app.rb

require 'rack/contrib'
require 'sinatra'
# require_relative 'lib/middleware/bad_multipart_form_data_sanitizer'
require 'sinatra/config_file'
require 'sinatra/reloader' if development?
require 'json'
require 'logger'
require_relative 'models/chunk'

config_file 'config/config.yml'

use Rack::MailExceptions do |mail|
  mail.subject '[html5-upload] %s'
  mail.from settings.exception_sender
  mail.to settings.exception_receiver
  mail.smtp false
end if settings.exception_receiver

# https://spin.atomicobject.com/2013/11/12/production-logging-sinatra/
# ::Logger.class_eval { alias :write :'<<' }
error_logger = ::File.new(::File.join(::File.dirname(::File.expand_path(__FILE__)), 'log/error.log'), 'a+')
error_logger.sync = true
before {
  env['rack.errors'] = error_logger
}

configure :production do
  disable :logging # https://groups.google.com/g/sinatrarb/c/lwd419mimJA
  enable :dump_errors, :raise_errors
end

before do
  if params[:id].to_i.zero?
    halt(403, 'ERROR: id not set')
  end
  if params[:secret] != Digest::MD5.hexdigest("#{params[:id]}-#{settings.uploader_mask}")
    halt(403, 'ERROR: secret not correct')
  end

  @upload_dir = File.expand_path("#{settings.upload_dir}/#{params[:id].to_i}")
  Dir.mkdir(@upload_dir) unless File.directory?(@upload_dir)
end

helpers do
  def validate_file_extension(file)
    ext = File.extname(file)[1..-1].to_s.downcase
    halt(415, "ext <#{ext}> not allowed") unless settings.accepted_file_types.include?(ext)
  end
end

# displays frontend
get '/' do
  raise StandardError, "ERROR: #{params[:error]}" unless params[:error].nil?

  erb :index
end

# receives file chunks
post '/upload' do
  files = []

  params[:files].each do |file|
    # fix Encoding::UndefinedConversionError - "\xC3" from ASCII-8BIT to UTF-8
    file[:filename].force_encoding('UTF-8')

    validate_file_extension(file[:filename])
    chunk = Chunk.new(@upload_dir, file[:filename])
    files << chunk.upload(file[:tempfile].path, request.env['HTTP_CONTENT_RANGE'])
  end

  if files.any?
    status 201
    { files: files }.to_json
  else
    raise 'should not happen'
  end
end

# returns the file info how much of the file has been uploaded so far
get '/upload' do
  if params[:file]
    chunk = Chunk.new(@upload_dir, params[:file])
    if chunk.file_complete?
      { file: {
        name: chunk.file_name,
        error: "ERROR: The file '#{chunk.file_name}' already exists at the server." }
      }.to_json
    else
      { file: { name: chunk.file_name, size: chunk.file_size } }.to_json
    end
  else
    raise 'should not happen'
  end
end

# returns a list of name and size of all partially uploaded files
get '/list' do
  files = []
  Dir.glob("#{@upload_dir}/*.*").each do |file|
    hash = {
      id: Digest::MD5.hexdigest(File.basename(file, '.part')),
      name: File.basename(file, '.part'),
      size: File.size(file),
    }
    if File.extname(file) == '.part'
      hash[:delete_url] = "/delete?id=#{params[:id]}&secret=#{params[:secret]}&file=#{CGI.escape(File.basename(file))}"
    else
      hash[:complete] = true
    end
    files << hash
  end
  { files: files }.to_json
end

delete '/delete' do
  file = "#{@upload_dir}/#{File.basename(params[:file])}"

  if File.file?(file)
    if File.delete(file)
      {
        files: [
          { params[:file] => true }
        ]
      }.to_json
    else
      raise "should not happen: Error deleting #{file}"
    end
  else
    raise "should not happen: Error finding file #{file}"
  end
end