js-bigchaindb-driver/src/transaction/utils/ccJsonLoad.js

import base58 from 'bs58';
import cc from 'five-bells-condition';
import { Buffer } from 'buffer';

/**
 * @public
 * Loads a crypto-condition class (Fulfillment or Condition) from a BigchainDB JSON object
 * @param {object} conditionJson
 * @returns {cc.Condition} Ed25519 Condition (that will need to wrapped in an Output)
 */
export default function ccJsonLoad(conditionJson) {

    if ('hash' in conditionJson) {
        let condition = new cc.Condition();
        condition.type = conditionJson.type_id;
        condition.bitmask = conditionJson.bitmask;
        condition.hash = new Buffer(base58.decode(conditionJson.hash));
        condition.maxFulfillmentLength = parseInt(conditionJson.max_fulfillment_length, 10);
        return condition
    } else {
        let fulfillment;

        if (conditionJson.type_id === 2) {
            fulfillment = new cc.ThresholdSha256();
            fulfillment.threshold = conditionJson.threshold;
            conditionJson.subfulfillments.forEach((subfulfillment) => {
                subfulfillment = ccJsonLoad(subfulfillment);
                if ('getConditionUri' in subfulfillment)
                    fulfillment.addSubfulfillment(subfulfillment);
                else if ('serializeUri' in subfulfillment)
                    fulfillment.addSubcondition(subfulfillment)
            })
        }

        if (conditionJson.type_id === 0) {
            fulfillment = new cc.PreimageSha256();
            fulfillment.preimage = new Buffer(conditionJson.preimage);

        }

        if (conditionJson.type_id === 4) {
            fulfillment = new cc.Ed25519();
            fulfillment.publicKey = new Buffer(base58.decode(conditionJson.public_key));
            if (conditionJson.signature)
                fulfillment.signature = new Buffer(base58.decode(conditionJson.signature));
        }
        return fulfillment;
    }
}