Challenge

I accepted the challenge call billing.

The objective is to create a console application to charge incoming calls, and list all charges per account.

Technologies used

To create the application I used:

• PHP
• Mysql
• PhpUnit
• Composer
• External packages:
  • Symfony Console
  • csv/league

Project Setup

###Prerequisites

To setup the project it is necessary to have installed on your machine:

• PHP
• Composer
• MySql
• PhpUnit

Get external dependencies

First of all we need to get the necessary external packages with the help of composer

$ composer install

Initial setup

Next we need to create the database to be the application storage

$ mysql -u<user> [-p<password>]

Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 308
Server version: 10.1.9-MariaDB Source distribution

Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> create database talkdesk;
Query OK, 1 row affected (0,00 sec)

After creating database we need to restore database structure usefull for the project

$ mysql -u root talkdesk < assets/DB/initial-mysql.sql

In order to billing is possible we should have at least one account with credit, for that we can insert in db account like this:

insert into account (name, credit) values ('Luis', 300);

Configuration

There is a file named config.ini that has the settings to:

• access database
  • host
  • user
  • database name
  • password
• the files paths used to get the cost values
  • toll free/not free
  • twillio numbers costs
  • margin

How to Use

Command is named call_billing, when invoked without arguments it will show the available commands and is invoked like so:

php call_billing.php

For help with a particular command you can write

php call_billing.php help <command>

The implemented commands are:

• chargeCall - Charges a call and remove credits from a given account
• listInboundCalls - Lists the charges for the given account

Examples

Add an inbound call

• lasts for 100 seconds,
• for Luis account,
• with talkdesknumber 12345545678,
• from client number 22422444446
• the call was taken to a forwarded phone with number 180022344

php call_billing.php chargeCall 100 "Luis" 12345545678 22422444446 180022344

List charges for user "Luis"

php call_billing.php listCalls "KLuis"

Assets used for costs calculation

• File tdMargin.csv:
  • Has the rules for margin calculation
  • Define the ranges of minutes used and the the correspondant margin
  • These values are used with the current month minutes used by the particular account
  • If user has a lot of minutes used then our margin decreases...
• File tollFreeNumbers.csv:
  • Has the begin of US and UK Toll free numbers, as it's cost
  • Fallback is 1cent
• File Twilio - Voice Prices.csv
  • Has the prices per location
  • This is only considered if call is forwarded to a regular phone

Running the tests

To run int tests that assert that the cost asserts are ok, simply do this:

$ cd tests
$ phpunit