confirmations?: number) => {
            return wait(confirmations).then((receipt: ContractReceipt) => {
                receipt.events = receipt.logs.map((log) => {
                    let event: Event = (<Event>deepCopy(log));
                    let parsed: LogDescription = null;
                    try {
                        parsed = contract.interface.parseLog(log);
                    } catch (e){ }

                    // Successfully parsed the event log; include it
                    if (parsed) {
                        event.args = parsed.args;
                        event.decode = (data: BytesLike, topics?: Array<any>) => {
                            return contract.interface.decodeEventLog(parsed.eventFragment, data, topics);
                        };
                        event.event = parsed.name;
                        event.eventSignature = parsed.signature;
                    }

                    // Useful operations
                    event.removeListener = () => { return contract.provider; }
                    event.getBlock = () => {
                        return contract.provider.getBlock(receipt.blockHash);
                    }
                    event.getTransaction = () => {
                        return contract.provider.getTransaction(receipt.transactionHash);
                    }
                    event.getTransactionReceipt = () => {
                        return Promise.resolve(receipt);
                    }

                    return event;
                });

                return receipt;
            });
        };
        return tx;
    };
}

function buildDefault(contract: Contract, fragment: FunctionFragment, collapseSimple: boolean): ContractFunction {
    if (fragment.constant) {
        return buildCall(contract, fragment, collapseSimple);
    }
    return buildSend(contract, fragment);
}

function getEventTag(filter: EventFilter): string {
    if (filter.address && (filter.topics == null || filter.topics.length === 0)) {
        return "*";
    }

    return (filter.address || "*") + "@" + (filter.topics ? filter.topics.map((topic) => {
        if (Array.isArray(topic)) {
            return topic.join("|");
        }
        return topic;
    }).join(":"): "");
}

class RunningEvent {
    readonly tag: string;
    readonly filter: EventFilter;
    private _listeners: Array<{ listener: Listener, once: boolean }>;

    constructor(tag: string, filter: EventFilter) {
        defineReadOnly(this, "tag", tag);
        defineReadOnly(this, "filter", filter);
        this._listeners = [ ];
    }

    addListener(listener: Listener, once: boolean): void {
        this._listeners.push({ listener: listener, once: once });
    }

    removeListener(listener: Listener): void {
        let done = false;
        this._listeners = this._listeners.filter((item) => {
            if (done || item.listener !== listener) { return true; }
            done = true;
            return false;
        });
    }

    removeAllListeners(): void {
        this._listeners = [];
    }

    listeners(): Array<Listener> {
        return this._listeners.map((i) => i.listener);
    }

    listenerCount(): number {
        return this._listeners.length;
    }

    run(args: Array<any>): number {
        const listenerCount = this.listenerCount();
        this._listeners = this._listeners.filter((item) => {

            const argsCopy = args.slice();

            // Call the callback in the next event loop
            setTimeout(() => {
                item.listener.apply(this, argsCopy);
            }, 0);

            // Reschedule it if it not "once"
            return !(item.once);
        });

        return listenerCount;
    }

    prepareEvent(event: Event): void {
    }

    // Returns the array that will be applied to an emit
    getEmit(event: Event): Array<any> {
        return [ event ];
    }
}

class ErrorRunningEvent extends RunningEvent {
    constructor() {
        super("error", null);
    }
}


// @TODO Fragment should inherit Wildcard? and just override getEmit?
//       or have a common abstract super class, with enough constructor
//       options to configure both.

// A Fragment Event will populate all the properties that Wildcard
// will, and additioanlly dereference the arguments when emitting
class FragmentRunningEvent extends RunningEvent {
    readonly address: string;
    readonly interface: Interface;
    readonly fragment: EventFragment;

    constructor(address: string, contractInterface: Interface, fragment: EventFragment, topics?: Array<string|Array<string>>) {
        const filter: EventFilter = {
            address: address
        }

        let topic = contractInterface.getEventTopic(fragment);
        if (topics) {
            if (topic !== topics[0]) { logger.throwArgumentError("topic mismatch", "topics", topics); }
            filter.topics = topics.slice();
        } else {
            filter.topics = [ topic ];
        }

