# frozen_string_literal: true

class ReMigrateRedisSlotKeys < Gitlab::Database::Migration[2.1]
  disable_ddl_transaction!

  restrict_gitlab_migration gitlab_schema: :gitlab_main

  KEY_EXPIRY_LENGTH = 6.weeks

  DAILY_EVENTS =
    %w[g_edit_by_web_ide
      g_edit_by_sfe
      g_edit_by_snippet_ide
      g_edit_by_live_preview
      wiki_action
      design_action
      project_action
      git_write_action
      merge_request_action
      i_source_code_code_intelligence
      g_project_management_issue_title_changed
      g_project_management_issue_description_changed
      g_project_management_issue_assignee_changed
      g_project_management_issue_made_confidential
      g_project_management_issue_made_visible
      g_project_management_issue_created
      g_project_management_issue_closed
      g_project_management_issue_reopened
      g_project_management_issue_label_changed
      g_project_management_issue_milestone_changed
      g_project_management_issue_cross_referenced
      g_project_management_issue_moved
      g_project_management_issue_related
      g_project_management_issue_unrelated
      g_project_management_issue_marked_as_duplicate
      g_project_management_issue_locked
      g_project_management_issue_unlocked
      g_project_management_issue_designs_added
      g_project_management_issue_designs_modified
      g_project_management_issue_designs_removed
      g_project_management_issue_due_date_changed
      g_project_management_issue_design_comments_removed
      g_project_management_issue_time_estimate_changed
      g_project_management_issue_time_spent_changed
      g_project_management_issue_comment_added
      g_project_management_issue_comment_edited
      g_project_management_issue_comment_removed
      g_project_management_issue_cloned
      g_geo_proxied_requests
      approval_project_rule_created
      g_project_management_issue_added_to_epic
      g_project_management_issue_changed_epic
      g_project_management_issue_health_status_changed
      g_project_management_issue_iteration_changed
      g_project_management_issue_removed_from_epic
      g_project_management_issue_weight_changed
      g_geo_proxied_requests
      g_project_management_users_creating_epic_boards
      g_project_management_users_viewing_epic_boards
      g_project_management_users_updating_epic_board_names
      g_project_management_epic_created
      project_management_users_unchecking_epic_task
      project_management_users_checking_epic_task
      g_project_management_users_updating_epic_titles
      g_project_management_users_updating_epic_descriptions
      g_project_management_users_creating_epic_notes
      g_project_management_users_updating_epic_notes
      g_project_management_users_destroying_epic_notes
      g_project_management_users_awarding_epic_emoji
      g_project_management_users_removing_epic_emoji
      g_project_management_users_setting_epic_start_date_as_fixed
      g_project_management_users_updating_fixed_epic_start_date
      g_project_management_users_setting_epic_start_date_as_inherited
      g_project_management_users_setting_epic_due_date_as_fixed
      g_project_management_users_updating_fixed_epic_due_date
      g_project_management_users_setting_epic_due_date_as_inherited
      g_project_management_epic_issue_added
      g_project_management_epic_issue_removed
      g_project_management_epic_issue_moved_from_project
      g_project_management_users_updating_epic_parent
      g_project_management_epic_closed
      g_project_management_epic_reopened
      g_project_management_issue_promoted_to_epic
      g_project_management_users_setting_epic_confidential
      g_project_management_users_setting_epic_visible
      g_project_management_epic_users_changing_labels
      g_project_management_epic_destroyed
      g_project_management_epic_cross_referenced
      g_project_management_users_epic_issue_added_from_epic
      g_project_management_epic_related_added
      g_project_management_epic_related_removed
      g_project_management_epic_blocking_added
      g_project_management_epic_blocking_removed
      g_project_management_epic_blocked_added
      g_project_management_epic_blocked_removed].freeze

  def up
    Gitlab::UsageDataCounters::HLLRedisCounter.known_events.each do |event|
      if DAILY_EVENTS.include?(event[:name].to_s)
        migrate_daily_aggregated(event)
      else
        migrate_weekly_aggregated(event)
      end
    end
  end

  def down
    # no-op
  end

  private

  def migrate_daily_aggregated(event)
    days_back = 29.days
    start_date = Date.today - days_back - 1.day
    end_date = Date.today + 1.day

    (start_date..end_date).each do |date|
      rename_key(event, date)
    end
  end

  def migrate_weekly_aggregated(event)
    weeks_back = KEY_EXPIRY_LENGTH
    start_date = (Date.today - weeks_back).beginning_of_week - 1.day
    end_date = Date.today.end_of_week + 1.day

    (start_date..end_date).step(7).each { |date| rename_key(event, date) }
  end

  def rename_key(event, date)
    old_key = old_redis_key(event, date)
    new_key = new_redis_key(event, date)

    # cannot simply rename due to different slots
    Gitlab::Redis::SharedState.with do |redis|
      hll_blob = redis.get(old_key)

      break unless hll_blob

      temp_key = new_key + "_#{Time.current.to_i}"
      ttl = redis.ttl(old_key)
      ttl = ttl > 0 ? ttl : KEY_EXPIRY_LENGTH

      redis.multi do |multi|
        multi.set(temp_key, hll_blob, ex: 1.day.to_i)
        multi.pfmerge(new_key, new_key, temp_key)
        multi.expire(new_key, ttl)
      end

      redis.del(temp_key)
    end
  end

  def old_redis_key(event, time)
    name_with_slot = if event[:redis_slot].present?
                       event[:name].to_s.gsub(event[:redis_slot], "{#{event[:redis_slot]}}")
                     else
                       "{#{event[:name]}}"
                     end

    apply_time_aggregation(name_with_slot, time, event)
  end

  def new_redis_key(event, time)
    key = "{hll_counters}_#{event[:name]}"
    apply_time_aggregation(key, time, event)
  end

  def apply_time_aggregation(key, time, event)
    if DAILY_EVENTS.include?(event[:name].to_s)
      year_day = time.strftime('%G-%j')
      "#{year_day}-#{key}"
    else
      year_week = time.strftime('%G-%V')
      "#{key}-#{year_week}"
    end
  end
end