require 'yaml'

module Cronenberg
  class Config
		REQUIRED_VALUES = {
			names: [:host, :user, :password],
			env_vars: ['VCENTER_SERVER', 'VCENTER_USER', 'VCENTER_PASSWORD'],
		}

		attr_reader :host, :user, :password, :datacenter, :insecure, :port, :ssl

    DEFAULT_CONFIG_LOCATION = File.join(Dir.home, '.vcenter.conf')

		def initialize(config_file_location=nil)
      settings = process_environment_variables || process_config_file(config_file_location || DEFAULT_CONFIG_LOCATION)
			if settings.nil?
				raise 'You must provide credentials in either environment variables or a config file.'
			else
				settings = settings.delete_if { |k, v| v.nil? }
				missing = REQUIRED_VALUES[:names] - settings.keys
				unless missing.empty?
					message = 'To use this module you must provide the following settings:'
					missing.each do |var|
						message += " #{var}"
					end
					raise message
				end
				@host = settings[:host]
				@user = settings[:user]
				@password = settings[:password]
				@datacenter = settings[:datacenter_name]
				@insecure = settings[:insecure].nil? ? false : settings[:insecure]
				@ssl = settings[:ssl].nil? ? true : settings[:ssl]
				@port = settings[:port]
			end

		end

		def process_environment_variables
			required = REQUIRED_VALUES[:env_vars]
			missing = required - ENV.keys
			if missing.size < required.size
				{
					host: ENV['VCENTER_SERVER'],
					user: ENV['VCENTER_USER'],
					password: ENV['VCENTER_PASSWORD'],
					datacenter_name: ENV['VCENTER_DATACENTER'],
					insecure: ENV['VCENTER_INSECURE'],
					port: ENV['VCENTER_PORT'],
					ssl: ENV['VCENTER_SSL'],
				}
			else
				nil
			end
		end



		def process_config_file(file_path)
			file_present = File.file?(file_path)
			unless file_present
				nil
			else
				begin
					configuration = YAML.load_file(file_path)
				rescue Psych::SyntaxError => e
					raise "Your configuration file at #{file_path} is invalid. The error from the YAML parser is:\n #{e.message}"
				end
				vsphere_config = configuration['vcenter']

        raise "Invalid configuration file, missing vcenter key." unless vsphere_config.keys.first == 'vcenter'

				required = REQUIRED_VALUES[:names].map { |var| var.to_s }
				missing = required - vsphere_config.keys
				if missing.size < required.size
					{
						host: vsphere_config['host'],
						user: vsphere_config['user'],
						password: vsphere_config['password'],
						datacenter_name: vsphere_config['datacenter'],
						insecure: vsphere_config['insecure'],
						port: vsphere_config['port'],
						ssl: vsphere_config['ssl'],
					}
				else
					nil
				end
			end
		end
  end
end