import {Result} from 'result'
import logger from 'log'

export type PrivKey = CryptoKey
export type PubKey = CryptoKey
export type KeyPair = [PrivKey, PubKey]

const algorithm: EcdsaParams = {
    name: "ECDSA",
    hash: {name: "SHA-512"},
}
const log = logger('crypto:signature')

/**
 * Create a new keypair for signing
 * @param extractable if the keys must be extractable or not
 * @return [privkey, pubkey] keys
 */
export async function gen_keypair(extractable: boolean = false) : Promise<KeyPair> {
    log.trace('Generating keypair')
    log.debug('Extractable :', extractable ? 'yes' : 'no')

    let key = await window.crypto.subtle.generateKey(
        {
            name: "ECDSA",
            namedCurve: "P-521"
        } as EcKeyGenParams,
        extractable,
        ['sign', 'verify']
    )

    return [key.privateKey, key.publicKey]
}
export async function sign(privkey: PrivKey, message: Uint8Array) : Promise<Result<ArrayBuffer>> {
    log.trace('sign')

    try {
        return Result.ok(await window.crypto.subtle.sign(
            algorithm,
            privkey,
            message,
        ))
    } catch(e) {
        log.warn('Signature failed')
        log.debug(`Error : ${e}`)
    }

    return Result.error([])
}

export async function verify(pubkey: PubKey, message: Uint8Array, signature: ArrayBuffer): Promise<boolean> {
    log.trace('Verify signature')

    try {
        return await window.crypto.subtle.verify(
            algorithm,
            pubkey,
            signature,
            message
        );
    } catch (e) {
        log.warn('Verification failed')
        log.debug(`Error : ${e}`)
    }

    return false;
}