class ErrorHighlight::Spotter

# File lib/error_highlight/base.rb, line 103
def initialize(node, point_type: :name, name: nil)
  @node = node
  @point_type = point_type
  @name = name

  # Not-implemented-yet options
  @arg = nil # Specify the index or keyword at which argument caused the TypeError/ArgumentError
  @multiline = false # Allow multiline spot

  @fetch = -> (lineno, last_lineno = lineno) do
    snippet = @node.script_lines[lineno - 1 .. last_lineno - 1].join("")
    snippet += "\n" unless snippet.end_with?("\n")

    # It require some work to support Unicode (or multibyte) characters.
    # Tentatively, we stop highlighting if the code snippet has non-ascii characters.
    # See https://github.com/ruby/error_highlight/issues/4
    raise NonAscii unless snippet.ascii_only?

    snippet
  end
end

# File lib/error_highlight/base.rb, line 128
def spot
  return nil unless @node

  if OPT_GETCONSTANT_PATH
    # In Ruby 3.2 or later, a nested constant access (like `Foo::Bar::Baz`)
    # is compiled to one instruction (opt_getconstant_path).
    # @node points to the node of the whole `Foo::Bar::Baz` even if `Foo`
    # or `Foo::Bar` causes NameError.
    # So we try to spot the sub-node that causes the NameError by using
    # `NameError#name`.
    case @node.type
    when :COLON2
      subnodes = []
      node = @node
      while node.type == :COLON2
        node2, const = node.children
        subnodes << node if const == @name
        node = node2
      end
      if node.type == :CONST || node.type == :COLON3
        if node.children.first == @name
          subnodes << node
        end

        # If we found only one sub-node whose name is equal to @name, use it
        return nil if subnodes.size != 1
        @node = subnodes.first
      else
        # Do nothing; opt_getconstant_path is used only when the const base is
        # NODE_CONST (`Foo`) or NODE_COLON3 (`::Foo`)
      end
    when :constant_path_node
      subnodes = []
      node = @node

      begin
        subnodes << node if node.name == @name
      end while (node = node.parent).is_a?(Prism::ConstantPathNode)

      if node.is_a?(Prism::ConstantReadNode) && node.name == @name
        subnodes << node
      end

      # If we found only one sub-node whose name is equal to @name, use it
      return nil if subnodes.size != 1
      @node = subnodes.first
    end
  end

  case @node.type

  when :CALL, :QCALL
    case @point_type
    when :name
      spot_call_for_name
    when :args
      spot_call_for_args
    end

  when :ATTRASGN
    case @point_type
    when :name
      spot_attrasgn_for_name
    when :args
      spot_attrasgn_for_args
    end

  when :OPCALL
    case @point_type
    when :name
      spot_opcall_for_name
    when :args
      spot_opcall_for_args
    end

  when :FCALL
    case @point_type
    when :name
      spot_fcall_for_name
    when :args
      spot_fcall_for_args
    end

  when :VCALL
    spot_vcall

  when :OP_ASGN1
    case @point_type
    when :name
      spot_op_asgn1_for_name
    when :args
      spot_op_asgn1_for_args
    end

  when :OP_ASGN2
    case @point_type
    when :name
      spot_op_asgn2_for_name
    when :args
      spot_op_asgn2_for_args
    end

  when :CONST
    spot_vcall

  when :COLON2
    spot_colon2

  when :COLON3
    spot_vcall

  when :OP_CDECL
    spot_op_cdecl

  when :call_node
    case @point_type
    when :name
      prism_spot_call_for_name
    when :args
      prism_spot_call_for_args
    end

  when :local_variable_operator_write_node
    case @point_type
    when :name
      prism_spot_local_variable_operator_write_for_name
    when :args
      prism_spot_local_variable_operator_write_for_args
    end

  when :call_operator_write_node
    case @point_type
    when :name
      prism_spot_call_operator_write_for_name
    when :args
      prism_spot_call_operator_write_for_args
    end

  when :index_operator_write_node
    case @point_type
    when :name
      prism_spot_index_operator_write_for_name
    when :args
      prism_spot_index_operator_write_for_args
    end

  when :constant_read_node
    prism_spot_constant_read

  when :constant_path_node
    prism_spot_constant_path

  when :constant_path_operator_write_node
    prism_spot_constant_path_operator_write

  end

  if @snippet && @beg_column && @end_column && @beg_column < @end_column
    return {
      first_lineno: @beg_lineno,
      first_column: @beg_column,
      last_lineno: @end_lineno,
      last_column: @end_column,
      snippet: @snippet,
      script_lines: @node.script_lines,
    }
  else
    return nil
  end

rescue NonAscii
  nil
end

# File lib/error_highlight/base.rb, line 622
def fetch_line(lineno)
  @beg_lineno = @end_lineno = lineno
  @snippet = @fetch[lineno]
end

