maxehmookau/echonest-ruby-api

require 'httparty'
require 'multi_json'

module Echonest
  class Base
    class EchonestConnectionError < Exception; end

    def initialize(api_key)
      @api_key = api_key
      @base_uri = "http://developer.echonest.com/api/v4/"
    end

    def get_response(options = {})
      get(endpoint, options)
    end

    def entity_name
      self.class.to_s.split('::').last.downcase
    end

    def endpoint
      calling_method = caller[1].split('`').last[0..-2]
      "#{ entity_name }/#{ calling_method }"
    end

    # Performs a simple HTTP get on an API endpoint.
    #
    # Examples:
    #     get('artist/biographies', results: 10)
    #     #=> Array of Biography objects.
    #
    # Raises an +ArgumentError+ if the Echonest API responds with
    # an error.
    #
    # * +endpoint+ - The name of an API endpoint as a String
    # * +options+ - A Hash of options to pass to the end point.
    #
    # Returns a response as a Hash
    def get(endpoint, options = {})
      Base.get_api_endpoint(@api_key, endpoint, options)
    end

    # Cross-platform way of finding an executable in the $PATH.
    #
    #   which('ruby') #=> /usr/bin/ruby
    def which(cmd)
      exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
      ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
        exts.each { |ext|
          exe = File.join(path, "#{ cmd }#{ ext }")
          return exe if File.executable? exe
        }
      end
      return nil
    end

    # Gets the base URI for all API calls
    #
    # Returns a String
    def self.base_uri
      "http://developer.echonest.com/api/v#{version}/"
    end

    # Gets an arbitrary Echonest endpoint
    def self.get_api_endpoint(api_key, endpoint, options = {})
      options.merge!(api_key: api_key,
                           format: "json")
      httparty_options = { query_string_normalizer: HTTParty::Request::NON_RAILS_QUERY_STRING_NORMALIZER,
                           query: options }

      response = HTTParty.get("#{ base_uri }#{ endpoint }", httparty_options)
      json = MultiJson.load(response.body, symbolize_keys: true)
      response_code = json[:response][:status][:code]

      if response_code.eql?(0)
        json[:response]
      else
        error = Echonest::Error.new(response_code, response)
        raise error, "Error code #{response_code}: #{error.description}"
      end
    end

    # The current version of the Echonest API to be supported.
    #
    # Returns a Fixnum
    def self.version
      4
    end
  end
end