solved the problem

SplitwiseMachineCoding/src/com/splitwise/machine/coding/CollectionUtils.java

@@ -0,0 +1,15 @@
+package com.splitwise.machine.coding;
+
+import java.util.Collection;
+
+public class CollectionUtils<E> {
+
+	public E get(Collection<E> collection, E object) {
+		for (E e : collection) {
+			if (e.hashCode() == object.hashCode() && e.equals(object)) {
+				return e;
+			}
+		}
+		return null;
+	}
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/Driver.java

@@ -0,0 +1,64 @@
+package com.splitwise.machine.coding;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Scanner;
+
+public class Driver {
+
+	static LedgerService ledgerService = new LedgerService();
+
+	public static void main(String[] args) {
+
+		Scanner sc = new Scanner(System.in);
+
+		while (sc.hasNext()) {
+			String line = sc.nextLine();
+			String[] inputs = line.split(" ");
+			String command = inputs[0];
+			if (command.equals("EXPENSE")) {
+				String payerId = inputs[1];
+				double amount = Double.valueOf(inputs[2]);
+				int users = Integer.valueOf(inputs[3]);
+				List<String> splitTo = new ArrayList<>(users);
+				int x = 0;
+				for (; x < users; x++) {
+					splitTo.add(inputs[x + 4]);
+				}
+				String expenseType = inputs[x + 4];
+				List<Integer> scales = new ArrayList<>();
+				if (!expenseType.equals("EQUAL")) {
+					for (int y = 0; y < users; y++) {
+						scales.add(Integer.valueOf((inputs[x + 4 + 1 + y])));
+					}
+				}
+
+				createUserBase();
+				ledgerService.splitExpenses(expenseType, payerId, amount, splitTo, scales);
+
+			}
+			if (command.equals("SHOW")) {
+				inputs = line.split(" ");
+				if (inputs.length > 1) {
+					ledgerService.getUserExpensesSheet(inputs[1]);
+				} else {
+					ledgerService.getAllUserExppenses();
+				}
+			}
+		}
+	}
+
+	private static void createUserBase() {
+		// Creating dummy users for now , it can be created using some file or
+		// some other ways.
+		User user1 = new User("u1", "User1", "User1@gmail.com", "123");
+		User user2 = new User("u2", "User2", "User2@gmail.com", "1234");
+		User user3 = new User("u3", "User3", "User3@gmail.com", "1235");
+		User user4 = new User("u4", "User4", "User4@gmail.com", "123455");
+		UserBase.addUser(user1);
+		UserBase.addUser(user2);
+		UserBase.addUser(user3);
+		UserBase.addUser(user4);
+
+	}
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/EqualExpense.java

@@ -0,0 +1,23 @@
+package com.splitwise.machine.coding;
+
+import java.text.DecimalFormat;
+import java.util.ArrayList;
+import java.util.List;
+
+public class EqualExpense implements Expense {
+
+	@Override
+	public List<UserExpenseProfile> splitExpense(double amount, List<String> splitTo, List<Integer> scales) {
+		List<UserExpenseProfile> userExpenseProfiles = new ArrayList<>();
+
+		DecimalFormat df = new DecimalFormat("#.##");      
+		double equalAmount = Double.valueOf(df.format(amount/splitTo.size()));
+
+		for(int x=0; x< splitTo.size(); x++) {
+			UserExpenseProfile profile = new UserExpenseProfile(splitTo.get(x), equalAmount);
+			userExpenseProfiles.add(profile);
+		}
+		return userExpenseProfiles;
+	}
+
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/ExactExpense.java

@@ -0,0 +1,18 @@
+package com.splitwise.machine.coding;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ExactExpense implements Expense {
+
+	@Override
+	public List<UserExpenseProfile> splitExpense(double amount, List<String> splitTo, List<Integer> scales) {
+		List<UserExpenseProfile> userExpenseProfiles = new ArrayList<>();
+
+		for(int x=0; x< splitTo.size(); x++) {
+			UserExpenseProfile profile = new UserExpenseProfile(splitTo.get(x), scales.get(x));
+			userExpenseProfiles.add(profile);
+		}
+		return userExpenseProfiles;
+	}
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/Expense.java

