class Psych::Visitors::ToRuby

def self.create(symbolize_names: false, freeze: false, strict_integer: false)
  class_loader = ClassLoader.new
  scanner      = ScalarScanner.new class_loader, strict_integer: strict_integer
  new(scanner, class_loader, symbolize_names: symbolize_names, freeze: freeze)
end

def accept target
  result = super
  unless @domain_types.empty? || !target.tag
    key = target.tag.sub(/^[!\/]*/, '').sub(/(,\d+)\//, '\1:')
    key = "tag:#{key}" unless key.match?(/^(?:tag:|x-private)/)
    if @domain_types.key? key
      value, block = @domain_types[key]
      result = block.call value, result
    end
  end
  result = deduplicate(result).freeze if @freeze
  result
end

def allocate_anon_data node, members
  klass = class_loader.data.define(*members.keys)
  register(node, klass.allocate)
end

def deduplicate key
  if key.is_a?(String)
    # It is important to untaint the string, otherwise it won't
    # be deduplicated into an fstring, but simply frozen.
    -(key.untaint)
  else
    key
  end
end

def deduplicate key
  if key.is_a?(String)
    -key
  else
    key
  end
end

def deserialize o
  if klass = resolve_class(@load_tags[o.tag])
    instance = klass.allocate
    if instance.respond_to?(:init_with)
      coder = Psych::Coder.new(o.tag)
      coder.scalar = o.value
      instance.init_with coder
    end
    return instance
  end
  return o.value if o.quoted
  return @ss.tokenize(o.value) unless o.tag
  case o.tag
  when '!binary', 'tag:yaml.org,2002:binary'
    o.value.unpack('m').first
  when /^!(?:str|ruby\/string)(?::(.*))?$/, 'tag:yaml.org,2002:str'
    klass = resolve_class($1)
    if klass
      klass.allocate.replace o.value
    else
      o.value
    end
  when '!ruby/object:BigDecimal'
    require 'bigdecimal' unless defined? BigDecimal
    class_loader.big_decimal._load o.value
  when "!ruby/object:DateTime"
    class_loader.date_time
    t = @ss.parse_time(o.value)
    DateTime.civil(*t.to_a[0, 6].reverse, Rational(t.utc_offset, 86400)) +
      (t.subsec/86400)
  when '!ruby/encoding'
    ::Encoding.find o.value
  when "!ruby/object:Complex"
    class_loader.complex
    Complex(o.value)
  when "!ruby/object:Rational"
    class_loader.rational
    Rational(o.value)
  when "!ruby/class", "!ruby/module"
    resolve_class o.value
  when "tag:yaml.org,2002:float", "!float"
    Float(@ss.tokenize(o.value))
  when "!ruby/regexp"
    klass = class_loader.regexp
    matches = /^\/(?<string>.*)\/(?<options>[mixn]*)$/m.match(o.value)
    source  = matches[:string].gsub('\/', '/')
    options = 0
    lang    = nil
    matches[:options].each_char do |option|
      case option
      when 'x' then options |= Regexp::EXTENDED
      when 'i' then options |= Regexp::IGNORECASE
      when 'm' then options |= Regexp::MULTILINE
      when 'n' then options |= Regexp::NOENCODING
      else lang = option
      end
    end
    klass.new(*[source, options, lang].compact)
  when "!ruby/range"
    klass = class_loader.range
    args = o.value.split(/([.]{2,3})/, 2).map { |s|
      accept Nodes::Scalar.new(s)
    }
    args.push(args.delete_at(1) == '...')
    klass.new(*args)
  when /^!ruby\/sym(bol)?:?(.*)?$/
    class_loader.symbolize o.value
  else
    @ss.tokenize o.value
  end
end

def init_with o, h, node
  c = Psych::Coder.new(node.tag)
  c.map = h
  if o.respond_to?(:init_with)
    o.init_with c
  else
    h.each { |k,v| o.instance_variable_set(:"@#{k}", v) }
  end
  o
end

