module Middleman::PreviewServer

def mount_instance(app)
  @app = app
  @webrick ||= setup_webrick(@options[:debug] || false)
  start_file_watcher
  rack_app = app.class.to_rack_app
  @webrick.mount '/', ::Rack::Handler::WEBrick, rack_app
end

def needs_to_reload?(paths)
  relative_paths = paths.map do |p|
    Pathname(p).relative_path_from(Pathname(app.root)).to_s
  end
  match_against = [
    %r{^config\.rb$},
    %r{^lib/[^\.](.*)\.rb$},
    %r{^helpers/[^\.](.*)\.rb$}
  ]
  if @options[:reload_paths]
    @options[:reload_paths].split(',').each do |part|
      match_against << %r{^#{part}}
    end
  end
  relative_paths.any? do |path|
    match_against.any? do |matcher|
      path =~ matcher
    end
  end
end

def new_app
  opts = @options.dup
  server = ::Middleman::Application.server
  # Add in the meta pages application
  meta_app = Middleman::MetaPages::Application.new(server)
  server.map '/__middleman' do
    run meta_app
  end
  @app = server.inst do
    ::Middleman::Logger.singleton(
      opts[:debug] ? 0 : 1,
      opts[:instrumenting] || false
    )
    config[:environment] = opts[:environment].to_sym if opts[:environment]
  end
end

def register_signal_handlers
  %w(INT HUP TERM QUIT).each do |sig|
    next unless Signal.list[sig]
    Signal.trap(sig) do
      # Do as little work as possible in the signal context
      $mm_shutdown = true
      @webrick.stop
    end
  end
end

def reload
  logger.info '== The Middleman is reloading'
  begin
    app = new_app
  rescue => e
    logger.error "Error reloading Middleman: #{e}\n#{e.backtrace.join("\n")}"
    logger.info '== The Middleman is still running the application from before the error'
    return
  end
  unmount_instance
  mount_instance(app)
  logger.info '== The Middleman has reloaded'
end

def setup_webrick(is_logging)
  http_opts = {
    BindAddress: host,
    Port: port,
    AccessLog: [],
    DoNotReverseLookup: true
  }
  if is_logging
    http_opts[:Logger] = FilteredWebrickLog.new
  else
    http_opts[:Logger] = ::WEBrick::Log.new(nil, 0)
  end
  begin
    ::WEBrick::HTTPServer.new(http_opts)
  rescue Errno::EADDRINUSE
    logger.error "== Port #{port} is unavailable. Either close the instance of Middleman already running on #{port} or start this Middleman on a new port with: --port=#{port.to_i + 1}"
    exit(1)
  end
end

def shutdown
  stop
  @webrick.shutdown
end

def start(opts={})
  @options = opts
  @host = @options[:host] || '0.0.0.0'
  @port = @options[:port] || DEFAULT_PORT
  mount_instance(new_app)
  logger.info "== The Middleman is standing watch at http://#{host}:#{port}"
  logger.info "== Inspect your site configuration at http://#{host}:#{port}/__middleman/"
  @initialized ||= false
  return if @initialized
  @initialized = true
  register_signal_handlers
  # Save the last-used @options so it may be re-used when
  # reloading later on.
  ::Middleman::Profiling.report('server_start')
  loop do
    @webrick.start
    # $mm_shutdown is set by the signal handler
    if $mm_shutdown
      shutdown
      exit
    elsif $mm_reload
      $mm_reload = false
      reload
    end
  end
end

def start_file_watcher
  return if @listener || @options[:disable_watcher]
  # Watcher Library
  require 'listen'
  options = { force_polling: @options[:force_polling] }
  options[:latency] = @options[:latency] if @options[:latency]
  @listener = Listen.to(Dir.pwd, options) do |modified, added, removed|
    added_and_modified = (modified + added)
    # See if the changed file is config.rb or lib/*.rb
    if needs_to_reload?(added_and_modified + removed)
      $mm_reload = true
      @webrick.stop
    else
      added_and_modified.each do |path|
        relative_path = Pathname(path).relative_path_from(Pathname(Dir.pwd)).to_s
        next if app.files.ignored?(relative_path)
        app.files.did_change(relative_path)
      end
      removed.each do |path|
        relative_path = Pathname(path).relative_path_from(Pathname(Dir.pwd)).to_s
        next if app.files.ignored?(relative_path)
        app.files.did_delete(relative_path)
      end
    end
  end
  # Don't block this thread
  @listener.start
end

def stop
  begin
    logger.info '== The Middleman is shutting down'
  rescue
    # if the user closed their terminal STDOUT/STDERR won't exist
  end
  if @listener
    @listener.stop
    @listener = nil
  end
  unmount_instance
end

def unmount_instance
  @webrick.unmount '/'
  @app = nil
end