class RBS::Location

def self.to_string(location, default: "*:*:*...*:*")
  location&.to_s || default
end

def +(other)
  if other
    raise "Invalid concat: buffer=#{buffer.name}, other.buffer=#{other.buffer.name}" unless other.buffer == buffer
    self.class.new(buffer: buffer,
                   start_pos: start_pos,
                   end_pos: other.end_pos)
  else
    self
  end
end

def <<(other)
  if other
    raise "Invalid concat: buffer=#{buffer.name}, other.buffer=#{other.buffer.name}" unless other.buffer == buffer
    @end_pos = other.end_pos
    @source = nil
    @end_loc = nil
  end
  self
end

def ==(other)
  other.is_a?(Location) &&
    other.buffer == buffer &&
    other.start_pos == start_pos &&
    other.end_pos == end_pos
end

def concat(*others)
  others.each { |other| self << other }
  self
end

def end_column
  end_loc[1]
end

def end_line
  end_loc[0]
end

def end_loc
  @end_loc ||= buffer.pos_to_loc(end_pos)
end

def initialize(buffer:, start_pos:, end_pos:)
  @buffer = buffer
  @start_pos = start_pos
  @end_pos = end_pos
end

def inspect
  "#<#{self.class}:#{self.__id__} @buffer=#{buffer.name}, @pos=#{start_pos}...#{end_pos}, source='#{source.lines.first}', start_line=#{start_line}, start_column=#{start_column}>"
end

def name
  buffer.name
end

def pred?(loc)
  loc.is_a?(Location) &&
    loc.name == name &&
    loc.start_pos == end_pos
end

def source
  @source ||= buffer.content[start_pos...end_pos] or raise
end

def start_column
  start_loc[1]
end

def start_line
  start_loc[0]
end

def start_loc
  @start_loc ||= buffer.pos_to_loc(start_pos)
end

def to_json(*args)
  {
    start: {
      line: start_line,
      column: start_column
    },
    end: {
      line: end_line,
      column: end_column
    },
    buffer: {
      name: name&.to_s
    }
  }.to_json(*args)
end

def to_s
  "#{name || "-"}:#{start_line}:#{start_column}...#{end_line}:#{end_column}"
end