rails/rails

# frozen_string_literal: true

require "active_record/associations/join_dependency/join_part"
require "active_support/core_ext/array/extract"

module ActiveRecord
  module Associations
    class JoinDependency # :nodoc:
      class JoinAssociation < JoinPart # :nodoc:
        attr_reader :reflection, :tables
        attr_accessor :table

        def initialize(reflection, children)
          super(reflection.klass, children)

          @reflection = reflection
        end

        def match?(other)
          return true if self == other
          super && reflection == other.reflection
        end

        def join_constraints(foreign_table, foreign_klass, join_type, alias_tracker)
          joins = []
          chain = []

          reflection.chain.each do |reflection|
            table, terminated = yield reflection
            @table ||= table

            if terminated
              foreign_table, foreign_klass = table, reflection.klass
              break
            end

            chain << [reflection, table]
          end

          base_klass.with_connection do |connection|
            # The chain starts with the target table, but we want to end with it here (makes
            # more sense in this context), so we reverse
            chain.reverse_each do |reflection, table|
              klass = reflection.klass

              scope = reflection.join_scope(table, foreign_table, foreign_klass)

              unless scope.references_values.empty?
                associations = scope.eager_load_values | scope.includes_values

                unless associations.empty?
                  scope.joins! scope.construct_join_dependency(associations, Arel::Nodes::OuterJoin)
                end
              end

              arel = scope.arel(alias_tracker.aliases)
              nodes = arel.constraints.first

              if nodes.is_a?(Arel::Nodes::And)
                others = nodes.children.extract! do |node|
                  !Arel.fetch_attribute(node) { |attr| attr.relation.name == table.name }
                end
              end

              joins << join_type.new(table, Arel::Nodes::On.new(nodes))

              if others && !others.empty?
                joins.concat arel.join_sources
                append_constraints(connection, joins.last, others)
              end

              # The current table in this iteration becomes the foreign table in the next
              foreign_table, foreign_klass = table, klass
            end
          end

          joins
        end

        def readonly?
          return @readonly if defined?(@readonly)

          @readonly = reflection.scope && reflection.scope_for(base_klass.unscoped).readonly_value
        end

        def strict_loading?
          return @strict_loading if defined?(@strict_loading)

          @strict_loading = reflection.scope && reflection.scope_for(base_klass.unscoped).strict_loading_value
        end

        private
          def append_constraints(connection, join, constraints)
            if join.is_a?(Arel::Nodes::StringJoin)
              join_string = Arel::Nodes::And.new(constraints.unshift join.left)
              join.left = Arel.sql(connection.visitor.compile(join_string))
            else
              right = join.right
              right.expr = Arel::Nodes::And.new(constraints.unshift right.expr)
            end
          end
      end
    end
  end
end