Somewhat futureproof helper function that resolves all blessed ATProto DID methods

resolve.ts

const resolvers: Map<string, (structure: string) => string> = new Map([
    ["plc", (structure) => {
        return `https://plc.directory/did:plc:${structure}`
    }],
    ["web", (structure) => {
        return `https://${structure}/.well-known/did.json`
    }],
    // Room for future DID methods
])

async function resolveDID(did: string) {
    const [type, method, structure] = did.split(":") // Break up DID into components
    if (type !== "did") throw new Error("Invalid DID"); // Drop anything that isn't a DID
    if (!resolvers.has(method)) throw new Error(`Method ${method} is not blessed`); // Drop methods that aren't blessed
    const url = resolvers.get(method)!(structure) // Get resolver and throw DID structure at it
    const response = await fetch(url) // Fetch from the URL given
    if (!response.ok) throw new Error(response.statusText) // Throw an error if the fetch fails
    return JSON.parse(await response.text()) // Parse the document and return
}