require 'active_support/concern'

module ActiveRecord
  module Sanitization
    extend ActiveSupport::Concern

    module ClassMethods
      def quote_value(value, column = nil) #:nodoc:
        connection.quote(value,column)
      end

      # Used to sanitize objects before they're used in an SQL SELECT statement. Delegates to <tt>connection.quote</tt>.
      def sanitize(object) #:nodoc:
        connection.quote(object)
      end

      protected

      # Accepts an array, hash, or string of SQL conditions and sanitizes
      # them into a valid SQL fragment for a WHERE clause.
      #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
      #   { :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
      #   "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
      def sanitize_sql_for_conditions(condition, table_name = self.table_name)
        return nil if condition.blank?

        case condition
        when Array; sanitize_sql_array(condition)
        when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
        else        condition
        end
      end
      alias_method :sanitize_sql, :sanitize_sql_for_conditions

      # Accepts an array, hash, or string of SQL conditions and sanitizes
      # them into a valid SQL fragment for a SET clause.
      #   { :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"
      def sanitize_sql_for_assignment(assignments)
        case assignments
        when Array; sanitize_sql_array(assignments)
        when Hash;  sanitize_sql_hash_for_assignment(assignments)
        else        assignments
        end
      end

      # Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.
      #   { :name => "foo'bar", :group_id => 4 }
      #     # => "name='foo''bar' and group_id= 4"
      #   { :status => nil, :group_id => [1,2,3] }
      #     # => "status IS NULL and group_id IN (1,2,3)"
      #   { :age => 13..18 }
      #     # => "age BETWEEN 13 AND 18"
      #   { 'other_records.id' => 7 }
      #     # => "`other_records`.`id` = 7"
      #   { :other_records => { :id => 7 } }
      #     # => "`other_records`.`id` = 7"
      # And for value objects on a composed_of relationship:
      #   { :address => Address.new("123 abc st.", "chicago") }
      #     # => "address_street='123 abc st.' and address_city='chicago'"
      def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
        table = Arel::Table.new(table_name).alias(default_table_name)
        PredicateBuilder.build_from_hash(arel_engine, attrs, table).map { |b|
          connection.visitor.accept b
        }.join(' AND ')
      end
      alias_method :sanitize_sql_hash, :sanitize_sql_hash_for_conditions

      # Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
      #   { :status => nil, :group_id => 1 }
      #     # => "status = NULL , group_id = 1"
      def sanitize_sql_hash_for_assignment(attrs)
        attrs.map do |attr, value|
          "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
        end.join(', ')
      end

      # Accepts an array of conditions. The array has each value
      # sanitized and interpolated into the SQL statement.
      #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
      def sanitize_sql_array(ary)
        statement, *values = ary
        if values.first.is_a?(Hash) && statement =~ /:\w+/
          replace_named_bind_variables(statement, values.first)
        elsif statement.include?('?')
          replace_bind_variables(statement, values)
        elsif statement.blank?
          statement
        else
          statement % values.collect { |value| connection.quote_string(value.to_s) }
        end
      end

      alias_method :sanitize_conditions, :sanitize_sql

      def replace_bind_variables(statement, values) #:nodoc:
        raise_if_bind_arity_mismatch(statement, statement.count('?'), values.size)
        bound = values.dup
        c = connection
        statement.gsub('?') { quote_bound_value(bound.shift, c) }
      end

      def replace_named_bind_variables(statement, bind_vars) #:nodoc:
        statement.gsub(/(:?):([a-zA-Z]\w*)/) do
          if $1 == ':' # skip postgresql casts
            $& # return the whole match
          elsif bind_vars.include?(match = $2.to_sym)
            quote_bound_value(bind_vars[match])
          else
            raise PreparedStatementInvalid, "missing value for :#{match} in #{statement}"
          end
        end
      end

      def expand_range_bind_variables(bind_vars) #:nodoc:
        expanded = []

        bind_vars.each do |var|
          next if var.is_a?(Hash)

          if var.is_a?(Range)
            expanded << var.first
            expanded << var.last
          else
            expanded << var
          end
        end

        expanded
      end

      def quote_bound_value(value, c = connection) #:nodoc:
        if value.respond_to?(:map) && !value.acts_like?(:string)
          if value.respond_to?(:empty?) && value.empty?
            c.quote(nil)
          else
            value.map { |v| c.quote(v) }.join(',')
          end
        else
          c.quote(value)
        end
      end

      def raise_if_bind_arity_mismatch(statement, expected, provided) #:nodoc:
        unless expected == provided
          raise PreparedStatementInvalid, "wrong number of bind variables (#{provided} for #{expected}) in: #{statement}"
        end
      end
    end

    # TODO: Deprecate this
    def quoted_id #:nodoc:
      quote_value(id, column_for_attribute(self.class.primary_key))
    end

    private

    # Quote strings appropriately for SQL statements.
    def quote_value(value, column = nil)
      self.class.connection.quote(value, column)
    end
  end
end