def initialize ss, class_loader, symbolize_names: false, freeze: false
  super()
  @st = {}
  @ss = ss
  @load_tags = Psych.load_tags
  @domain_types = Psych.domain_types
  @class_loader = class_loader
  @symbolize_names = symbolize_names
  @freeze = freeze
end

def merge_key hash, key, val
end

def register node, object
  @st[node.anchor] = object if node.anchor
  object
end

def register_empty object
  list = register(object, [])
  object.children.each { |c| list.push accept c }
  list
end

def resolve_class klassname
  class_loader.load klassname
end

def revive klass, node
  s = register(node, klass.allocate)
  init_with(s, revive_hash({}, node, true), node)
end

def revive_data_members hash, o
  o.children.each_slice(2) do |k,v|
    name  = accept(k)
    value = accept(v)
    hash[class_loader.symbolize(name)] = value
  end
  hash
end

def revive_hash hash, o, tagged= false
  o.children.each_slice(2) { |k,v|
    key = accept(k)
    val = accept(v)
    if key == '<<' && k.tag != "tag:yaml.org,2002:str"
      case v
      when Nodes::Alias, Nodes::Mapping
        begin
          hash.merge! val
        rescue TypeError
          hash[key] = val
        end
      when Nodes::Sequence
        begin
          h = {}
          val.reverse_each do |value|
            h.merge! value
          end
          hash.merge! h
        rescue TypeError
          hash[key] = val
        end
      else
        hash[key] = val
      end
    else
      if !tagged && @symbolize_names && key.is_a?(String)
        key = key.to_sym
      elsif !@freeze
        key = deduplicate(key)
      end
      hash[key] = val
    end
  }
  hash
end

def visit_Psych_Nodes_Alias o
  @st.fetch(o.anchor) { raise AnchorNotDefined, o.anchor }
end

