module ActiveRecord::Sanitization::ClassMethods

def disallow_raw_sql!(args, permit: connection.column_name_matcher) # :nodoc:
  unexpected = nil
  args.each do |arg|
    next if arg.is_a?(Symbol) || Arel.arel_node?(arg) || permit.match?(arg.to_s.strip)
    (unexpected ||= []) << arg
  end
  if unexpected
    raise(ActiveRecord::UnknownAttributeReference,
      "Dangerous query method (method whose arguments are used as raw " \
      "SQL) called with non-attribute argument(s): " \
      "#{unexpected.map(&:inspect).join(", ")}." \
      "This method should not be called with user-provided values, such as request " \
      "parameters or model attributes. Known-safe values can be passed " \
      "by wrapping them in Arel.sql()."
    )
  end
end

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

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

def replace_bind_variable(value, c = connection)
  if ActiveRecord::Relation === value
    value.to_sql
  else
    quote_bound_value(value, c)
  end
end

def replace_bind_variables(statement, values)
  raise_if_bind_arity_mismatch(statement, statement.count("?"), values.size)
  bound = values.dup
  c = connection
  statement.gsub(/\?/) do
    replace_bind_variable(bound.shift, c)
  end
end

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

def sanitize_sql_array(ary)
  statement, *values = ary
  if values.first.is_a?(Hash) && /:\w+/.match?(statement)
    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

def sanitize_sql_for_assignment(assignments, default_table_name = table_name)
  case assignments
  when Array; sanitize_sql_array(assignments)
  when Hash;  sanitize_sql_hash_for_assignment(assignments, default_table_name)
  else        assignments
  end
end

def sanitize_sql_for_conditions(condition)
  return nil if condition.blank?
  case condition
  when Array; sanitize_sql_array(condition)
  else        condition
  end
end

def sanitize_sql_for_order(condition)
  if condition.is_a?(Array) && condition.first.to_s.include?("?")
    disallow_raw_sql!(
      [condition.first],
      permit: connection.column_name_with_order_matcher
    )
    # Ensure we aren't dealing with a subclass of String that might
    # override methods we use (e.g. Arel::Nodes::SqlLiteral).
    if condition.first.kind_of?(String) && !condition.first.instance_of?(String)
      condition = [String.new(condition.first), *condition[1..-1]]
    end
    Arel.sql(sanitize_sql_array(condition))
  else
    condition
  end
end

def sanitize_sql_hash_for_assignment(attrs, table)
  c = connection
  attrs.map do |attr, value|
    type = type_for_attribute(attr)
    value = type.serialize(type.cast(value))
    "#{c.quote_table_name_for_assignment(table, attr)} = #{c.quote(value)}"
  end.join(", ")
end

def sanitize_sql_like(string, escape_character = "\\")
  pattern = Regexp.union(escape_character, "%", "_")
  string.gsub(pattern) { |x| [escape_character, x].join }
end