        super(getEventTag(filter), filter);
        defineReadOnly(this, "address", address);
        defineReadOnly(this, "interface", contractInterface);
        defineReadOnly(this, "fragment", fragment);
    }


    prepareEvent(event: Event): void {
        super.prepareEvent(event);

        event.event = this.fragment.name;
        event.eventSignature = this.fragment.format();

        event.decode = (data: BytesLike, topics?: Array<string>) => {
            return this.interface.decodeEventLog(this.fragment, data, topics);
        };

        try {
            event.args = this.interface.decodeEventLog(this.fragment, event.data, event.topics);
        } catch (error) {
            event.args = null;
            event.decodeError = error;
        }
    }

    getEmit(event: Event): Array<any> {
        const errors = checkResultErrors(event.args);
        if (errors.length) { throw errors[0].error; }

        const args = (event.args || []).slice();
        args.push(event);
        return args;
    }
}

// A Wildard Event will attempt to populate:
//  - event            The name of the event name
//  - eventSignature   The full signature of the event
//  - decode           A function to decode data and topics
//  - args             The decoded data and topics
class WildcardRunningEvent extends RunningEvent {
    readonly address: string;
    readonly interface: Interface;

    constructor(address: string, contractInterface: Interface) {
        super("*", { address: address });
        defineReadOnly(this, "address", address);
        defineReadOnly(this, "interface", contractInterface);
    }

    prepareEvent(event: Event): void {
        super.prepareEvent(event);

        try {
            const parsed = this.interface.parseLog(event);
            event.event = parsed.name;
            event.eventSignature = parsed.signature;

            event.decode = (data: BytesLike, topics?: Array<string>) => {
                return this.interface.decodeEventLog(parsed.eventFragment, data, topics);
            };

            event.args = parsed.args;
        } catch (error) {
            // No matching event
        }
    }
}

export type ContractInterface = string | ReadonlyArray<Fragment | JsonFragment | string> | Interface;

type InterfaceFunc = (contractInterface: ContractInterface) => Interface;


export class BaseContract {
    readonly address: string;
    readonly interface: Interface;

    readonly signer: Signer;
    readonly provider: Provider;

    readonly functions: { [ name: string ]: ContractFunction };

    readonly callStatic: { [ name: string ]: ContractFunction };
    readonly estimateGas: { [ name: string ]: ContractFunction<BigNumber> };
    readonly populateTransaction: { [ name: string ]: ContractFunction<PopulatedTransaction> };

    readonly filters: { [ name: string ]: (...args: Array<any>) => EventFilter };

    // This will always be an address. This will only differ from
    // address if an ENS name was used in the constructor
    readonly resolvedAddress: Promise<string>;

    // This is only set if the contract was created with a call to deploy
    readonly deployTransaction: TransactionResponse;

    _deployedPromise: Promise<Contract>;

    // A list of RunningEvents to track listsners for each event tag
    _runningEvents: { [ eventTag: string ]: RunningEvent };

    // Wrapped functions to call emit and allow deregistration from the provider
    _wrappedEmits: { [ eventTag: string ]: (...args: Array<any>) => void };

    constructor(addressOrName: string, contractInterface: ContractInterface, signerOrProvider?: Signer | Provider) {
        logger.checkNew(new.target, Contract);

        // @TODO: Maybe still check the addressOrName looks like a valid address or name?
        //address = getAddress(address);
        defineReadOnly(this, "interface", getStatic<InterfaceFunc>(new.target, "getInterface")(contractInterface));

        if (signerOrProvider == null) {
            defineReadOnly(this, "provider", null);
            defineReadOnly(this, "signer", null);
        } else if (Signer.isSigner(signerOrProvider)) {
            defineReadOnly(this, "provider", signerOrProvider.provider || null);
            defineReadOnly(this, "signer", signerOrProvider);
        } else if (Provider.isProvider(signerOrProvider)) {
            defineReadOnly(this, "provider", signerOrProvider);
            defineReadOnly(this, "signer", null);
        } else {
            logger.throwArgumentError("invalid signer or provider", "signerOrProvider", signerOrProvider);
        }

        defineReadOnly(this, "callStatic", { });
        defineReadOnly(this, "estimateGas", { });
        defineReadOnly(this, "functions", { });
        defineReadOnly(this, "populateTransaction", { });

        defineReadOnly(this, "filters", { });