def visit_Psych_Nodes_Document o
  accept o.root
end

def visit_Psych_Nodes_Mapping o
  if @load_tags[o.tag]
    return revive(resolve_class(@load_tags[o.tag]), o)
  end
  return revive_hash(register(o, {}), o) unless o.tag
  case o.tag
  when /^!ruby\/struct:?(.*)?$/
    klass = resolve_class($1) if $1
    if klass
      s = register(o, klass.allocate)
      members = {}
      struct_members = s.members.map { |x| class_loader.symbolize x }
      o.children.each_slice(2) do |k,v|
        member = accept(k)
        value  = accept(v)
        if struct_members.include?(class_loader.symbolize(member))
          s.send("#{member}=", value)
        else
          members[member.to_s.sub(/^@/, '')] = value
        end
      end
      init_with(s, members, o)
    else
      klass = class_loader.struct
      members = o.children.map { |c| accept c }
      h = Hash[*members]
      s = klass.new(*h.map { |k,v|
        class_loader.symbolize k
      }).new(*h.map { |k,v| v })
      register(o, s)
      s
    end
  when /^!ruby\/data(-with-ivars)?(?::(.*))?$/
    data = register(o, resolve_class($2).allocate) if $2
    members = {}
    if $1 # data-with-ivars
      ivars   = {}
      o.children.each_slice(2) do |type, vars|
        case accept(type)
        when 'members'
          revive_data_members(members, vars)
          data ||= allocate_anon_data(o, members)
        when 'ivars'
          revive_hash(ivars, vars)
        end
      end
      ivars.each do |ivar, v|
        data.instance_variable_set ivar, v
      end
    else
      revive_data_members(members, o)
    end
    data ||= allocate_anon_data(o, members)
    init_struct(data, **members)
    data.freeze
    data
  when /^!ruby\/object:?(.*)?$/
    name = $1 || 'Object'
    if name == 'Complex'
      class_loader.complex
      h = Hash[*o.children.map { |c| accept c }]
      register o, Complex(h['real'], h['image'])
    elsif name == 'Rational'
      class_loader.rational
      h = Hash[*o.children.map { |c| accept c }]
      register o, Rational(h['numerator'], h['denominator'])
    elsif name == 'Hash'
      revive_hash(register(o, {}), o)
    else
      obj = revive((resolve_class(name) || class_loader.object), o)
      obj
    end
  when /^!(?:str|ruby\/string)(?::(.*))?$/, 'tag:yaml.org,2002:str'
    klass   = resolve_class($1)
    members = {}
    string  = nil
    o.children.each_slice(2) do |k,v|
      key   = accept k
      value = accept v
      if key == 'str'
        if klass
          string = klass.allocate.replace value
        else
          string = value
        end
        register(o, string)
      else
        members[key] = value
      end
    end
    init_with(string, members.map { |k,v| [k.to_s.sub(/^@/, ''),v] }, o)
  when /^!ruby\/array:(.*)$/
    klass = resolve_class($1)
    list  = register(o, klass.allocate)
    members = Hash[o.children.map { |c| accept c }.each_slice(2).to_a]
    list.replace members['internal']
    members['ivars'].each do |ivar, v|
      list.instance_variable_set ivar, v
    end
    list
  when '!ruby/range'
    klass = class_loader.range
    h = Hash[*o.children.map { |c| accept c }]
    register o, klass.new(h['begin'], h['end'], h['excl'])
  when /^!ruby\/exception:?(.*)?$/
    h = Hash[*o.children.map { |c| accept c }]
    e = build_exception((resolve_class($1) || class_loader.exception),
                        h.delete('message'))
    e.set_backtrace h.delete('backtrace') if h.key? 'backtrace'
    init_with(e, h, o)
  when '!set', 'tag:yaml.org,2002:set'
    set = class_loader.psych_set.new
    @st[o.anchor] = set if o.anchor
    o.children.each_slice(2) do |k,v|
      set[accept(k)] = accept(v)
    end
    set
  when /^!ruby\/hash-with-ivars(?::(.*))?$/
    hash = $1 ? resolve_class($1).allocate : {}
    register o, hash
    o.children.each_slice(2) do |key, value|
      case key.value
      when 'elements'
        revive_hash hash, value
      when 'ivars'
        value.children.each_slice(2) do |k,v|
          hash.instance_variable_set accept(k), accept(v)
        end
      end
    end
    hash
  when /^!map:(.*)$/, /^!ruby\/hash:(.*)$/
    revive_hash register(o, resolve_class($1).allocate), o
  when '!omap', 'tag:yaml.org,2002:omap'
    map = register(o, class_loader.psych_omap.new)
    o.children.each_slice(2) do |l,r|
      map[accept(l)] = accept r
    end
    map
  when /^!ruby\/marshalable:(.*)$/
    name = $1
    klass = resolve_class(name)
    obj = register(o, klass.allocate)
    if obj.respond_to?(:init_with)
      init_with(obj, revive_hash({}, o), o)
    elsif obj.respond_to?(:marshal_load)
      marshal_data = o.children.map(&method(:accept))
      obj.marshal_load(marshal_data)
      obj
    else
      raise ArgumentError, "Cannot deserialize #{name}"
    end
  else
    revive_hash(register(o, {}), o)
  end
end

def visit_Psych_Nodes_Scalar o
  register o, deserialize(o)
end

def visit_Psych_Nodes_Sequence o
  if klass = resolve_class(@load_tags[o.tag])
    instance = klass.allocate
    if instance.respond_to?(:init_with)
      coder = Psych::Coder.new(o.tag)
      coder.seq = o.children.map { |c| accept c }
      instance.init_with coder
    end
    return instance
  end
  case o.tag
  when nil
    register_empty(o)
  when '!omap', 'tag:yaml.org,2002:omap'
    map = register(o, Psych::Omap.new)
    o.children.each { |a|
      map[accept(a.children.first)] = accept a.children.last
    }
    map
  when /^!(?:seq|ruby\/array):(.*)$/
    klass = resolve_class($1)
    list  = register(o, klass.allocate)
    o.children.each { |c| list.push accept c }
    list
  else
    register_empty(o)
  end
end

def visit_Psych_Nodes_Stream o
  o.children.map { |c| accept c }
end