module Puppet
    class Parameter < Puppet::Element
        class << self
            attr_reader :validater, :munger, :name, :default
            attr_accessor :ismetaparameter, :element

            # Define the default value for a given parameter or parameter.  This
            # means that 'nil' is an invalid default value.  This defines
            # the 'default' instance method.
            def defaultto(value = nil, &block)
                if block
                    define_method(:default, &block)
                else
                    if value.nil?
                        raise Puppet::DevError,
                            "Either a default value or block must be provided"
                    end
                    define_method(:default) do value end
                end
            end

            def nodefault
                if public_method_defined? :default
                    undef_method :default
                end
            end

            # Store documentation for this parameter.
            def desc(str)
                @doc = str
            end

            # This is how we munge the value.  Basically, this is our
            # opportunity to convert the value from one form into another.
            def munge(&block)
                # I need to wrap the unsafe version in begin/rescue parameterments,
                # but if I directly call the block then it gets bound to the
                # class's context, not the instance's, thus the two methods,
                # instead of just one.
                define_method(:unsafe_munge, &block)

                define_method(:munge) do |*args|
                    begin
                        unsafe_munge(*args)
                    rescue Puppet::Error => detail
                        Puppet.debug "Reraising %s" % detail
                        raise
                    rescue => detail
                        if Puppet[:debug]
                            puts detail.backtrace
                        end
                        raise Puppet::DevError, "Munging failed for class %s: %s" %
                            [self.name, detail]
                    end
                end
                #@munger = block
            end

            #def inspect
            #    "Parameter(#{self.name})"
            #end

            # Mark whether we're the namevar.
            def isnamevar
                @isnamevar = true
                @required = true
            end

            # Is this parameter the namevar?  Defaults to false.
            def isnamevar?
                if defined? @isnamevar
                    return @isnamevar
                else
                    return false
                end
            end

            # This parameter is required.
            def isrequired
                @required = true
            end

            # Is this parameter required?  Defaults to false.
            def required?
                if defined? @required
                    return @required
                else
                    return false
                end
            end

            def to_s
                if self.ismetaparameter
                    "Puppet::Type::" + @name.to_s.capitalize
                else
                    self.element.to_s + @name.to_s.capitalize
                end
            end

            # Verify that we got a good value
            def validate(&block)
                #@validater = block
                define_method(:unsafe_validate, &block)

                define_method(:validate) do |*args|
                    begin
                        unsafe_validate(*args)
                    rescue ArgumentError, Puppet::Error, TypeError
                        raise
                    rescue => detail
                        if Puppet[:debug]
                            puts detail.backtrace
                        end
                        raise Puppet::DevError,
                            "Validate method failed for class %s: %s" %
                            [self.name, detail]
                    end
                end
            end

            # Define a new value for our parameter.
            def newvalues(*names)
                @parametervalues ||= []

                names.each { |name|
                    if @parametervalues.include?(name)
                        Puppet.warning "%s already has a value for %s" %
                            [name, name]
                    end
                    @parametervalues << name
                }
            end

            def aliasvalue(name, other)
                @parametervalues ||= []
                unless @parametervalues.include?(other)
                    raise Puppet::DevError,
                        "Cannot alias nonexistent value %s" % other
                end

                @aliasvalues ||= {}
                @aliasvalues[name] = other
            end

            def alias(name)
                @aliasvalues[name]
            end

            # Return the list of valid values.
            def values
                @parametervalues ||= []
                @aliasvalues ||= {}

                #[@aliasvalues.keys, @parametervalues.keys].flatten
                if @parametervalues.is_a? Array
                    return @parametervalues.dup
                elsif @parametervalues.is_a? Hash
                    return @parametervalues.keys
                else
                    return []
                end
            end
        end

        # Just a simple method to proxy instance methods to class methods
        def self.proxymethods(*values)
            values.each { |val|
                eval "def #{val}; self.class.#{val}; end"
            }
        end

        # And then define one of these proxies for each method in our
        # ParamHandler class.
        proxymethods("required?", "isnamevar?")

        attr_accessor :parent

        def devfail(msg)
            self.fail(Puppet::DevError, msg)
        end

        def fail(*args)
            type = nil
            if args[0].is_a?(Class)
                type = args.shift
            else
                type = Puppet::Error
            end

            error = type.new(args.join(" "))

            if defined? @parent and @parent and @parent.line
                error.line = @parent.line
            end

            if defined? @parent and @parent and @parent.file
                error.file = @parent.file
            end

            raise error
        end

        # Log a message using the parent's log level.
        def log(msg)
            unless @parent[:loglevel]
                p @parent
                self.devfail "Parent %s has no loglevel" %
                    @parent.name
            end
            Puppet::Log.create(
                :level => @parent[:loglevel],
                :message => msg,
                :source => self
            )
        end

        # each parameter class must define the name() method, and parameter
        # instances do not change that name this implicitly means that a given
        # object can only have one parameter instance of a given parameter
        # class
        def name
            return self.class.name
        end

        # for testing whether we should actually do anything
        def noop
            unless defined? @noop
                @noop = false
            end
            tmp = @noop || self.parent.noop || Puppet[:noop] || false
            #debug "noop is %s" % tmp
            return tmp
        end

        # return the full path to us, for logging and rollback; not currently
        # used
        def path
            return [@parent.path, self.name].join("/")
        end

        # If the specified value is allowed, then munge appropriately.
        munge do |value|
            if self.class.values.empty?
                # This parameter isn't using defined values to do its work.
                return value
            end
            intern = value.to_s.intern
            # If it's a valid value, always return it as a symbol.
            if self.class.values.include?(intern)
                retval = intern
            elsif other = self.class.alias(intern)
                self.info "returning alias %s for %s" % [other, intern]
                retval = other
            else
                retval = value
            end
            retval
        end

        # Verify that the passed value is valid.
        validate do |value|
            values = self.class.values
            if values.empty?
                # This parameter isn't using defined values to do its work.
                return 
            end
            unless value.is_a?(Symbol)
                value = value.to_s.intern
            end
            unless values.include?(value) or self.class.alias(value)
                self.fail "Invalid '%s' value '%s'.  Valid values are '%s'" %
                        [self.class.name, value, values.join(", ")]
            end
        end

        # This should only be called for parameters, but go ahead and make
        # it possible to call for states, too.
        def value
            if self.is_a?(Puppet::State)
                # We should return the 'is' value if there's not 'should' value.
                # This might be bad, though, because the 'should' method
                # knows whether to return an array or not and that info is
                # not exposed, and the 'is' value could be a symbol.  I can't
                # seem to create a test in which this is a problem, but that doesn't
                # mean it's not one.
                if self.should
                    return self.should
                else
                    return self.is
                end
            else
                if defined? @value
                    return @value
                else
                    return nil
                end
            end
        end

        # Store the value provided.  All of the checking should possibly be
        # late-binding (e.g., users might not exist when the value is assigned
        # but might when it is asked for).
        def value=(value)
            # If we're a parameter, just hand the processing off to the should
            # method.
            if self.is_a?(Puppet::State)
                return self.should = value
            end
            if respond_to?(:validate)
                validate(value)
            end

            if respond_to?(:munge)
                value = munge(value)
            end
            @value = value
        end

        def inspect
            s = "Parameter(%s = %s" % [self.name, self.value || "nil"]
            if defined? @parent
                s += ", @parent = %s)" % @parent
            else
                s += ")"
            end
        end

        def to_s
            s = "Parameter(%s)" % self.name
        end
    end
end