# Merch Calendar

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This gem allows for finding retail/merchandising weeks for a given date, along with manipulating the retail calendar. This gem is used at [StitchFix](http://www.stitchfix.com/).

## Installation

```bash
$ gem install merch_calendar
```

Add the following line to your `Gemfile`:
```ruby
gem "merch_calendar"
```

## Usage

For converting a date into a `MerchWeek` object.

```ruby
merch_week = MerchCalendar::MerchWeek.from_date("2014-01-01")
puts merch_week.year # 2013 (the merch year associated with this date)
puts merch_week.month # 12 (the julian month that the date falls in)
puts merch_week.week # 5 (the week number within the month)
puts merch_week.year_week # 48 (the week number within the year)
puts merch_week.quarter # 2

puts merch_week.start_of_week # <Date: 2013-12-29>
puts merch_week.end_of_week # <Date>

puts merch_week.start_of_month # <Date>
puts merch_week.end_of_month # <Date>

puts merch_week.start_of_quarter # <Date>
puts merch_week.end_of_quarter # <Date>

puts merch_week.start_of_year # <Date>
puts merch_week.end_of_year # <Date>

# Formatting
puts merch_week.to_s # "Dec W5"
puts merch_week.to_s(:short) # "Dec W5"
puts merch_week.to_s(:long) # "2013:48 Dec W5"
puts merch_week.to_s(:elasticsearch) # "2013-12w05"
```


### Merch retail calendar

Merch calendars have their first month in February, and the last (12th) month is in January of the
following year.

```ruby
# This is asking "In the Merch year of 2014, what is the Gregorian calendar date of
# the start of the first month?"
retail_calendar = MerchCalendar::RetailCalendar.new

retail_calendar.start_of_month(2014, 1)
# => 2014-02-02

retail_calendar.start_of_month(2014, 12)
# => 2015-01-04
```

This table should describe the progression of dates:

| N   |  `start_of_month(2014, N)` |
| ------------- | ------------- |
| 1   | 2014-02-02 |
| 2   | 2014-03-02 |
| 3   | 2014-04-06 |
| 4   | 2014-05-04 |
| 5   | 2014-06-01 |
| 6   | 2014-07-06 |
| 7   | 2014-08-03 |
| 8   | 2014-08-31 |
| 9   | 2014-10-05 |
| 10  | 2014-11-02 |
| 11  | 2014-11-30 |
| 12  | 2015-01-04 |


Other useful methods:

```ruby
# 52 or 53 (depending on leap year)
retail_calendar.weeks_in_year(2016)
# => 52
retail_calendar.weeks_in_year(2017)
# => 53

# get the start date of a given merch week
retail_calendar.start_of_week(2017, 4, 1)
# => #<Date: 2017-04-30 ((2457874j,0s,0n),+0s,2299161j)>

# get the end date of a given merch week
retail_calendar.end_of_week(2017, 4, 1)
#=> #<Date: 2017-05-06 ((2457880j,0s,0n),+0s,2299161j)>
```

### Offset fiscal year calendars
Some companies, one of which being Stitch Fix, operate on a fiscal year calendar that is offset of
the traditional retail calendar.  The `MerchCalendar::FiscalYearCalendar` class allows you to easily
offset the start of year to match your fiscal calendar.

```ruby
fiscal_calendar = MerchCalendar::FiscalYearCalendar.new

# 52 or 53 (depending on leap year)
fiscal_calendar.weeks_in_year(2017)
# => 52
fiscal_calendar.weeks_in_year(2018)
# => 53

# get the start date of a given merch week
fiscal_calendar.start_of_week(2017, 1, 1)
# => #<Date: 2016-07-31 ((2457601j,0s,0n),+0s,2299161j)>

# get the end date of a given merch week
fiscal_calendar.end_of_week(2017, 4, 1)
#=> #<Date: 2017-05-06 ((2457880j,0s,0n),+0s,2299161j)>
```

## Documentation
You can view the documentation for this gem on [RubyDoc.info](http://www.rubydoc.info/github/stitchfix/merch_calendar/master).

## License
MerchCalendar is released under the [MIT License](http://www.opensource.org/licenses/MIT).