class ActionView::Template::Handlers::ERB

def self.call(template, source)
  new.call(template, source)
end

def call(template, source)
  # First, convert to BINARY, so in case the encoding is
  # wrong, we can still find an encoding tag
  # (<%# encoding %>) inside the String using a regular
  # expression
  template_source = source.b
  erb = template_source.gsub(ENCODING_TAG, "")
  encoding = $2
  erb.force_encoding valid_encoding(source.dup, encoding)
  # Always make sure we return a String in the default_internal
  erb.encode!
  # Strip trailing newlines from the template if enabled
  erb.chomp! if strip_trailing_newlines
  options = {
    escape: (self.class.escape_ignore_list.include? template.type),
    trim: (self.class.erb_trim_mode == "-")
  }
  if ActionView::Base.annotate_rendered_view_with_filenames && template.format == :html
    options[:preamble] = "@output_buffer.safe_append='<!-- BEGIN #{template.short_identifier}\n-->';"
    options[:postamble] = "@output_buffer.safe_append='<!-- END #{template.short_identifier} -->';@output_buffer"
  end
  self.class.erb_implementation.new(erb, options).src
end

def find_lineno_offset(compiled, source_lines, highlight, error_lineno)
  first_index = error_lineno - 1 - compiled.size + source_lines.size
  first_index = 0 if first_index < 0
  last_index = error_lineno - 1
  last_index = source_lines.size - 1 if last_index >= source_lines.size
  last_index.downto(first_index) do |line_index|
    next unless source_lines[line_index].include?(highlight)
    return error_lineno - 1 - line_index
  end
  raise LocationParsingError, "Couldn't find code snippet"
end

def find_offset(compiled, source_tokens, error_column)
  compiled = StringScanner.new(compiled)
  offset_source_tokens(source_tokens).each_cons(2) do |(name, str, offset), (_, next_str, _)|
    matched_str = false
    until compiled.eos?
      if matched_str && next_str && compiled.match?(next_str)
        break
      elsif compiled.match?(str)
        matched_str = true
        if name == :CODE && compiled.pos <= error_column && compiled.pos + str.bytesize >= error_column
          return compiled.pos - offset
        end
        compiled.pos += str.bytesize
      else
        compiled.pos += 1
      end
    end
  end
  raise LocationParsingError, "Couldn't find code snippet"
end

def handles_encoding?
  true
end

def offset_source_tokens(source_tokens)
  source_offset = 0
  with_offset = source_tokens.filter_map do |name, str|
    result = [:CODE, str, source_offset] if name == :CODE || name == :PLAIN
    result = [:TEXT, str, source_offset] if name == :TEXT
    source_offset += str.bytesize
    result
  end
  with_offset << [:EOS, nil, source_offset]
end

def supports_streaming?
  true
end

def translate_location(spot, _backtrace_location, source)
  compiled = spot[:script_lines]
  highlight = compiled[spot[:first_lineno] - 1]&.byteslice((spot[:first_column] - 1)...spot[:last_column])
  return nil if highlight.blank?
  source_lines = source.lines
  lineno_delta = find_lineno_offset(compiled, source_lines, highlight, spot[:first_lineno])
  tokens = ::ERB::Util.tokenize(source_lines[spot[:first_lineno] - lineno_delta - 1])
  column_delta = find_offset(spot[:snippet], tokens, spot[:first_column])
  spot[:first_lineno] -= lineno_delta
  spot[:last_lineno] -= lineno_delta
  spot[:first_column] -= column_delta
  spot[:last_column] -= column_delta
  spot[:script_lines] = source_lines
  spot
rescue NotImplementedError, LocationParsingError
  nil
end

def valid_encoding(string, encoding)
  # If a magic encoding comment was found, tag the
  # String with this encoding. This is for a case
  # where the original String was assumed to be,
  # for instance, UTF-8, but a magic comment
  # proved otherwise
  string.force_encoding(encoding) if encoding
  # If the String is valid, return the encoding we found
  return string.encoding if string.valid_encoding?
  # Otherwise, raise an exception
  raise WrongEncodingError.new(string, string.encoding)
end