Sales Engine

• Build a sales engine which takes an input of csvs of customers, transactions, invoices, merchants. Build a system to query data to monitor sales

Data source

We have several files of source data including:

• customers.csv - customer names and other attributes
• transactions.csv - individual transactions with a marker relating a customer, merchant, invoice, and credit card
• invoices.csv - invoices that link transactions to invoice items and hold a status
• invoice_items.csv``` - the item, quantity, and unit price paid for an item in a transaction
• items.csv - items available for sale at the merchants
• merchants.csv - merchant names and identifying information

Understandings

• The data was created from customer orders where:
• One invoice connects the customer to multiple invoice items, one or more transactions, and one merchant
• At least one transaction where their credit card is charged. If the charge fails, more transactions may be created for that single invoice.
• One or more invoice items: one for each item that they ordered
• The transaction references only the invoice
• The invoice item references an item and an invoice
• The item is connected to many invoice items and one merchant
• The merchant is connected to many invoices and many items
• Prices, as represented in the CSVs, are in cents. Anytime you return a revenue total (like in Merchant#revenue) you must return a BigDecimal representating dollars and cents (two decimals, rounded to the nearest cent).

Restrictions

Project implementation may not use:

• Databases (sqlite3, PostgreSQL, MySQL, MongoDB, Redis, etc)
• Rails’ ActiveRecord library or a similar object-relational mappers (including Sequel, DataMapper, etc)
• Your implementation may not use Struct or OpenStruct
• Metaprogramming (method_missing, define_method, etc)