import { Hyper } from '@stellar/js-xdr';
import BigNumber from '../util/bignumber';
import xdr from '../xdr';
import { Asset } from '../asset';
import { LiquidityPoolAsset } from '../liquidity_pool_asset';

const MAX_INT64 = '9223372036854775807';

/**
 * Returns an XDR ChangeTrustOp. A "change trust" operation adds, removes, or updates a
 * trust line for a given asset from the source account to another.
 * @function
 * @alias Operation.changeTrust
 * @param {object} opts Options object
 * @param {Asset | LiquidityPoolAsset} opts.asset - The asset for the trust line.
 * @param {string} [opts.limit] - The limit for the asset, defaults to max int64.
 *                                If the limit is set to "0" it deletes the trustline.
 * @param {string} [opts.source] - The source account (defaults to transaction source).
 * @returns {xdr.ChangeTrustOp} Change Trust operation
 */
export function changeTrust(opts) {
  const attributes = {};

  if (opts.asset instanceof Asset) {
    attributes.line = opts.asset.toChangeTrustXDRObject();
  } else if (opts.asset instanceof LiquidityPoolAsset) {
    attributes.line = opts.asset.toXDRObject();
  } else {
    throw new TypeError('asset must be Asset or LiquidityPoolAsset');
  }

  if (opts.limit !== undefined && !this.isValidAmount(opts.limit, true)) {
    throw new TypeError(this.constructAmountRequirementsError('limit'));
  }

  if (opts.limit) {
    attributes.limit = this._toXDRAmount(opts.limit);
  } else {
    attributes.limit = Hyper.fromString(new BigNumber(MAX_INT64).toString());
  }

  if (opts.source) {
    attributes.source = opts.source.masterKeypair;
  }
  const changeTrustOP = new xdr.ChangeTrustOp(attributes);

  const opAttributes = {};
  opAttributes.body = xdr.OperationBody.changeTrust(changeTrustOP);
  this.setSourceAccount(opAttributes, opts);

  return new xdr.Operation(opAttributes);
}