class ActiveRecord::PredicateBuilder

def self.references(attributes)
  attributes.each_with_object([]) do |(key, value), result|
    if value.is_a?(Hash)
      result << Arel.sql(key, retryable: true)
    elsif (idx = key.rindex("."))
      result << Arel.sql(key[0, idx], retryable: true)
    end
  end
end

def [](attr_name, value, operator = nil)
  build(table.arel_table[attr_name], value, operator)
end

def build(attribute, value, operator = nil)
  value = value.id if value.respond_to?(:id)
  if operator ||= table.type(attribute.name).force_equality?(value) && :eq
    bind = build_bind_attribute(attribute.name, value)
    attribute.public_send(operator, bind)
  else
    handler_for(value).call(attribute, value)
  end
end

def build_bind_attribute(column_name, value)
  Relation::QueryAttribute.new(column_name, value, table.type(column_name))
end

def build_from_hash(attributes, &block)
  attributes = convert_dot_notation_to_hash(attributes)
  expand_from_hash(attributes, &block)
end

def convert_dot_notation_to_hash(attributes)
  attributes.each_with_object({}) do |(key, value), converted|
    if value.is_a?(Hash)
      if (existing = converted[key])
        existing.merge!(value)
      else
        converted[key] = value.dup
      end
    elsif (idx = key.rindex("."))
      table_name, column_name = key[0, idx], key[idx + 1, key.length]
      if (existing = converted[table_name])
        existing[column_name] = value
      else
        converted[table_name] = { column_name => value }
      end
    else
      converted[key] = value
    end
  end
end

def expand_from_hash(attributes, &block)
  return ["1=0"] if attributes.empty?
  attributes.flat_map do |key, value|
    if key.is_a?(Array) && key.size == 1
      key = key.first
      value = value.flatten
    end
    if key.is_a?(Array)
      queries = Array(value).map do |ids_set|
        raise ArgumentError, "Expected corresponding value for #{key} to be an Array" unless ids_set.is_a?(Array)
        expand_from_hash(key.zip(ids_set).to_h)
      end
      grouping_queries(queries)
    elsif value.is_a?(Hash) && !table.has_column?(key)
      table.associated_table(key, &block)
        .predicate_builder.expand_from_hash(value.stringify_keys)
    elsif table.associated_with?(key)
      # Find the foreign key when using queries such as:
      # Post.where(author: author)
      #
      # For polymorphic relationships, find the foreign key and type:
      # PriceEstimate.where(estimate_of: treasure)
      associated_table = table.associated_table(key)
      if associated_table.polymorphic_association?
        value = [value] unless value.is_a?(Array)
        klass = PolymorphicArrayValue
      elsif associated_table.through_association?
        next associated_table.predicate_builder.expand_from_hash(
          associated_table.primary_key => value
        )
      end
      klass ||= AssociationQueryValue
      queries = klass.new(associated_table, value).queries.map! do |query|
        # If the query produced is identical to attributes don't go any deeper.
        # Prevents stack level too deep errors when association and foreign_key are identical.
        query == attributes ? self[key, value] : expand_from_hash(query)
      end
      grouping_queries(queries)
    elsif table.aggregated_with?(key)
      mapping = table.reflect_on_aggregation(key).mapping
      values = value.nil? ? [nil] : Array.wrap(value)
      if mapping.length == 1 || values.empty?
        column_name, aggr_attr = mapping.first
        values = values.map do |object|
          object.respond_to?(aggr_attr) ? object.public_send(aggr_attr) : object
        end
        self[column_name, values]
      else
        queries = values.map do |object|
          mapping.map do |field_attr, aggregate_attr|
            self[field_attr, object.try!(aggregate_attr)]
          end
        end
        grouping_queries(queries)
      end
    else
      self[key, value]
    end
  end
end

def grouping_queries(queries)
  if queries.one?
    queries.first
  else
    queries.map! { |query| query.reduce(&:and) }
    queries = Arel::Nodes::Or.new(queries)
    Arel::Nodes::Grouping.new(queries)
  end
end

def handler_for(object)
  @handlers.detect { |klass, _| klass === object }.last
end

def initialize(table)
  @table = table
  @handlers = []
  register_handler(BasicObject, BasicObjectHandler.new(self))
  register_handler(Range, RangeHandler.new(self))
  register_handler(Relation, RelationHandler.new)
  register_handler(Array, ArrayHandler.new(self))
  register_handler(Set, ArrayHandler.new(self))
end

def register_handler(klass, handler)
  @handlers.unshift([klass, handler])
end

def resolve_arel_attribute(table_name, column_name, &block)
  table.associated_table(table_name, &block).arel_table[column_name]
end

def with(table)
  other = dup
  other.table = table
  other
end