import { InvalidMultiaddrError } from '@libp2p/interface'
import { peerIdFromString } from '@libp2p/peer-id'
import { getNetConfig } from '@libp2p/utils'
import { WebTransport } from '@multiformats/multiaddr-matcher'
import { bases, digest } from 'multiformats/basics'
import type { PeerId } from '@libp2p/interface'
import type { Multiaddr } from '@multiformats/multiaddr'
import type { MultihashDigest } from 'multiformats/hashes/interface'

// @ts-expect-error - Not easy to combine these types.
const multibaseDecoder = Object.values(bases).map(b => b.decoder).reduce((d, b) => d.or(b))

function decodeCerthashStr (s: string): MultihashDigest {
  return digest.decode(multibaseDecoder.decode(s))
}

export interface ParsedMultiaddr {
  url: string
  certhashes: MultihashDigest[]
  remotePeer?: PeerId
}

export function parseMultiaddr (ma: Multiaddr): ParsedMultiaddr {
  if (!WebTransport.matches(ma)) {
    throw new InvalidMultiaddrError('Invalid multiaddr, was not a WebTransport address')
  }

  const certhashes: MultihashDigest[] = []
  let remotePeer: PeerId | undefined

  for (const components of ma.getComponents()) {
    if (components.name === 'certhash') {
      certhashes.push(decodeCerthashStr(components.value ?? ''))
    }

    // only take the first peer id in the multiaddr as it may be a relay
    if (components.name === 'p2p' && remotePeer == null) {
      remotePeer = peerIdFromString(components.value ?? '')
    }
  }

  const opts = getNetConfig(ma)
  let host = opts.host

  if (opts.type === 'ip6' && host.includes(':')) {
    /**
     * This resolves cases where `new WebTransport()` fails to construct because of an invalid URL being passed.
     *
     * `new URL('https://::1:4001/blah')` will throw a `TypeError: Failed to construct 'URL': Invalid URL`
     * `new URL('https://[::1]:4001/blah')` is valid and will not.
     *
     * @see https://datatracker.ietf.org/doc/html/rfc3986#section-3.2.2
     */
    host = `[${host}]`
  }

  return {
    // All webtransport urls are https
    url: `https://${host}:${opts.port}`,
    certhashes,
    remotePeer
  }
}