class SearchUI::Search

def getc
  system 'stty raw -echo'
  c = STDIN.getc
  system 'stty cooked echo'
  case c
  when "\x03"
    false
  when "\e"
    STDIN.getc == ?[ or return nil
    STDIN.getc =~ /\A([AB])\z/ or return nil
    if $1 == ?A
      @selector -= 1
    else
      @selector += 1
    end
    @selector = [ @selector, 0 ].max
    nil
  when ?\r
    true
  when "\x7f"
    @selector = 0
    @answer.chop!
    nil
  when "\v"
    @selector = 0
    @answer.clear
    nil
  when /\A[\x00-\x1f]\z/
    nil
  else
    @selector = 0
    @answer << c
    nil
  end
end

def initialize(
  match:,
  query:,
  found:,
  output: STDOUT,
  prompt: 'Search? %s'
)
  @match        = match
  @query        = query
  @found        = found
  @output       = output
  @prompt       = prompt
  @selector     = 0
  @max_selector = nil
  @answer       = ''
end

def start
  @output.print reset
  @matches = @match.(@answer)
  @selector = [ 0, [ @selector, @matches.size - 1 ].min ].max
  result = @query.(@answer, @matches, @selector)
  @output.print clear_screen
  @output.print move_home { ?\n + result }
  loop do
    @output.print move_home { @prompt % @answer }
    case getc
    when true
      @output.print clear_screen, move_home, reset
      if result = @found.(@answer, @matches, @selector)
        return result
      else
        return nil
      end
    when false
      return nil
    end
    @matches = @match.(@answer)
    @selector = [ 0, [ @selector, @matches.size - 1 ].min ].max
    result = @query.(@answer, @matches, @selector)
    @output.print clear_screen
    @output.print move_home { ?\n + result }
  end
end