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# Redmine - project management software

# Copyright (C) 2006-2014  Jean-Philippe Lang

#

# 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.

class MailHandler < ActionMailer::Base

  include ActionView::Helpers::SanitizeHelper

  include Redmine::I18n

  class UnauthorizedAction < StandardError; end

  class MissingInformation < StandardError; end

  attr_reader :email, :user

  def self.receive(email, options={})

    @@handler_options = options.dup

    @@handler_options[:issue] ||= {}

    if @@handler_options[:allow_override].is_a?(String)

      @@handler_options[:allow_override] = @@handler_options[:allow_override].split(',').collect(&:strip)

    end

    @@handler_options[:allow_override] ||= []

    # Project needs to be overridable if not specified

    @@handler_options[:allow_override] << 'project' unless @@handler_options[:issue].has_key?(:project)

    # Status overridable by default

    @@handler_options[:allow_override] << 'status' unless @@handler_options[:issue].has_key?(:status)

    @@handler_options[:no_account_notice] = (@@handler_options[:no_account_notice].to_s == '1')

    @@handler_options[:no_notification] = (@@handler_options[:no_notification].to_s == '1')

    @@handler_options[:no_permission_check] = (@@handler_options[:no_permission_check].to_s == '1')

    email.force_encoding('ASCII-8BIT') if email.respond_to?(:force_encoding)

    super(email)

  end

  # Extracts MailHandler options from environment variables

  # Use when receiving emails with rake tasks

  def self.extract_options_from_env(env)

    options = {:issue => {}}

    %w(project status tracker category priority).each do |option|

      options[:issue][option.to_sym] = env[option] if env[option]

    end

    %w(allow_override unknown_user no_permission_check no_account_notice default_group).each do |option|

      options[option.to_sym] = env[option] if env[option]

    end

    options

  end

  def logger

    Rails.logger

  end

  cattr_accessor :ignored_emails_headers

  @@ignored_emails_headers = {

    'X-Auto-Response-Suppress' => 'oof',

    'Auto-Submitted' => /^auto-/

  }

  # Processes incoming emails

  # Returns the created object (eg. an issue, a message) or false

  def receive(email)

    @email = email

    sender_email = email.from.to_a.first.to_s.strip

    # Ignore emails received from the application emission address to avoid hell cycles

    if sender_email.downcase == Setting.mail_from.to_s.strip.downcase

      if logger

        logger.info  "MailHandler: ignoring email from Redmine emission address [#{sender_email}]"

      end

      return false

    end

    # Ignore auto generated emails

    self.class.ignored_emails_headers.each do |key, ignored_value|

      value = email.header[key]

      if value

        value = value.to_s.downcase

        if (ignored_value.is_a?(Regexp) && value.match(ignored_value)) || value == ignored_value

          if logger

            logger.info "MailHandler: ignoring email with #{key}:#{value} header"

          end

          return false

        end

      end

    end

    @user = User.find_by_mail(sender_email) if sender_email.present?

    if @user && !@user.active?

      if logger

        logger.info  "MailHandler: ignoring email from non-active user [#{@user.login}]"

      end

      return false

    end

    if @user.nil?

      # Email was submitted by an unknown user

      case @@handler_options[:unknown_user]

      when 'accept'

        @user = User.anonymous

      when 'create'

        @user = create_user_from_email

        if @user

          if logger

            logger.info "MailHandler: [#{@user.login}] account created"

          end

          add_user_to_group(@@handler_options[:default_group])

          unless @@handler_options[:no_account_notice]

            Mailer.account_information(@user, @user.password).deliver

          end

        else

          if logger

            logger.error "MailHandler: could not create account for [#{sender_email}]"

          end

          return false

        end

      else

        # Default behaviour, emails from unknown users are ignored

        if logger

          logger.info  "MailHandler: ignoring email from unknown user [#{sender_email}]"

        end

        return false

      end

    end

    User.current = @user

    dispatch

  end

  private

  MESSAGE_ID_RE = %r{^<?redmine\.([a-z0-9_]+)\-(\d+)\.\d+(\.[a-f0-9]+)?@}

  ISSUE_REPLY_SUBJECT_RE = %r{\[[^\]]*#(\d+)\]}

  MESSAGE_REPLY_SUBJECT_RE = %r{\[[^\]]*msg(\d+)\]}

  def dispatch

    headers = [email.in_reply_to, email.references].flatten.compact

    subject = email.subject.to_s

    if headers.detect {|h| h.to_s =~ MESSAGE_ID_RE}

      klass, object_id = $1, $2.to_i

      method_name = "receive_#{klass}_reply"

      if self.class.private_instance_methods.collect(&:to_s).include?(method_name)

