# ByStar

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ByStar (by_*) allows you easily and reliably query ActiveRecord and Mongoid objects based on time.

### Examples

```ruby
Post.by_year(2013)                           # all posts in 2013
Post.before(Date.today)                      # all posts for before today
Post.yesterday                               # all posts for yesterday
Post.between_times(Time.zone.now - 3.hours,  # all posts in last 3 hours
                   Time.zone.now)
@post.next                                   # next post after a given post
```

## Installation

Install this gem by adding this to your Gemfile:

```ruby
gem 'by_star', git: 'https://github.com/radar/by_star'
```

Then run `bundle install`

If you are using ActiveRecord, you're done!

Mongoid users, please include the Mongoid::ByStar module for each model you wish to use the functionality.
This is the convention among Mongoid plugins.

```ruby
class MyModel
  include Mongoid::Document
  include Mongoid::ByStar
```

## Finder Methods

### Base Scopes

ByStar adds the following finder scopes (class methods) to your model to query time ranges.
These accept a `Date`, `Time`, or `DateTime` object as an argument, which defaults to `Time.zone.now` if not specified:

| Scope | Meaning |
| --- | --- |
| `between_times(start_time, end_time)` | Finds all records occurring between two given times. |
| `between_dates(start_date, end_date)` | Finds all records occurring between two given dates, from beginning of start_date until end of end_date. |
| `before(end_time)` | Finds all records occurring before the given time. |
| `after(start_time)` | Finds all records occurring after the given time. |
| `at_time(time)` | Finds all records occurring exactly at the given time, or which overlap the time in the case of "timespan"-type object (see below) |

`between_times` and `between_dates` supports alternate argument forms:
* `between_times(Range)`
* `between_times(Array)`
* `between_times(start_time, nil)` - same as `after(start_time)`
* `between_times(nil, end_time)` - same as `before(end_time)`

### Time Range Scopes

ByStar adds additional shortcut scopes based on commonly used time ranges.
See sections below for detailed argument usage of each:

| Scope | Meaning |
| --- | --- |
| `by_day` | Query by a given date. |
| `by_week` | Allows zero-based week value from 0 to 52. |
| `by_cweek` | Allows one-based week value from 1 to 53. |
| `by_weekend` | Saturday and Sunday only of the given week. |
| `by_fortnight` | A two-week period, with the first fortnight of the year beginning on 1st January. |
| `by_month` | Query by month. Allows integer arg, e.g. `11` for November. |
| `by_calendar_month` | Month as it appears on a calendar; days form previous/following months which are part of the first/last weeks of the given month. |
| `by_quarter` | 3-month intervals of the year. |
| `by_year` | Query by year. Allows integer arg, e.g. `2017`. |

### Relative Scopes

ByStar also adds scopes which are relative to the current time.
Note the `past_*` and `next_*` methods represent a time distance from current time (`Time.zone.now`),
and do not strictly end/begin evenly on a calendar week/month/year (unlike `by_*` methods which do.)

| Scope | Meaning |
| --- | --- |
| `today` | Finds all occurrences on today's date. |
| `yesterday` | Finds all occurrences on yesterday's date. |
| `tomorrow` | Finds all occurrences on tomorrow's date. |
| `past_day` | Prior 24-hour period from current time. |
| `past_week` | Prior 7-day period from current time. |
| `past_fortnight` | Prior 14-day period from current time. |
| `past_month` | Prior 30-day period from current time. |
| `past_year` | Prior 365-day period from current time. |
| `next_day` | Subsequent 24-hour period from current time. |
| `next_week` | Subsequent 7-day period from current time. |
| `next_fortnight` | Subsequent 14-day period from current time. |
| `next_month` | Subsequent 30-day period from current time. |
| `next_year` | Subsequent 365-day period from current time. |

### Superlative Finders

Find the oldest or newest records. Returns an object instance (not a relation):

* `newest`
* `oldest`

### Instance Methods

In addition, ByStar adds instance methods to return the next / previous record in the timewise sequence.
Returns an object instance (not a relation):

* `object.next`
* `object.previous`

### Kernel Extensions

ByStar extends the kernel `Date`, `Time`, and `DateTime` objects with the following instance methods,
which mirror the ActiveSupport methods `beginning_of_day`, `end_of_week`, etc:

* `beginning_of_weekend`
* `end_of_weekend`
* `beginning_of_fortnight`
* `end_of_fortnight`
* `beginning_of_calendar_month`
* `end_of_calendar_month`

Lastly, ByStar aliases Rails 3 `Date#to_time_in_current_zone` to the Rails 4 syntax `#in_time_zone`, if it has not already been defined.

