# Copyright 2011-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
#     http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.

require 'bigdecimal'
require 'json'

module AWS
  module Core

    # @api private
    class OptionGrammar

      # @api private
      class DefaultOption; end

      # @api private
      class FormatError < ArgumentError
        attr_accessor :expectation
        attr_accessor :context_description

        def initialize(expectation, context)
          @expectation = expectation
          @context_description = context
        end

        def to_s
          "expected #{expectation} for #{context_description}"
        end
      end

      # @api private
      module Descriptors

        # @api private
        module NoArgs
          def apply(option)
            option.extend self
          end
        end

        module Timestamp

          extend NoArgs

          def validate(value, context = nil)
            true
  #             raise format_error("timestamp value", context) unless
  #               case value
  #               when String
  #                 value =~ /^\d+$/ or value =~ /^\d{4}-\d{2}-d{2}T\d{2}:\d{2}:\d{2}Z$/
  #               when String then value =~ /^2009-12-04T20:56:05.000Z\d+$/
  #               when Integer then true
  #               when DateTime then true
  #               when Timestamp then true
  #               when Date then true
  #               else false
  #               end
  #             end
  #               value.respond_to? :to_str
          end

          def encode_value(value)
            value.to_s
  #             value.to_s
  #             case value
  #             when Integer
  #             when
  #             case value
  #             when nil, ''  then nil
  #             when DateTime then raw
  #             when Integer  then DateTime.parse(Time.at(raw).to_s) # timestamp
  #             else DateTime.parse(raw.to_s) # work with Time, Date and String objects
  #             end
          end
        end

        # @api private
        module String

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("string value", context) unless
              value.respond_to? :to_str
          end

          def encode_value(value)
            value.to_s
          end

        end

        # @api private
        module Blob

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("string value", context) unless
              value.respond_to? :to_str
          end

          def encode_value(value)
            [value.to_s].pack("m0").gsub("\n", '')
          end

          def hash_format(value)
            [value.to_s].pack("m0").gsub("\n", '')
          end

        end

        # @api private
        module Integer

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("integer value", context) unless
              value.respond_to? :to_int
          end

          def encode_value(value)
            value.to_s
          end

        end

        Long = Integer

        # @api private
        module Boolean

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("boolean value", context) unless
              value == true || value == false
          end

          def encode_value(value)
            value.to_s
          end

        end

        # @api private
        module Required
          extend NoArgs
          def required?; true; end
        end

        module Position
          def self.apply *args; end
        end

        # @api private
        module Float

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("float value", context) unless
              value.kind_of?(Numeric) or
              value.respond_to? :to_f
          end

          def encode_value(value)
            value.to_f.to_s
          end

        end

        Double = Float

        # @api private
        module Rename
          def self.apply(option, new_name)
            new_name = Inflection.ruby_name(new_name)
            MetaUtils.extend_method(option, :ruby_name) { new_name }
          end
        end

        # @api private
        module Pattern

  #         def validate value, context = nil
  #           unless value =~ regex
  #             raise format_error("value to match #{regex}", context)
  #           end
  #         end
  #
  #         def self.apply option, regex
  #           option.extend(self)
  #           MetaUtils.extend_method(option, :regex) { regex }
  #         end

          def self.apply *args
          end

        end

        # @api private
        module ListMethods

          module ClassMethods

            def apply(option, member_descriptors)
              super(option)
              member_option = option.member_option if option.respond_to?(:member_option)

              # ignoring member name descriptors for lists, only useful for rest
              descriptors = []
              member_descriptors.each do |descriptor|
                unless descriptor.is_a?(Hash) and descriptor[:member_name]
                  descriptors << descriptor
                end
              end

              member_option ||= ListMember.new
              member_option = member_option.extend_with_config(*descriptors)
              MetaUtils.extend_method(option, :member_option) { member_option }
            end

          end

          module InstanceMethods

            def validate(value, context = nil)
              raise format_error("enumerable value", context) unless
                value.respond_to? :each
              i = 0
              value.each do |member|
                i += 1
                member_option.validate(member,
                                       "member #{i} of #{context_description(context)}")
              end
            end

            def request_params(value, prefix = nil)
              params = []
              value.each do |v|
                name = prefixed_name(prefix) + join + (params.size + 1).to_s
                params << member_option.request_params(v, name)
              end
              return [Http::Request::Param.new(prefixed_name(prefix), "")] if params.empty?
              params
            end

            def hash_format(value)
              value.map do |v|
                member_option.hash_format(v)
              end
            end

            def join
              '.'
            end

          end

        end

        module List

          extend NoArgs
          extend ListMethods::ClassMethods
          include ListMethods::InstanceMethods

        end

        module MemberedList

          extend NoArgs
          extend ListMethods::ClassMethods
          include ListMethods::InstanceMethods

          def join
            '.member.'
          end

        end

        class ListMember < DefaultOption

          def initialize options = {}
            super("##list-member##")
            @prefix = options[:prefix] || ''
          end

          def prefixed_name(prefix)
            "#{prefix}#{@prefix}"
          end

        end

        # @api private
        module Structure

          extend NoArgs

          def self.apply(option, members)
            options = {}
            options = option.member_options.inject({}) do |memo, member_option|
              memo[member_option.name] = member_option
              memo
            end if option.respond_to?(:member_options)

            super(option)

            members.each do |(name, descriptors)|
              member_option = options[name] || DefaultOption.new(name)
              member_option = member_option.extend_with_config(*descriptors)
              options[name] = member_option
            end

