Simple Calendar
===============

Simple Calendar is design to do one thing really really well: render a
calendar. It lets you render a calendar of any size. Maybe you want a
day view, a 4 day agenda, a week view, a month view, or a 6 week
calendar. You can do all of that with the new gem, just give it a range
of dates to render.

It doesn't depend on any ORM so you're free to use it with ActiveRecord,
Mongoid, any other ORM, or pure Ruby objects.

Thanks to all contributors for your wonderful help!

Installation
------------

Just add this into your Gemfile followed by a bundle install:

    gem "simple_calendar", "~> 1.1.0"

Usage
-----

Generating calendars is extremely simple with simple_calendar in version 1.1.

The first parameter is a symbol that looks up the current date in
`params`. If no date is found, it will use the current date.

In these examples, we're using `:start_date` which is the default.

### Month Calendar

You can generate a calendar for the month with the `month_calendar`
method.

```erb
<%= month_calendar do |date| %>
  <%= date %>
<% end %>
```

### Week Calendar

You can generate a week calendar with the `week_calendar` method.

```erb
<%= week_calendar number_of_weeks: 2 do |date| %>
  <%= date %>
<% end %>
```

Setting `number_of_weeks` is optional and defaults to 1.

### Custom Length Calendar

You can generate calendars of any length by passing in the number of days you want to render.

```erb
<%= calendar number_of_days: 4 do |date| %>
  <%= date %>
<% end %>
```

Setting `number_of_days` is optional and defaults to 4.

## Rendering Events

What's a calendar without events in it? There are two simple steps for
creating calendars with events.

The first step is to add the following to your model. We'll be using a
model called Event, but you can add this to any model or Ruby object.

We use the `has_calendar` method to tell simple_calendar how to filter
and sort the events on the different calendar days. This should be the
start date/time of your event. By default it uses `starts_at` as the
attribute name.

```ruby
class Event < ActiveRecord::Base
  extend SimpleCalendar
  has_calendar

  # Or set a custom attribute for simple_calendar to sort by
  # has_calendar :attribute => :your_starting_time_column_name
end
```

In your controller, query for these events and store them in an instance
variable. We'll just load up all the events for this example.

```ruby
def index
  @events = Event.all
end
```

Then in your view, you can pass in the `events` option to render. The
events will automatically be filter out by day for you.

```erb
<%= month_calendar events: @events do |date, events| %>
  <%= date %>

  <% events.each do |event| %>
    <div>
      <%= event.name %>
    </div>
  <% end %>
<% end %>
```

If you pass in objects that don't respond to the attribute method (like
starts_at), then all the events will be yielded each day. This lets you
do custom filtering however you want.

## Customizing The Calendar

You can change a couple of global options that will affect how the
calendars are generated:

```ruby
Time.zone = "Central Time (US & Canada)"
```

Setting `Time.zone` will make sure the calendar start days are correctly computed
in the right timezone. You can set this globally in your `application.rb` file or
if you have a User model with a time_zone attribute, you can set it on every request by using
a before_filter like the following example.

This code example uses [Devise](https://github.com/plataformatec/devise)'s
`current_user` and `user_signed_in?` methods to retrieve the user's timezone and set it for the duration of the request.
Make sure to change the `:user_signed_in?` and `current_user` methods if you are
using some other method of authentication.

```ruby
class ApplicationController < ActionController::Base
  before_filter :set_time_zone, if: :user_signed_in?

  private

    def set_time_zone
      Time.zone = current_user.time_zone
    end
end
```

You can also change the beginning day of the week. If you want to set
this globally, you can put this line in
`config/initializers/simple_calendar.rb`:

```ruby
Date.beginning_of_week = :sunday
```

Setting classes on the table and elements are pretty easy.

Each of the options are passed directly to the
the `content_tag` method so each of them **must** be a hash.

```ruby

<%= calendar table: {class: "table table-bordered"}, tr: {class: "row"}, td: {class: "day"}, do |day| %>
<% end %>
```

This will set the class of `table table-bordered` on the `table` HTML
element.

### Custom Day Classes

`td` is an option for setting the options on the td content tag that is
generated. By default, simple_calendar renders the following classes for
any given day in a calendar:


```ruby
td_class = ["day"]
td_class << "today"  if today == current_calendar_date
td_class << "past"   if today > current_calendar_date
td_class << "future" if today < current_calendar_date
td_class << "prev-month"    if start_date.month != current_calendar_date.month && current_calendar_date < start_date
td_class << "next-month"    if start_date.month != current_calendar_date.month && current_calendar_date > start_date
td_class << "current-month" if start_date.month == current_calendar_date.month
td_class << "wday-#{current_calendar_date.wday.to_s}"
```

You can set your CSS styles based upon these if you want to highlight
specific days or types of days. If you wish to override this
functionality, just set the `tr` option to a lambda that accepts two
dates and returns a hash. The hash will be passed in directly to the
content_tag options. If you wish to set a class or data attributes, just
set them as you normally would in a content_tag call.

```erb
<%= month_calendar td: ->(start_date, current_calendar_date) { {class: "calendar-date", data: {day: current_calendar_date}} } do |day| %>
<% end %>
```

This generate each day in the calendar like this:

```html
<td class="calendar-date" data-day="2014-05-11">
</td>
```

Instead of writing the lambdas inline, a cleaner approach is to write a
helper that returns a lambda. You can duplicate the following example by
adding this to your helpers

```ruby
def month_calendar_td_options
  ->(start_date, current_calendar_date) {
    {class: "calendar-date", data: {day: current_calendar_date}}
  }
end
```

And then your view would use `month_calendar_td_options` as the value.

```erb
<%= month_calendar td: month_calendar_td_options do |day| %>
<% end %>
```

### Custom Header Links

Each of the calendar methods will generate a header with links to the
previous and next views. The `month_calendar` also includes a header
that tells you the current month and year that you are viewing.

To change these, you can pass in the `prev_link`, `header`, and
`next_link` options into the calendar methods.

The default `month_calendar` look like this:

```erb
<%= month_calendar prev_link: ->(range) { link_to raw("&laquo;"), param_name => range.first - 1.day },
  header: ->{ content_tag :span, "#{I18n.t("date.month_names")[start_date.month]} #{start_date.year}", class: "calendar-header" },
  next_link: ->(range) { link_to raw("&raquo;"), param_name => range.last + 1.day } do |day| %>

<% end %>
```

`prev_link` option is a standard `link_to` that is a left arrow and
with the current url having `?start_date=2014-04-30` appended to it as
a date in the previous view of the calendar.

`next_link` option is a standard `link_to` that is a right arrow and
with the current url having `?start_date=2014-06-01` appended to it as
a date in the next view of the calendar.

`header` option is just a simple span tag with the month and year
inside of it.

If you wish to disable any of these partsof the header, just pass in
`false` and that will hide it:

```erb
<%= month_calendar header: false do |day| %>
<% end %>
```

## TODO

- Multi-day events?

## Author

Chris Oliver <chris@gorails.com>

[https://gorails.com](https://gorails.com)

[@excid3](https://twitter.com/excid3)