# frozen-string-literal: true

module Sequel
  class Database
    # ---------------------
    # :section: 5 - Methods that set defaults for created datasets
    # This methods change the default behavior of this database's datasets.
    # ---------------------

    # The default class to use for datasets
    DatasetClass = Sequel::Dataset
    Sequel::Deprecation.deprecate_constant(self, :DatasetClass)

    # SEQUEL5: Remove
    @identifier_input_method = nil
    @identifier_output_method = nil
    @quote_identifiers = nil
    class << self
      # The identifier input method to use by default for all databases (default: adapter default)
      attr_reader :identifier_input_method

      # The identifier output method to use by default for all databases (default: adapter default)
      attr_reader :identifier_output_method

      # Whether to quote identifiers (columns and tables) by default for all databases (default: adapter default)
      attr_reader :quote_identifiers
    end

    # Change the default identifier input method to use for all databases,
    def self.identifier_input_method=(v)
      Sequel::Deprecation.deprecate("Sequel.identifier_input_method= and Sequel::Database.identifier_input_method=", "Call Sequel::Database#identifier_input_method= instead")
      @identifier_input_method = v.nil? ? false : v
    end

    # Change the default identifier output method to use for all databases,
    def self.identifier_output_method=(v)
      Sequel::Deprecation.deprecate("Sequel.identifier_output_method= and Sequel::Database.identifier_output_method=", "Call Sequel::Database#identifier_output_method= instead")
      @identifier_output_method = v.nil? ? false : v
    end

    def self.quote_identifiers=(v)
      Sequel::Deprecation.deprecate("Sequel.quote_identifiers= and Sequel::Database.quote_identifiers=", "Call Sequel::Database#quote_identifiers= instead")
      @quote_identifiers = v
    end

    # The class to use for creating datasets.  Should respond to
    # new with the Database argument as the first argument, and
    # an optional options hash.
    attr_reader :dataset_class

    # If the database has any dataset modules associated with it,
    # use a subclass of the given class that includes the modules
    # as the dataset class.
    def dataset_class=(c)
      unless @dataset_modules.empty?
        c = Class.new(c)
        @dataset_modules.each{|m| c.send(:include, m)}
      end
      @dataset_class = c
      reset_default_dataset
    end

    # Equivalent to extending all datasets produced by the database with a
    # module.  What it actually does is use a subclass of the current dataset_class
    # as the new dataset_class, and include the module in the subclass.
    # Instead of a module, you can provide a block that is used to create an
    # anonymous module.
    #
    # This allows you to override any of the dataset methods even if they are
    # defined directly on the dataset class that this Database object uses.
    #
    # Examples:
    #
    #   # Introspec columns for all of DB's datasets
    #   DB.extend_datasets(Sequel::ColumnsIntrospection)
    #   
    #   # Trace all SELECT queries by printing the SQL and the full backtrace
    #   DB.extend_datasets do
    #     def fetch_rows(sql)
    #       puts sql
    #       puts caller
    #       super
    #     end
    #   end
    def extend_datasets(mod=nil, &block)
      raise(Error, "must provide either mod or block, not both") if mod && block
      mod = Module.new(&block) if block
      if @dataset_modules.empty?
       @dataset_modules = [mod]
       @dataset_class = Class.new(@dataset_class)
      else
       @dataset_modules << mod
      end
      @dataset_class.send(:include, mod)
      reset_default_dataset
    end

    private
    
    # The default dataset class to use for the database
    def dataset_class_default
      if self.class == Sequel::Database
        Sequel::Dataset
      else
        Sequel::Deprecation.deprecate("Using self.class.const_get(:DatasetClass) to get the default dataset class", "Modify the database adapter to implement Database#dataset_class_default")
        self.class.const_get(:DatasetClass)
      end
    end

    # Reset the default dataset used by most Database methods that
    # create datasets.  Usually done after changes to the identifier
    # mangling methods.
    def reset_default_dataset
      Sequel.synchronize{@symbol_literal_cache.clear}
      @default_dataset = dataset
    end

    # Whether to quote identifiers by default for this database, true
    # by default.
    def quote_identifiers_default
      true
    end
  end
end