            MetaUtils.extend_method(option, :member_options) { options.values }
            by_ruby_name = options.values.inject({}) do |memo, member_option|
              memo[member_option.ruby_name] = member_option
              memo[member_option.name] = member_option
              memo
            end
            MetaUtils.extend_method(option, :member_option) { |n| by_ruby_name[n] }
          end

          def validate(value, context = nil)
            raise format_error("hash value", context) unless
              value.respond_to?(:to_hash)

            context = context_description(context)

            value.each do |name, v|
              name = name.to_s
              raise ArgumentError.new("unexpected key #{name} for #{context}") unless
                member_option(name)
              member_option(name).validate(v, "key #{name} of #{context}")
            end

            member_options.each do |option|
              raise ArgumentError.new("missing required key #{option.ruby_name} for #{context}") if
                option.required? and
                !value.has_key?(option.ruby_name) and
                !value.has_key?(option.ruby_name.to_sym) and
                !value.has_key?(option.name)
            end
          end

          def request_params(values, prefix = nil)
            values.map do |name, value|
              name = name.to_s
              member_option(name).request_params(value, prefixed_name(prefix))
            end.flatten
          end

          def hash_format(hash)
            hash.inject({}) do |hash, (name, value)|
              option = member_option(name.to_s)
              hash[option.name] = option.hash_format(value)
              hash
            end
          end

        end

        module Map

          def self.apply option, members = {}

            option.extend self

            key_option = option.key_option
            if key_descriptors = members[:key]
              key_option = key_option.extend_with_config(*key_descriptors)
              MetaUtils.extend_method(option, :key_option) { key_option }
            end

            value_option = option.value_option
            if value_descriptors = members[:value]
              value_option = value_option.extend_with_config(*value_descriptors)
              MetaUtils.extend_method(option, :value_option) { value_option }
            end

            key_option.param_name = members[:key_param] if members[:key_param]
            value_option.param_name = members[:value_param] if members[:value_param]

            separator = members[:flattened] ? '.' : '.entry.'
            MetaUtils.extend_method(option, :separator) { separator }

          end

          def validate(value, context = nil)

            raise format_error("hash value", context) unless
              value.respond_to?(:to_hash)

            context = context_description(context)

            value.each do |key, value|
              key_option.validate(key, "key of #{context}")
              value_option.validate(value, "value at key #{key} of #{context}")
            end

          end

          def request_params values, prefix = nil
            values.inject([]) do |params, (key,value)|

              index = params.size / 2 + 1
              common_prefix = "#{prefixed_name(prefix)}#{separator}#{index}."

              key_name = common_prefix + key_option.param_name
              value_name = common_prefix + value_option.param_name

              params << Http::Request::Param.new(key_name, key)
              params << Http::Request::Param.new(value_name, value)

            end
          end


          def hash_format(value)
            value.inject({}) do |hash, (key, value)|
              hash[key_option.hash_format(key)] =
                value_option.hash_format(value)
              hash
            end
          end

          def key_option
            @_key_option ||= MapOption.new("key")
          end

          def value_option
            @_value_option ||= MapOption.new("value")
          end

        end

        module Bigdecimal

          extend NoArgs

          def validate(value, context = nil)
            raise format_error("decimal value", context) unless
              value.kind_of?(Numeric) or
              value.respond_to?(:to_int)
          end

          def hash_format(value)
            BigDecimal(value.to_s)
          end

        end

        # @api private
        module Boolean
          extend NoArgs
        end

      end

      class DefaultOption

        attr_reader :name

        def initialize(name)
          @name = name
        end

        def ruby_name
          Inflection.ruby_name(name)
        end

        def request_params(value, prefix = nil)
          [Http::Request::Param.new(prefixed_name(prefix), encode_value(value))]
        end

        def hash_format(value)
          value
        end

        def prefixed_name(prefix)
          return "#{prefix}.#{name}" if prefix
          name
        end

        def encode_value(value)
          value
        end

        def required?
          false
        end

        def format_error(expected, context = nil)
          context = context_description(context)
          FormatError.new(expected, context)
        end

        def context_description(context)
          context or "option #{ruby_name}"
        end

        def extend_with_config(*descriptors)
          option = clone
          descriptors.each do |desc|
            if desc.kind_of?(Hash)
              (name, arg) = desc.to_a.first
              next if name == :documentation
            else
              name = desc
              arg = nil
            end
            class_name = Inflection.class_name(name.to_s)
            mod = Descriptors::const_get(class_name)
            if arg
              mod.apply(option, arg)
            else
              mod.apply(option)
            end
          end
          option
        end

