;;;; Copyright (C) 2020 Julien Lepiller <julien@lepiller.eu>

;;;; 

;;;; This library is free software; you can redistribute it and/or

;;;; modify it under the terms of the GNU Lesser General Public

;;;; License as published by the Free Software Foundation; either

;;;; version 3 of the License, or (at your option) any later version.

;;;; 

;;;; This library is distributed in the hope that it will be useful,

;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of

;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

;;;; Lesser General Public License for more details.

;;;; 

;;;; You should have received a copy of the GNU Lesser General Public

;;;; License along with this library; if not, write to the Free Software

;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

;;;; 

(define-module (jsonld merge-node-maps)

  #:use-module (jsonld json)

  #:export (merge-node-maps))

(define* (merge-node-maps graph-map)

  ;; 1

  (let ((result '()))

    (for-each-pair

      (lambda (graph-name node-map)

        (for-each-pair

          (lambda (id node)

            (let ((merged-node (or (assoc-ref result id) `(("@id" . ,id)))))

              (for-each-pair

                (lambda (property values)

                  (if (json-keyword? property)

                      (set! merged-node

                        (alist-set merged-node property values))

                      (set! merged-node

                        (alist-set

                          merged-node property

                          (list->array 1

                            (append

                              (if (assoc-ref merged-node property)

                                  (array->list (assoc-ref merged-node property))

                                  '())

                              (if (json-array? values)

                                (array->list values)

                                (list values))))))))

                node)

              (set! result (alist-set result id merged-node))))

          node-map))

      graph-map)

    result))