Mocapi

mocapi is a simple HTTPd application server which calculates mortgage payment given schedule and financial details provided by end users.

Usage

bundle # install dependencies
bundle exec ./bin/mocapi

# or with ENV variables:
bundle exec ./bin/mocapi APP_ENV=production MAX_MORTGAGE=150_000_99 \
    RATE_UNDER=0.1 RATE_OVER=0.2 # etc...

Environmental Variables

The constants used by mocapi to calculate payments and mortgages can be altered at startup via environmental variables:

Variable	Default Value	Description
APP_ENV	'development'	Sinatra's runmode: 'development' or 'production'
RATE_UNDER	0.05	The required rate of downpayment for the portion of a mortgage below OVERAGE_FLOOR
RATE_OVER	0.10	The required rate of downpayment for the portion of a mortgage over OVERAGE_FLOOR
OVERAGE_FLOOR	500_000_00	The mortgage amount (in cents) above which a downpayment of RATE_OVER is required, instead of RATE_UNDER
MAX_MORTGAGE	1_000_000_00	The maximum mortgage (in cents) that insurance can be provided for. Mortgages above this limit will require a large enough downpayment or an error will be returned
MORTGAGE_INTEREST	0.025	The default mortgage interest when the application boots. Users may change this value with PATCH /interest-rate

Routes

GET /payment-amount

Get the recurring payment amount of a mortgage (in cents).

Parameter	Description
mortgage	The total mortgage, in cents
downpayment	The down payent, in cents
schedule	The payment schedule. Either 'weekly', 'biweekly', or 'monthly'
amortization	The duration of the mortgage, in whole years

Example cURL

curl -i -X GET -H "Accept: application/json" \
     -d 'mortgage=10000000&downpayment=2000000&schedule=weekly&amortization=10' \
     'localhost:4567/payment-amount'

Output

{
  "amount": 15769
}

GET /mortgage-amount

Get the maximum mortgage amount (in cents).

Parameter	Description
payment	The payment amount, in cents
downpayment	An optional down payent, in cents
schedule	The payment schedule. Either 'weekly', 'biweekly', or 'monthly'
amortization	The duration of the mortgage, in whole years

Example cURL

curl -i -X GET -H "Accept: application/json" \
     -d 'payment=10000&schedule=weekly&amortization=20' \
     'localhost:4567/mortgage-amount'

Output

{
  "maximum": 10400000
}

PATCH /interest-rate

Change the interest rate used by the application.

Parameter	Description
payment	The payment amount, in cents
downpayment	An optional down payent, in cents
schedule	The payment schedule. Either 'weekly', 'biweekly', or 'monthly'
amortization	The duration of the mortgage, in whole years

Example cURL

curl -i -X PATCH -H "Accept: application/json" \
     -d 'interest=0.0355' \
     'localhost:4567/interest-rate'

Output

{
  "old": 0.025,
  "new": 0.0355
}

Development

Testing

A few Rake commands will help your testing:

• bundle exec guard: Start Red/Green development cycle
• rake test: Run the test suite
• rake lint: Run the code linters
• rake simplecov: Run the code coverage reporter
• rake: Run all tests, linters, and code coverage reporters

To facilitate development, consider running guard in the background while you work. Whenver a source file it changed, it will automatically run the relevent tests. This will provide you immediate test feedback at all times.

Documentation

Generate code docs with:

rake doc

Contributing to Mocapi

• Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.
• Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
• Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.