feat: support to show fiat amounts

[vojtechsimetka]

Resolves #128

What is missing but will not be part of this PR:

• fetching the fiat (DAI) amounts from blockchain - issues with uniswap SDK

Design reasoning:

When implementing, i played with several ideas how to best expose the rates to the app. The minimum that I need is:

refreshing: boolean // info whether I am currently fetching the rates
error?: Error
checkedAt?: number // last time checked to avoid spamming endpoints
rates?: {
    DAI: number
    ...
}

With this we can detect if rates have been checked (checkedAt and rates or error are defined/populated).

1. [REJECTED] Making the rates part of Token interface in balanceStore

This was rejected, because token balances are updated in the waku adapter and it already has a lot of things to do, it did not feel like this is the right place to add more responsibility. I played with the TokenAmount looking like this:

interface TokenAmountWithRates {
    symbol: string
    amount: bigint
    decimals: number
    name: string
    image?: string | undefined
    address?: string | undefined
    exchangeRates: {
        DAI?: number
        EUR?: number
        ...
        refreshing: boolean
        error?: Error
        checkedAt?: number
    }
}

2. [IMPLEMENTED] Exchange store with rates for all app tokens

Instead I opted to implement extra store, where the rates are in Map<string, Rates>.

interface Rates {
    rates?: {
        DAI: number
        EUR: number
        ...
    }
    refreshing: boolean
    checkedAt?: number
    error?: Error
}

I considered writing a store function that fetches the appropriate rate, but that felt quite unnecessary and does not work in waku object where we are not trying to import the stores directly.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
waku-objects-playground	✅ Ready (Inspect)	Visit Preview	Sep 21, 2023 3:12pm