require 'rest-core'

require 'weakref'

module RestCore::Client
  include RestCore

  Unserializable = [Proc, Method, IO]

  def self.included mod
    # honor default attributes
    src = mod.members.map{ |name|
      <<-RUBY
        def #{name}
          if (r = super).nil?
            self.#{name} = default_#{name}
          else
            r
          end
        end

        def default_#{name} app=app
          if self.class.respond_to?("default_#{name}")
            self.class.default_#{name}      # old class default style
          elsif app.respond_to?(:#{name})
            app.#{name}({})                 # middleware instance value
          elsif app.respond_to?(:wrapped)
            default_#{name}(app.wrapped) || # wrapper value
            default_#{name}(app.app)        # walk into it
          elsif app.respond_to?(:app)
            default_#{name}(app.app)        # walk into next app
          else
            nil
          end
        end
        private :default_#{name}
      RUBY
    }
    # if RUBY_VERSION < '1.9.2'
    src << <<-RUBY if mod.members.first.kind_of?(String)
      def members
        super.map(&:to_sym)
      end
    RUBY
    # end
    accessor = Module.new
    accessor.module_eval(src.join("\n"), __FILE__, __LINE__)
    mod.const_set('Accessor', accessor)
    mod.send(:include, accessor)
  end

  attr_reader :app, :dry, :futures
  def initialize o={}
    @app ||= self.class.builder.to_app # lighten! would reinitialize anyway
    @dry ||= self.class.builder.to_app(Dry)
    @futures = []  # don't record any futures in lighten!
    @mutex   = nil # for locking futures, lazily initialized for serialization
    o.each{ |key, value| send("#{key}=", value) if respond_to?("#{key}=") }
  end

  def attributes
    Hash[each_pair.map{ |k, v| [k, send(k)] }]
  end

  def inspect
    fields = attributes.map{ |k, v| "#{k}=#{v.inspect}" }.join(', ')
    "#<struct #{self.class.name}#{if fields.empty? then '' else fields end}>"
  end

  def lighten! o={}
    attributes.each{ |k, v| vv = case v;
                                   when  Hash; lighten_hash(v)
                                   when Array; lighten_array(v)
                                   when *Unserializable; nil
                                   else v
                                 end
                            send("#{k}=", vv)}
    initialize(o)
    @app, @dry = lighten_app(app), lighten_app(dry)
    self
  end

  def lighten o={}
    dup.lighten!(o)
  end

  def wait
    return self if futures.empty?
    current_futures = nil
    mutex.synchronize{
      current_futures = futures.dup
      futures.clear
    }
    current_futures.each{ |f|
      begin
        f.wait
      rescue WeakRef::RefError # it's gc'ed after we think it's alive
      end if f.weakref_alive?
    }
    wait
  end

  def url path, query={}, opts={}
    dry.call(build_env({
      REQUEST_PATH  => path,
      REQUEST_QUERY => query,
      DRY           => true}.merge(opts)), &Middleware.method(:request_uri))
  end

  def get    path, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :get   ,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  }.merge(opts), &cb)
  end

  def delete path, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :delete,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  }.merge(opts), &cb)
  end

  def head path, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :head  ,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  }.merge(opts), RESPONSE_HEADERS, &cb)
  end

  def options path, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :options,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  }.merge(opts), &cb)
  end

  def post   path, payload={}, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :post  ,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  ,
       REQUEST_PAYLOAD => payload}.merge(opts), &cb)
  end

  def put    path, payload={}, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :put   ,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  ,
       REQUEST_PAYLOAD => payload}.merge(opts), &cb)
  end

  def patch  path, payload={}, query={}, opts={}, &cb
    request(
      {REQUEST_METHOD  => :patch ,
       REQUEST_PATH    => path   ,
       REQUEST_QUERY   => query  ,
       REQUEST_PAYLOAD => payload}.merge(opts), &cb)
  end

  def request env, key=RESPONSE_BODY, app=app
    if block_given?
      request_full(env, app){ |response|
        yield(response[key])
      }
    else
      request_full(env, app)[key]
    end
  end

  def request_full env, app=app, &k
    response = app.call(build_env(
      {REQUEST_METHOD  => :get,
       REQUEST_PATH    => '/' ,
       REQUEST_QUERY   => {}  ,
       REQUEST_PAYLOAD => {}  ,
       REQUEST_HEADERS => {}  ,
       FAIL            => []  ,
       LOG             => []  ,
       ASYNC           => !!k }.merge(env)),
       &(k || Middleware.id))

    # under ASYNC callback, response might not be a response hash
    # in that case (maybe in a user created engine), Client#wait
    # won't work because we have no way to track the future.
    if response.kind_of?(Hash) && RestCore.const_defined?(:Future) &&
       response[FUTURE].kind_of?(Future)
      mutex.synchronize{ futures << WeakRef.new(response[FUTURE]) }
    end

    if block_given?
      self
    else
      response
    end
  end

  def build_env env={}
    Middleware.string_keys(attributes).merge(Middleware.string_keys(env))
  end
  # ------------------------ instance ---------------------



  private
  def mutex
    @mutex ||= Mutex.new
  end

  def lighten_hash hash
    Hash[hash.map{ |(key, value)|
      case value
        when  Hash; lighten_hash(value)
        when Array; lighten_array(value)
        when *Unserializable; [key, nil]
        else [key, value]
      end
    }]
  end

  def lighten_array array
    array.map{ |value|
      case value
        when  Hash; lighten_hash(value)
        when Array; lighten_array(value)
        when *Unserializable; nil
        else value
      end
    }.compact
  end

  def lighten_app app
    members = if app.class.respond_to?(:members)
                app.class.members.map{ |key|
                  case value = app.send(key, {})
                    when  Hash; lighten_hash(value)
                    when Array; lighten_array(value)
                    when *Unserializable; nil
                    else value
                  end
                }
              else
                []
              end

    if app.respond_to?(:app) && app.app
      wrapped = if app.respond_to?(:wrapped) && app.wrapped
                  lighten_app(app.wrapped)
                else
                  nil
                end
      app.class.new(lighten_app(app.app), *members){
        @wrapped = wrapped if wrapped
      }
    else
      app.class.new(*members)
    end
  end
end