import java.awt.*;
import java.applet.*;

// Domain Logic
public class TradeExecution extends DomainLogic { // inherits from DomainLogic
  public TradeExecution(TextArea textArea1) {
    super(textArea1);
  }
  void chgCash(Account account, double amount) {  // adjust cash after BUY/SELL
    account.CASH = account.CASH + amount;
  }
  private Holding getHolding(Account account, Stock stock) { // find the holding record
    Holding holding = null;
    for (int i=0; i<account.holdings.size(); i++) {
      Holding holding1 = (Holding)account.holdings.elementAt(i);
      if (holding1.stock == stock) {
        holding = holding1;
        break;
      }
    }
    return holding;
  }
  // adjust QTY of holding, or remove
  private void chgHolding(Account account, Stock stock, int qty) { 
    Holding holding = getHolding(account, stock);
    if (holding == null)
      new Holding(account, stock, qty);
    else {
      holding.QTY += qty;
      if (holding.QTY <= 0) 
        holding.remove();
    }
  }
  private void chkOrder(Order order, int qty) { // adjust QTY of order, or remove
    if (qty <= 0) 
      order.remove();
    else
      order.QTY = qty;
  }
  
  // make sure a seller actually has the stock in the correct amount
  private boolean validOrder(Account account, Stock stock, String type, 
                             String price, String shares) {
    boolean OK = true;
    if (type.equals("SELL")) {
      OK = false;
      Holding holding = getHolding(account, stock);
      if (holding == null)
        textArea1.append("Account does not have any shares of " + stock.SYM + "\n");
      else  
        if (toInt(shares) > holding.QTY)
          textArea1.append("Account only has " + holding.QTY + " shares of "+ stock.SYM + "\n");
        else
          OK = true;
    }
    return OK;
  }
  // new buyer has to pay at least as much as pending seller wants, vice versa for a new seller
  private boolean chkPrices(String type, double p1, double p2) {
    boolean OK = false;
    if (type.equals("BUY")) {
      if (p1 >= p2)
        OK = true;
    } 
    else // SELL
      if (p1 <= p2)
        OK = true;
    return OK;
  } 
  // process a sale for buyer/seller updating cash, holdings, transaction. 
  //Also, this sale price represents the stocks new "value", used in all portfolios
  private void doSale(Account sellAccount,Account buyAccount,Stock stock,int qty, double price){
    chgCash(sellAccount,+qty*price);
    chgCash(buyAccount,-qty*price);
    chgHolding(sellAccount,stock,-qty);
    chgHolding(buyAccount,stock,+qty);
    new Transaction(sellAccount,stock,"SELL",price,qty);
    new Transaction(buyAccount,stock, "BUY",price,qty);
    stock.PRICE = price;
  } 
  // main algorithm (see pseudocode) for matching buys with sells 
  private void scanOrders(Account account, Stock stock, String type, int qty1, double price) {
    int qty2, qty;
    Heap heap = stock.buyheap;
    if (type.equals("BUY"))
      heap = stock.sellheap;
    while (true) {
      if (qty1 <= 0) break; 
      Order order = (Order) heap.testRoot();
      if (order == null) break;
      if (!chkPrices(type, price,order.PRICE)) break;

      order = heap.getRoot();
      qty2 = order.QTY;
      Account acct2 = order.account;
      if (qty1 <= qty2)
        qty = qty1;
      else  
        qty = qty2;
      Account seller;
      Account buyer;
      if (type.equals("BUY")) {
        buyer = account;
        seller = acct2;
      } 
      else {
        seller = account;
        buyer = acct2;
      } 
      qty1 -= qty;
      qty2 -= qty;
      doSale(seller,buyer,stock,qty,price);
      chkOrder(order,qty2);
      textArea1.append("Sale completed: " + qty + " shares of " + stock.SYM + 
                       " at $" + price + " with account: " + acct2.ACCOUNT_NO + "\n"); 
    } // while
    if (qty1 <= 0)
      textArea1.append(type + " completed.\n");
    else {
      new Order(account, stock, type, price, qty1);
      textArea1.append("Current outstanding order: " + type + " " + qty1 + 
                       " shares of " + stock.SYM + " at $" + price + "\n");
     }
  }
  // StockApplet calls doOrder when a BUY/SELL button is pushed
  // Validate the input fields and lookup the stock in the hashtable
  public void doOrder(String type, String sym, String shares, String price) {
    sym = sym.toUpperCase();
    if (chkLogin())
      if ((sym.equals("")) || (shares.equals("")) || (price.equals("")))  
        textArea1.append("Must enter Stock, Shares, and Price.\n");
        else {
          Stock stock = (Stock)Stock.stocks.get(sym);
          if (stock == null) 
            textArea1.append("Stock does not exist: " + sym);
          else 
            if (validOrder(account,stock,type,price,shares))
              scanOrders(account,stock,type,toInt(shares),toDouble(price));
        }
  }
} // class TradeExecution