module Authlogic
  module Session
    # Handles authenticating via a traditional username and password.
    module Password
      def self.included(klass)
        klass.class_eval do
          extend Config
          include InstanceMethods
          validate :validate_by_password, :if => :authenticating_with_password?
          
          class << self
            attr_accessor :configured_password_methods
          end
        end
      end
      
      # Password configuration
      module Config
        # Authlogic tries to validate the credentials passed to it. One part of validation is actually finding the user and
        # making sure it exists. What method it uses the do this is up to you.
        #
        # Let's say you have a UserSession that is authenticating a User. By default UserSession will call User.find_by_login(login).
        # You can change what method UserSession calls by specifying it here. Then in your User model you can make that method do
        # anything you want, giving you complete control of how users are found by the UserSession.
        #
        # Let's take an example: You want to allow users to login by username or email. Set this to the name of the class method
        # that does this in the User model. Let's call it "find_by_username_or_email"
        #
        #   class User < ActiveRecord::Base
        #     def self.find_by_username_or_email(login)
        #       find_by_username(login) || find_by_email(login)
        #     end
        #   end
        #
        # Now just specify the name of this method for this configuration option and you are all set. You can do anything you
        # want here. Maybe you allow users to have multiple logins and you want to search a has_many relationship, etc. The sky is the limit.
        #
        # * <tt>Default:</tt> "find_by_smart_case_login_field"
        # * <tt>Accepts:</tt> Symbol or String
        def find_by_login_method(value = nil)
          rw_config(:find_by_login_method, value, "find_by_smart_case_login_field")
        end
        alias_method :find_by_login_method=, :find_by_login_method
        
        # The text used to identify credentials (username/password) combination when a bad login attempt occurs.
        # When you show error messages for a bad login, it's considered good security practice to hide which field
        # the user has entered incorrectly (the login field or the password field). For a full explanation, see
        # http://www.gnucitizen.org/blog/username-enumeration-vulnerabilities/
        #
        # Example of use:
        #
        #   class UserSession < Authlogic::Session::Base
        #     generalize_credentials_error_messages true
        #   end
        #
        #   This would make the error message for bad logins and bad passwords look identical:
        #
        #   Login/Password combination is not valid
        #  
        #   Alternatively you may use a custom message:
        # 
        #   class UserSession < AuthLogic::Session::Base
        #     generalize_credentials_error_messages "Your login information is invalid"
        #   end
        #
        #   This will instead show your custom error message when the UserSession is invalid.
        #
        # The downside to enabling this is that is can be too vague for a user that has a hard time remembering
        # their username and password combinations. It also disables the ability to to highlight the field
        # with the error when you use form_for.
        #
        # If you are developing an app where security is an extreme priority (such as a financial application),
        # then you should enable this. Otherwise, leaving this off is fine.
        # 
        # * <tt>Default</tt> false
        # * <tt>Accepts:</tt> Boolean
        def generalize_credentials_error_messages(value = nil)
          rw_config(:generalize_credentials_error_messages, value, false)
        end
        alias_method :generalize_credentials_error_messages=, :generalize_credentials_error_messages
        
        # The name of the method you want Authlogic to create for storing the login / username. Keep in mind this is just for your
        # Authlogic::Session, if you want it can be something completely different than the field in your model. So if you wanted people to
        # login with a field called "login" and then find users by email this is compeltely doable. See the find_by_login_method configuration
        # option for more details.
        #
        # * <tt>Default:</tt> klass.login_field || klass.email_field
        # * <tt>Accepts:</tt> Symbol or String
        def login_field(value = nil)
          rw_config(:login_field, value, klass.login_field || klass.email_field)
        end
        alias_method :login_field=, :login_field
        
        # Works exactly like login_field, but for the password instead. Returns :password if a login_field exists.
        #
        # * <tt>Default:</tt> :password
        # * <tt>Accepts:</tt> Symbol or String
        def password_field(value = nil)
          rw_config(:password_field, value, login_field && :password)
        end
        alias_method :password_field=, :password_field
        
