@elephant-xyz/cli/dist/services/event-decoder.service.js

CLI tool for Elephant Network

import { AbiCoder, getAddress, dataSlice } from 'ethers';
import { isValidCID, deriveCIDFromHash } from '../utils/validation.js';
export class EventDecoderService {
    abiCoder;
    constructor() {
        this.abiCoder = AbiCoder.defaultAbiCoder();
    }
    decodePropertyHash(bytes) {
        // Decode the bytes32 hash from event data
        const decoded = this.abiCoder.decode(['bytes32'], bytes)[0];
        // Derive CID v0 from the hash
        const cid = deriveCIDFromHash(decoded);
        if (!isValidCID(cid)) {
            throw new Error(`Invalid CID format: ${cid}`);
        }
        return cid;
    }
    parseOracleAssignedEvent(event) {
        const propertyCid = this.decodePropertyHash(event.data);
        let elephantAddress = '';
        // Assuming elephant address is always the second topic (index 1) if present
        // and is a full 32-byte address (hence dataSlice from byte 12 of the 32-byte topic)
        if (event.topics && event.topics.length > 1 && event.topics[1]) {
            // topics[0] is the event signature
            // topics[1] is the first indexed argument, `elephant`
            // Indexed addresses are stored as 32-byte values; getAddress expects a 20-byte address.
            // We need to get the last 20 bytes (40 hex characters) of the topic.
            // A common way is to slice the hex string.
            // topics[1] is '0x' + 64 hex chars. Address is last 40 hex chars.
            // So, '0x' + (24 leading zeros) + (40 address chars).
            // Slice from 2 + 24 = 26th char, or use dataSlice(event.topics[1], 12) if topic is 0x-prefixed.
            const addressFromTopic = dataSlice(event.topics[1], 12); // Skips the first 12 bytes (24 hex chars) of the 32-byte topic
            elephantAddress = getAddress(addressFromTopic); // Normalizes the address
        }
        return {
            cid: propertyCid,
            elephant: elephantAddress,
            blockNumber: event.blockNumber,
            transactionHash: event.transactionHash,
        };
    }
}
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