# encoding: utf-8

module HTTPkit
  class Body
    include Adamantium::Mutable

    def self.build(source = nil, length = nil)
      if source.is_a?(self)
        source
      else
        new(source, length)
      end
    end

    attr_reader :closed

    # @param [String,#each,nil] source
    def initialize(source = nil, length = nil, closed = Promise.new)
      @source, @length = source, length
      @closed = closed
      @chunks = []

      apply_source
      @closed.fulfill if source
    end

    def length
      @length || 0
    end

    def length_known?
      !@length.nil?
    end

    def write(chunk)
      if @closed.pending? && !chunk.empty?
        @chunks << chunk
        @closed.progress(chunk)
      end
    end

    def each(&block)
      return to_enum(__method__) unless block

      if @source.respond_to?(:each)
        @source.each(&block)
      else
        each_chunk(&block)
      end
    end

    def to_s
      each.to_a.join
    end

    def inspect
      len = length_known? ? length : 'unknown'
      sprintf('#<%s:0x%d @length=%s>', self.class.name, object_id, len)
    end

    private

    def apply_source
      if @source.respond_to?(:to_str) && (chunk = @source.to_str)
        @length = chunk.bytesize
        write(chunk)
      elsif @source.respond_to?(:bytesize)
        @length = @source.bytesize
      end
    end

    def each_chunk(&block)
      @closed.on_progress(&block)
      @chunks.dup.each(&block)
      @closed.sync
    end
  end
end