import logger from 'log'
import {DHusage, ecdh} from './kdf'
import SecretWrap from './secret-wrap'
import * as misc from './misc'
import * as consts from './const'

const log = logger('crypto:private-wrap')

export default class PrivateWrap {
  private constructor(
    private readonly box: SecretWrap,
    private readonly pubkey: CryptoKey
  ) {}

  public static async gen(extractable: boolean = true): Promise<CryptoKeyPair> {
    log.trace('generate keypair')
    return await crypto.subtle.generateKey(consts.ECDH, extractable, ['deriveKey']) as CryptoKeyPair
  }

  public static async wrap(data: CryptoKey, pubkey: CryptoKey): Promise<PrivateWrap> {
    log.trace('wrap')
    const tmp_keypair = await PrivateWrap.gen()
    const kd = await ecdh(tmp_keypair.privateKey, pubkey, DHusage.wrap)
    const box = await SecretWrap.wrap(data, kd)
    return new this(box, tmp_keypair.publicKey)
  }
  public async unwrap(privkey: CryptoKey): Promise<CryptoKey | null> {
    log.trace('unwrap')
    const kd = await ecdh(privkey, this.pubkey, DHusage.wrap)
    return await this.box.unwrap(kd)
  }

  public async toString(): Promise<string> {
    log.trace('toString')
    const pubkey = await PrivateWrap.pubkey_toString(this.pubkey)
    const box = this.box.toString()
    return `${pubkey}.${box}`
  }
  public static async fromString(data: string): Promise<PrivateWrap | null> {
    log.trace('fromString')

    const parts = data.split('.')
    if (parts.length < 2) return null

    const pubkey = await PrivateWrap.pubkey_fromString(parts[0])
    if (pubkey === null) return null
    const box = SecretWrap.fromString(parts.slice(1).join('.'))
    if (box === null) return null

    return new PrivateWrap(box, pubkey)
  }

  public static async pubkey_toString(pubkey: CryptoKey): Promise<string> {
    return await misc.pubkey_toString(pubkey)
  }
  public static async pubkey_fromString(pubkey: string): Promise<CryptoKey | null> {
    return await misc.pubkey_fromString(pubkey, misc.Usage.ecdh)
  }
}