Rewrite import feature (#21054)

app/models/bulk_import.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: bulk_imports
+#
+#  id                :bigint(8)        not null, primary key
+#  type              :integer          not null
+#  state             :integer          not null
+#  total_items       :integer          default(0), not null
+#  imported_items    :integer          default(0), not null
+#  processed_items   :integer          default(0), not null
+#  finished_at       :datetime
+#  overwrite         :boolean          default(FALSE), not null
+#  likely_mismatched :boolean          default(FALSE), not null
+#  original_filename :string           default(""), not null
+#  account_id        :bigint(8)        not null
+#  created_at        :datetime         not null
+#  updated_at        :datetime         not null
+#
+class BulkImport < ApplicationRecord
+  self.inheritance_column = false
+
+  belongs_to :account
+  has_many :rows, class_name: 'BulkImportRow', inverse_of: :bulk_import, dependent: :delete_all
+
+  enum type: {
+    following: 0,
+    blocking: 1,
+    muting: 2,
+    domain_blocking: 3,
+    bookmarks: 4,
+  }
+
+  enum state: {
+    unconfirmed: 0,
+    scheduled: 1,
+    in_progress: 2,
+    finished: 3,
+  }
+
+  validates :type, presence: true
+
+  def self.progress!(bulk_import_id, imported: false)
+    # Use `increment_counter` so that the incrementation is done atomically in the database
+    BulkImport.increment_counter(:processed_items, bulk_import_id) # rubocop:disable Rails/SkipsModelValidations
+    BulkImport.increment_counter(:imported_items, bulk_import_id) if imported # rubocop:disable Rails/SkipsModelValidations
+
+    # Since the incrementation has been done atomically, concurrent access to `bulk_import` is now bening
+    bulk_import = BulkImport.find(bulk_import_id)
+    bulk_import.update!(state: :finished, finished_at: Time.now.utc) if bulk_import.processed_items == bulk_import.total_items
+  end
+end

app/models/bulk_import_row.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: bulk_import_rows
+#
+#  id             :bigint(8)        not null, primary key
+#  bulk_import_id :bigint(8)        not null
+#  data           :jsonb
+#  created_at     :datetime         not null
+#  updated_at     :datetime         not null
+#
+class BulkImportRow < ApplicationRecord
+  belongs_to :bulk_import
+end

app/models/concerns/account_associations.rb

@@ -68,5 +68,8 @@ module AccountAssociations
 
     # Account statuses cleanup policy
     has_one :statuses_cleanup_policy, class_name: 'AccountStatusesCleanupPolicy', inverse_of: :account, dependent: :destroy
+
+    # Imports
+    has_many :bulk_imports, inverse_of: :account, dependent: :delete_all
   end
 end

