btrc-hub/backend/db/migrate/20261102010000_backfill_events_from_existing_versions.rb

class BackfillEventsFromExistingVersions < ActiveRecord::Migration[8.0]
  class MigrationEvent < ActiveRecord::Base
    self.table_name = 'events'
  end

  class MigrationPostVersion < ActiveRecord::Base
    self.table_name = 'post_versions'
  end

  class MigrationTagVersion < ActiveRecord::Base
    self.table_name = 'tag_versions'
  end

  class MigrationMaterialVersion < ActiveRecord::Base
    self.table_name = 'material_versions'
  end

  class MigrationTagDescriptionVersion < ActiveRecord::Base
    self.table_name = 'tag_description_versions'
  end

  class MigrationTagGroupVersion < ActiveRecord::Base
    self.table_name = 'tag_group_versions'
  end

  class MigrationLocale < ActiveRecord::Base
    self.table_name = 'locales'
  end

  def up
    # create → posts.create
    # update → posts.update
    raise if MigrationPostVersion.where.not(event_type: ['create', 'update']).exists?

    # create → materials.create
    # update → materials.update
    if MigrationMaterialVersion.where.not(event_type: ['create', 'update']).exists?
      raise
    end

    # create → posts.create / posts.update / materials.create / materials.update / unknown
    # update → tags.update / locales.create
    # discard → unknown
    if MigrationTagVersion.where.not(event_type: ['create', 'update', 'discard']).exists?
      raise
    end

    # create → tag_descriptions.create
    # update → tag_descriptions.update
    if MigrationTagDescriptionVersion.where.not(event_type: ['create', 'update']).exists?
      raise
    end

    # create → tag_groups.create
    # update → tag_groups.update
    if MigrationTagGroupVersion.where.not(event_type: ['create', 'update']).exists?
      raise
    end

    # post_versions の Backfill
    MigrationPostVersion.find_each do |pv|
      ev = MigrationEvent.create!(event_type: "posts.#{ pv.event_type }",
                                  reason: nil,
                                  reverted_from_event_id: nil,
                                  metadata: nil,
                                  ip_address: nil,
                                  created_by_user_id: pv.created_by_user_id,
                                  created_at: pv.created_at)
      pv.update_columns(event_id: ev.id)
    end

    # material_versions の Backfill
    MigrationMaterialVersion.find_each do |m|
      ev = MigrationEvent.create!(event_type: "materials.#{ m.event_type }",
                                  reason: nil,
                                  reverted_from_event_id: nil,
                                  metadata: nil,
                                  ip_address: nil,
                                  created_by_user_id: m.created_by_user_id,
                                  created_at: m.created_at)
      m.update_columns(event_id: ev.id)
    end

    # ロカール追加に伴ふ該当語言のタグ名称追加異動のみ分離
    ids_cause_of_locale_creation = []
    MigrationLocale.where('created_at > ?', MigrationLocale.minimum(:created_at)).find_each do |l|
      ev = MigrationEvent.create!(event_type: 'locales.create',
                                  reason: nil,
                                  reverted_from_event_id: nil,
                                  metadata: nil,
                                  ip_address: nil,
                                  created_by_user_id: nil,
                                  created_at: l.created_at)

      MigrationTagVersion
          .where('created_at > ?', l.created_at)
          .where(event_type: 'update', event_id: nil)
          .find_each do |t|
        next unless t.names.key?(l.language_code)

        prev = MigrationTagVersion.find_by(tag_id: t.tag_id, version_no: t.version_no - 1)
        next if prev.nil? || prev.names.key?(l.language_code)

        t.update_columns(event_id: ev.id)

        ids_cause_of_locale_creation << t.id
      end

      ev.destroy! unless MigrationTagVersion.where(event_id: ev.id).exists?
    end

    # tag_versions の Backfill
    MigrationTagVersion.where.not(id: ids_cause_of_locale_creation).find_each do |t|
      ev =
          case t.event_type
          when 'create'
            post =
                MigrationPostVersion
                .where('JSON_CONTAINS(tags_json, ?) <> 0', { tag_id: t.tag_id }.to_json)
                .find_by(created_at: MigrationPostVersion
                                     .where('JSON_CONTAINS(tags_json, ?) <> 0',
                                            { tag_id: t.tag_id }.to_json)
                                     .minimum(:created_at))
            material =
                MigrationMaterialVersion
                .where(tag_id: t.tag_id)
                .find_by(created_at: MigrationMaterialVersion
                                     .where(tag_id: t.tag_id)
                                     .minimum(:created_at))
            if post
              if material
                if post.created_at < material.created_at
                  MigrationEvent.find(post.event_id)
                else
                  MigrationEvent.find(material.event_id)
                end
              else
                MigrationEvent.find(post.event_id)
              end
            else
              if material
                MigrationEvent.find(material.event_id)
              else
                MigrationEvent.create!(event_type: 'unknown',
                                       reason: nil,
                                       reverted_from_event_id: nil,
                                       metadata: nil,
                                       ip_address: nil,
                                       created_by_user_id: t.created_by_user_id,
                                       created_at: t.created_at)
              end
            end
          when 'update'
            MigrationEvent.create!(event_type: 'tags.update',
                                   reason: nil,
                                   reverted_from_event_id: nil,
                                   metadata: nil,
                                   ip_address: nil,
                                   created_by_user_id: t.created_by_user_id,
                                   created_at: t.created_at)
          when 'discard'
            MigrationEvent.create!(event_type: 'unknown',
                                   reason: nil,
                                   reverted_from_event_id: nil,
                                   metadata: nil,
                                   ip_address: nil,
                                   created_by_user_id: t.created_by_user_id,
                                   created_at: t.created_at)
          end
      t.update_columns(event_id: ev.id)
    end

    # tag_description_versions の Backfill
    MigrationTagDescriptionVersion.find_each do |td|
      ev = MigrationEvent.create!(event_type: "tag_descriptions.#{ td.event_type }",
                                  reason: nil,
                                  reverted_from_event_id: nil,
                                  metadata: nil,
                                  ip_address: nil,
                                  created_by_user_id: td.created_by_user_id,
                                  created_at: td.created_at)
      td.update_columns(event_id: ev.id)
    end

    # tag_group_versions の Backfill
    MigrationTagGroupVersion.find_each do |tg|
      ev = MigrationEvent.create!(event_type: "tag_groups.#{ tg.event_type }",
                                  reason: nil,
                                  reverted_from_event_id: nil,
                                  metadata: nil,
                                  ip_address: nil,
                                  created_by_user_id: tg.created_by_user_id,
                                  created_at: tg.created_at)
      tg.update_columns(event_id: ev.id)
    end

    change_column_null :post_versions, :event_id, false
    change_column_null :tag_versions, :event_id, false
    change_column_null :material_versions, :event_id, false
    change_column_null :tag_description_versions, :event_id, false
    change_column_null :tag_group_versions, :event_id, false
  end

  def down
    raise ActiveRecord::IrreversibleMigration, '戻せません．'
  end
end