@@ -0,0 +1,8 @@
+package com.splitwise.machine.coding;
+
+import java.util.List;
+
+public interface Expense {
+
+	List<UserExpenseProfile> splitExpense(double amount, List<String> splitTo, List<Integer> scales);
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/ExpenseFactory.java

@@ -0,0 +1,24 @@
+package com.splitwise.machine.coding;
+
+public class ExpenseFactory {
+
+	public static Expense getInstance(ExpenseType expenseType) {
+
+		switch (expenseType) {
+		case EQUAL:
+			return new EqualExpense();
+		case EXACT:
+			return new ExactExpense();
+		case PERCENT:
+			return new PercentExpense();
+
+		default:
+			break;
+		}
+		return null;
+	}
+}
+
+enum ExpenseType {
+	EQUAL,EXACT,PERCENT
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/LedgerBook.java

@@ -0,0 +1,82 @@
+package com.splitwise.machine.coding;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+/**
+ * @author Hakim.s
+ *
+ */
+public class LedgerBook {
+
+	private Map<String, List<UserExpenseProfile>> userExpensesProfile;
+
+	public LedgerBook() {
+
+		this.userExpensesProfile = new HashMap<>();
+	}
+
+	public void addExpenseEntry(String payer, UserExpenseProfile paidTo) {
+
+		UserExpenseProfile payerProfile = new UserExpenseProfile(payer, (paidTo.getExpenses() * -1));
+
+		updateExpense(payer, paidTo);
+
+		// update reverse association.
+		updateExpense(paidTo.getUserId(), payerProfile);
+
+	}
+
+	private void updateExpense(String payer, UserExpenseProfile paidTo) {
+
+		if (getUserExpensesProfile().containsKey(payer)) {
+			List<UserExpenseProfile> profiles = getUserExpensesProfile().get(payer);
+
+			if (profiles.contains(paidTo)) {
+				UserExpenseProfile existingProfile = new CollectionUtils<UserExpenseProfile>().get(profiles, paidTo);
+				existingProfile.setExpenses(existingProfile.getExpenses() + paidTo.getExpenses());
+				// System.out.println(existingProfile.getExpenses());
+			} else {
+				profiles.add(paidTo);
+			}
+
+		} else {
+			// Add new entry.
+			List<UserExpenseProfile> userExpenseProfiles = new ArrayList<>();
+			userExpenseProfiles.add(paidTo);
+			getUserExpensesProfile().put(payer, userExpenseProfiles);
+		}
+	}
+
+	public List<UserExpenseProfile> getExpensesForUser(String userId) {
+		return getUserExpensesProfile().get(userId);
+	}
+
+	public Map<String, List<UserExpenseProfile>> getAllLedgerExpenses() {
+
+		Map<String, List<UserExpenseProfile>> filteredUserExpenses = new HashMap<>();
+		Set<Entry<String, List<UserExpenseProfile>>> entrySet = userExpensesProfile.entrySet();
+		for (Entry<String, List<UserExpenseProfile>> entry : entrySet) {
+			List<UserExpenseProfile> value = entry.getValue();
+			List<UserExpenseProfile> filteredProfiles = new ArrayList<>();
+			for (UserExpenseProfile userExpenseProfile : value) {
+				if (userExpenseProfile.getExpenses() < 0) {
+					filteredProfiles.add(userExpenseProfile);
+				}
+			}
+			if(!filteredProfiles.isEmpty())
+				filteredUserExpenses.put(entry.getKey(), filteredProfiles);
+		}
+		return filteredUserExpenses;
+
+	}
+
+	private Map<String, List<UserExpenseProfile>> getUserExpensesProfile() {
+		return userExpensesProfile;
+	}
+
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/LedgerService.java

