;;;; 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 (turtle tordf)

  #:use-module (ice-9 match)

  #:use-module (ice-9 textual-ports)

  #:use-module (iri iri)

  #:use-module (turtle parser)

  #:use-module (srfi srfi-9)

  #:use-module (rdf rdf)

  #:use-module ((rdf xsd) #:prefix xsd:)

  #:export (turtle->rdf))

(define-record-type parser-state

  (make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate

                     blank-node-gen result)

  parser-state?

  (base-uri       parser-state-base-uri)

  (namespaces     parser-state-namespaces)

  (bnode-labels   parser-state-bnode-labels)

  (cur-subject    parser-state-cur-subject)

  (cur-predicate  parser-state-cur-predicate)

  (blank-node-gen parser-state-blank-node-gen)

  (result         parser-state-result))

(define* (update-parser-state

           state #:key (base-uri (parser-state-base-uri state))

                       (namespaces (parser-state-namespaces state))

                       (bnode-labels (parser-state-bnode-labels state))

                       (cur-subject (parser-state-cur-subject state))

                       (cur-predicate (parser-state-cur-predicate state))

                       (blank-node-gen (parser-state-blank-node-gen state))

                       (result (parser-state-result state)))

  (make-parser-state base-uri namespaces bnode-labels cur-subject cur-predicate

                     blank-node-gen result))

(define (create-generate-blank-node)

  (define num 0)

  (lambda ()

    (set! num (+ num 1))

    num))

(define (add-ns-to-state state ns iri)

  (pk 'iri iri)

  (update-parser-state state

    #:namespaces (cons (cons ns iri) (parser-state-namespaces state))))

(define (parse-iri iri state)

  (format #t "iri: ~a~%" iri)

  (match iri

    (('iri ('prefixed-name ('pname-ln ('pname-ns ns) suffix)))

     `(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) ns)

                               suffix))

       ("state" . ,state)))

    (('iri ('prefixed-name ('pname-ln ('pname-ns suffix))))

     `(("iri" . ,(string-append (assoc-ref (parser-state-namespaces state) "")

                               suffix))

       ("state" . ,state)))

    (('iri 'iriref)

     `(("iri" . ,(resolve-iri (parser-state-base-uri state) ""))

       ("state" . ,state)))

    (('iri ('iriref iri))

     `(("iri" . ,(resolve-iri (parser-state-base-uri state) iri))

       ("state" . ,state)))

    (('blank-node ('blank-node-label label))

     (if (assoc-ref (parser-state-bnode-labels state) label)

         `(("iri" . ,(assoc-ref (parser-state-bnode-labels state) label))

           ("state" . ,state))

         (let ((node ((parser-state-blank-node-gen state))))

           `(("iri" . ,node)

             ("state" . ,(update-parser-state state

                           #:bnode-labels

                           (cons

                             (cons label node)

                             (parser-state-bnode-labels state))))))))))

(define (parse-verb verb state)

  (match verb

    ("a" `(("verb" . "http://www.w3.org/1999/02/22-rdf-syntax-ns#type")

           ("state" . ,state)))

    (('predicate iri)

     (let ((res (parse-iri iri state)))

       `(("verb" . ,(assoc-ref res "iri"))

         ("state" . ,(assoc-ref res "state")))))))

(define (parse-object object state)

  (pk 'object object)

  (match object

    (('rdf-literal ('string-pat ('string-literal-quote str)))

     (update-parser-state state

       #:result

       (cons

         (make-rdf-triple

           (parser-state-cur-subject state)

           (parser-state-cur-predicate state)

           (make-rdf-literal str xsd:string #f))

         (parser-state-result state))))

    (('blank-node-property-list ('predicate-object-list po ...))

     (let* ((node ((parser-state-blank-node-gen state)))

            (new-state (parse-predicate-object

                         po (update-parser-state state #:cur-subject node))))

       (update-parser-state new-state

         #:cur-subject (parser-state-cur-subject state)

         #:cur-predicate (parser-state-cur-predicate state)

         #:result

         (cons

           (make-rdf-triple

             (parser-state-cur-subject state)

             (parser-state-cur-predicate state)

             node)

           (parser-state-result new-state)))))

    (('collection objects ...)

