Generate CID

[jasny]

There are issues with trying to use IPFS packages blockstore-core and ipfs-unixfs-importer in the react native app.

• package.json isn't exported

warn Package blockstore-core has been ignored because it contains invalid configuration. Reason: Package subpath './package.json' is not defined by "exports" in /home/arnold/Projects/ltonetwork/universal-wallet/node_modules/blockstore-core/package.json

• It's complaining about main for these and other packages.
• Submodules in defined in exports of package.json aren't being loaded.

[jasny]

utils/calculateCid.ts

import {BackHoleBlockstore} from "blockstore-core/black-hole"
import {importer} from "ipfs-unixfs-importer"

export default async function calculateCid(files: Array<{name: string, read: () => Promise<Uint8Array>}>): Promise<string> {
  const source = await Promise.all(
    files.map(async file => ({
      path: `./${file.name}`,
      content: await file.read(),
    }))
  )

  const blockstore = new BackHoleBlockstore()

  for await (const entry of importer(source, blockstore)) {
    if (entry.path === '' && entry.unixfs?.type === 'directory') return entry.cid.toString()
  }

  throw new Error("Failed to calculate directory CID: importer did not find a directory entry in the input files")
}

[jasny]

I tried patching package.json, which worked up to a point. But the rabbit hole was too deep.

It might be necessary to fork the packages and modify them. We can submit a pull request and use our fork in the meantime. The problem also occurs with some of the dependencies

https://www.npmjs.com/package/ipfs-unixfs-importer?activeTab=dependencies

[jasny]

ipfs/js-stores#230
ipfs/js-ipfs-unixfs#336

[jasny]

Start with importing the multiformats library (which has no dependencies).

Copy/paste this code from the README and create a method in utils/calculateCid.

import { CID } from 'multiformats/cid'
import * as json from 'multiformats/codecs/json'
import { sha256 } from 'multiformats/hashes/sha2'

export function cidFromData(data: any) {
  const bytes = json.encode(data)

  const hash = await sha256.digest(bytes)
  return CID.create(1, json.code, hash)
}

Try to build the project for Android (yarn android) with this code.