require 'eim_xml'

module EimXML
  class Formatter
    attr_reader :out

    def self.write(element, opt = {})
      opt = { out: '' }.merge(opt)
      new(opt).write(element)
      opt[:out]
    end

    def initialize(opt)
      @out = opt[:out]
      @preservers = opt[:preservers]
      @preserve_space = false
      @indent_string = '  '
      @indent_depth = 0
      @option = opt.dup.tap { |h| %i[out preservers].each { |k| h.delete(k) } }
    end

    def write(src)
      case src
      when ElementWrapper
        write_wrapper(src)
      when Comment
        write_comment(src)
      when Element
        write_element(src)
      when PCString
        write_pcstring(src)
      else
        write_string(src.to_s)
      end
    end

    def indent(&proc)
      @indent_depth += 1
      proc.call
    ensure
      @indent_depth -= 1
    end

    def preserve_space_element?(elm)
      @preservers&.any? do |e|
        case e
        when Symbol
          e == elm.name
        when Class
          elm.is_a?(e)
        end
      end
    end

    def write_indent
      out << (@indent_string * @indent_depth) unless @preserve_space
    end

    def write_newline
      out << "\n" unless @preserve_space
    end

    def write_comment(commend)
      write_indent
      commend.write_to(out)
      write_newline
    end

    def write_contents_of(elm)
      flag = @preserve_space
      @preserve_space = true if preserve_space_element?(elm)
      write_newline
      indent do
        elm.contents.each do |c|
          write(c)
        end
      end
      write_indent
    ensure
      @preserve_space = flag
    end

    def write_element(elm)
      write_indent
      out << '<'
      elm.name_and_attributes(out)
      case elm.contents.size
      when 0
        out << ' />'
      else
        out << '>'
        write_contents_of(elm)
        out << "</#{elm.name}>"
      end
      write_newline
    end

    def write_pcstring(pcs)
      pcs.encoded_string.each_line do |l|
        write_indent
        out << l
      end
      write_newline
    end

    def write_string(str)
      PCString.encode(str).each_line do |l|
        write_indent
        out << l
      end
      write_newline
    end

    def write_wrapper(wrapper)
      wrapper.each(@option) do |i|
        write(i)
      end
    end
  end
end

require 'eim_xml/formatter/element_wrapper'