# Lite::Service

[![Gem Version](https://badge.fury.io/rb/lite-service.svg)](http://badge.fury.io/rb/lite-service)
[![Build Status](https://travis-ci.org/drexed/lite-service.svg?branch=master)](https://travis-ci.org/drexed/lite-service)

Lite::Service provides an API for building command based service objects.
It also has mixins for handling errors and memoization.

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'lite-service'
```

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install lite-service

## Table of Contents

* [Setup](#setup)
* [Base](#base)
* [Errors](#errors)
* [Memoize](#memoize)

## Setup

Setting up the service object is very easy and provides a high level API for memoizing pre-resulted
values and for surfacing errors.

```ruby
class SearchMovies < Lite::Service::Base

  def initialize(name)
    @name = name
  end

  # NOTE: This method is required
  def command
    { generate_fingerprint => movies_by_name }
  end

  private

  def movies_by_name
    HTTP.get("http://movies.com?title=#{title}")
  end

  def generate_fingerprint
    Digest::MD5.hexdigest(movies_by_name)
  end

end
```

**Caller**

```ruby
service = SearchMovies.new('Toy Story')
service.called? #=> false
service.call    #=> { 'fingerprint_1' => [ 'Toy Story 1', ... ] }
service.called? #=> true

# - or -

service = SearchMovies.call('Toy Story')
service.called? #=> true
service.call    #=> { 'fingerprint_1' => [ 'Toy Story 1', ... ] }

# - or -

# Use full when you are not using the Errors mixin.
SearchMovies.run('Toy Story') #=> { 'fingerprint_1' => [ 'Toy Story 1', ... ] }
```

**Result**

```ruby
service = SearchMovies.new('Toy Story')
service.result  #=> nil

service.call    #=> { 'fingerprint_1' => [ 'Toy Story 1', ... ] }
service.result  #=> { 'fingerprint_1' => [ 'Toy Story 1', ... ] }

service.recall! #=> Clears the call, cache, errors, and then re-performs the call
service.result  #=> { 'fingerprint_2' => [ 'Toy Story 2', ... ] }
```

## Errors (optional)

Learn more about using [Lite::Errors](https://github.com/drexed/lite-errors)

```ruby
class SearchMovies < Lite::Service::Base
  include Lite::Service::Errors

  # ... ommited ...

  private

  # Add a fingerprint error to the error pool
  def generate_fingerprint
    Digest::MD5.hexdigest(movies_by_name)
  rescue
    errors.add(:fingerprint, 'invalid md5 request value')
  end

end
```

**Methods**

```ruby
service = SearchMovies.call('Toy Story')
service.errors    #=> Lite::Errors::Messages object

service.validate! #=> Raises Lite::Service::ValidationError if it has any errors
service.valid?    #=> Alias for validate!

service.errored?  #=> false
service.success?  #=> true
service.failure?  #=> Checks that it has been called and has errors

service.result!   #=> Raises Lite::Service::ValidationError if it has any errors, if not it returns the result
```

## Memoize (optional)

Learn more about using [Lite::Memoize](https://github.com/drexed/lite-memoize)

```ruby
class SearchMovies < Lite::Service::Base
  include Lite::Service::Memoize

  # ... ommited ...

  private

  # Sets the value in the cache
  # Subsequent method calls gets the cached value
  # This saves you the extra external HTTP.get call
  def movies_by_name
    cache.memoize { HTTP.get("http://movies.com?title=#{title}") }
  end

  # Gets the value in the cache
  def generate_fingerprint
    Digest::MD5.hexdigest(movies_by_name)
  end

end
```

**Methods**

```ruby
service = SearchMovies.call('Toy Story')
service.cache #=> Lite::Memoize::Instance object
```

## Development

After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).

## Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/lite-service. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [Contributor Covenant](http://contributor-covenant.org) code of conduct.

## License

The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).

## Code of Conduct

Everyone interacting in the Lite::Service project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/[USERNAME]/lite-service/blob/master/CODE_OF_CONDUCT.md).