        include Descriptors::String

      end

      # @api private
      module ModuleMethods

        include Inflection

        def customize(config = [])
          m = Class.new(self)
          supported_options = m.supported_options.inject({}) do |memo, opt|
            memo[opt.name] = opt
            memo
          end
          config.each do |option_config|
            if config.kind_of?(Hash)
              (name, value_desc) = option_config
            else
              (name, value_desc) = parse_option(option_config)
            end
            option = supported_options[name] || DefaultOption.new(name)
            option = option.extend_with_config(*value_desc)
            supported_options[option.name] = option
          end

          supported_ary = supported_options.values
          MetaUtils.extend_method(m, :supported_options) { supported_ary }
          supported_ruby_names = supported_ary.inject({}) do |memo, opt|
            memo[opt.ruby_name] = opt
            memo
          end
          MetaUtils.extend_method(m, :option) { |n| supported_ruby_names[n] }
          supported_ary.each do |opt|
            MetaUtils.extend_method(m, "validate_#{opt.ruby_name}") do |value|
              opt.validate(value)
            end
          end

          m
        end

        def option(name)
          nil
        end

        def supported_options
          []
        end

        def validate(options)
          options.each do |name, value|
            name = name.to_s
            raise ArgumentError.new("unexpected option #{name}") unless
              option(name)
            option(name).validate(value)
          end
          supported_options.each do |option|
            raise ArgumentError.new("missing required option #{option.ruby_name}") unless
              !option.required? ||
              options.has_key?(option.ruby_name) || options.has_key?(option.ruby_name.to_sym)
          end
        end

        # Returns the options in AWS/Query format
        def request_params(options)
          validate(options)
          options.map do |(name, value)|
            name = name.to_s
            option(name).request_params(value)
          end.flatten
        end

        # Returns the options as a hash (which is used to generate JSON
        # in to_json).
        def to_h(options)
          validate(options)
          options.inject({}) do |hash, (name, value)|
            option = self.option(name.to_s)
            hash[option.name] = option.hash_format(value)
            hash
          end
        end

        # Returns the options in JSON format
        def to_json(options)
          to_h(options).to_json
        end

        def included(m)
          m.extend(self::ModuleMethods)
        end

        protected
        def parse_option(option)
          value_desc = nil
          if option.kind_of? Hash
            raise ArgumentError.new("passed empty hash where an option was expected") if
              option.empty?

            raise ArgumentError.new("too many entries in option description") if
              option.size > 1

            (name, value_desc) = option.to_a.first
            name = name.to_s

            raise ArgumentError.new("expected an array for "+
                                    "value description of option #{name},"+
                                    "got #{value_desc.inspect}") unless
              value_desc.nil? or value_desc.kind_of?(Array)
          else
            name = option
          end

          value_desc ||= []

          [name, value_desc]
        end

        protected
        def apply_required_descriptor(m, name)
          name = ruby_name(name)
          MetaUtils.extend_method(m, :validate) do |opts|
            raise ArgumentError.new("missing required option #{name}") unless
              opts.key? name or opts.key? name.to_sym
          end
        end

        protected
        def apply_integer_descriptor(m, name)
          MetaUtils.extend_method(m, "validate_#{ruby_name(name)}") do |value|
            raise ArgumentError.new("expected integer value for option #{ruby_name(name)}") unless
              value.respond_to? :to_int
          end
        end

        protected
        def apply_string_descriptor(m, name)
          MetaUtils.extend_method(m, "validate_#{ruby_name(name)}") do |value|
            raise ArgumentError.new("expected string value for option #{ruby_name(name)}") unless
              value.respond_to? :to_str
          end
        end

        protected
        def apply_list_descriptor(m, name, arg)
          MetaUtils.extend_method(m, "validate_#{ruby_name(name)}") do |value|
            raise ArgumentError.new("expected value for option #{ruby_name(name)} "+
                                    "to respond to #each") unless
              value.respond_to? :each
          end
          MetaUtils.extend_method(m, "params_for_#{ruby_name(name)}") do |value|
            i = 0
            values = []
            value.each do |member|
              i += 1
              values << Http::Request::Param.new(name+"."+i.to_s, member.to_s)
            end
            if i > 0
              values
            else
              Http::Request::Param.new(name, "")
            end
          end
        end

        protected
        def apply_rename_descriptor(m, name, new_name)
          name = ruby_name(name)
          MetaUtils.extend_method(m, :validate) do |opts|
            raise ArgumentError.new("unexpected option foo") if
              opts.key?(name) or opts.key?(name.to_sym)

            opts = opts.dup
            opts[name] = opts[new_name] if opts.key?(new_name)
            opts[name.to_sym] = opts[new_name.to_sym] if opts.key?(new_name.to_sym)
            opts.delete(new_name)
            opts.delete(new_name.to_sym)
            super(opts)
          end

          # couldn't find a better way to alias a class method
          method = m.method("params_for_#{name}")
          MetaUtils.extend_method(m, "params_for_#{new_name}") do |value|
            method.call(value)
          end
        end

      end

      class MapOption < DefaultOption
        def param_name
          @param_name || name
        end
        def param_name= name
          @param_name = name
        end
      end

      extend ModuleMethods

    end
  end
end