AutistMask/src/shared/prices.js

// USD prices, read from Chainlink price feeds on Ethereum mainnet, with USD
// formatting and value aggregation. The feeds are in src/shared/tokenList.js.

const { Contract } = require("ethers");
const { ETH_USD_FEED, PRICE_FEED_BY_ADDRESS } = require("./tokenList");
const { getProvider } = require("./balances");
const { isBelowOneMillionth } = require("./amountDisplay");
const { networkByChainId } = require("./networks");
const { log } = require("./log");

const PRICE_CACHE_TTL = 300000; // 5 minutes

// A reading older than its feed's heartbeat plus this many seconds is no price.
const STALE_MARGIN = 1800; // 30 minutes

const FEED_ABI = [
    "function latestRoundData() view returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound)",
];

// USD prices: ether's under "ETH", each token's under its lowercased contract
// address.
const prices = {};
let lastFetchedAt = 0;

// Reads the price of ether and of each token any address holds or the user
// tracks, when that token has a feed. Mainnet only. The reads go to the RPC
// endpoint as one batched request, at most every 5 minutes. A failed read is
// logged, and that token then has no price.
//
// `signal`, passed by the popup, is aborted when the popup closes. A read that
// fails once `signal` is aborted is not logged, because closing the popup
// cancelled it.
async function refreshPrices(signal) {
    const { state, currentNetwork } = require("./state");
    if (currentNetwork().id !== "mainnet") {
        clearPrices();
        return;
    }
    const now = Date.now();
    if (now - lastFetchedAt < PRICE_CACHE_TTL) return;
    const feeds = new Map([["ETH", ETH_USD_FEED]]);
    for (const address of heldOrTrackedTokens(state)) {
        const feed = PRICE_FEED_BY_ADDRESS.get(address);
        if (feed) feeds.set(address, feed);
    }
    // ethers sends calls made together on one provider as one batch.
    const provider = getProvider(state.rpcUrl, state.networkId);
    const read = {};
    await Promise.all(
        [...feeds].map(async ([key, feed]) => {
            try {
                const contract = new Contract(feed.address, FEED_ABI, provider);
                const round = await contract.latestRoundData();
                const price = priceFromRound(round, feed, now);
                if (price === null) {
                    log.warnf(
                        "price feed reading is stale or not positive",
                        key,
                    );
                    return;
                }
                read[key] = price;
            } catch (e) {
                if (signal?.aborted) return;
                log.errorf(
                    "price feed read failed",
                    key,
                    e.shortMessage || e.message,
                );
            }
        }),
    );
    clearPrices();
    Object.assign(prices, read);
    lastFetchedAt = now;
}

// The lowercased contract address of each token that any address holds or
// that the user tracks.
function heldOrTrackedTokens(state) {
    const addresses = new Set();
    for (const wallet of state.wallets) {
        for (const addr of wallet.addresses) {
            for (const token of addr.tokenBalances || []) {
                addresses.add(token.address.toLowerCase());
            }
        }
    }
    for (const token of state.trackedTokens || []) {
        addresses.add(token.address.toLowerCase());
    }
    return addresses;
}

// The USD price in a feed's latestRoundData() result, or null when the answer
// is not positive or was written longer ago than the feed's heartbeat plus
// STALE_MARGIN. `now` is in milliseconds.
function priceFromRound(round, feed, now) {
    const ageSeconds = now / 1000 - Number(round.updatedAt);
    if (ageSeconds > feed.heartbeat + STALE_MARGIN) return null;
    if (round.answer <= 0n) return null;
    return Number(round.answer) / 10 ** feed.decimals;
}

// Clear all cached prices and reset the fetch timestamp so the
// next refreshPrices() call will fetch fresh data.
function clearPrices() {
    for (const key of Object.keys(prices)) {
        delete prices[key];
    }
    lastFetchedAt = 0;
}

// Return the USD price of the token at the contract address `token`, or of
// ether when `token` is "ETH". The price is for the network with `chainId`, or
// for the active network when no chain id is given. Returns null on testnet,
// on a chain id that names no network, and for a token with no price.
function getPrice(token, chainId) {
    const { currentNetwork } = require("./state");
    const network = chainId ? networkByChainId(chainId) : currentNetwork();
    if (!network || network.isTestnet) return null;
    return prices[token === "ETH" ? "ETH" : token.toLowerCase()] || null;
}

function formatUsd(amount) {
    if (amount === null || amount === undefined || isNaN(amount)) return "";
    if (amount === 0) return "$0.00";
    if (amount < 0.01) return "< $0.01";
    return (
        "$" +
        amount.toLocaleString("en-US", {
            minimumFractionDigits: 2,
            maximumFractionDigits: 2,
        })
    );
}

// What an address is worth, as { usd, partial }.
//
// Only a token with a price feed has a price, so an address can hold real
// assets this code has no price for. Adding up the priced ones and calling the
// result the total states a number the holdings do not support: an address
// holding nothing but unpriced tokens comes out at $0.00, which tells the user
// their address is worth nothing when it may hold a great deal. Worth zero and
// worth an unknown amount are separate facts and get separate fields, the same
// way an absent holders_count is not a count of zero.
//
//   usd:     the value of the holdings a price is known for, or null when
//            nothing is knowable at all — testnet, or before the first fetch.
//   partial: the address also holds a token with no price, so usd is a floor
//            and not the total.
//
// Render it through formatAddressTotal() rather than reading usd alone.
function getAddressValue(addr) {
    const { currentNetwork } = require("./state");
    if (currentNetwork().isTestnet) return { usd: null, partial: false };
    if (!prices.ETH) return { usd: null, partial: false };
    let usd = parseFloat(addr.balance || "0") * prices.ETH;
    let partial = false;
    for (const token of addr.tokenBalances || []) {
        // A holding below 0.000001 is left out, as the balance lists leave it
        // out, so the total never counts a holding the list does not show.
        if (isBelowOneMillionth(token.balance)) continue;
        // A null balance is a holding whose scale nothing knows, so it has no
        // quantity to price — but it is still a holding, and a total that
        // silently omits it would read as complete. That is exactly what
        // `partial` is for (https://git.eeqj.de/sneak/AutistMask/issues/349).
        if (token.balance == null) {
            partial = true;
            continue;
        }
        const tokenBal = parseFloat(token.balance);
        // A balance of zero is not a holding: it can neither add to the total
        // nor make it incomplete. Anything that is not a number at all is not
        // a holding this can price either, and is left to the same rule.
        if (!(tokenBal > 0)) continue;
        const price = prices[token.address.toLowerCase()];
        if (price) {
            usd += tokenBal * price;
        } else {
            partial = true;
        }
    }
    return { usd, partial };
}

// The one rendering of an address total, so no screen says it differently.
//
// A partial total is shown and named as partial: the figure is the ETH and
// priced tokens the user does hold, which is worth having, and suppressing it
// would throw away a number that is correct as far as it goes. What is never
// shown is a figure covering no holdings at all — the $0.00 sum of an empty
// set beside a list of tokens is the bug this replaces.
function formatAddressTotal(value) {
    if (!value || value.usd === null) return "";
    if (!value.partial) return "Total: " + formatUsd(value.usd);
    if (value.usd > 0) {
        return "Total: " + formatUsd(value.usd) + " plus unpriced tokens";
    }
    return "Total: unpriced tokens only";
}

module.exports = {
    prices,
    refreshPrices,
    clearPrices,
    getPrice,
    formatUsd,
    formatAddressTotal,
    getAddressValue,
};