# File lib/error_highlight/base.rb, line 629
def prism_location(location)
  @beg_lineno = location.start_line
  @beg_column = location.start_column
  @end_lineno = location.end_line
  @end_column = location.end_column
  @snippet = @fetch[@beg_lineno, @end_lineno]
end

# File lib/error_highlight/base.rb, line 702
def prism_spot_call_for_args
  # Disallow highlighting arguments if there are no arguments.
  return if @node.arguments.nil?

  # Explicitly turn off foo.() syntax because error_highlight expects this
  # to not work.
  return nil if @node.name == :call && @node.message_loc.nil?

  if @node.name == :[]= && @node.opening == "[" && (@node.arguments&.arguments || []).length == 1
    prism_location(@node.opening_loc.copy(start_offset: @node.opening_loc.start_offset + 1).join(@node.arguments.location))
  else
    prism_location(@node.arguments.location)
  end
end

# File lib/error_highlight/base.rb, line 660
def prism_spot_call_for_name
  # Explicitly turn off foo.() syntax because error_highlight expects this
  # to not work.
  return nil if @node.name == :call && @node.message_loc.nil?

  location = @node.message_loc || @node.call_operator_loc || @node.location
  location = @node.call_operator_loc.join(location) if @node.call_operator_loc&.start_line == location.start_line

  # If the method name ends with "=" but the message does not, then this is
  # a method call using the "attribute assignment" syntax
  # (e.g., foo.bar = 1). In this case we need to go retrieve the = sign and
  # add it to the location.
  if (name = @node.name).end_with?("=") && !@node.message.end_with?("=")
    location = location.adjoin("=")
  end

  prism_location(location)

  if !name.end_with?("=") && !name.match?(/[[:alpha:]_\[]/)
    # If the method name is an operator, then error_highlight only
    # highlights the first line.
    fetch_line(location.start_line)
  end
end

# File lib/error_highlight/base.rb, line 755
def prism_spot_call_operator_write_for_args
  prism_location(@node.value.location)
end

# File lib/error_highlight/base.rb, line 738
def prism_spot_call_operator_write_for_name
  if !@name.start_with?(/[[:alpha:]_]/)
    prism_location(@node.binary_operator_loc.chop)
  else
    location = @node.message_loc
    if @node.call_operator_loc.start_line == location.start_line
      location = @node.call_operator_loc.join(location)
    end

    location = location.adjoin("=") if @name.end_with?("=")
    prism_location(location)
  end
end

# File lib/error_highlight/base.rb, line 805
def prism_spot_constant_path
  if @node.parent && @node.parent.location.end_line == @node.location.end_line
    fetch_line(@node.parent.location.end_line)
    prism_location(@node.delimiter_loc.join(@node.name_loc))
  else
    fetch_line(@node.location.end_line)
    location = @node.name_loc
    location = @node.delimiter_loc.join(location) if @node.delimiter_loc.end_line == location.start_line
    prism_location(location)
  end
end

# File lib/error_highlight/base.rb, line 820
def prism_spot_constant_path_operator_write
  if @name == (target = @node.target).name
    prism_location(target.delimiter_loc.join(target.name_loc))
  else
    prism_location(@node.binary_operator_loc.chop)
  end
end

# File lib/error_highlight/base.rb, line 798
def prism_spot_constant_read
  prism_location(@node.location)
end

# File lib/error_highlight/base.rb, line 784
def prism_spot_index_operator_write_for_args
  opening_loc =
    if @node.arguments.nil?
      @node.opening_loc.copy(start_offset: @node.opening_loc.start_offset + 1)
    else
      @node.arguments.location
    end

  prism_location(opening_loc.join(@node.value.location))
end

# File lib/error_highlight/base.rb, line 766
def prism_spot_index_operator_write_for_name
  case @name
  when :[]
    prism_location(@node.opening_loc.join(@node.closing_loc))
  when :[]=
    prism_location(@node.opening_loc.join(@node.closing_loc).adjoin("="))
  else
    # Explicitly turn off foo[] += 1 syntax when the operator is not on
    # the same line because error_highlight expects this to not work.
    return nil if @node.binary_operator_loc.start_line != @node.opening_loc.start_line

    prism_location(@node.binary_operator_loc.chop)
  end
end

# File lib/error_highlight/base.rb, line 727
def prism_spot_local_variable_operator_write_for_args
  prism_location(@node.value.location)
end

