add gate spots service

app/services/gate_spots_service.rb

@@ -0,0 +1,60 @@
+require 'openssl'
+require 'rest-client'
+
+class GateSpotsService
+  BASE_URL = ENV['GATE_API_URL']
+  attr_reader :user_id
+
+  def initialize(user_id: nil)
+    @user = User.find_by id: user_id
+
+    if @user.present?
+      @api_key = @user.gate_api_key
+      @secret_key = Base64.decode64(@user.gate_secret_key)
+    else
+      @api_key = ENV["GATE_KEY"]
+      @secret_key = ENV["GATE_SECRET"]
+    end
+  end
+
+  def get_orders
+    begin
+      request_path = '/api/v4/spot/orders'
+      query_string = 'status=finished'
+      do_request("get", request_path, query_string)
+    rescue => e
+      format_error_msg(e)
+    end
+  end
+
+  private
+  def do_request(method, request_path, query_string, payload_string = nil)
+    url = BASE_URL + request_path + "?" + query_string
+    timestamp = get_timestamp.to_s
+    hashed_payload = Digest::SHA512.hexdigest(payload_string || "")
+    sign = signed_data("#{method.upcase}\n#{request_path}\n#{query_string || ""}\n#{hashed_payload}\n#{timestamp}")
+    headers = {
+      "KEY" => @api_key,
+      "SIGN" => sign,
+      "Timestamp" => timestamp,
+      "Content-Type" => "application/json",
+      "Accept" => "application/json"
+    }
+
+    puts headers
+    response = RestClient.get(url, headers)
+    summary = JSON.parse(response)
+  end
+
+  def signed_data(data)
+    hmac = OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha512'), @secret_key, data)
+  end
+
+  def get_timestamp
+    Time.now.utc.to_f
+  end
+
+  def format_error_msg(e)
+    "Error: #{e}"
+  end
+end