        # The name of the method in your model used to verify the password. This should be an instance method. It should also
        # be prepared to accept a raw password and a crytped password.
        #
        # * <tt>Default:</tt> "valid_password?"
        # * <tt>Accepts:</tt> Symbol or String
        def verify_password_method(value = nil)
          rw_config(:verify_password_method, value, "valid_password?")
        end
        alias_method :verify_password_method=, :verify_password_method
      end
      
      # Password related instance methods
      module InstanceMethods
        def initialize(*args)
          if !self.class.configured_password_methods
            if login_field
              self.class.send(:attr_writer, login_field) if !respond_to?("#{login_field}=")
              self.class.send(:attr_reader, login_field) if !respond_to?(login_field)
            end
            
            if password_field
              self.class.send(:attr_writer, password_field) if !respond_to?("#{password_field}=")
              self.class.send(:define_method, password_field) {} if !respond_to?(password_field)

              self.class.class_eval <<-"end_eval", __FILE__, __LINE__
                private
                  # The password should not be accessible publicly. This way forms using form_for don't fill the password with the
                  # attempted password. To prevent this we just create this method that is private.
                  def protected_#{password_field}
                    @#{password_field}
                  end
              end_eval
            end

            self.class.configured_password_methods = true
          end
          
          super
        end
        
        # Returns the login_field / password_field credentials combination in hash form.
        def credentials
          if authenticating_with_password?
            details = {}
            details[login_field.to_sym] = send(login_field)
            details[password_field.to_sym] = "<protected>"
            details
          else
            super
          end
        end
        
        # Accepts the login_field / password_field credentials combination in hash form.
        def credentials=(value)
          super
          values = value.is_a?(Array) ? value : [value]
          if values.first.is_a?(Hash)
            values.first.with_indifferent_access.slice(login_field, password_field).each do |field, value|
              next if value.blank?
              send("#{field}=", value)
            end
          end
        end
        
        def invalid_password?
          invalid_password == true
        end
        
        private
          def authenticating_with_password?
            login_field && (!send(login_field).nil? || !send("protected_#{password_field}").nil?)
          end
          
          def validate_by_password
            self.invalid_password = false
            
            errors.add(login_field, I18n.t('error_messages.login_blank', :default => "cannot be blank")) if send(login_field).blank?
            errors.add(password_field, I18n.t('error_messages.password_blank', :default => "cannot be blank")) if send("protected_#{password_field}").blank?
            return if errors.count > 0
            
            self.attempted_record = search_for_record(find_by_login_method, send(login_field))
            if attempted_record.blank?
              generalize_credentials_error_messages? ?
                add_general_credentials_error :
                errors.add(login_field, I18n.t('error_messages.login_not_found', :default => "is not valid"))
              return
            end

            if !attempted_record.send(verify_password_method, send("protected_#{password_field}"))
              self.invalid_password = true
              generalize_credentials_error_messages? ?
                add_general_credentials_error :
                errors.add(password_field, I18n.t('error_messages.password_invalid', :default => "is not valid"))
              return
            end
          end
          
          def invalid_password
            @invalid_password
          end
          
          def invalid_password=(value)
            @invalid_password = value
          end
          
          def find_by_login_method
            self.class.find_by_login_method
          end
          
          def login_field
            self.class.login_field
          end
          
          def add_general_credentials_error
            error_message = 
            if self.class.generalize_credentials_error_messages.is_a? String
              self.class.generalize_credentials_error_messages
            else
              "#{login_field.to_s.humanize}/Password combination is not valid"
            end
            errors.add(:base, I18n.t('error_messages.general_credentials_error', :default => error_message))
          end
          
          def generalize_credentials_error_messages?
            self.class.generalize_credentials_error_messages
          end
          
          def password_field
            self.class.password_field
          end
          
          def verify_password_method
            self.class.verify_password_method
          end
      end
    end
  end
end