fix ethers event decoding

[leovigna]

What it solves

Resolves #505

How this PR fixes it

We check the topics.length to determine which encoding to use and then decode the args directly using ethers.

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[leovigna]

Link to CLA is broken
Edit: I think found it https://github.com/gnosis/CLA

[leovigna]

I have read the CLA Document and I hereby sign the CLA

[leovigna]

Also here is a simple util function to abstract this decoding logic

/**
 * Take an arbitrary event log and parse out if it is ProxyCreation(address proxy, address singleton) or ProxyCreation(address indexed proxy, address singleton)
 * @param event
 * @returns address/singleton kv or undefined
 */
export function parseProxyCreationEvent(event: Event): { proxy: string; singleton: string } | undefined {
    if (event.topics[0] != "0x4f51faf6c4561ff95f067657e43439f0f856d97c04d9ec9070a6199ad418e235") return undefined;

    if (event.topics.length == 1) {
        const ifaceNonIndexedProxyAddress = new ethers.utils.Interface([
            "event ProxyCreation(address proxy, address singleton)",
        ]);
        return ifaceNonIndexedProxyAddress.decodeEventLog("ProxyCreation", event.data, event.topics) as any;
    } else if (event.topics.length == 2) {
        const ifaceIndexedProxyAddress = new ethers.utils.Interface([
            "event ProxyCreation(address indexed proxy, address singleton)",
        ]);
        return ifaceIndexedProxyAddress.decodeEventLog("ProxyCreation", event.data, event.topics) as any;
    }
}

[leovigna]

Anyone willing to review this? 😄
Open to any suggestions