bphenriques / interview-challenge-phone-calls-billing

Challenge made in 2017.

Some thoughts in 2020:

• Good that I went light on dependencies.
• Liked the way I wrote the acceptance tests.
• Too many docs. Unnecessary as the code is self-explanatory (as it should be).
• Good abstractions as they are composable but not necessary in the scope of this challenge.
• Licence?

Project updated in 2022 using Cats-Effects and FS2: https://github.com/bphenriques-interview-challenges/phone-calls-billing-challenge-fs2

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Goal

Given a list of calls with the following format:

time_of_start;time_of_finish;call_from;call_to

And the following rules:

• The first 5 minutes of each call are billed at 5 cents per minute
• The remainer of the call is billed at 2 cents per minute
• The caller with the highest total call duration of the day will not be charged (i.e., the caller that has the highest total call duration among all of its calls)

Calculate the total cost for these calls.

Additional Notes

• A call between 23:59:00 and 01:00:00 means that the call lasted 2 minutes.
• Both time_of_start and time_of_finish are in the same timezone.
• The following phone numbers are considered different: [phone], 00351911234567, and 911234567.

Example

Input:

09:11:30;09:15:22;[phone];[phone]
15:20:04;15:23:49;[phone];[phone]
16:43:02;16:50:20;[phone];[phone]
17:44:04;17:49:30;[phone];[phone]

Output:

15.05

Running

$ bin/billing <path-to-file>

Where <path-to-file> is the path to the file.

Configuration

The simulation configuration is defined in the conf/application.conf file:

cost-format = "0.00"

csv {
  separator = ";"
  header = false
}

Where:

• cost-format: How the bill cost should be formatted. This uses the DecimalFormat.
• csv: The configuration object of the CSV reader.
  • separator: If the CSV file contains an header.
  • header: If the CSV file contains an header.