# Redmine - project management software
# Copyright (C) 2006-2016  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.

module Redmine
  module NestedSet
    module ProjectNestedSet
      def self.included(base)
        base.class_eval do
          belongs_to :parent, :class_name => self.name

          before_create :add_to_nested_set
          before_update :move_in_nested_set, :if => lambda {|project| project.parent_id_changed? || project.name_changed?}
          before_destroy :destroy_children
        end
        base.extend ClassMethods
        base.send :include, Redmine::NestedSet::Traversing
      end

      private

      def target_lft
        siblings_rgt = self.class.where(:parent_id => parent_id).where("name < ?", name).maximum(:rgt)
        if siblings_rgt
          siblings_rgt + 1
        elsif parent_id
          parent_lft = self.class.where(:id => parent_id).pluck(:lft).first
          raise "Project id=#{id} with parent_id=#{parent_id}: parent missing or without 'lft' value" unless parent_lft
          parent_lft + 1
        else
          1
        end
      end

      def add_to_nested_set(lock=true)
        lock_nested_set if lock
        self.lft = target_lft
        self.rgt = lft + 1
        self.class.where("lft >= ? OR rgt >= ?", lft, lft).update_all([
          "lft = CASE WHEN lft >= :lft THEN lft + 2 ELSE lft END, " +
          "rgt = CASE WHEN rgt >= :lft THEN rgt + 2 ELSE rgt END",
          {:lft => lft}
        ])
      end

      def move_in_nested_set
        lock_nested_set
        reload_nested_set_values
        a = lft
        b = rgt
        c = target_lft
        unless c == a
          if c > a
            # Moving to the right
            d = c - (b - a + 1)
            scope = self.class.where(["lft BETWEEN :a AND :c - 1 OR rgt BETWEEN :a AND :c - 1", {:a => a, :c => c}])
            scope.update_all([
              "lft = CASE WHEN lft BETWEEN :a AND :b THEN lft + (:d - :a) WHEN lft BETWEEN :b + 1 AND :c - 1 THEN lft - (:b - :a + 1) ELSE lft END, " +
              "rgt = CASE WHEN rgt BETWEEN :a AND :b THEN rgt + (:d - :a) WHEN rgt BETWEEN :b + 1 AND :c - 1 THEN rgt - (:b - :a + 1) ELSE rgt END",
              {:a => a, :b => b, :c => c, :d => d}
            ])
          elsif c < a
            # Moving to the left
            scope = self.class.where("lft BETWEEN :c AND :b OR rgt BETWEEN :c AND :b", {:a => a, :b => b, :c => c})
            scope.update_all([
              "lft = CASE WHEN lft BETWEEN :a AND :b THEN lft - (:a - :c) WHEN lft BETWEEN :c AND :a - 1 THEN lft + (:b - :a + 1) ELSE lft END, " +
              "rgt = CASE WHEN rgt BETWEEN :a AND :b THEN rgt - (:a - :c) WHEN rgt BETWEEN :c AND :a - 1 THEN rgt + (:b - :a + 1) ELSE rgt END",
              {:a => a, :b => b, :c => c, :d => d}
            ])
          end
          reload_nested_set_values
        end
      end

      def destroy_children
        unless @without_nested_set_update
          lock_nested_set
          reload_nested_set_values
        end
        children.each {|c| c.send :destroy_without_nested_set_update}
        unless @without_nested_set_update
          self.class.where("lft > ? OR rgt > ?", lft, lft).update_all([
            "lft = CASE WHEN lft > :lft THEN lft - :shift ELSE lft END, " +
            "rgt = CASE WHEN rgt > :lft THEN rgt - :shift ELSE rgt END",
            {:lft => lft, :shift => rgt - lft + 1}
          ])
        end
      end

      def destroy_without_nested_set_update
        @without_nested_set_update = true
        destroy
      end

      def reload_nested_set_values
        self.lft, self.rgt = Project.where(:id => id).pluck(:lft, :rgt).first
      end

      def save_nested_set_values
        self.class.where(:id => id).update_all(:lft => lft, :rgt => rgt)
      end

      def move_possible?(project)
        new_record? || !is_or_is_ancestor_of?(project)
      end

      def lock_nested_set
        lock = true
        if self.class.connection.adapter_name =~ /sqlserver/i
          lock = "WITH (ROWLOCK HOLDLOCK UPDLOCK)"
        end
        self.class.order(:id).lock(lock).ids
      end

      def nested_set_scope
        self.class.order(:lft)
      end

      def same_nested_set_scope?(project)
        true
      end

      module ClassMethods
        def rebuild_tree!
          transaction do
            reorder(:id).lock.ids
            update_all(:lft => nil, :rgt => nil)
            rebuild_nodes
          end
        end

        private

        def rebuild_nodes(parent_id = nil)
          nodes = Project.where(:parent_id => parent_id).where(:rgt => nil, :lft => nil).reorder(:name)

          nodes.each do |node|
            node.send :add_to_nested_set, false
            node.send :save_nested_set_values
            rebuild_nodes node.id
          end
        end
      end
    end
  end
end
