y-fdp-storage/src/feeds/feed.ts

fdp-storage database provider for Yjs

import { BatchId, Bee, Reference, Signer, Topic } from '@ethersphere/bee-js'
import { SingleOwnerChunk } from '@ethersphere/bee-js/dist/types/chunk/soc'
import { Utils } from '@ethersphere/bee-js'
const { assertBytes, bytesToHex, hexToBytes, makeHexString } = Utils

import {
  Bytes,
  ChunkReference,
  readUint64BigEndian,
  serializeBytes,
  TOPIC_BYTES_LENGTH,
  TOPIC_HEX_LENGTH,
  writeUint64BigEndian,
} from './utils'
import { EthAddress, HexEthAddress } from '@ethersphere/bee-js/dist/types/utils/eth'
import { FetchFeedUpdateResponse } from '@ethersphere/bee-js/dist/types/modules/feed'

export const FEED_TYPES = ['sequential', 'fault-tolerant-stream'] as const

export type FeedData = {
  timestamp: number
  reference: ChunkReference
  // TODO metadata
}

export type FeedType = (typeof FEED_TYPES)[number]

export type FeedIndex<T extends FeedType> = T extends 'sequential'
  ? number
  : T extends 'fault-tolerant-stream'
  ? number
  : never

export type useSwarmFeed<T extends FeedType> = (type: T) => SwarmFeed<T>

export interface FeedChunk<Index = number> extends SingleOwnerChunk {
  index: Index
  reference: Reference
  timestamp: number
  // TODO metadata
}

export interface SwarmFeedHandler {
  readonly type: FeedType
  readonly owner: HexEthAddress
  readonly topic: Topic
}

/** Interface for feed type classes */
export interface SwarmFeed<Index> {
  /** Feed type identifier */
  readonly type: FeedType
  /** initialised BeeJS instance */
  readonly bee: Bee
  /** get Feed interface with read operations */
  makeFeedR(
    topic: Topic | Uint8Array | string,
    owner: EthAddress | Uint8Array | string,
    ...options: any[]
  ): SwarmFeedR<Index>
  /** get Feed interface with write and read operations */
  makeFeedRW(
    topic: Topic | Uint8Array | string,
    signer: Signer | Uint8Array | string,
    options?: any,
  ): SwarmFeedRW<Index>
  /** Get Single Owner Chunk identifier */
  getIdentifier(topic: Bytes<32>, index: Index): Bytes<32>
}

/** Swarm Feed Read operations */
export interface SwarmFeedR<Index = number> extends SwarmFeedHandler {
  getLastUpdate(): Promise<FetchFeedUpdateResponse>
  getLastIndex(): Promise<Index> | Index
  findLastUpdate(options?: any): Promise<FeedChunk<Index>>
  getUpdate(index: Index): Promise<FeedChunk<Index>>
  getUpdates(indices: Index[]): Promise<FeedChunk<Index>[]>
}

/** Swarm Feed Read and operations */
export interface SwarmFeedRW<Index = number> extends SwarmFeedR {
  setLastUpdate(
    postageBatchId: string | BatchId,
    reference: Reference,
    // TODO metadata
  ): Promise<Reference>
  setUpdate(
    index: Index,
    postageBatchId: string | BatchId,
    reference: Reference,
    // TODO metadata
  ): Promise<Reference>
}

export function extractDataFromSocPayload(payload: Uint8Array): FeedData {
  const timestamp = readUint64BigEndian(payload.slice(0, 8) as Bytes<8>)
  const p = payload.slice(8)

  if (p.length === 32 || p.length === 64) {
    return {
      timestamp,
      reference: p as ChunkReference,
    }
  }

  // TODO handle JSON-like metadata
  throw new Error('NotImplemented: payload is longer than expected')
}

export function mapSocToFeed<Index = number>(socChunk: SingleOwnerChunk, index: Index): FeedChunk<Index> {
  const { reference, timestamp } = extractDataFromSocPayload(socChunk.payload())

  return {
    ...socChunk,
    index,
    timestamp,
    reference: bytesToHex(reference),
  }
}

export function assembleSocPayload(
  reference: ChunkReference,
  options?: { at?: number }, //TODO metadata
): Uint8Array {
  const at = options?.at ?? Date.now() / 1000.0
  const timestamp = writeUint64BigEndian(at)

  return serializeBytes(timestamp, reference)
}

/** Converts feedIndex response to integer */
export function fetchIndexToInt(fetchIndex: string): number {
  const indexBytes = hexToBytes(fetchIndex)
  let index = 0
  for (let i = indexBytes.length - 1; i >= 0; i--) {
    const byte = indexBytes[i]

    if (byte === 0) break

    index += byte
  }

  return index
}

export function makeTopic(topic: Uint8Array | string): Topic {
  if (typeof topic === 'string') {
    return makeHexString(topic, TOPIC_HEX_LENGTH)
  } else if (topic instanceof Uint8Array) {
    // @ts-ignore TODO fix this
    assertBytes<32>(topic, TOPIC_BYTES_LENGTH)

    return bytesToHex(topic, TOPIC_HEX_LENGTH)
  }
  throw new TypeError('invalid topic')
}