## Usage

### Setting the Query Field

By default, ByStar assumes you will use the `created_at` field to query objects by time.
You may specify an alternate field on all query methods as follows:

```ruby
Post.by_month("January", field: :updated_at)
```

Alternatively, you may set a default in your model using the `by_star_field` macro:

```ruby
class Post < ActiveRecord::Base
  by_star_field :updated_at
end
```

### Scoping the Query

All ByStar methods (except `oldest`, `newest`, `previous`, `next`) return an `ActiveRecord::Relation`
(or `Mongoid::Criteria`) which can be daisy-chained with other scopes/finder methods:

```ruby
Post.by_month.your_scope
Post.by_month(1).include(:tags).where("tags.name" => "ruby")
```

Want to count records? Simple:

```ruby
Post.by_month.count
```

### Timezone Handling

ByStar date-range finders will use value of `Time.zone` to evaluate the args.
This may cause unexpected behavior when use Time values in timezones other than `Time.zone`.

```ruby
Time.zone = 'Australia/Sydney'
Post.by_day('2020-04-05 18:00:00 EST')
#=> Returns Apr 6th, 0:00 until Apr 6th, 23:59 in Sydney timezone.
```

### `:offset` Option

All ByStar finders support an `:offset` option which is applied to time period of the query condition.
This is useful in cases where the daily cycle occurs at a time other than midnight.

For example, if you'd like to find all Posts from 9:00 on 2014-03-05 until 8:59:59.999 on 2014-03-06, you can do:

```ruby
Post.by_day('2014-03-05', offset: 9.hours)
```

**Note:** When passing `offset` in date finders, it will set the hour, minute, and second on the queried date in order to properly handle DST transitions. Example:

```ruby
Time.zone = 'Australia/Sydney'
Post.by_day('2020-04-05', offset: 9.hours)
#=> Returns Apr 5th, 09:00 until Apr 6th, 08:59
```

### Timespan Objects

If your object has both a start and end time, you may pass both params to `by_star_field`:

```ruby
by_star_field :start_time, :end_time
```

By default, ByStar queries will return all objects whose range has any overlap within the desired period (permissive):

```ruby
MultiDayEvent.by_month("January")
#=> returns MultiDayEvents that overlap in January,
#   even if they start in December and/or end in February
```

### Timespan Objects: `#at_time`

To find all instances of a timespan object which contain a specific time:

```ruby
Post.at_time(time)
```

This can be useful to find all currently active instances. Note that object instances which start
exactly at the given `time` will be included in the result, but instances that end exactly at the given
`time` will not be.

### Timespan Objects: `:strict` Option

If you'd like to confine results to only those both starting and ending within the given range, use the `:strict` option:

```ruby
MultiDayEvent.by_month("January", :strict => true)
#=> returns MultiDayEvents that both start AND end in January
```

### Timespan Objects: Database Indexing and `:index_scope` Option

In order to ensure query performance on large dataset, you must add an index to the query field (e.g. "created_at") be indexed. ByStar does **not** define indexes automatically.

Database indexes require querying a range query on a single field, i.e. `start_time >= X and start_time <= Y`.
If we use a single-sided query, the database will iterate through all items either from the beginning or until the end of time.
This poses a challenge for timespan-type objects which have two fields, i.e. `start_time` and `end_time`.
There are two cases to consider:

1) Timespan with `:strict` option, e.g. `start_time >= X and end_time <= Y`.

Given that this gem requires `start_time >= end_time`, we add the converse constraint `start_time <= Y and end_time >= X`
to ensure both fields are double-sided, i.e. an index can be used on either field.

2) Timespan without `:strict` option, e.g. "start_time < Y and end_time > X".

Here we need to add a condition `start_time >= X` to ensure `start_time` is bounded on both sides.
To achieve this, we allow an `:index_scope` option which is the minimum "strict" bound on the querying range,
in other words, it is an assumption about the maximum timespan of objects.

