#-- encoding: UTF-8
#-- copyright
# OpenProject is a project management system.
# Copyright (C) 2012-2015 the OpenProject Foundation (OPF)
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License version 3.
#
# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
# Copyright (C) 2006-2013 Jean-Philippe Lang
# Copyright (C) 2010-2013 the ChiliProject Team
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# See doc/COPYRIGHT.rdoc for more details.
#++

require 'digest/md5'

class Attachment < ActiveRecord::Base
  ALLOWED_IMAGE_TYPES = %w[ image/gif image/jpeg image/png image/tiff image/bmp ]

  belongs_to :container, polymorphic: true

  belongs_to :author, class_name: 'User', foreign_key: 'author_id'

  attr_protected :author_id

  validates_presence_of :container, :filename, :author, :content_type
  validates_length_of :filename, maximum: 255
  validates_length_of :description, maximum: 255
  validates_length_of :disk_filename, maximum: 255

  validate :filesize_below_allowed_maximum

  after_initialize :set_default_content_type

  before_save :copy_file_to_destination
  after_destroy :delete_file_on_disk

  acts_as_journalized
  acts_as_event title: :filename,
                url: (Proc.new do |o|
                        { controller: '/attachments', action: 'download', id: o.id, filename: o.filename }
                      end)

  cattr_accessor :storage_path
  @@storage_path = OpenProject::Configuration['attachments_storage_path'] ||
                   Rails.root.join('files').to_s

  def filesize_below_allowed_maximum
    if filesize > Setting.attachment_max_size.to_i.kilobytes
      errors.add(:base, :too_long, count: Setting.attachment_max_size.to_i.kilobytes)
    end
  end

  def file=(incoming_file)
    unless incoming_file.nil?
      @temp_file = incoming_file
      if @temp_file.size > 0
        # Incoming_file might be a String if you parse an incoming mail having an attachment
        # It is a Mail::Part.decoded String then, which doesn't have the usual file methods.
        if @temp_file.respond_to?(:original_filename)
          self.filename = @temp_file.original_filename
          filename.force_encoding('UTF-8') if filename.respond_to?(:force_encoding)
        end
        self.filesize = @temp_file.size
      end
    end
  end

  def filename=(arg)
    write_attribute :filename, sanitize_filename(arg.to_s)
    if new_record? && disk_filename.blank?
      self.disk_filename = Attachment.disk_filename(filename)
    end
    filename
  end

  def file
    nil
  end

  # Copies the temporary file to its final location
  # and computes its MD5 hash
  def copy_file_to_destination
    if @temp_file && (@temp_file.size > 0)
      logger.info("Saving attachment '#{diskfile}' (#{@temp_file.size} bytes)")
      md5 = Digest::MD5.new
      File.open(diskfile, 'wb') do |f|
        # @temp_file might be a String if you parse an incoming mail having an attachment
        # It is a Mail::Part.decoded String then, which doesn't have the usual file methods.
        if @temp_file.is_a? String
          f.write(@temp_file)
          md5.update(@temp_file)
        else
          buffer = ''
          while (buffer = @temp_file.read(8192))
            f.write(buffer)
            md5.update(buffer)
          end
        end
      end
      self.digest = md5.hexdigest
      self.content_type = self.class.content_type_for(diskfile)
    end
  end

  # Deletes file on the disk
  def delete_file_on_disk
    File.delete(diskfile) if filename.present? && File.exist?(diskfile)
  end

  # Returns file's location on disk
  def diskfile
    "#{@@storage_path}/#{disk_filename}"
  end

  def increment_download
    increment!(:downloads)
  end

  def project
    # not every container has a project (example: LandingPage)
    container.respond_to?(:project) ? container.project : nil
  end

  def content_disposition
    inlineable? ? 'inline' : 'attachment'
  end

  def visible?(user = User.current)
    container.attachments_visible?(user)
  end

  def deletable?(user = User.current)
    container.attachments_deletable?(user)
  end

  # images are sent inline
  def inlineable?
    is_image?
  end

  def is_image?
    ALLOWED_IMAGE_TYPES.include?(content_type)
  end

  # backwards compatibility for plugins
  alias :image? :is_image?

  def is_pdf?
    content_type == 'application/pdf'
  end

  def is_text?
    content_type =~ /\Atext\/.+/
  end

  def is_diff?
    is_text? && filename =~ /\.(patch|diff)\z/i
  end

  # Returns true if the file is readable
  def readable?
    File.readable?(diskfile)
  end

  def set_default_content_type
    self.content_type = OpenProject::ContentTypeDetector::SENSIBLE_DEFAULT if content_type.blank?
  end

  # Bulk attaches a set of files to an object
  #
  # Returns a Hash of the results:
  # :files => array of the attached files
  # :unsaved => array of the files that could not be attached
  def self.attach_files(obj, attachments)
    attached = []
    if attachments && attachments.is_a?(Hash)
      attachments.each_value do |attachment|
        file = attachment['file']
        next unless file && file.size > 0
        a = Attachment.create(container: obj,
                              file: file,
                              description: attachment['description'].to_s.strip,
                              author: User.current)

        if a.new_record?
          obj.unsaved_attachments ||= []
          obj.unsaved_attachments << a
        else
          attached << a
        end
      end
    end
    { files: attached, unsaved: obj.unsaved_attachments }
  end

  def self.content_type_for(file_path)
    Redmine::MimeType.narrow_type(file_path, OpenProject::ContentTypeDetector.new(file_path).detect)
  end

  private

  def sanitize_filename(value)
    # get only the filename, not the whole path
    just_filename = value.gsub(/\A.*(\\|\/)/, '')
    # NOTE: File.basename doesn't work right with Windows paths on Unix
    # INCORRECT: just_filename = File.basename(value.gsub('\\\\', '/'))

    # Finally, replace all non alphanumeric, hyphens or periods with underscore
    @filename = just_filename.gsub(/[^\w\.\-]/, '_')
  end

  # Returns an ASCII or hashed filename
  def self.disk_filename(filename)
    timestamp = DateTime.now.strftime('%y%m%d%H%M%S')
    ascii = ''
    if filename =~ %r{\A[a-zA-Z0-9_\.\-]*\z}
      ascii = filename
    else
      ascii = Digest::MD5.hexdigest(filename)
      # keep the extension if any
      ascii << $1 if filename =~ %r{(\.[a-zA-Z0-9]+)\z}
    end
    while File.exist?(File.join(@@storage_path, "#{timestamp}_#{ascii}"))
      timestamp.succ!
    end
    "#{timestamp}_#{ascii}"
  end
end