        send method_name, object_id

      else

        # ignoring it

      end

    elsif m = subject.match(ISSUE_REPLY_SUBJECT_RE)

      receive_issue_reply(m[1].to_i)

    elsif m = subject.match(MESSAGE_REPLY_SUBJECT_RE)

      receive_message_reply(m[1].to_i)

    else

      dispatch_to_default

    end

  rescue ActiveRecord::RecordInvalid => e

    # TODO: send a email to the user

    logger.error e.message if logger

    false

  rescue MissingInformation => e

    logger.error "MailHandler: missing information from #{user}: #{e.message}" if logger

    false

  rescue UnauthorizedAction => e

    logger.error "MailHandler: unauthorized attempt from #{user}" if logger

    false

  end

  def dispatch_to_default

    receive_issue

  end

  # Creates a new issue

  def receive_issue

    project = target_project

    # check permission

    unless @@handler_options[:no_permission_check]

      raise UnauthorizedAction unless user.allowed_to?(:add_issues, project)

    end

    issue = Issue.new(:author => user, :project => project)

    issue.safe_attributes = issue_attributes_from_keywords(issue)

    issue.safe_attributes = {'custom_field_values' => custom_field_values_from_keywords(issue)}

    issue.subject = cleaned_up_subject

    if issue.subject.blank?

      issue.subject = '(no subject)'

    end

    issue.description = cleaned_up_text_body

    issue.start_date ||= Date.today if Setting.default_issue_start_date_to_creation_date?

    # add To and Cc as watchers before saving so the watchers can reply to Redmine

    add_watchers(issue)

    issue.save!

    add_attachments(issue)

    logger.info "MailHandler: issue ##{issue.id} created by #{user}" if logger

    issue

  end

  # Adds a note to an existing issue

  def receive_issue_reply(issue_id, from_journal=nil)

    issue = Issue.find_by_id(issue_id)

    return unless issue

    # check permission

    unless @@handler_options[:no_permission_check]

      unless user.allowed_to?(:add_issue_notes, issue.project) ||

               user.allowed_to?(:edit_issues, issue.project)

        raise UnauthorizedAction

      end

    end

    # ignore CLI-supplied defaults for new issues

    @@handler_options[:issue].clear

    journal = issue.init_journal(user)

    if from_journal && from_journal.private_notes?

      # If the received email was a reply to a private note, make the added note private

      issue.private_notes = true

    end

    issue.safe_attributes = issue_attributes_from_keywords(issue)

    issue.safe_attributes = {'custom_field_values' => custom_field_values_from_keywords(issue)}

    journal.notes = cleaned_up_text_body

    add_attachments(issue)

    issue.save!

    if logger

      logger.info "MailHandler: issue ##{issue.id} updated by #{user}"

    end

    journal

  end

  # Reply will be added to the issue

  def receive_journal_reply(journal_id)

    journal = Journal.find_by_id(journal_id)

    if journal && journal.journalized_type == 'Issue'

      receive_issue_reply(journal.journalized_id, journal)

    end

  end

  # Receives a reply to a forum message

  def receive_message_reply(message_id)

    message = Message.find_by_id(message_id)

    if message

      message = message.root

      unless @@handler_options[:no_permission_check]

        raise UnauthorizedAction unless user.allowed_to?(:add_messages, message.project)

      end

      if !message.locked?

        reply = Message.new(:subject => cleaned_up_subject.gsub(%r{^.*msg\d+\]}, '').strip,

                            :content => cleaned_up_text_body)

        reply.author = user

        reply.board = message.board

        message.children << reply

        add_attachments(reply)

        reply

      else

        if logger

          logger.info "MailHandler: ignoring reply from [#{sender_email}] to a locked topic"

        end

      end

    end

  end

  def add_attachments(obj)

    if email.attachments && email.attachments.any?

      email.attachments.each do |attachment|

        next unless accept_attachment?(attachment)

        obj.attachments << Attachment.create(:container => obj,

                          :file => attachment.decoded,

                          :filename => attachment.filename,

                          :author => user,

                          :content_type => attachment.mime_type)

      end

    end

  end

  # Returns false if the +attachment+ of the incoming email should be ignored

  def accept_attachment?(attachment)

    @excluded ||= Setting.mail_handler_excluded_filenames.to_s.split(',').map(&:strip).reject(&:blank?)