        {
            const uniqueFilters: { [ name: string ]: Array<string> } = { };
            Object.keys(this.interface.events).forEach((eventSignature) => {
                const event = this.interface.events[eventSignature];
                defineReadOnly(this.filters, eventSignature, (...args: Array<any>) => {
                    return {
                        address: this.address,
                        topics: this.interface.encodeFilterTopics(event, args)
                   }
                });
                if (!uniqueFilters[event.name]) { uniqueFilters[event.name] = [ ]; }
                uniqueFilters[event.name].push(eventSignature);
            });

            Object.keys(uniqueFilters).forEach((name) => {
                const filters = uniqueFilters[name];
                if (filters.length === 1) {
                    defineReadOnly(this.filters, name, this.filters[filters[0]]);
                } else {
                    logger.warn(`Duplicate definition of ${ name } (${ filters.join(", ")})`);
                }
            });
        }

        defineReadOnly(this, "_runningEvents", { });
        defineReadOnly(this, "_wrappedEmits", { });

        if (addressOrName == null) {
            logger.throwArgumentError("invalid contract address or ENS name", "addressOrName", addressOrName);
        }

        defineReadOnly(this, "address", addressOrName);
        if (this.provider) {
            defineReadOnly(this, "resolvedAddress", resolveName(this.provider, addressOrName));
        } else {
            try {
                defineReadOnly(this, "resolvedAddress", Promise.resolve(getAddress(addressOrName)));
            } catch (error) {
                // Without a provider, we cannot use ENS names
                logger.throwError("provider is required to use ENS name as contract address", Logger.errors.UNSUPPORTED_OPERATION, {
                    operation: "new Contract"
                });
            }
        }

        const uniqueNames: { [ name: string ]: Array<string> } = { };
        const uniqueSignatures: { [ signature: string ]: boolean } = { };
        Object.keys(this.interface.functions).forEach((signature) => {
            const fragment = this.interface.functions[signature];

            // Check that the signature is unique; if not the ABI generation has
            // not been cleaned or may be incorrectly generated
            if (uniqueSignatures[signature]) {
                logger.warn(`Duplicate ABI entry for ${ JSON.stringify(name) }`);
                return;
            }
            uniqueSignatures[signature] = true;

            // Track unique names; we only expose bare named functions if they
            // are ambiguous
            {
                const name = fragment.name;
                if (!uniqueNames[name]) { uniqueNames[name] = [ ]; }
                uniqueNames[name].push(signature);
            }

            if ((<Contract>this)[signature] == null) {
                defineReadOnly<any, any>(this, signature, buildDefault(this, fragment, true));
            }

            // We do not collapse simple calls on this bucket, which allows
            // frameworks to safely use this without introspection as well as
            // allows decoding error recovery.
            if (this.functions[signature] == null) {
                defineReadOnly(this.functions, signature, buildDefault(this, fragment, false));
            }

            if (this.callStatic[signature] == null) {
                defineReadOnly(this.callStatic, signature, buildCall(this, fragment, true));
            }

            if (this.populateTransaction[signature] == null) {
                defineReadOnly(this.populateTransaction, signature, buildPopulate(this, fragment));
            }

            if (this.estimateGas[signature] == null) {
                defineReadOnly(this.estimateGas, signature, buildEstimate(this, fragment));
            }
        });

        Object.keys(uniqueNames).forEach((name) => {

            // Ambiguous names to not get attached as bare names
            const signatures = uniqueNames[name];
            if (signatures.length > 1) { return; }

            const signature = signatures[0];

