module Polyamorous::JoinDependencyExtensions

def build(associations, base_klass)
  associations.map do |name, right|
    if name.is_a? Join
      reflection = find_reflection base_klass, name.name
      reflection.check_validity!
      reflection.check_eager_loadable!
      klass = if reflection.polymorphic?
                name.klass || base_klass
              else
                reflection.klass
              end
      JoinAssociation.new(reflection, build(right, klass), name.klass, name.type)
    else
      reflection = find_reflection base_klass, name
      reflection.check_validity!
      reflection.check_eager_loadable!
      if reflection.polymorphic?
        raise ActiveRecord::EagerLoadPolymorphicError.new(reflection)
      end
      JoinAssociation.new reflection, build(right, reflection.klass)
    end
  end
end

def build(associations, base_klass)
  associations.map do |name, right|
    if name.is_a? Join
      reflection = find_reflection base_klass, name.name
      reflection.check_validity!
      reflection.check_eager_loadable!
      klass = if reflection.polymorphic?
        name.klass || base_klass
      else
        reflection.klass
      end
      JoinAssociation.new(reflection, build(right, klass), alias_tracker, name.klass, name.type)
    else
      reflection = find_reflection base_klass, name
      reflection.check_validity!
      reflection.check_eager_loadable!
      if reflection.polymorphic?
        raise ActiveRecord::EagerLoadPolymorphicError.new(reflection)
      end
      JoinAssociation.new(reflection, build(right, reflection.klass), alias_tracker)
    end
  end
end

def build(associations, base_klass)
  associations.map do |name, right|
    if name.is_a? Join
      reflection = find_reflection base_klass, name.name
      reflection.check_validity!
      reflection.check_eager_loadable!
      klass = if reflection.polymorphic?
        name.klass || base_klass
      else
        reflection.klass
      end
      JoinAssociation.new(reflection, build(right, klass), name.klass, name.type)
    else
      reflection = find_reflection base_klass, name
      reflection.check_validity!
      reflection.check_eager_loadable!
      if reflection.polymorphic?
        raise ActiveRecord::EagerLoadPolymorphicError.new(reflection)
      end
      JoinAssociation.new(reflection, build(right, reflection.klass))
    end
  end
end

def join_constraints(outer_joins, join_type)
  joins = join_root.children.flat_map { |child|
    if join_type == Arel::Nodes::OuterJoin
      make_polyamorous_left_outer_joins join_root, child
    else
      make_polyamorous_inner_joins join_root, child
    end
  }
  joins.concat outer_joins.flat_map { |oj|
    if join_root.match? oj.join_root
      walk(join_root, oj.join_root)
    else
      oj.join_root.children.flat_map { |child|
        make_outer_joins(oj.join_root, child)
      }
    end
  }
end

def join_constraints(outer_joins, join_type)
  @alias_tracker = alias_tracker
  joins = join_root.children.flat_map { |child|
    if join_type == Arel::Nodes::OuterJoin
      make_polyamorous_left_outer_joins join_root, child
    else
      make_polyamorous_inner_joins join_root, child
    end
  }
  joins.concat outer_joins.flat_map { |oj|
    if join_root.match? oj.join_root
      walk(join_root, oj.join_root)
    else
      oj.join_root.children.flat_map { |child|
        make_outer_joins(oj.join_root, child)
      }
    end
  }
end

def make_polyamorous_inner_joins(parent, child)
  tables    = child.tables
  join_type = child.join_type || Arel::Nodes::InnerJoin
  info      = make_constraints parent, child, tables, join_type
  [info] + child.children.flat_map { |c|
    make_polyamorous_inner_joins(child, c)
  }
end

def make_polyamorous_inner_joins(parent, child)
  tables    = child.tables
  join_type = child.join_type || Arel::Nodes::InnerJoin
  info      = make_constraints parent, child, tables, join_type
  info + child.children.flat_map { |c|
    make_polyamorous_inner_joins(child, c)
  }
end

def make_polyamorous_left_outer_joins(parent, child)
  tables    = child.tables
  join_type = Arel::Nodes::OuterJoin
  info      = make_constraints parent, child, tables, join_type
  [info] + child.children.flat_map { |c|
    make_polyamorous_left_outer_joins(child, c)
  }
end

def make_polyamorous_left_outer_joins(parent, child)
  tables    = child.tables
  join_type = Arel::Nodes::OuterJoin
  info      = make_constraints parent, child, tables, join_type
  info + child.children.flat_map { |c|
    make_polyamorous_left_outer_joins(child, c)
  }
end