# File lib/error_highlight/base.rb, line 720
def prism_spot_local_variable_operator_write_for_name
  prism_location(@node.binary_operator_loc.chop)
end

# File lib/error_highlight/base.rb, line 400
def spot_attrasgn_for_args
  nd_recv, mid, nd_args = @node.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G[\s)]*\[/, nd_recv.last_column)
    @beg_column = $~.end(0)
    if nd_recv.last_lineno == nd_args.last_lineno
      @end_column = nd_args.last_column
    end
  elsif nd_args && nd_args.first_lineno == nd_args.last_lineno
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
  # TODO: support @arg
end

# File lib/error_highlight/base.rb, line 374
def spot_attrasgn_for_name
  nd_recv, mid, nd_args = @node.children
  *nd_args, _nd_last_arg, _nil = nd_args.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    args_last_column = $~.end(0)
    if nd_args.last && nd_recv.last_lineno == nd_args.last.last_lineno
      args_last_column = nd_args.last.last_column
    end
    if @snippet.match(/[\s)]*\]\s*=/, args_last_column)
      @end_column = $~.end(0)
    end
  elsif @snippet.match(/\G[\s)]*(\.\s*#{ Regexp.quote(mid.to_s.sub(/=\z/, "")) }\s*=)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

# File lib/error_highlight/base.rb, line 359
def spot_call_for_args
  _nd_recv, _mid, nd_args = @node.children
  if nd_args && nd_args.first_lineno == nd_args.last_lineno
    fetch_line(nd_args.first_lineno)
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
  # TODO: support @arg
end

# File lib/error_highlight/base.rb, line 315
def spot_call_for_name
  nd_recv, mid, nd_args = @node.children
  lineno = nd_recv.last_lineno
  lines = @fetch[lineno, @node.last_lineno]
  if mid == :[] && lines.match(/\G[\s)]*(\[(?:\s*\])?)/, nd_recv.last_column)
    @beg_column = $~.begin(1)
    @snippet = lines[/.*\n/]
    @beg_lineno = @end_lineno = lineno
    if nd_args
      if nd_recv.last_lineno == nd_args.last_lineno && @snippet.match(/\s*\]/, nd_args.last_column)
        @end_column = $~.end(0)
      end
    else
      if lines.match(/\G[\s)]*?\[\s*\]/, nd_recv.last_column)
        @end_column = $~.end(0)
      end
    end
  elsif lines.match(/\G[\s)]*?(\&?\.)(\s*?)(#{ Regexp.quote(mid) }).*\n/, nd_recv.last_column)
    lines = $` + $&
    @beg_column = $~.begin($2.include?("\n") ? 3 : 1)
    @end_column = $~.end(3)
    if i = lines[..@beg_column].rindex("\n")
      @beg_lineno = @end_lineno = lineno + lines[..@beg_column].count("\n")
      @snippet = lines[i + 1..]
      @beg_column -= i + 1
      @end_column -= i + 1
    else
      @snippet = lines
      @beg_lineno = @end_lineno = lineno
    end
  elsif mid.to_s =~ /\A\W+\z/ && lines.match(/\G\s*(#{ Regexp.quote(mid) })=.*\n/, nd_recv.last_column)
    @snippet = $` + $&
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

# File lib/error_highlight/base.rb, line 578
def spot_colon2
  nd_parent, const = @node.children
  if nd_parent.last_lineno == @node.last_lineno
    fetch_line(nd_parent.last_lineno)
    @beg_column = nd_parent.last_column
    @end_column = @node.last_column
  else
    @snippet = @fetch[@node.last_lineno]
    if @snippet[...@node.last_column].match(/#{ Regexp.quote(const) }\z/)
      @beg_column = $~.begin(0)
      @end_column = $~.end(0)
    end
  end
end

# File lib/error_highlight/base.rb, line 470
def spot_fcall_for_args
  _mid, nd_args = @node.children
  if nd_args && nd_args.first_lineno == nd_args.last_lineno
    # binary operator
    fetch_line(nd_args.first_lineno)
    @beg_column = nd_args.first_column
    @end_column = nd_args.last_column
  end
end

# File lib/error_highlight/base.rb, line 456
def spot_fcall_for_name
  mid, _nd_args = @node.children
  fetch_line(@node.first_lineno)
  if @snippet.match(/(#{ Regexp.quote(mid) })/, @node.first_column)
    @beg_column = $~.begin(1)
    @end_column = $~.end(1)
  end
end