app/models/form/import.rb

@@ -0,0 +1,151 @@
+# frozen_string_literal: true
+
+require 'csv'
+
+# A non-ActiveRecord helper class for CSV uploads.
+# Handles saving contents to database.
+class Form::Import
+  include ActiveModel::Model
+
+  MODES = %i(merge overwrite).freeze
+
+  FILE_SIZE_LIMIT       = 20.megabytes
+  ROWS_PROCESSING_LIMIT = 20_000
+
+  EXPECTED_HEADERS_BY_TYPE = {
+    following: ['Account address', 'Show boosts', 'Notify on new posts', 'Languages'],
+    blocking: ['Account address'],
+    muting: ['Account address', 'Hide notifications'],
+    domain_blocking: ['#domain'],
+    bookmarks: ['#uri'],
+  }.freeze
+
+  KNOWN_FIRST_HEADERS = EXPECTED_HEADERS_BY_TYPE.values.map(&:first).uniq.freeze
+
+  ATTRIBUTE_BY_HEADER = {
+    'Account address' => 'acct',
+    'Show boosts' => 'show_reblogs',
+    'Notify on new posts' => 'notify',
+    'Languages' => 'languages',
+    'Hide notifications' => 'hide_notifications',
+    '#domain' => 'domain',
+    '#uri' => 'uri',
+  }.freeze
+
+  class EmptyFileError < StandardError; end
+
+  attr_accessor :current_account, :data, :type, :overwrite, :bulk_import
+
+  validates :type, presence: true
+  validates :data, presence: true
+  validate :validate_data
+
+  def guessed_type
+    return :muting if csv_data.headers.include?('Hide notifications')
+    return :following if csv_data.headers.include?('Show boosts') || csv_data.headers.include?('Notify on new posts') || csv_data.headers.include?('Languages')
+    return :following if data.original_filename&.start_with?('follows') || data.original_filename&.start_with?('following_accounts')
+    return :blocking if data.original_filename&.start_with?('blocks') || data.original_filename&.start_with?('blocked_accounts')
+    return :muting if data.original_filename&.start_with?('mutes') || data.original_filename&.start_with?('muted_accounts')
+    return :domain_blocking if data.original_filename&.start_with?('domain_blocks') || data.original_filename&.start_with?('blocked_domains')
+    return :bookmarks if data.original_filename&.start_with?('bookmarks')
+  end
+
+  # Whether the uploaded CSV file seems to correspond to a different import type than the one selected
+  def likely_mismatched?
+    guessed_type.present? && guessed_type != type.to_sym
+  end
+
+  def save
+    return false unless valid?
+
+    ApplicationRecord.transaction do
+      now = Time.now.utc
+      @bulk_import = current_account.bulk_imports.create(type: type, overwrite: overwrite || false, state: :unconfirmed, original_filename: data.original_filename, likely_mismatched: likely_mismatched?)
+      nb_items = BulkImportRow.insert_all(parsed_rows.map { |row| { bulk_import_id: bulk_import.id, data: row, created_at: now, updated_at: now } }).length # rubocop:disable Rails/SkipsModelValidations
+      @bulk_import.update(total_items: nb_items)
+    end
+  end
+
+  def mode
+    overwrite ? :overwrite : :merge
+  end
+
+  def mode=(str)
+    self.overwrite = str.to_sym == :overwrite
+  end
+
+  private
+
+  def default_csv_header
+    case type.to_sym
+    when :following, :blocking, :muting
+      'Account address'
+    when :domain_blocking
+      '#domain'
+    when :bookmarks
+      '#uri'
+    end
+  end
+
+  def csv_data
+    return @csv_data if defined?(@csv_data)
+
+    csv_converter = lambda do |field, field_info|
+      case field_info.header
+      when 'Show boosts', 'Notify on new posts', 'Hide notifications'
+        ActiveModel::Type::Boolean.new.cast(field)
+      when 'Languages'
+        field&.split(',')&.map(&:strip)&.presence
+      when 'Account address'
+        field.strip.gsub(/\A@/, '')
+      when '#domain', '#uri'
+        field.strip
+      else
+        field
+      end
+    end
+
+    @csv_data = CSV.open(data.path, encoding: 'UTF-8', skip_blanks: true, headers: true, converters: csv_converter)
+    @csv_data.take(1) # Ensure the headers are read
+    raise EmptyFileError if @csv_data.headers == true
+
+    @csv_data = CSV.open(data.path, encoding: 'UTF-8', skip_blanks: true, headers: [default_csv_header], converters: csv_converter) unless KNOWN_FIRST_HEADERS.include?(@csv_data.headers&.first)
+    @csv_data
+  end
+
+  def csv_row_count
+    return @csv_row_count if defined?(@csv_row_count)
+
+    csv_data.rewind
+    @csv_row_count = csv_data.take(ROWS_PROCESSING_LIMIT + 2).count
+  end
+
+  def parsed_rows
+    csv_data.rewind
+
+    expected_headers = EXPECTED_HEADERS_BY_TYPE[type.to_sym]
+
+    csv_data.take(ROWS_PROCESSING_LIMIT + 1).map do |row|
+      row.to_h.slice(*expected_headers).transform_keys { |key| ATTRIBUTE_BY_HEADER[key] }
+    end
+  end
+
+  def validate_data
+    return if data.nil?
+    return errors.add(:data, I18n.t('imports.errors.too_large')) if data.size > FILE_SIZE_LIMIT
+    return errors.add(:data, I18n.t('imports.errors.incompatible_type')) unless csv_data.headers.include?(default_csv_header)
+
+    errors.add(:data, I18n.t('imports.errors.over_rows_processing_limit', count: ROWS_PROCESSING_LIMIT)) if csv_row_count > ROWS_PROCESSING_LIMIT
+
+    if type.to_sym == :following
+      base_limit = FollowLimitValidator.limit_for_account(current_account)
+      limit = base_limit
+      limit -= current_account.following_count unless overwrite
+      errors.add(:data, I18n.t('users.follow_limit_reached', limit: base_limit)) if csv_row_count > limit
+    end
+  rescue CSV::MalformedCSVError => e
+    errors.add(:data, I18n.t('imports.errors.invalid_csv_file', error: e.message))
+  rescue EmptyFileError
+    errors.add(:data, I18n.t('imports.errors.empty'))
+  end
+end

app/models/import.rb

@@ -17,6 +17,9 @@
 #  overwrite         :boolean          default(FALSE), not null
 #
 
+# NOTE: This is a deprecated model, only kept to not break ongoing imports
+# on upgrade. See `BulkImport` and `Form::Import` for its replacements.
+
 class Import < ApplicationRecord
   FILE_TYPES = %w(text/plain text/csv application/csv).freeze
   MODES = %i(merge overwrite).freeze
@@ -28,7 +31,6 @@ class Import < ApplicationRecord
   enum type: { following: 0, blocking: 1, muting: 2, domain_blocking: 3, bookmarks: 4 }
 
   validates :type, presence: true
-  validates_with ImportValidator, on: :create
 
   has_attached_file :data
   validates_attachment_content_type :data, content_type: FILE_TYPES