            // If overwriting a member property that is null, swallow the error
            try {
                if ((<Contract>this)[name] == null) {
                    defineReadOnly(<Contract>this, name, (<Contract>this)[signature]);
                }
            } catch (e) { }

            if (this.functions[name] == null) {
                defineReadOnly(this.functions, name, this.functions[signature]);
            }

            if (this.callStatic[name] == null) {
                defineReadOnly(this.callStatic, name, this.callStatic[signature]);
            }

            if (this.populateTransaction[name] == null) {
                defineReadOnly(this.populateTransaction, name, this.populateTransaction[signature]);
            }

            if (this.estimateGas[name] == null) {
                defineReadOnly(this.estimateGas, name, this.estimateGas[signature]);
            }
        });
    }

    static getContractAddress(transaction: { from: string, nonce: BigNumberish }): string {
        return getContractAddress(transaction);
    }

    static getInterface(contractInterface: ContractInterface): Interface {
        if (Interface.isInterface(contractInterface)) {
            return contractInterface;
        }
        return new Interface(contractInterface);
    }

    // @TODO: Allow timeout?
    deployed(): Promise<Contract> {
        return this._deployed();
    }

    _deployed(blockTag?: BlockTag): Promise<Contract> {
        if (!this._deployedPromise) {

            // If we were just deployed, we know the transaction we should occur in
            if (this.deployTransaction) {
                this._deployedPromise = this.deployTransaction.wait().then(() => {
                    return this;
                });

            } else {
                // @TODO: Once we allow a timeout to be passed in, we will wait
                // up to that many blocks for getCode

                // Otherwise, poll for our code to be deployed
                this._deployedPromise = this.provider.getCode(this.address, blockTag).then((code) => {
                    if (code === "0x") {
                        logger.throwError("contract not deployed", Logger.errors.UNSUPPORTED_OPERATION, {
                            contractAddress: this.address,
                            operation: "getDeployed"
                        });
                    }
                    return this;
                });
            }
        }

        return this._deployedPromise;
    }

    // @TODO:
    // estimateFallback(overrides?: TransactionRequest): Promise<BigNumber>

    // @TODO:
    // estimateDeploy(bytecode: string, ...args): Promise<BigNumber>

    fallback(overrides?: TransactionRequest): Promise<TransactionResponse> {
        if (!this.signer) {
            logger.throwError("sending a transactions require a signer", Logger.errors.UNSUPPORTED_OPERATION, { operation: "sendTransaction(fallback)" })
        }

        const tx: Deferrable<TransactionRequest> = shallowCopy(overrides || {});

        ["from", "to"].forEach(function(key) {
            if ((<any>tx)[key] == null) { return; }
            logger.throwError("cannot override " + key, Logger.errors.UNSUPPORTED_OPERATION, { operation: key })
        });

        tx.to = this.resolvedAddress;
        return this.deployed().then(() => {
            return this.signer.sendTransaction(tx);
        });
    }

    // Reconnect to a different signer or provider
    connect(signerOrProvider: Signer | Provider | string): Contract {
        if (typeof(signerOrProvider) === "string") {
            signerOrProvider = new VoidSigner(signerOrProvider, this.provider);
        }

        const contract = new (<{ new(...args: any[]): Contract }>(this.constructor))(this.address, this.interface, signerOrProvider);
        if (this.deployTransaction) {
            defineReadOnly(contract, "deployTransaction", this.deployTransaction);
        }
        return contract;
    }

    // Re-attach to a different on-chain instance of this contract
    attach(addressOrName: string): Contract {
        return new (<{ new(...args: any[]): Contract }>(this.constructor))(addressOrName, this.interface, this.signer || this.provider);
    }

    static isIndexed(value: any): value is Indexed {
        return Indexed.isIndexed(value);
    }

    private _normalizeRunningEvent(runningEvent: RunningEvent): RunningEvent {
        // Already have an instance of this event running; we can re-use it
        if (this._runningEvents[runningEvent.tag]) {
            return this._runningEvents[runningEvent.tag];
         }
         return runningEvent
    }

    private _getRunningEvent(eventName: EventFilter | string): RunningEvent {
        if (typeof(eventName) === "string") {

            // Listen for "error" events (if your contract has an error event, include
            // the full signature to bypass this special event keyword)
            if (eventName === "error") {
                return this._normalizeRunningEvent(new ErrorRunningEvent());
            }

            // Listen for any event that is registered
            if (eventName === "event") {
                return this._normalizeRunningEvent(new RunningEvent("event", null));
            }

