/**
 * The `@polkadot/extension-dapp` package can be dynamically imported.
 * Usually it is wise to use a package manager like npm or yarn to install it as a dependency.
 *
 * The `getPolkadotJsExtensionMod` closure returns the `@polkadot/extension-dapp` module on demand.
 */
let getPolkadotJsExtensionMod = (() => {
    let mod = null;

    // initialize `@polkadot/extension-dapp` module on page load
    let initPromise = (async () => {
        mod = await import(
            "https://cdn.jsdelivr.net/npm/@polkadot/extension-dapp@0.46.3/+esm"
            );
    })();

    // return a function that waits for initialization to be finished, in case mod is not initialized yet.
    return async () => {
        if (mod == null) {
            await initPromise;
        }
        return mod;
    };
})();

/**
 *  Queries wallets from browser extensions like Talisman and the Polkadot.js extension for user accounts.
 *
 *  @returns a json string that contains all the accounts that were found.
 */
async function getAccounts() {
    const extensionMod = await getPolkadotJsExtensionMod();
    await extensionMod.web3Enable("Subxt Example App");
    const allAccounts = await extensionMod.web3Accounts();
    const accountObjects = allAccounts.map((account) => ({
        name: account.meta.name, // e.g. "Alice"
        source: account.meta.source, // e.g. "talisman", "polkadot-js"
        ty: account.type, // e.g. "sr25519"
        address: account.address // e.g. "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY"
    }));
    console.log(accountObjects);
    return JSON.stringify(accountObjects);
}

/**
 * Signs a payload via browser extension
 *
 * @param payloadAsStr a string representing a JSON object like this:
 * let payload = {
 *     "specVersion": "0x000024d6",
 *     "transactionVersion": "0x00000018",
 *     "address": "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY",
 *     "blockHash": "0xd7aad6185db012b7ffbce710b55234d6c9589170566b925ee50cfa3d7f1e6f8f",
 *     "blockNumber": "0x00000000",
 *     "era": "0x0000",
 *     "genesisHash": "0xd7aad6185db012b7ffbce710b55234d6c9589170566b925ee50cfa3d7f1e6f8f",
 *     "method": "0x0503001cbd2d43530a44705ad088af313e18f80b53ef16b36177cd4b77b846f2a5f07c0b00c465f14670",
 *     "nonce": "0x00000000",
 *     "signedExtensions": [
 *         "CheckNonZeroSender",
 *         "CheckSpecVersion",
 *         "CheckTxVersion",
 *         "CheckGenesis",
 *         "CheckMortality",
 *         "CheckNonce",
 *         "CheckWeight",
 *         "ChargeTransactionPayment",
 *         "PrevalidateAttests"
 *     ],
 *     "tip": "0x00000000000000000000000000000000",
 *     "version": 4
 * };
 * @param source the extension used for signing as a string
 * @param address the ss58 encoded address as a string
 * @returns {Promise<*>}
 */
async function signPayload(payloadAsStr, source, address) {
    let payload = JSON.parse(payloadAsStr);
    const extensionMod = await getPolkadotJsExtensionMod();
    const injector = await extensionMod.web3FromSource(source);
    const signPayload = injector?.signer?.signPayload;
    if (!!signPayload) {
        const {signature} = await signPayload(payload);
        console.log("signature js:", signature)
        return signature;
    } else {
        throw "The extension's injector does not have a `signPayload` function on its `signer`";
    }
}