import errCode from 'err-code'
import { CID } from 'multiformats/cid'
import type { BlockAPI } from '../block/index.js'
import type { Codecs } from '../index.js'
import type { AbortOptions } from '@libp2p/interface'

export interface ResolveResult {
  value: any
  remainderPath?: string
}

/**
 * Retrieves IPLD Nodes along the `path` that is rooted at `cid`
 */
export async function * resolve (cid: CID, path: string, codecs: Codecs, getBlock: BlockAPI['get'], options?: AbortOptions): AsyncGenerator<ResolveResult> {
  const load = async (cid: CID): Promise<any> => {
    const codec = await codecs.getCodec(cid.code)
    const block = await getBlock(cid, options)

    return codec.decode(block)
  }

  const parts = path.split('/').filter(Boolean)
  let value = await load(cid)
  let lastCid = cid

  // End iteration if there isn't a CID to follow any more
  while (parts.length > 0) {
    const key = parts.shift()

    if (key == null) {
      throw errCode(new Error(`Could not resolve path "${path}"`), 'ERR_INVALID_PATH')
    }

    if (Object.prototype.hasOwnProperty.call(value, key)) {
      value = value[key]

      yield {
        value,
        remainderPath: parts.join('/')
      }
    } else {
      throw errCode(new Error(`no link named "${key}" under ${lastCid}`), 'ERR_NO_LINK')
    }

    const cid = CID.asCID(value)

    if (cid != null) {
      lastCid = cid
      value = await load(value)
    }
  }

  yield {
    value,
    remainderPath: ''
  }
}