# File lib/error_highlight/base.rb, line 523
def spot_op_asgn1_for_args
  nd_recv, mid, nd_args, nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if mid == :[]= && @snippet.match(/\G\s*\[/, nd_recv.last_column)
    @beg_column = $~.end(0)
    if nd_recv.last_lineno == nd_rhs.last_lineno
      @end_column = nd_rhs.last_column
    end
  elsif nd_args && nd_args.first_lineno == nd_rhs.last_lineno
    @beg_column = nd_args.first_column
    @end_column = nd_rhs.last_column
  end
  # TODO: support @arg
end

# File lib/error_highlight/base.rb, line 498
def spot_op_asgn1_for_name
  nd_recv, op, nd_args, _nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if @snippet.match(/\G[\s)]*(\[)/, nd_recv.last_column)
    bracket_beg_column = $~.begin(1)
    args_last_column = $~.end(0)
    if nd_args && nd_recv.last_lineno == nd_args.last_lineno
      args_last_column = nd_args.last_column
    end
    if @snippet.match(/\s*\](\s*)(#{ Regexp.quote(op) })=()/, args_last_column)
      case @name
      when :[], :[]=
        @beg_column = bracket_beg_column
        @end_column = $~.begin(@name == :[] ? 1 : 3)
      when op
        @beg_column = $~.begin(2)
        @end_column = $~.end(2)
      end
    end
  end
end

# File lib/error_highlight/base.rb, line 566
def spot_op_asgn2_for_args
  _nd_recv, _qcall, _attr, _op, nd_rhs = @node.children
  if nd_rhs.first_lineno == nd_rhs.last_lineno
    fetch_line(nd_rhs.first_lineno)
    @beg_column = nd_rhs.first_column
    @end_column = nd_rhs.last_column
  end
end

# File lib/error_highlight/base.rb, line 545
def spot_op_asgn2_for_name
  nd_recv, _qcall, attr, op, _nd_rhs = @node.children
  fetch_line(nd_recv.last_lineno)
  if @snippet.match(/\G[\s)]*(\.)\s*#{ Regexp.quote(attr) }()\s*(#{ Regexp.quote(op) })(=)/, nd_recv.last_column)
    case @name
    when attr
      @beg_column = $~.begin(1)
      @end_column = $~.begin(2)
    when op
      @beg_column = $~.begin(3)
      @end_column = $~.end(3)
    when :"#{ attr }="
      @beg_column = $~.begin(1)
      @end_column = $~.end(4)
    end
  end
end

# File lib/error_highlight/base.rb, line 596
def spot_op_cdecl
  nd_lhs, op, _nd_rhs = @node.children
  *nd_parent_lhs, _const = nd_lhs.children
  if @name == op
    @snippet = @fetch[nd_lhs.last_lineno]
    if @snippet.match(/\G\s*(#{ Regexp.quote(op) })=/, nd_lhs.last_column)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  else
    # constant access error
    @end_column = nd_lhs.last_column
    if nd_parent_lhs.empty? # example: ::C += 1
      if nd_lhs.first_lineno == nd_lhs.last_lineno
        @snippet = @fetch[nd_lhs.last_lineno]
        @beg_column = nd_lhs.first_column
      end
    else # example: Foo::Bar::C += 1
      if nd_parent_lhs.last.last_lineno == nd_lhs.last_lineno
        @snippet = @fetch[nd_lhs.last_lineno]
        @beg_column = nd_parent_lhs.last.last_column
      end
    end
  end
end

# File lib/error_highlight/base.rb, line 441
def spot_opcall_for_args
  _nd_recv, _op, nd_arg = @node.children
  if nd_arg && nd_arg.first_lineno == nd_arg.last_lineno
    # binary operator
    fetch_line(nd_arg.first_lineno)
    @beg_column = nd_arg.first_column
    @end_column = nd_arg.last_column
  end
end

# File lib/error_highlight/base.rb, line 420
def spot_opcall_for_name
  nd_recv, op, nd_arg = @node.children
  fetch_line(nd_recv.last_lineno)
  if nd_arg
    # binary operator
    if @snippet.match(/\G[\s)]*(#{ Regexp.quote(op) })/, nd_recv.last_column)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  else
    # unary operator
    if @snippet[...nd_recv.first_column].match(/(#{ Regexp.quote(op.to_s.sub(/@\z/, "")) })\s*\(?\s*\z/)
      @beg_column = $~.begin(1)
      @end_column = $~.end(1)
    end
  end
end

# File lib/error_highlight/base.rb, line 483
def spot_vcall
  if @node.first_lineno == @node.last_lineno
    fetch_line(@node.last_lineno)
    @beg_column = @node.first_column
    @end_column = @node.last_column
  end
end