# frozen_string_literal: true

module RuboCop
  module Cop
    # Methods that calculate and return Parser::Source::Ranges
    module RangeHelp
      private

      BYTE_ORDER_MARK = 0xfeff # The Unicode codepoint

      def source_range(source_buffer, line_number, column, length = 1)
        if column.is_a?(Range)
          column_index = column.begin
          length = column.size
        else
          column_index = column
        end

        line_begin_pos = if line_number.zero?
                           0
                         else
                           source_buffer.line_range(line_number).begin_pos
                         end
        begin_pos = line_begin_pos + column_index
        end_pos = begin_pos + length

        Parser::Source::Range.new(source_buffer, begin_pos, end_pos)
      end

      def range_between(start_pos, end_pos)
        Parser::Source::Range.new(processed_source.buffer, start_pos, end_pos)
      end

      def range_with_surrounding_comma(range, side = :both)
        buffer = @processed_source.buffer
        src = buffer.source

        go_left, go_right = directions(side)

        begin_pos = range.begin_pos
        end_pos = range.end_pos
        begin_pos = move_pos(src, begin_pos, -1, go_left, /,/)
        end_pos = move_pos(src, end_pos, 1, go_right, /,/)

        Parser::Source::Range.new(buffer, begin_pos, end_pos)
      end

      def range_with_surrounding_space(range:, side: :both,
                                       newlines: true, whitespace: false)
        buffer = @processed_source.buffer
        src = buffer.source

        go_left, go_right = directions(side)

        begin_pos = range.begin_pos
        if go_left
          begin_pos =
            final_pos(src, begin_pos, -1, newlines, whitespace)
        end
        end_pos = range.end_pos
        end_pos = final_pos(src, end_pos, 1, newlines, whitespace) if go_right
        Parser::Source::Range.new(buffer, begin_pos, end_pos)
      end

      def range_by_whole_lines(range, include_final_newline: false)
        buffer = @processed_source.buffer

        last_line = buffer.source_line(range.last_line)
        end_offset = last_line.length - range.last_column
        end_offset += 1 if include_final_newline

        range
          .adjust(begin_pos: -range.column, end_pos: end_offset)
          .intersect(buffer.source_range)
      end

      def column_offset_between(base_range, range)
        effective_column(base_range) - effective_column(range)
      end

      ## Helpers for above range methods. Do not use inside Cops.

      # Returns the column attribute of the range, except if the range is on
      # the first line and there's a byte order mark at the beginning of that
      # line, in which case 1 is subtracted from the column value. This gives
      # the column as it appears when viewing the file in an editor.
      def effective_column(range)
        if range.line == 1 &&
           @processed_source.raw_source.codepoints.first == BYTE_ORDER_MARK
          range.column - 1
        else
          range.column
        end
      end

      def directions(side)
        if side == :both
          [true, true]
        else
          [side == :left, side == :right]
        end
      end

      def final_pos(src, pos, increment, newlines, whitespace)
        pos = move_pos(src, pos, increment, true, /[ \t]/)
        pos = move_pos(src, pos, increment, newlines, /\n/)
        move_pos(src, pos, increment, whitespace, /\s/)
      end

      def move_pos(src, pos, step, condition, regexp)
        offset = step == -1 ? -1 : 0
        pos += step while condition && src[pos + offset] =~ regexp
        pos < 0 ? 0 : pos
      end
    end
  end
end