Solution for Geektrust Backend Challenge - MyMoney

Problem Statement

MyMoney platform lets investors consolidated portfolio value across equity, debt, and gold. We need to ensure that the desired allocation percentages are equal to the actual percentages invested. The desired allocation percentage should be derived from the initial allocation made.

Your program should take as input:

1. The money allocated in equity, debt and gold funds.
2. Monthly SIP payments.
3. Monthly change rate (loss or growth) for each type of fund.

The output should be:

1. Balanced amount of each fund for a certain month.
2. Rebalanced amount of each month if applicable.

The supported commands are:
ALLOCATE, SIP, CHANGE, BALANCE, REBALANCE

Complete problem statement

Assumptions

From Problem Statement

1. The money allocated in equity, debt and gold funds.
2. Monthly SIP payments.
3. Monthly change rate (loss or growth) for each type of fund.

Additional Assumptions Made

1. Only 3 allocation class are currently available.
2. The default input order for asset class is - EQUITY, DEBT, GOLD.
3. All the inputs must be explicitly provided, no default value as 0 is used.
4. SIP, Change percentages can be declared only once for a month.
5. The system only works for 1-year (Jan-Dec) as there is no way to distinguish between years from input.

Running the Project

The project can be run in following modes:

1. Batch Mode - takes a file as input & produce output for execution of each and every command on the file
2. Interactive Shell Mode - takes a command as input & produce output corresponding to that command

Running in Batch Mode

1. Download the latest geektrust.jar
2. Execute the following command replacing with the path for input file

java -jar geektrust.jar <path-to-inputfile>

3. The output will be printed on the console

Running in Interactive Shell Mode

1. Download the latest geektrust.jar
2. Execute the following command

java -jar geektrust.jar SHELL

3. Execute one of the available command ALLOCATE, SIP, CHANGE, BALANCE, REBALANCE
   • Note: in shell node the command should be entered in lower-case
4. The output will be printed on the console

Sample Input/Output

Running in Batch Mode

1. Say we have a inputfile with following commands

ALLOCATE 6000 3000 1000
SIP 2000 1000 500
CHANGE 4.00% 10.00% 2.00% JANUARY
CHANGE -10.00% 40.00% 0.00% FEBRUARY
CHANGE 12.50% 12.50% 12.50% MARCH
CHANGE 8.00% -3.00% 7.00% APRIL
CHANGE 13.00% 21.00% 10.50% MAY
CHANGE 10.00% 8.00% -5.00% JUNE
BALANCE MARCH
REBALANCE

2. Command to execute:

java -jar geektrust.jar inputfile

3. The output printed on the console

Sep 12, 2021 12:04:01 PM org.hibernate.validator.internal.util.Version <clinit>
INFO: HV000001: Hibernate Validator 6.1.7.Final
10593 7897 2272
23619 11809 3936

Note: The project uses Spring Boot framework and the first two lines of logs are from the framework, and are safe to be ignored.

Running in Interactive Shell Mode

1. We will execute the following commands in sequence on the interactive shell

allocate 6000,3000,1000
sip 2000,1000,500
change 4,10,2 JANUARY
change -10,40,0 FEBRUARY
change 12.50,12.50,12.50 MARCH
change 8,-3,7 APRIL
change 13,21,10.5 MAY
change 10,8,-5 JUNE
balance JANUARY
balance MARCH
rebalance

2. Open the Interactive Shell using:

java -jar geektrust.jar SHELL

3. The Interactive Shell opens a my-money-cli:> prompt
4. Execute the commands & get the output

my-money-cli:> allocate 6000,3000,1000
my-money-cli:> sip 2000,1000,500
my-money-cli:> change 4,10,2 JANUARY
my-money-cli:> change -10,40,0 FEBRUARY
my-money-cli:> change 12.50,12.50,12.50 MARCH
my-money-cli:> change 8,-3,7 APRIL
my-money-cli:> change 13,21,10.5 MAY
my-money-cli:> change 10,8,-5 JUNE
my-money-cli:> balance JANUARY
6240 3300 1020
my-money-cli:> balance MARCH
10593 7897 2272
my-money-cli:> balance MARCH
10593 7897 2272
my-money-cli:> rebalance
23619 11809 3936
my-money-cli:> exit

5. Use exit to exit the shell

Key Points regarding Design

• Calculations done lazily - not unless the balance is asked or re-balancing is required,
• Calculated values are cached to avoid re-calculations

Points to Ponder

1. Is using Spring Boot required?

   • No, This could be implemented using POJOs as well.
   • Spring Boot is used to make the solution mimic the Enterprise Java Solution preferred by companies over POJO solutions.
   • Spring Boot comes with additional features like inherent dependency-injection that makes code more maintainable.

2. The Exceptions thrown by service class are being propagated but not handled.

   • This can be improved; it is not good user experience to display Exceptions, rather user-friendly error messages should be used to handle these exceptions.

3. Using a lazy-calculation scheme - i.e. we compute the balance only when user checks for balance or re-balacing is required.

   • This can be replaced with eager calculation to improve response time for user.
   • Can also be done as a background batch job, without impacting performance.