TimeZoneConverter CLI

A small gem, that can be used as a Command Line Interface. Inspired by:

• https://www.timeanddate.com/worldclock/converter.html
• https://stackoverflow.com/questions/8349817/ruby-gem-for-finding-timezone-of-location

In a few words, it prints out the time in other cities. Cities are passed as arguments.

Usage:

'c' command: current time in other cities

time_zone_converter c Warszawa Bangkok

Output:

[
  ["Warszawa", Tue, 22 Oct 2019 13:30:02 CEST +02:00],
  ["Bangkok", Tue, 22 Oct 2019 18:30:02 +07 +07:00]
]

'ct' command: given time in other cities (formant 'HH:MM' 24-hour)

time_zone_converter ct 'Chiang Mai' Skopje '19:00'

Output:

[
  ["Chiang Mai", 2019-10-22 19:00:00 +0700], 
  ["Skopje", Tue, 22 Oct 2019 14:00:00 CEST +02:00]
]

Note: Time ranges are also supported:

time_zone_converter ct Warszawa Bangkok '19:00-21:00'

Output:

[
  ["Warszawa",
    [
      2019-10-29 19:00:00 +0100,
      2019-10-29 21:00:00 +0100
    ]
  ],
  ["Bangkok",
    [
      Wed, 30 Oct 2019 01:00:00 +07 +07:00, 
      Wed, 30 Oct 2019 03:00:00 +07 +07:00
    ]
  ]
]

'ctu' command: given UTC+0 time in other cities

time_zone_converter ctu Bangkok Warszawa '10:00'

Output:

[
  ["Bangkok", Tue, 22 Oct 2019 17:00:00 +07 +07:00], 
  ["Warszawa", Tue, 22 Oct 2019 12:00:00 CEST +02:00]
]

Help:

time_zone_converter
time_zone_converter help c

More

It supports multiple cities, however, it may be a bit slow in that case. Any ideas how to make it faster are highly welcomed :)

Technically, this gem uses other gems under the hood: cities gem, see here: https://github.com/joecorcoran/cities which provides latitude and longitude for all cities around the world.

The code responsible for extracting json data is placed in json_data_transformer.rb file.

For nearest time zone calculation it uses another gem called nearest_tine_zone: https://rubygems.org/gems/nearest_time_zone

Summing up, it does not use any external API, just pure Ruby with ActiveSupport dependency.