fission-suite/webnative

/**
 * Filesystem UCANs, read keys and namefilters,
 * attained from elsewhere in confidence.
 */

import * as Crypto from "./components/crypto/implementation.js"
import * as Identifiers from "./common/identifiers.js"
import * as Path from "./path/index.js"
import * as Permissions from "./permissions.js"
import * as UcansRepo from "./repositories/ucans.js"
import * as Reference from "./components/reference/implementation.js"
import * as Storage from "./components/storage/implementation.js"
import * as Ucan from "./ucan/index.js"

import Repository from "./repository.js"
import { Maybe } from "./common/types.js"


// 🧩


export type Capabilities = {
  fileSystemSecrets: FileSystemSecret[]
  ucans: Ucan.Ucan[]
  username: string
}


export type FileSystemSecret = {
  bareNameFilter: string
  path: Path.Distinctive<Path.Segments>
  readKey: Uint8Array
}



// 🏔


export const SESSION_TYPE = "capabilities"



// 🛠


export async function collect({ capabilities, crypto, reference, storage }: {
  capabilities: Capabilities
  crypto: Crypto.Implementation
  reference: Reference.Implementation
  storage: Storage.Implementation
}): Promise<void> {
  if (capabilities.ucans.length === 0) throw new Error("Expected at least one UCAN")

  await collectPermissions({ reference, ucans: capabilities.ucans })

  const accountDID = await reference.didRoot.lookup(capabilities.username)

  await capabilities.fileSystemSecrets.reduce(
    async (acc: Promise<void>, fsSecret: FileSystemSecret) => {
      await acc
      await collectSecret({
        accountDID,
        crypto,
        storage,
        bareNameFilter: fsSecret.bareNameFilter,
        readKey: fsSecret.readKey,
        path: fsSecret.path,
      })
    },
    Promise.resolve()
  )
}


export async function collectSecret({ accountDID, bareNameFilter, crypto, path, readKey, storage }: {
  accountDID: string
  bareNameFilter: string
  crypto: Crypto.Implementation
  path: Path.DistinctivePath<Path.Segments>
  readKey: Uint8Array
  storage: Storage.Implementation
}) {
  const readKeyId = await Identifiers.readKey({ accountDID, crypto, path })
  const bareNameFilterId = await Identifiers.bareNameFilter({ accountDID, crypto, path })

  await crypto.keystore.importSymmKey(readKey, readKeyId)
  await storage.setItem(bareNameFilterId, bareNameFilter)
}

export async function collectPermissions({ reference, ucans }: {
  reference: Reference.Implementation
  ucans: Ucan.Ucan[]
}): Promise<void> {
  await reference.repositories.ucans.add(ucans)
}


/**
 * See if the stored UCANs in a repository
 * conform to the given `Permissions`.
 *
 * This returns the last encountered valid UCAN.
 */
export function validatePermissions(
  repo: Repository<Ucan.Ucan>,
  { app, fs, raw }: Permissions.Permissions
): Maybe<Ucan.Ucan> {
  let ucan

  const prefix = UcansRepo.filesystemPrefix()

  // Root access
  const rootUcan = repo.getByKey("*")
  if (rootUcan && !Ucan.isExpired(rootUcan) && !Ucan.isSelfSigned(rootUcan)) return rootUcan

  // Check permissions
  if (app) {
    const k = prefix + Path.toPosix(Path.appData(app))
    const u = repo.getByKey(k)
    if (!u || Ucan.isExpired(u)) return null
    ucan = u
  }

  if (fs?.private) {
    const priv = fs.private.every(path => {
      const pathWithPrefix = `${prefix}private/` + Path.toPosix(path)
      const u = repo.getByKey(pathWithPrefix)
      ucan = u
      return u && !Ucan.isExpired(u)
    })
    if (!priv) return null
  }

  if (fs?.public) {
    const publ = fs.public.every(path => {
      const pathWithPrefix = `${prefix}public/` + Path.toPosix(path)
      const u = repo.getByKey(pathWithPrefix)
      ucan = u
      return u && !Ucan.isExpired(u)
    })
    if (!publ) return null
  }

  if (raw) {
    const hasRaw = raw.every(r => {
      const label = UcansRepo.resourceLabel(r.rsc)
      const u = repo.getByKey(label)
      ucan = u
      return u && !Ucan.isExpired(u)
    })
    if (!hasRaw) return null
  }

  return ucan || null
}


/**
 * Ensure the existence and validity of the read keys and namefilters
 * we need for the filesystem based on the permissions we asked for.
 */
export async function validateSecrets(
  crypto: Crypto.Implementation,
  accountDID: string,
  permissions: Permissions.Permissions
): Promise<boolean> {
  return Permissions.permissionPaths(permissions).reduce(
    (acc: Promise<boolean>, path: Path.Distinctive<Path.Partitioned<Path.Partition>>): Promise<boolean> =>
      acc.then(async (bool: boolean) => {
        if (bool === false) return bool
        if (Path.isPartition(Path.RootBranch.Public, path)) return bool

        const keyName = await Identifiers.readKey({ accountDID, crypto, path })
        return crypto.keystore.keyExists(keyName)
      }),
    Promise.resolve(true)
  )
}