    @excluded.each do |pattern|

      regexp = %r{\A#{Regexp.escape(pattern).gsub("\\*", ".*")}\z}i

      if attachment.filename.to_s =~ regexp

        logger.info "MailHandler: ignoring attachment #{attachment.filename} matching #{pattern}"

        return false

      end

    end

    true

  end

  # Adds To and Cc as watchers of the given object if the sender has the

  # appropriate permission

  def add_watchers(obj)

    if user.allowed_to?("add_#{obj.class.name.underscore}_watchers".to_sym, obj.project)

      addresses = [email.to, email.cc].flatten.compact.uniq.collect {|a| a.strip.downcase}

      unless addresses.empty?

        User.active.where('LOWER(mail) IN (?)', addresses).each do |w|

          obj.add_watcher(w)

        end

      end

    end

  end

  def get_keyword(attr, options={})

    @keywords ||= {}

    if @keywords.has_key?(attr)

      @keywords[attr]

    else

      @keywords[attr] = begin

        if (options[:override] || @@handler_options[:allow_override].include?(attr.to_s)) &&

              (v = extract_keyword!(plain_text_body, attr, options[:format]))

          v

        elsif !@@handler_options[:issue][attr].blank?

          @@handler_options[:issue][attr]

        end

      end

    end

  end

  # Destructively extracts the value for +attr+ in +text+

  # Returns nil if no matching keyword found

  def extract_keyword!(text, attr, format=nil)

    keys = [attr.to_s.humanize]

    if attr.is_a?(Symbol)

      if user && user.language.present?

        keys << l("field_#{attr}", :default => '', :locale =>  user.language)

      end

      if Setting.default_language.present?

        keys << l("field_#{attr}", :default => '', :locale =>  Setting.default_language)

      end

    end

    keys.reject! {|k| k.blank?}

    keys.collect! {|k| Regexp.escape(k)}

    format ||= '.+'

    keyword = nil

    regexp = /^(#{keys.join('|')})[ \t]*:[ \t]*(#{format})\s*$/i

    if m = text.match(regexp)

      keyword = m[2].strip

      text.gsub!(regexp, '')

    end

    keyword

  end

  def target_project

    # TODO: other ways to specify project:

    # * parse the email To field

    # * specific project (eg. Setting.mail_handler_target_project)

    target = Project.find_by_identifier(get_keyword(:project))

    if target.nil?

      # Invalid project keyword, use the project specified as the default one

      default_project = @@handler_options[:issue][:project]

      if default_project.present?

        target = Project.find_by_identifier(default_project)

      end

    end

    raise MissingInformation.new('Unable to determine target project') if target.nil?

    target

  end

  # Returns a Hash of issue attributes extracted from keywords in the email body

  def issue_attributes_from_keywords(issue)

    assigned_to = (k = get_keyword(:assigned_to, :override => true)) && find_assignee_from_keyword(k, issue)

    attrs = {

      'tracker_id' => (k = get_keyword(:tracker)) && issue.project.trackers.named(k).first.try(:id),

      'status_id' =>  (k = get_keyword(:status)) && IssueStatus.named(k).first.try(:id),

      'priority_id' => (k = get_keyword(:priority)) && IssuePriority.named(k).first.try(:id),

      'category_id' => (k = get_keyword(:category)) && issue.project.issue_categories.named(k).first.try(:id),

      'assigned_to_id' => assigned_to.try(:id),

      'fixed_version_id' => (k = get_keyword(:fixed_version, :override => true)) &&

                                issue.project.shared_versions.named(k).first.try(:id),

      'start_date' => get_keyword(:start_date, :override => true, :format => '\d{4}-\d{2}-\d{2}'),

      'due_date' => get_keyword(:due_date, :override => true, :format => '\d{4}-\d{2}-\d{2}'),

      'estimated_hours' => get_keyword(:estimated_hours, :override => true),

      'done_ratio' => get_keyword(:done_ratio, :override => true, :format => '(\d|10)?0')

    }.delete_if {|k, v| v.blank? }

    if issue.new_record? && attrs['tracker_id'].nil?

      attrs['tracker_id'] = issue.project.trackers.first.try(:id)

    end

    attrs

  end

  # Returns a Hash of issue custom field values extracted from keywords in the email body

  def custom_field_values_from_keywords(customized)

    customized.custom_field_values.inject({}) do |h, v|

      if keyword = get_keyword(v.custom_field.name, :override => true)

        h[v.custom_field.id.to_s] = v.custom_field.value_from_keyword(keyword, customized)

      end

      h

    end

  end

  # Returns the text/plain part of the email

  # If not found (eg. HTML-only email), returns the body with tags removed

  def plain_text_body

    return @plain_text_body unless @plain_text_body.nil?

    parts = if (text_parts = email.all_parts.select {|p| p.mime_type == 'text/plain'}).present?

              text_parts

            elsif (html_parts = email.all_parts.select {|p| p.mime_type == 'text/html'}).present?

              html_parts

            else

              [email]

            end

    parts.reject! do |part|

      part.header[:content_disposition].try(:disposition_type) == 'attachment'

    end

    @plain_text_body = parts.map do |p|

      body_charset = p.charset.respond_to?(:force_encoding) ?

