;;; lib/obj/db/proto.lisp --- Database Protocol

 ;;

 ;;; Commentary:

 ;; This set of 

 ;;; Code:

 (in-package :obj/db)

 ;;; Vars

 (declaim (sb-kernel:type-specifier *default-database-type* *default-database-collection-type*))

 (defparameter *default-database-type* 'vector)

 (defparameter *default-database-collection-type* 'list)

 ;;; Database

 (defgeneric db (self)

   (:documentation "Return the Database associated with SELF."))

 (defclass database ()

   ((db :initform nil :initarg :db :accessor db)))

 (defclass database-collection () ())

 ;; TODO 2024-05-30: maybe make into a macro?

 (defgeneric make-db (engine &rest initargs &key &allow-other-keys)

   (:documentation "Dispatch initializer for databases. An ENGINE must be supplied, which is

 usually a key such as :ROCKSDB or :SQLITE."))

 (defgeneric connect-db (db &key &allow-other-keys)

   (:documentation "Connect the database DB."))

 (defgeneric query-db (db query &key &allow-other-keys)

   (:documentation "Execute QUERY against DB."))

 (defgeneric db-get (db key &key &allow-other-keys)

   (:documentation "Return the value associated with KEY from DB."))

 (defgeneric (setf db-get) (db key val &key &allow-other-keys))

 (defgeneric close-db (db &key &allow-other-keys)

   (:documentation "Close the database DB."))

 (defgeneric open-db (self))

 (defgeneric destroy-db (self)

   (:documentation "Destroy all traces of a database, deleting any on-disk data and shutting down

 in-memory objects."))

 (defgeneric find-db (dbs name &key &allow-other-keys)

   (:documentation "Return the db by NAME, from a collection of databases DBS."))

 (defgeneric insert-db (dbs name &key &allow-other-keys)

   (:documentation "Inserts a database by NAME into the database-collection DBS."))

 (defgeneric db-open-p (self)

   (:documentation "Return T when database SELF is open.")

   (:method ((self t)) nil)

   (:method ((self database)) (when (db self) t)))

 (defgeneric db-closed-p (self)

   (:documentation "Return T when database SELF is closed.")

   (:method ((self t)) t)

   (:method ((self database)) (unless (db self) t)))

 ;;; Common

 (defun slot-val (instance slot-name)

   (if (and instance

            (slot-boundp instance slot-name))

       (slot-value instance slot-name)))

 (defgeneric get-val (object element &optional data-type)

   (:documentation "Returns the value in a object based on the supplied element name and possible

 type hints.")

   (:method (object element &optional data-type)

   (when object

     (typecase (or data-type object)

       (hash-table

        (gethash element object))

       (standard-object

        (slot-val object element))

       (t

        (if data-type

            (cond 

              ((equal 'alist data-type)

               (second (assoc element object :test #'equal)))

              ((equal 'plist data-type)

               (get object element))

              (t

               (error "Does not handle this type of object. Implement your own get-val method.")))

            (if (listp object)

                (second (assoc element object :test #'equal))

                (error "Does not handle this type of object. Implement your own get-val method."))))))))

 (defgeneric (setf get-val) (new-value object element &optional data-type)

   (:documentation "Set the value in a object based on the supplied element name and possible type

 hints.")

   (:method (new-value object element &optional data-type)

     (typecase (or data-type object)

       (hash-table (setf (gethash element object) new-value))

       (standard-object (setf (slot-value object element) new-value))

       (t

        (if data-type

            (cond ((equal 'alist data-type)

                   (replace object (list (list element new-value))))

                  ((equal 'plist data-type)

                   ;;TODO: Implement this properly.

                   (get object element ))

                  (t

                   (error "Does not handle this type of object. Implement your own get-val method.")))

            (if (listp object)

                (replace object (list (list element new-value)))

                (error "Does not handle this type of object. Implement your own get-val method.")))))))