# frozen_string_literal: true

# Redmine - project management software
# Copyright (C) 2006-  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.

require_relative '../test_helper'

class IssueNestedSetConcurrencyTest < ActiveSupport::TestCase
  self.use_transactional_tests = false

  def setup
    @connection_pool_mutex = Mutex.new
    skip if sqlite?
    if mysql?
      connection = ActiveRecord::Base.connection_db_config.configuration_hash.deep_dup
      connection[:variables] = mysql8? ? { transaction_isolation: "READ-COMMITTED" } : { tx_isolation: "READ-COMMITTED" }
      ActiveRecord::Base.establish_connection connection
    end
    User.current = nil
    CustomField.destroy_all
  end

  def teardown
    Issue.delete_all
  end

  def test_concurrency
    # Generates an issue and destroys it in order
    # to load all needed classes before starting threads
    i = Issue.generate!
    i.destroy

    root = Issue.generate!
    assert_difference 'Issue.count', 60 do
      threaded(3) do
        10.times do
          i = Issue.generate! :parent_issue_id => root.id
          c1 = Issue.generate! :parent_issue_id => i.id
          c2 = Issue.generate! :parent_issue_id => i.id
          c3 = Issue.generate! :parent_issue_id => i.id
          c2.reload.destroy
          c1.reload.destroy
        end
      end
    end
  end

  def test_concurrent_subtasks_creation
    root = Issue.generate!
    assert_difference 'Issue.count', 30 do
      threaded(3) do
        10.times do
          Issue.generate! :parent_issue_id => root.id
        end
      end
    end
    root.reload
    assert_equal [1, 62], [root.lft, root.rgt]
    children_bounds = root.children.sort_by(&:lft).map {|c| [c.lft, c.rgt]}.flatten
    assert_equal (2..61).to_a, children_bounds
  end

  def test_concurrent_subtask_removal
    with_settings :notified_events => [] do
      root = Issue.generate!
      60.times do
        Issue.generate! :parent_issue_id => root.id
      end
      # pick 40 random subtask ids
      child_ids = Issue.where(root_id: root.id, parent_id: root.id).pluck(:id)
      ids_to_remove = child_ids.sample(40).shuffle
      ids_to_keep = child_ids - ids_to_remove
      # remove these from the set, using four parallel threads
      threads = []
      ids_to_remove.each_slice(10) do |ids|
        threads << Thread.new do
          begin
            with_thread_connection do
              ids.each do |id|
                Issue.find(id).update(parent_id: nil)
              end
            end
          rescue => e
            Thread.current[:exception] = e.message
          end
        end
      end
      threads.each do |thread|
        thread.join
        assert_nil thread[:exception]
      end
      assert_equal 20, Issue.where(parent_id: root.id).count
      Issue.where(id: ids_to_remove).each do |issue|
        assert_nil issue.parent_id
        assert_equal issue.id, issue.root_id
        assert_equal 1, issue.lft
        assert_equal 2, issue.rgt
      end
      root.reload
      assert_equal [1, 42], [root.lft, root.rgt]
      children_bounds = root.children.sort_by(&:lft).map {|c| [c.lft, c.rgt]}.flatten
      assert_equal (2..41).to_a, children_bounds
    end
  end

  private

  def threaded(count, &block)
    with_settings :notified_events => [] do
      threads = []
      count.times do |i|
        threads << Thread.new(i) do
          begin
            with_thread_connection(&block)
          rescue => e
            Thread.current[:exception] = e.message
          end
        end
      end
      threads.each do |thread|
        thread.join
        assert_nil thread[:exception]
      end
    end
  end

  def with_thread_connection(&)
    # Active Record updates its connection lease registry when a thread obtains a
    # connection for the first time, which can race when test threads start
    # together.
    @connection_pool_mutex.synchronize do
      # Initialize this thread's connection lease before concurrent updates.
      ActiveRecord::Base.connection_pool.with_connection { nil }
    end
    ActiveRecord::Base.connection_pool.with_connection(&)
  end
end