            // Listen for any event
            if (eventName === "*") {
                return this._normalizeRunningEvent(new WildcardRunningEvent(this.address, this.interface));
            }

            // Get the event Fragment (throws if ambiguous/unknown event)
            const fragment = this.interface.getEvent(eventName)
            return this._normalizeRunningEvent(new FragmentRunningEvent(this.address, this.interface, fragment));
        }

        // We have topics to filter by...
        if (eventName.topics && eventName.topics.length > 0) {

            // Is it a known topichash? (throws if no matching topichash)
            try {
                const topic = eventName.topics[0];
                if (typeof(topic) !== "string") {
                    throw new Error("invalid topic"); // @TODO: May happen for anonymous events
                }
                const fragment = this.interface.getEvent(topic);
                return this._normalizeRunningEvent(new FragmentRunningEvent(this.address, this.interface, fragment, eventName.topics));
            } catch (error) { }

            // Filter by the unknown topichash
            const filter: EventFilter = {
                address: this.address,
                topics: eventName.topics
            }

            return this._normalizeRunningEvent(new RunningEvent(getEventTag(filter), filter));
        }

        return this._normalizeRunningEvent(new WildcardRunningEvent(this.address, this.interface));
    }

    _checkRunningEvents(runningEvent: RunningEvent): void {
        if (runningEvent.listenerCount() === 0) {
            delete this._runningEvents[runningEvent.tag];

            // If we have a poller for this, remove it
            const emit = this._wrappedEmits[runningEvent.tag];
            if (emit && runningEvent.filter) {
                this.provider.off(runningEvent.filter, emit);
                delete this._wrappedEmits[runningEvent.tag];
            }
        }
    }

    // Subclasses can override this to gracefully recover
    // from parse errors if they wish
    _wrapEvent(runningEvent: RunningEvent, log: Log, listener: Listener): Event {
        const event = <Event>deepCopy(log);

        event.removeListener = () => {
            if (!listener) { return; }
            runningEvent.removeListener(listener);
            this._checkRunningEvents(runningEvent);
        };

        event.getBlock = () => { return this.provider.getBlock(log.blockHash); }
        event.getTransaction = () => { return this.provider.getTransaction(log.transactionHash); }
        event.getTransactionReceipt = () => { return this.provider.getTransactionReceipt(log.transactionHash); }

        // This may throw if the topics and data mismatch the signature
        runningEvent.prepareEvent(event);

        return event;
    }

    private _addEventListener(runningEvent: RunningEvent, listener: Listener, once: boolean): void {
        if (!this.provider) {
            logger.throwError("events require a provider or a signer with a provider", Logger.errors.UNSUPPORTED_OPERATION, { operation: "once" })
        }

        runningEvent.addListener(listener, once);

        // Track this running event and its listeners (may already be there; but no hard in updating)
        this._runningEvents[runningEvent.tag] = runningEvent;

        // If we are not polling the provider, start polling
        if (!this._wrappedEmits[runningEvent.tag]) {
            const wrappedEmit = (log: Log) => {
                let event = this._wrapEvent(runningEvent, log, listener);

                // Try to emit the result for the parameterized event...
                if (event.decodeError == null) {
                    try {
                        const args = runningEvent.getEmit(event);
                        this.emit(runningEvent.filter, ...args);
                    } catch (error) {
                        event.decodeError = error.error;
                    }
                }

                // Always emit "event" for fragment-base events
                if (runningEvent.filter != null) {
                    this.emit("event", event);
                }

                // Emit "error" if there was an error
                if (event.decodeError != null) {
                    this.emit("error", event.decodeError, event);
                }
            };
            this._wrappedEmits[runningEvent.tag] = wrappedEmit;

