require 'faraday'
require 'active_model'
require 'active_support/core_ext/hash/indifferent_access'
require 'active_support/core_ext/numeric/conversions'

module Icalia
  module Artanis
    class ClientAuth
      include ActiveModel::Model
      attr_accessor :access_token, :token_type, :created_at

      def created_at=(value)
        value = Time.at(value) if value.is_a? Integer
        @created_at = value
      end

      def ==(other)
        other.is_a?(self.class) && other.access_token == access_token
      end

      def to_s
        access_token
      end

      def to_authorization_header
        "Bearer #{to_s}"
      end

      #Override Icalia::Artanis::ClientAuth.store to define a custom Cache. By default it uses MemoryStore.
      cattr_accessor :store do
        ActiveSupport::Cache::MemoryStore.new
      end

      cattr_reader :http do
        artanis_url = ENV.fetch 'ARTANIS_URL', 'https://artanis.icalialabs.com'

        Faraday.new(url: artanis_url) do |faraday|
          faraday.request  :url_encoded             # form-encode POST params
          faraday.response :logger                  # log requests to STDOUT
          faraday.adapter  Faraday.default_adapter  # make requests with Net::HTTP
        end
      end

      cattr_reader :client_credentials_authorization_header do
        client_key = ENV.fetch 'ARTANIS_CLIENT_KEY'
        client_secret = ENV.fetch 'ARTANIS_CLIENT_SECRET'
        "Basic #{::Base64.strict_encode64("#{client_key}:#{client_secret}")}"
      end

      def self.fetch
        store.fetch 'my-artanis-client-token' do
          response = http.post do |req|
            req.url '/oauth/token'
            req.headers['Authorization'] = client_credentials_authorization_header
            req.params['grant_type'] = 'client_credentials'
          end
          # Return a new instance of the Client Auth:
          new ActiveSupport::JSON.decode(response.body)
        end
      end
    end
  end
end