module GraphQL::Language::BlockString

def self.trim_whitespace(str)
  lines = str.split("\n")
  common_indent = nil
  # find the common whitespace
  lines.each_with_index do |line, idx|
    if idx == 0
      next
    end
    line_length = line.size
    line_indent = line[/\A */].size
    if line_indent < line_length && (common_indent.nil? || line_indent < common_indent)
      common_indent = line_indent
    end
  end
  # Remove the common whitespace
  if common_indent
    lines.each_with_index do |line, idx|
      if idx == 0
        next
      else
        line[0, common_indent] = ""
      end
    end
  end
  # Remove leading & trailing blank lines
  while lines.first.empty?
    lines.shift
  end
  while lines.last.empty?
    lines.pop
  end
  # Rebuild the string
  lines.join("\n")
end