`:index_scope` supports multiple value types:

| `:index_scope` Value | Meaning |
| --- | --- |
| `nil` or `false` | No constraint set; query will be one-sided (default, but not recommended) |
| `Date` or `Time`, etc. | A fixed point in time |
| `ActiveSupport::Duration` (e.g. `1.month`) | The duration value will be subtracted from the start of the range. In other words, a value of `1.month` would imply the longest possible object in the database is no longer than `1.month`. |
| `Numeric` | Will be converted to seconds, then handled the same as `ActiveSupport::Duration` |
| `:beginning_of_day` (`Symbol` literal) |
| `Proc<Range, Hash(options)>` | A proc which evaluates to one of the above types. Args are `(start_time, end_time, options)` |

An example settings of `:index_scope`:

```
# The maximum possible object length is 5 hours.
by_star index_scope: 5.hours

# Objects are guaranteed to start within the same month, with some offset.
by_star index_scope: ->(start_time, end_time, options){ start_time.beginning_of_month + (options[:offset] || 0) }

# The maximum possible object length half the range being queried.
by_star index_scope: ->(start_time, end_time, options){ ((start_time - end_time)*0.5).seconds }
```

### Chronic Support

If [Chronic](https://github.com/mojombo/chronic) gem is present, it will be used to parse natural-language date/time
strings in all ByStar finder methods. Otherwise, the Ruby `Time.parse` kernel method will be used as a fallback.

As of ByStar 2.2.0, you must explicitly include `gem 'chronic'` into your Gemfile in order to use Chronic.

## Advanced Usage

### between_times

To find records between two times:

```ruby
Post.between_times(time1, time2)
```

You use a Range like so:

```ruby
Post.between_times(time1..time2)
```

Also works with dates - WARNING: there are currently some caveats see [Issue #49](https://github.com/radar/by_star/issues/49):

```ruby
Post.between_times(date1, date2)
```

It will query records from `date1` (00:00:00 Hrs) until `date2` (23:59:59 Hrs).

### before and after

To find all posts before / after the current time:

```ruby
Post.before
Post.after
```

To find all posts before certain time or date:

```ruby
Post.before(Date.today + 2)
Post.after(Time.now + 5.days)
```

You can also pass a string:

```ruby
Post.before("next tuesday")
```

For Time-Range type objects, only the start time is considered for `before` and `after`.

### previous and next

To find the prior/subsequent record to a model instance, `previous`/`next` on it:

```ruby
Post.last.previous
Post.first.next
```

You can specify a field also:

```ruby
Post.last.previous(field: "published_at")
Post.first.next(field: "published_at")
```

For Time-Range type objects, only the start time is considered for `previous` and `next`.

### by_year

To find records from the current year, simply call the method without any arguments:

```ruby
Post.by_year
```

To find records based on a year you can pass it a two or four digit number:

```ruby
Post.by_year(09)
```

This will return all posts in 2009, whereas:

```ruby
Post.by_year(99)
```

will return all the posts in the year 1999.

You can also specify the full year:

```ruby
Post.by_year(2009)
Post.by_year(1999)
```

### by_month

If you know the number of the month you want:

```ruby
Post.by_month(1)
```

This will return all posts in the first month (January) of the current year.

If you like being verbose:

```ruby
Post.by_month("January")
```

This will return all posts created in January of the current year.

If you want to find all posts in January of last year just do

```ruby
Post.by_month(1, year: 2007)
```

or

```ruby
Post.by_month("January", year: 2007)
```

This will perform a find using the column you've specified.

If you have a Time object you can use it to find the posts:

```ruby
Post.by_month(Time.local(2012, 11, 24))
```

This will find all the posts in November 2012.

### by_calendar_month

Finds records for a given month as shown on a calendar. Includes all the results of `by_month`, plus any results which fall in the same week as the first and last of the month. Useful for working with UI calendars which show rows of weeks.

```ruby
Post.by_calendar_month
```

Parameter behavior is otherwise the same as `by_month`. Also, `:start_day` option is supported to specify the start day of the week (`:monday`, `:tuesday`, etc.)

### by_fortnight

Fortnight numbering starts at 0. The beginning of a fortnight is Monday, 12am.

To find records from the current fortnight:

```ruby
Post.by_fortnight
```

To find records based on a fortnight, you can pass in a number (representing the fortnight number) or a time object:

```ruby
Post.by_fortnight(18)
```

This will return all posts in the 18th fortnight of the current year.

```ruby
Post.by_fortnight(18, year: 2012)
```

This will return all posts in the 18th fortnight week of 2012.

```ruby
Post.by_fortnight(Time.local(2012,1,1))
```

This will return all posts from the first fortnight of 2012.