@@ -0,0 +1,37 @@
+package com.splitwise.machine.coding;
+
+import java.util.List;
+import java.util.Map;
+
+public class LedgerService {
+
+	LedgerBook ledgerBook = new LedgerBook();
+
+	public void splitExpenses(String expenseType, String payer, double amount, List<String> splitTo,
+			List<Integer> scales) {
+		List<UserExpenseProfile> userExpenseProfiles = null;
+
+		// Calling factory which will create a Expense Type object, we can take
+		// any type in future.
+		Expense expenseTypeInstance = ExpenseFactory.getInstance(ExpenseType.valueOf(expenseType));
+		userExpenseProfiles = expenseTypeInstance.splitExpense(amount, splitTo, scales);
+
+		for (UserExpenseProfile userExpenseProfile : userExpenseProfiles) {
+			if (!payer.equals(userExpenseProfile.getUserId())) {
+				ledgerBook.addExpenseEntry(payer, userExpenseProfile);
+			}
+		}
+
+	}
+
+	public void getUserExpensesSheet(String userId) {
+		List<UserExpenseProfile> userExpensesSheet = ledgerBook.getExpensesForUser(userId);
+		PrintReport.printUserBalances(userId, userExpensesSheet);
+	}
+
+	public void getAllUserExppenses() {
+		Map<String, List<UserExpenseProfile>> userExpensesSheet = ledgerBook.getAllLedgerExpenses();
+
+		PrintReport.printAllBalances(userExpensesSheet);
+	}
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/PercentExpense.java

@@ -0,0 +1,23 @@
+package com.splitwise.machine.coding;
+
+import java.text.DecimalFormat;
+import java.util.ArrayList;
+import java.util.List;
+
+public class PercentExpense implements Expense {
+
+	@Override
+	public List<UserExpenseProfile> splitExpense(double amount, List<String> splitTo, List<Integer> scales) {
+		List<UserExpenseProfile> userExpenseProfiles = new ArrayList<>();
+
+		for (int x = 0; x < splitTo.size(); x++) {
+			DecimalFormat df = new DecimalFormat("#.##");
+			double percentAmount = Double.valueOf(df.format((amount * scales.get(x)) / 100));
+
+			UserExpenseProfile profile = new UserExpenseProfile(splitTo.get(x), percentAmount);
+			userExpenseProfiles.add(profile);
+		}
+		return userExpenseProfiles;
+	}
+
+}

SplitwiseMachineCoding/src/com/splitwise/machine/coding/PrintReport.java

@@ -0,0 +1,52 @@
+package com.splitwise.machine.coding;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+/**
+ * @author Hakim.s
+ * 
+ *         Optional requirement 3 can be done using this class. A way to show
+ *         the passbook for a user. [The entries should show all the
+ *         transactions a user was part of. You can print in any format you
+ *         like]
+ *
+ */
+public class PrintReport {
+
+	public static void printUserBalances(String userId, List<UserExpenseProfile> userExpensesSheet) {
+		if (userExpensesSheet == null || userExpensesSheet.isEmpty()) {
+			System.out.println("No balances");
+			return;
+		}
+		for (UserExpenseProfile userExpenseProfile : userExpensesSheet) {
+			if (userExpenseProfile.getExpenses() < 0) {
+				printMessage(userId, userExpenseProfile.getUserId(), userExpenseProfile.getExpenses());
+			} else if (userExpenseProfile.getExpenses() > 0) {
+				printMessage(userExpenseProfile.getUserId(), userId, userExpenseProfile.getExpenses());
+
+			}
+		}
+
+	}
+
+	public static void printAllBalances(Map<String, List<UserExpenseProfile>> userExpensesMap) {
+		if (userExpensesMap == null || userExpensesMap.isEmpty()) {
+			System.out.println("No balances");
+			return;
+		}
+		Set<Entry<String, List<UserExpenseProfile>>> entries = userExpensesMap.entrySet();
+		for (Entry<String, List<UserExpenseProfile>> entry : entries) {
+			printUserBalances(entry.getKey(), entry.getValue());
+		}
+
+	}
+
+	private static void printMessage(String borrower, String payer, double expenses) {
+		System.out.println(UserBase.getUser(borrower).getName() + " owes " + UserBase.getUser(payer).getName() + ": "
+				+ Math.abs(expenses));
+	}
+
+}