Adaptive Pay
============

A wrapper for the Paypal Adaptive Payments API. For details see: https://www.x.com/docs/DOC-1408

The adaptive payments API allows you to:
1) send money to multiple (up to 5) recipients in one transaction
2) preapprove payments, which can then be executed later without user intervention


Installation
-----------
As plugin:
script/plugin install git://github.com/derfred/adaptive_pay.git

As gem:
(in config/environment.rb)
config.gem "adaptive_pay"
Then run:
rake gems:install


Configuration
-------------

This plugin expects a file named config/adaptive_pay.yml to contain the configuration

development:
  instance: "sandbox"
  username: "my_development_username"
  password: "my_development_password"
  signature: "my_development_signature"
  application_id: "my_development_app_id"

test:
  retain_requests_for_test: true

production:
  instance: "production"
  username: "my_production_username"
  password: "my_production_password"
  signature: "my_production_signature"
  application_id: "my_production_app_id"

Description of config parameters:
  instance: can be either sandbox or production and refers to which instance of the Paypal service should be used
  username, password, signature, application_id: the relevant authentication parameters for your account
  retain_requests_for_test: mark this Rails environment as a test environment. If this parameter is set then all interactions with the API will remain local. For details see the testing section.
  

Chained/Split Payment Usage
-------------------------------------

The following example shows how to set up a chained payment for a total of 110 GBP, 10 GBP going to a primary receipient with the paypal account "[email protected]" and 100 GBP going to the account "[email protected]". Because this is a chained payment it will seem to the user that the complete total will go to the primary account.

interface = AdaptivePay::Interface.new
response = interface.request_payment do |request|
  request.currency_code = "GBP"

  request.cancel_url = "http://example.com/cancelled_payment"        # this is where the user will be redirected should he cancel the payment
  request.return_url = "http://example.com/completed_payment"       # and here should the payment be succesful
  request.ipn_notification_url = "http://example.com/ipn_callback"      

  request.add_recipient :email => "[email protected]",
                        :amount => 100,
                        :primary => false

  request.add_recipient :email => "[email protected]",
                        :amount => 10,
                        :primary => true
end

if response.created?
  # the payment has been setup successfully, now the user will need to be redirected to the Paypal site:
  redirect_to response.payment_page_url
else
  # the payment could not be setup, most likely because of a missing parameter or validation error
  # the array of errors reported by the service can be retrieved using:
  response.errors
end

This example could be changed to a Split Payment by setting the primary parameter to false for each recipient.

After the payment has been set up and the user has been redirected to the payment page url, the application will need to wait for the IPN callback which indicates whether the payment has actually gone through. This is done in the next snippet. For this to work the ipn_callback_url specified above needs to be connected to a controller action.

def ipn_callback
  callback = AdaptivePay::Callback.new params
  if callback.completed?
    # payment has been processed, now mark order as paid etc
  else
    # payment failed
  end
end



Preapproved Payment Usage
---------------------------

The next example will ask the user to preapprove a payment of 300 dollars and then distribute it equally among three recipients at a later date

interface = AdaptivePay::Interface.new
response = interface.request_preapproval do |request|
  request.currency_code = "USD"

  request.max_total_amount_of_all_payments = 300
  request.ending_date = 3.months.from_now
  request.starting_date = Time.now
end

if response.created?
  # The preapproval has been set up. In addition to redirecting the user to the payment page we will have to keep track of the
  # preapproval key for making the payment at a later time:
  Approval.create :key => response.preapproval_key
  redirect_to response.payment_page_url
else
  # error in request, same as above
end

Now at a later time the payment can be initiated without user intervention, in a cron job or rake task etc:

approval = Approval.first :conditions => ....   # find the approval object created above
interface = AdaptivePay::Interface.new
response = interface.request_payment do |request|
  request.currency_code = "USD"

  request.ipn_notification_url = "http://example.com/ipn_callback"

  request.preapproval_key = approval.key    # this is the preapproval key generated in the first step
  request.add_recipient :email => "[email protected]", :amount => 100
  request.add_recipient :email => "[email protected]", :amount => 100
  request.add_recipient :email => "[email protected]", :amount => 100
end

if response.pending?
  # some payment methods require longer to process, in that case the API will return pending and notify using IPN callback
elsif response.completed?
  # payment has been processed, mark the order as paid etc
else
  # there was an error, see the errors array for details
  response.errors
end


Object based calls
-----------------

Rather than using the block based calls shown above you can explicitly create a Request object and pass it to the perform method:

payment_request = AdaptivePay::PaymentRequest.new
payment_request.currency_code = "USD"
payment_request.ipn_notification_url = "http://example.com/ipn_callback"
payment_request.add_recipient :email => "[email protected]", :amount => 100

interface = AdaptivePay::Interface.new
interface.perform  payment_request


This is equivalent to:

interface = AdaptivePay::Interface.new
response = interface.request_payment do |request|
  request.currency_code = "USD"
  request.ipn_notification_url = "http://example.com/ipn_callback"
  request.add_recipient :email => "[email protected]", :amount => 100
end

Since the Request objects are stateless you can reuse them.


Testing
---------

The main benefit to using this library is the support for testing. When a RAILS_ENV has the retain_requests_for_test parameter set in the config/adaptive_pay.yml file requests will not be delivered to the Paypal servers but rather added to a queue, just like ActionMailer does. One difference though is that you need to provide a stub response.

it "should create preapproval request" do
  AdaptivePay::Interface.test_response = stub(:response, :completed? => true, :pending? => false)
  @payment_processor.process @order

  AdaptivePay::Interface.requests.size.should == 1
  request = AdaptivePay::Interface.requests.first

  request.should be_a(AdaptivePay::PreapprovalRequest)
  request.max_total_amount_of_all_payments.should == 130
  request.currency_code.should == "GBP"
end