module Faraday
  # Subclasses Struct with some special helpers for converting from a Hash to
  # a Struct.
  class Options < Struct
    # Public
    def self.from(value)
      value ? new.update(value) : new
    end

    # Public
    def each(&block)
      members.each do |key|
        block.call key.to_sym, send(key)
      end
    end

    # Public
    def update(obj)
      obj.each do |key, value|
        if sub_options = self.class.options_for(key)
          value = sub_options.from(value) if value
        elsif Hash === value
          hash = {}
          value.each do |hash_key, hash_value|
            hash[hash_key] = hash_value
          end
          value = hash
        end

        self.send("#{key}=", value) unless value.nil?
      end
      self
    end

    alias merge! update

    # Public
    def delete(key)
      value = send(key)
      send("#{key}=", nil)
      value
    end

    # Public
    def merge(value)
      dup.update(value)
    end

    # Public
    def fetch(key, *args)
      return send(key) if symbolized_key_set.include?(key.to_sym)

      key_setter = "#{key}="

      if args.size > 0
        return send(key_setter, args.first)
      end

      if block_given?
        return send(key_setter, Proc.new.call(key))
      end

      raise self.class.fetch_error_class, "key not found: #{key.inspect}"
    end

    # Public
    def values_at(*keys)
      keys.map { |key| send(key) }
    end

    # Public
    def keys
      members.reject { |m| send(m).nil? }
    end

    # Public
    def to_hash
      hash = {}
      members.each do |key|
        value = send(key)
        hash[key.to_sym] = value unless value.nil?
      end
      hash
    end

    # Internal
    def inspect
      values = []
      members.each do |m|
        value = send(m)
        values << "#{m}=#{value.inspect}" if value
      end
      values = values.empty? ? ' (empty)' : (' ' << values.join(", "))

      %(#<#{self.class}#{values}>)
    end

    # Internal
    def self.options(mapping)
      attribute_options.update(mapping)
    end

    # Internal
    def self.options_for(key)
      attribute_options[key]
    end

    # Internal
    def self.attribute_options
      @attribute_options ||= {}
    end

    def self.memoized(key)
      memoized_attributes[key.to_sym] = Proc.new
      class_eval <<-RUBY, __FILE__, __LINE__ + 1
        def #{key}() self[:#{key}]; end
      RUBY
    end

    def self.memoized_attributes
      @memoized_attributes ||= {}
    end

    def [](key)
      key = key.to_sym
      if method = self.class.memoized_attributes[key]
        super(key) || (self[key] = instance_eval(&method))
      else
        super
      end
    end

    def symbolized_key_set
      @symbolized_key_set ||= Set.new(keys.map { |k| k.to_sym })
    end

    def self.inherited(subclass)
      super
      subclass.attribute_options.update(attribute_options)
      subclass.memoized_attributes.update(memoized_attributes)
    end

    def self.fetch_error_class
      @fetch_error_class ||= if Object.const_defined?(:KeyError)
        ::KeyError
      else
        ::IndexError
      end
    end
  end

  class RequestOptions < Options.new(:params_encoder, :proxy, :bind,
    :timeout, :open_timeout, :boundary,
    :oauth)

    def []=(key, value)
      if key && key.to_sym == :proxy
        super(key, value ? ProxyOptions.from(value) : nil)
      else
        super(key, value)
      end
    end
  end

  class SSLOptions < Options.new(:verify, :ca_file, :ca_path, :verify_mode,
    :cert_store, :client_cert, :client_key, :certificate, :private_key, :verify_depth, :version)

    def verify?
      verify != false
    end

    def disable?
      !verify?
    end
  end

  class ProxyOptions < Options.new(:uri, :user, :password)
    extend Forwardable
    def_delegators :uri, :scheme, :scheme=, :host, :host=, :port, :port=, :path, :path=

    def self.from(value)
      case value
      when String then value = {:uri => Utils.URI(value)}
      when URI then value = {:uri => value}
      when Hash, Options
        if uri = value.delete(:uri)
          value[:uri] = Utils.URI(uri)
        end
      end
      super(value)
    end

    memoized(:user) { uri.user && Utils.unescape(uri.user) }
    memoized(:password) { uri.password && Utils.unescape(uri.password) }
  end

  class ConnectionOptions < Options.new(:request, :proxy, :ssl, :builder, :url,
    :parallel_manager, :params, :headers, :builder_class)

    options :request => RequestOptions, :ssl => SSLOptions

    memoized(:request) { self.class.options_for(:request).new }

    memoized(:ssl) { self.class.options_for(:ssl).new }

    memoized(:builder_class) { RackBuilder }

    def new_builder(block)
      builder_class.new(&block)
    end
  end

  class Env < Options.new(:method, :body, :url, :request, :request_headers,
    :ssl, :parallel_manager, :params, :response, :response_headers, :status)

    ContentLength = 'Content-Length'.freeze
    StatusesWithoutBody = Set.new [204, 304]
    SuccessfulStatuses = 200..299

    # A Set of HTTP verbs that typically send a body.  If no body is set for
    # these requests, the Content-Length header is set to 0.
    MethodsWithBodies = Set.new [:post, :put, :patch, :options]

    options :request => RequestOptions,
      :request_headers => Utils::Headers, :response_headers => Utils::Headers

    extend Forwardable

    def_delegators :request, :params_encoder

    # Public
    def [](key)
      if in_member_set?(key)
        super(key)
      else
        custom_members[key]
      end
    end

    # Public
    def []=(key, value)
      if in_member_set?(key)
        super(key, value)
      else
        custom_members[key] = value
      end
    end

    # Public
    def success?
      SuccessfulStatuses.include?(status)
    end

    # Public
    def needs_body?
      !body && MethodsWithBodies.include?(method)
    end

    # Public
    def clear_body
      request_headers[ContentLength] = '0'
      self.body = ''
    end

    # Public
    def parse_body?
      !StatusesWithoutBody.include?(status)
    end

    # Public
    def parallel?
      !!parallel_manager
    end

    def inspect
      attrs = [nil]
      members.each do |mem|
        if value = send(mem)
          attrs << "@#{mem}=#{value.inspect}"
        end
      end
      if !custom_members.empty?
        attrs << "@custom=#{custom_members.inspect}"
      end
      %(#<#{self.class}#{attrs.join(" ")}>)
    end

    # Internal
    def custom_members
      @custom_members ||= {}
    end

    # Internal
    if members.first.is_a?(Symbol)
      def in_member_set?(key)
        self.class.member_set.include?(key.to_sym)
      end
    else
      def in_member_set?(key)
        self.class.member_set.include?(key.to_s)
      end
    end

    # Internal
    def self.member_set
      @member_set ||= Set.new(members)
    end
  end
end