transfer_pha_to_evm_by_wanbridge.js

require('dotenv').config();

const { ApiPromise, WsProvider, Keyring } = require('@polkadot/api');
const { blake2AsU8a } = require('@polkadot/util-crypto');
const BN = require('bn.js');

const bn1e12 = new BN(10).pow(new BN(12));

function getPhaAssetId(khalaApi) {
    return khalaApi.createType('XcmV1MultiassetAssetId', {
        Concrete: khalaApi.createType('XcmV1MultiLocation', {
            parents: 0,
            interior: khalaApi.createType('Junctions', 'Here')
        })
    })
}

// Make sure amount > bridge fee
async function transferPhaFromKhalaToEvm(khalaApi, sender, recipient, amount) {
    console.log(`Transfer PHA from Khala to EVM...`);
    return new Promise(async (resolve) => {
        const unsub = await khalaApi.tx.xTransfer.transfer(
            khalaApi.createType('XcmV1MultiAsset', {
                id: getPhaAssetId(khalaApi),
                fun: khalaApi.createType('XcmV1MultiassetFungibility', {
                    Fungible: khalaApi.createType('Compact<U128>', amount)
                })
            }),
            khalaApi.createType('XcmV1MultiLocation', {
                parents: 0,
                interior: khalaApi.createType('Junctions', {
                    X3: [
                        khalaApi.createType('XcmV1Junction', {
                            GeneralKey: '0x7762'    // string "wb", indentity of WanBridge path
                        }),
                        khalaApi.createType('XcmV1Junction', {
                            GeneralIndex: 0 // 0 is chainid of ethereum
                        }),
                        khalaApi.createType('XcmV1Junction', {
                            GeneralKey: recipient // EVM address, 20 bytes hex string
                        }),
                    ]
                })
            }),
            null,   // No need to specify a certain weight if transfer will not through XCM
        ).signAndSend(sender, (result) => {
            if (result.status.isInBlock) {
                console.log(`Transaction included at blockHash ${result.status.asInBlock}`);
            } else if (result.status.isFinalized) {
                console.log(`Transaction finalized at blockHash ${result.status.asFinalized}`);
                unsub();
                resolve();
            }
        });
    });
}

async function main() {
    // create khala api
    const khalaEndpoint = process.env.ENDPOINT || 'ws://localhost:9944';
    const khalaProvider = new WsProvider(khalaEndpoint);
    const khalaApi = await ApiPromise.create({
        provider: khalaProvider,
    });

    const keyring = new Keyring({ type: 'sr25519' });
    const khalaAccount = keyring.addFromUri('//Alice');
    const evmRecipient = "0xA29D4E0F035cb50C0d78c8CeBb56Ca292616Ab20";

    // Transfer 50 PHA from Khala::Alice to Ethereum::0xA29D4E0F035cb50C0d78c8CeBb56Ca292616Ab20
    await transferPhaFromKhalaToEvm(khalaApi, khalaAccount, evmRecipient, bn1e12.mul(new BN(50)));    
}

main().catch(console.error).finally(() => process.exit());