### by_week and by_cweek

Week numbering starts at 0, and cweek numbering starts at 1 (same as `Date#cweek`). The beginning of a week is as defined in `ActiveSupport#beginning_of_week`, which can be configured.

To find records from the current week:

```ruby
Post.by_week
Post.by_cweek  # same result
```

This will return all posts in the 37th week of the current year (remember week numbering starts at 0):

```ruby
Post.by_week(36)
Post.by_cweek(37)  # same result
```

This will return all posts in the 37th week of 2012:

```ruby
Post.by_week(36, year: 2012)
Post.by_cweek(37, year: 2012)  # same result
```

This will return all posts in the week which contains Jan 1, 2012:

```ruby
Post.by_week(Time.local(2012,1,1))
Post.by_cweek(Time.local(2012,1,1))  # same result
```

You may pass in a `:start_day` option (`:monday`, `:tuesday`, etc.) to specify the starting day of the week. This may also be configured in Rails.

### by_weekend

If the time passed in (or the time now is a weekend) it will return posts from 0:00 Saturday to 23:59:59 Sunday. If the time is a week day, it will show all posts for the coming weekend.

```ruby
Post.by_weekend(Time.now)
```

### by_day and today

To find records for today:

```ruby
Post.by_day
Post.today
```

To find records for a certain day:

```ruby
Post.by_day(Time.local(2012, 1, 1))
```

You can also pass a string:

```ruby
Post.by_day("next tuesday")
```

This will return all posts for the given day.

### by_quarter

Finds records by 3-month quarterly period of year. Quarter numbering starts at 1. The four quarters of the year begin on Jan 1, Apr 1, Jul 1, and Oct 1 respectively.

To find records from the current quarter:

```ruby
Post.by_quarter
```

To find records based on a quarter, you can pass in a number (representing the quarter number) or a time object:

```ruby
Post.by_quarter(4)
```

This will return all posts in the 4th quarter of the current year.

```ruby
Post.by_quarter(2, year: 2012)
```

This will return all posts in the 2nd quarter of 2012.

```ruby
Post.by_week(Time.local(2012,1,1))
```

This will return all posts from the first quarter of 2012.

## Version Support

ByStar is tested against the following versions:

* Ruby 2.0.0+
* Rails/ActiveRecord 3.2+
* Mongoid 3.1+

Note that ByStar automatically adds the following version compatibility shims:

* ActiveSupport 3.x: Add `Time/Date/DateTime#in_time_zone` (as an alias to `#to_time_in_current_zone`) for compatibility with Rails 4+.
* Mongoid 3.x: Adds `Criteria#reorder` method from Mongoid 4.


## Testing

### Test Setup

Specify a database by supplying a `DB` environmental variable:

```bash
bundle exec rake spec DB=sqlite
```

You can also take an ORM-specific test task for a ride:

```bash
bundle exec rake spec:active_record
```

Have an Active Record or Mongoid version in mind? Set the environment variables
`ACTIVE_RECORD_VERSION` and `MONGOID_VERSION` to a version of your choice. A
version number provided will translate to `~> VERSION`, and the string `master`
will grab the latest from Github.

```bash
# Update your bundle appropriately...
ACTIVE_RECORD_VERSION=4.0.0 MONGOID_VERSION=master bundle update

# ...then run the specs
ACTIVE_RECORD_VERSION=4.0.0 MONGOID_VERSION=master bundle exec rpsec spec
```

### Test Implementation

ByStar tests use TimeCop to lock the system `Time.now` at Jan 01, 2014, and seed
objects with fixed dates according to `spec/fixtures/shared/seeds.rb`.
Note that the timezone is randomized on each run to shake-out timezone related quirks.


## Collaborators

ByStar is actively maintained by Ryan Bigg (radar) and Johnny Shields (johnnyshields)

Thank you to the following people:

* Thomas Sinclair for the original bump for implementing ByStar
* [Ruby on Rails](http://rubyonrails.org/) for their support
* Mislav Marohnic
* August Lilleas (leethal)
* gte351s
* Sam Elliott (lenary)
* The creators of the [Chronic](https://github.com/mojombo/chronic) gem
* Erik Fonselius
* Johnny Shields (johnnyshields)