                       Mail::RubyVer.pick_encoding(p.charset).to_s : p.charset

      Redmine::CodesetUtil.to_utf8(p.body.decoded, body_charset)

    end.join("\r\n")

    # strip html tags and remove doctype directive

    if parts.any? {|p| p.mime_type == 'text/html'}

      @plain_text_body = strip_tags(@plain_text_body.strip)

      @plain_text_body.sub! %r{^<!DOCTYPE .*$}, ''

    end

    @plain_text_body

  end

  def cleaned_up_text_body

    cleanup_body(plain_text_body)

  end

  def cleaned_up_subject

    subject = email.subject.to_s

    subject.strip[0,255]

  end

  def self.full_sanitizer

    @full_sanitizer ||= HTML::FullSanitizer.new

  end

  def self.assign_string_attribute_with_limit(object, attribute, value, limit=nil)

    limit ||= object.class.columns_hash[attribute.to_s].limit || 255

    value = value.to_s.slice(0, limit)

    object.send("#{attribute}=", value)

  end

  # Returns a User from an email address and a full name

  def self.new_user_from_attributes(email_address, fullname=nil)

    user = User.new

    # Truncating the email address would result in an invalid format

    user.mail = email_address

    assign_string_attribute_with_limit(user, 'login', email_address, User::LOGIN_LENGTH_LIMIT)

    names = fullname.blank? ? email_address.gsub(/@.*$/, '').split('.') : fullname.split

    assign_string_attribute_with_limit(user, 'firstname', names.shift, 30)

    assign_string_attribute_with_limit(user, 'lastname', names.join(' '), 30)

    user.lastname = '-' if user.lastname.blank?

    user.language = Setting.default_language

    user.generate_password = true

    user.mail_notification = 'only_my_events'

    unless user.valid?

      user.login = "user#{Redmine::Utils.random_hex(6)}" unless user.errors[:login].blank?

      user.firstname = "-" unless user.errors[:firstname].blank?

      (puts user.errors[:lastname];user.lastname  = "-") unless user.errors[:lastname].blank?

    end

    user

  end

  # Creates a User for the +email+ sender

  # Returns the user or nil if it could not be created

  def create_user_from_email

    from = email.header['from'].to_s

    addr, name = from, nil

    if m = from.match(/^"?(.+?)"?\s+<(.+@.+)>$/)

      addr, name = m[2], m[1]

    end

    if addr.present?

      user = self.class.new_user_from_attributes(addr, name)

      if @@handler_options[:no_notification]

        user.mail_notification = 'none'

      end

      if user.save

        user

      else

        logger.error "MailHandler: failed to create User: #{user.errors.full_messages}" if logger

        nil

      end

    else

      logger.error "MailHandler: failed to create User: no FROM address found" if logger

      nil

    end

  end

  # Adds the newly created user to default group

  def add_user_to_group(default_group)

    if default_group.present?

      default_group.split(',').each do |group_name|

        if group = Group.named(group_name).first

          group.users << @user

        elsif logger

          logger.warn "MailHandler: could not add user to [#{group_name}], group not found"

        end

      end

    end

  end

  # Removes the email body of text after the truncation configurations.

  def cleanup_body(body)

    delimiters = Setting.mail_handler_body_delimiters.to_s.split(/[\r\n]+/).reject(&:blank?).map {|s| Regexp.escape(s)}

    unless delimiters.empty?

      regex = Regexp.new("^[> ]*(#{ delimiters.join('|') })\s*[\r\n].*", Regexp::MULTILINE)

      body = body.gsub(regex, '')

    end

    body.strip

  end

  def find_assignee_from_keyword(keyword, issue)

    keyword = keyword.to_s.downcase

    assignable = issue.assignable_users

    assignee = nil

    assignee ||= assignable.detect {|a|

                   a.mail.to_s.downcase == keyword ||

                     a.login.to_s.downcase == keyword

                 }

    if assignee.nil? && keyword.match(/ /)

      firstname, lastname = *(keyword.split) # "First Last Throwaway"

      assignee ||= assignable.detect {|a|

                     a.is_a?(User) && a.firstname.to_s.downcase == firstname &&

                       a.lastname.to_s.downcase == lastname

                   }

    end

    if assignee.nil?

      assignee ||= assignable.detect {|a| a.name.downcase == keyword}

    end

    assignee

  end

end