#-- encoding: UTF-8

#-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2020 the OpenProject GmbH
#
# 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) 2006-2017 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 docs/COPYRIGHT.rdoc for more details.
#++

require 'digest/md5'

class Attachment < ApplicationRecord
  ALLOWED_TEXT_TYPES = %w[text/plain].freeze
  ALLOWED_IMAGE_TYPES = %w[image/gif image/jpeg image/png image/tiff image/bmp].freeze

  belongs_to :container, polymorphic: true
  belongs_to :author, class_name: 'User', foreign_key: 'author_id'

  validates_presence_of :author, :content_type, :filesize
  validates_length_of :description, maximum: 255

  validate :filesize_below_allowed_maximum,
           :container_changed_more_than_once

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

  mount_uploader :file, OpenProject::Configuration.file_uploader

  after_commit :extract_fulltext, on: :create

  after_create :schedule_cleanup_uncontainered_job,
               unless: :containered?

  ##
  # Returns an URL if the attachment is stored in an external (fog) attachment storage
  # or nil otherwise.
  def external_url(expires_in: nil)
    url = URI.parse file.download_url(content_disposition: content_disposition, expires_in: expires_in) # returns a path if local

    url if url.host
  rescue URI::InvalidURIError
    nil
  end

  def external_storage?
    !external_url.nil?
  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
    # Do not use filename with attachment as this may break for Unicode files
    # specifically when using S3 for attachments.
    inlineable? ? "inline" : "attachment"
  end

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

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

  # images are sent inline
  def inlineable?
    is_plain_text? || is_image?
  end

  def is_plain_text?
    ALLOWED_TEXT_TYPES.include?(content_type)
  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?
  end

  def containered?
    container.present?
  end

  ##
  # Retrieve a local file,
  # this may result in downloading the file first
  def diskfile
    file.local_file
  end

  ##
  # Retrieve the local file path,
  # this may result in downloading the file first to a tmpdir
  def local_path
    diskfile.path
  end

  def filename
    attributes['file']
  end

  ##
  # Returns the file extension name,
  # if any (with leading dot)
  def extension
    File.extname filename
  end

  def file=(file)
    super.tap do
      set_file_size file

      set_content_type file

      if File.readable? file.path
        set_digest file
      end
    end
  end

  def set_file_size(file)
    self.filesize = file.size
  end

  def set_content_type(file)
    self.content_type = self.class.content_type_for(file.path) if content_type.blank?
  end

  def set_digest(file)
    self.digest = Digest::MD5.file(file.path).hexdigest
  end

  def self.content_type_for(file_path, fallback = OpenProject::ContentTypeDetector::SENSIBLE_DEFAULT)
    content_type = Redmine::MimeType.narrow_type file_path, OpenProject::ContentTypeDetector.new(file_path).detect
    content_type || fallback
  end

  def copy(&block)
    attachment = dup
    attachment.file = diskfile

    yield attachment if block_given?

    attachment
  end

  def copy!(&block)
    attachment = copy &block

    attachment.save!
  end

  def extract_fulltext
    return unless OpenProject::Database.allows_tsv? && (!container || container.class.attachment_tsv_extracted?)

    ExtractFulltextJob.perform_later(id)
  end

  # Extract the fulltext of any attachments where fulltext is still nil.
  # This runs inline and not in an asynchronous worker.
  def self.extract_fulltext_where_missing(run_now: true)
    return unless OpenProject::Database.allows_tsv?

    Attachment
      .where(fulltext: nil)
      .where(container_type: tsv_extracted_containers)
      .pluck(:id)
      .each do |id|
      if run_now
        ExtractFulltextJob.perform_now(id)
      else
        ExtractFulltextJob.perform_later(id)
      end
    end
  end

  def self.force_extract_fulltext
    return unless OpenProject::Database.allows_tsv?

    Attachment.pluck(:id).each do |id|
      ExtractFulltextJob.perform_now(id)
    end
  end

  def self.tsv_extracted_containers
    Attachment
      .select(:container_type)
      .distinct
      .pluck(:container_type)
      .compact
      .select do |container_class|
      klass = container_class.constantize

      klass.respond_to?(:attachment_tsv_extracted?) && klass.attachment_tsv_extracted?
    rescue NameError
      false
    end
  end

  private

  def schedule_cleanup_uncontainered_job
    Attachments::CleanupUncontaineredJob.perform_later
  end

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

  def container_changed_more_than_once
    if container_id_changed_more_than_once? || container_type_changed_more_than_once?
      errors.add(:container, :unchangeable)
    end
  end

  def container_id_changed_more_than_once?
    container_id_changed? && container_id_was.present? && container_id_was != container_id
  end

  def container_type_changed_more_than_once?
    container_type_changed? && container_type_was.present? && container_type_was != container_type
  end

  def allowed_or_author?(user)
    containered? && !(container.class.attachable_options[:only_user_allowed] && author_id != user.id) && yield ||
      !containered? && author_id == user.id
  end
end