            // Special events, like "error" do not have a filter
            if (runningEvent.filter != null) {
                this.provider.on(runningEvent.filter, wrappedEmit);
            }
        }
    }

    queryFilter(event: EventFilter, fromBlockOrBlockhash?: BlockTag | string, toBlock?: BlockTag): Promise<Array<Event>> {
        const runningEvent = this._getRunningEvent(event);
        const filter = shallowCopy(runningEvent.filter);

        if (typeof(fromBlockOrBlockhash) === "string" && isHexString(fromBlockOrBlockhash, 32)) {
            if (toBlock != null) {
                logger.throwArgumentError("cannot specify toBlock with blockhash", "toBlock", toBlock);
            }
            (<FilterByBlockHash>filter).blockHash = fromBlockOrBlockhash;
        } else {
             (<Filter>filter).fromBlock = ((fromBlockOrBlockhash != null) ? fromBlockOrBlockhash: 0);
             (<Filter>filter).toBlock = ((toBlock != null) ? toBlock: "latest");
        }

        return this.provider.getLogs(filter).then((logs) => {
            return logs.map((log) => this._wrapEvent(runningEvent, log, null));
        });
    }

    on(event: EventFilter | string, listener: Listener): this {
        this._addEventListener(this._getRunningEvent(event), listener, false);
        return this;
    }

    once(event: EventFilter | string, listener: Listener): this {
        this._addEventListener(this._getRunningEvent(event), listener, true);
        return this;
    }

    emit(eventName: EventFilter | string, ...args: Array<any>): boolean {
        if (!this.provider) { return false; }

        const runningEvent = this._getRunningEvent(eventName);
        const result = (runningEvent.run(args) > 0);

        // May have drained all the "once" events; check for living events
        this._checkRunningEvents(runningEvent);

        return result;
    }

    listenerCount(eventName?: EventFilter | string): number {
        if (!this.provider) { return 0; }
        if (eventName == null) {
            return Object.keys(this._runningEvents).reduce((accum, key) => {
                return accum + this._runningEvents[key].listenerCount();
            }, 0);
        }
        return this._getRunningEvent(eventName).listenerCount();
    }

    listeners(eventName?: EventFilter | string): Array<Listener> {
        if (!this.provider) { return []; }

        if (eventName == null) {
            const result: Array<Listener> = [ ];
            for (let tag in this._runningEvents) {
                this._runningEvents[tag].listeners().forEach((listener) => {
                    result.push(listener)
                });
            }
            return result;
        }

        return this._getRunningEvent(eventName).listeners();
    }

    removeAllListeners(eventName?: EventFilter | string): this {
        if (!this.provider) { return this; }

        if (eventName == null) {
            for (const tag in this._runningEvents) {
                const runningEvent = this._runningEvents[tag];
                runningEvent.removeAllListeners();
                this._checkRunningEvents(runningEvent);
            }
            return this;
        }

        // Delete any listeners
        const runningEvent = this._getRunningEvent(eventName);
        runningEvent.removeAllListeners();
        this._checkRunningEvents(runningEvent);

        return this;
    }

    off(eventName: EventFilter | string, listener: Listener): this {
        if (!this.provider) { return this; }
        const runningEvent = this._getRunningEvent(eventName);
        runningEvent.removeListener(listener);
        this._checkRunningEvents(runningEvent);
        return this;
    }

    removeListener(eventName: EventFilter | string, listener: Listener): this {
        return this.off(eventName, listener);
    }

}

export class Contract extends BaseContract {
    // The meta-class properties
    readonly [ key: string ]: ContractFunction | any;
}

export class ContractFactory {

    readonly interface: Interface;
    readonly bytecode: string;
    readonly signer: Signer;

    constructor(contractInterface: ContractInterface, bytecode: BytesLike | { object: string }, signer?: Signer) {

        let bytecodeHex: string = null;

        if (typeof(bytecode) === "string") {
            bytecodeHex = bytecode;
        } else if (isBytes(bytecode)) {
            bytecodeHex = hexlify(bytecode);
        } else if (bytecode && typeof(bytecode.object) === "string") {
            // Allow the bytecode object from the Solidity compiler
            bytecodeHex = (<any>bytecode).object;
        } else {
            // Crash in the next verification step
            bytecodeHex = "!";
        }

        // Make sure it is 0x prefixed
        if (bytecodeHex.substring(0, 2) !== "0x") { bytecodeHex = "0x" + bytecodeHex; }

        // Make sure the final result is valid bytecode
        if (!isHexString(bytecodeHex) || (bytecodeHex.length % 2)) {
            logger.throwArgumentError("invalid bytecode", "bytecode", bytecode);
        }

