/******************************************************************************
 * Copyright © 2013-2016 The Nxt Core Developers.                             *
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 * See the AUTHORS.txt, DEVELOPER-AGREEMENT.txt and LICENSE.txt files at      *
 * the top-level directory of this distribution for the individual copyright  *
 * holder information and the developer policies on copyright and licensing.  *
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 * Unless otherwise agreed in a custom licensing agreement, no part of the    *
 * Nxt software, including this file, may be copied, modified, propagated,    *
 * or distributed except according to the terms contained in the LICENSE.txt  *
 * file.                                                                      *
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 * Removal or modification of this copyright notice is prohibited.            *
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 ******************************************************************************/

package nxt.http;

import nxt.Account;
import nxt.Attachment;
import nxt.Currency;
import nxt.NxtException;
import org.json.simple.JSONStreamAware;

import javax.servlet.http.HttpServletRequest;

/**
 * Sell currency for NXT
 * <p>
 * Parameters
 * <ul>
 * <li>currency - currency id
 * <li>rateNQT - exchange rate between NXT amount and currency units
 * <li>units - number of units to sell
 * </ul>
 *
 * <p>
 * currency sell transaction attempts to match existing exchange offers. When a match is found, the minimum number of units
 * between the number of units offered and the units requested are exchanged at a rate matching the lowest buy offer<br>
 * A single transaction can match multiple buy offers or none.
 * Unlike asset ask order, currency sell is not saved. It's either executed immediately (fully or partially) or not executed
 * at all.
 * For every match between buyer and seller an exchange record is saved, exchange records can be retrieved using the {@link GetExchanges} API
 */
public final class CurrencySell extends CreateTransaction {

    static final CurrencySell instance = new CurrencySell();

    private CurrencySell() {
        super(new APITag[] {APITag.MS, APITag.CREATE_TRANSACTION}, "currency", "rateNQT", "units");
    }

    @Override
    JSONStreamAware processRequest(HttpServletRequest req) throws NxtException {
        Currency currency = ParameterParser.getCurrency(req);
        long rateNQT = ParameterParser.getLong(req, "rateNQT", 0, Long.MAX_VALUE, true);
        long units = ParameterParser.getLong(req, "units", 0, Long.MAX_VALUE, true);
        Account account = ParameterParser.getSenderAccount(req);

        Attachment attachment = new Attachment.MonetarySystemExchangeSell(currency.getId(), rateNQT, units);
        try {
            return createTransaction(req, account, attachment);
        } catch (NxtException.InsufficientBalanceException e) {
            return JSONResponses.NOT_ENOUGH_CURRENCY;
        }
    }

}