        // If we have a signer, make sure it is valid
        if (signer && !Signer.isSigner(signer)) {
            logger.throwArgumentError("invalid signer", "signer", signer);
        }

        defineReadOnly(this, "bytecode", bytecodeHex);
        defineReadOnly(this, "interface", getStatic<InterfaceFunc>(new.target, "getInterface")(contractInterface));
        defineReadOnly(this, "signer", signer || null);
    }

    // @TODO: Future; rename to populteTransaction?
    getDeployTransaction(...args: Array<any>): TransactionRequest {
        let tx: TransactionRequest = { };

        // If we have 1 additional argument, we allow transaction overrides
        if (args.length === this.interface.deploy.inputs.length + 1 && typeof(args[args.length - 1]) === "object") {
            tx = shallowCopy(args.pop());
            for (const key in tx) {
                if (!allowedTransactionKeys[key]) {
                    throw new Error("unknown transaction override " + key);
                }
            }
        }

        // Do not allow these to be overridden in a deployment transaction
        ["data", "from", "to"].forEach((key) => {
            if ((<any>tx)[key] == null) { return; }
            logger.throwError("cannot override " + key, Logger.errors.UNSUPPORTED_OPERATION, { operation: key })
        });

        // Make sure the call matches the constructor signature
        logger.checkArgumentCount(args.length, this.interface.deploy.inputs.length, " in Contract constructor");

        // Set the data to the bytecode + the encoded constructor arguments
        tx.data = hexlify(concat([
            this.bytecode,
            this.interface.encodeDeploy(args)
        ]));

        return tx
    }

    async deploy(...args: Array<any>): Promise<Contract> {

        let overrides: any = { };

        // If 1 extra parameter was passed in, it contains overrides
        if (args.length === this.interface.deploy.inputs.length + 1) {
            overrides = args.pop();
        }

        // Make sure the call matches the constructor signature
        logger.checkArgumentCount(args.length, this.interface.deploy.inputs.length, " in Contract constructor");

        // Resolve ENS names and promises in the arguments
        const params = await resolveAddresses(this.signer, args, this.interface.deploy.inputs);
        params.push(overrides);

        // Get the deployment transaction (with optional overrides)
        const unsignedTx = this.getDeployTransaction(...params);

        // Send the deployment transaction
        const tx = await this.signer.sendTransaction(unsignedTx);

        const address = getStatic<(tx: TransactionResponse) => string>(this.constructor, "getContractAddress")(tx);
        const contract = getStatic<(address: string, contractInterface: ContractInterface, signer?: Signer) => Contract>(this.constructor, "getContract")(address, this.interface, this.signer);
        defineReadOnly(contract, "deployTransaction", tx);
        return contract;
    }

    attach(address: string): Contract {
        return (<any>(this.constructor)).getContract(address, this.interface, this.signer);
    }

    connect(signer: Signer) {
        return new (<{ new(...args: any[]): ContractFactory }>(this.constructor))(this.interface, this.bytecode, signer);
    }

    static fromSolidity(compilerOutput: any, signer?: Signer): ContractFactory {
        if (compilerOutput == null) {
            logger.throwError("missing compiler output", Logger.errors.MISSING_ARGUMENT, { argument: "compilerOutput" });
        }

        if (typeof(compilerOutput) === "string") {
            compilerOutput = JSON.parse(compilerOutput);
        }

        const abi = compilerOutput.abi;

        let bytecode: any = null;
        if (compilerOutput.bytecode) {
            bytecode = compilerOutput.bytecode;
        } else if (compilerOutput.evm && compilerOutput.evm.bytecode) {
            bytecode = compilerOutput.evm.bytecode;
        }

        return new this(abi, bytecode, signer);
    }

    static getInterface(contractInterface: ContractInterface) {
        return Contract.getInterface(contractInterface);
    }

    static getContractAddress(tx: { from: string, nonce: BytesLike | BigNumber | number }): string {
        return getContractAddress(tx);
    }

    static getContract(address: string, contractInterface: ContractInterface, signer?: Signer): Contract {
        return new Contract(address, contractInterface, signer);
    }
}