     (let loop ((objects objects) (state state))

       (match objects

         ('() state)

         ((('object object) objects ...)

          (loop objects (parse-object object state))))))

    (('iri _)

     (let* ((res (parse-iri object state))

            (iri (assoc-ref res "iri"))

            (state (assoc-ref res "state")))

       (update-parser-state state

         #:result

         (cons

           (make-rdf-triple

             (parser-state-cur-subject state)

             (parser-state-cur-predicate state)

             iri)

           (parser-state-result state)))))))

(define (parse-object-list ol state)

  (let loop ((ol ol) (state state))

    (pk 'ol ol)

    (match ol

      ('() state)

      ((('object object) ol ...)

       (loop ol (parse-object object state)))

      ((ol)

       (loop ol state)))))

(define (parse-predicate-object po state)

  (let loop ((po po) (state state))

    (pk 'po po)

    (match po

      ((('verb verb) ('object-list ol ...) po)

       (let* ((verb (parse-verb verb state))

              (state (assoc-ref verb "state"))

              (verb (assoc-ref verb "verb"))

              (new-state (update-parser-state state #:cur-predicate verb))

              (res (parse-object-list ol new-state)))

         (loop po res)))

      ((('verb verb) ('object-list ol ...))

       (let* ((verb (parse-verb verb state))

              (state (assoc-ref verb "state"))

              (verb (assoc-ref verb "verb"))

              (new-state (update-parser-state state #:cur-predicate verb))

              (res (parse-object-list ol new-state)))

         res))

      (((('verb verb) ('object-list ol ...)) po ...)

       (let* ((verb (parse-verb verb state))

              (state (assoc-ref verb "state"))

              (verb (assoc-ref verb "verb"))

              (new-state (update-parser-state state #:cur-predicate verb))

              (res (parse-object-list ol new-state)))

         (loop po res)))

      ('() state)

      ((po)

       (loop po state)))))

(define (parse-triples t state)

  (match t

    ((('subject iri) ('predicate-object-list predicate-object ...))

     (let* ((res (parse-iri iri state))

            (iri (assoc-ref res "iri"))

            (state (assoc-ref res "state"))

            (state (update-parser-state state

                    #:cur-subject iri)))

       (parse-predicate-object predicate-object state)))))

(define (parse-turtle-doc parse-tree state)

  (let loop ((parse-tree parse-tree) (state state))

    (match parse-tree

      ('() (parser-state-result state))

      ((('prefix-id ('pname-ns ns) ('iriref iri)) parse-tree ...)

       (loop parse-tree

             (add-ns-to-state

               state ns (resolve-iri (parser-state-base-uri state) iri))))

      ((('prefix-id ('pname-ns ('iriref iri))) parse-tree ...)

       (loop parse-tree

             (add-ns-to-state

               state "" (resolve-iri (parser-state-base-uri state) iri))))

      ((('sparql-prefix ('pname-ns ns) ('iriref iri)) parse-tree ...)

       (loop parse-tree

             (add-ns-to-state

               state ns (resolve-iri (parser-state-base-uri state) iri))))

      ((('sparql-prefix ('pname-ns ('iriref iri))) parse-tree ...)

       (loop parse-tree

             (add-ns-to-state

               state "" (resolve-iri (parser-state-base-uri state) iri))))

      ((('base ('iriref iri)) parse-tree ...)

       (loop parse-tree

             (update-parser-state

               state #:base-uri (resolve-iri (parser-state-base-uri state) iri))))

      ((('sparql-base ('iriref iri)) parse-tree ...)

       (loop parse-tree

             (update-parser-state

               state #:base-uri (resolve-iri iri (parser-state-base-uri state)))))

      ((('triples t ...) parse-tree ...)

       (format #t "triples: ~a~%" t)

       (let ((res (parse-triples t state)))

         (loop parse-tree (parse-triples t state))))

      ;; otherwise, it's a single element, not a list of statements

      (((? symbol? _) _ ...) (loop (list parse-tree) state)))))

(define (tordf parse-tree base)

  (define state

    (make-parser-state base '() '() #f #f (create-generate-blank-node) '()))

  (parse-turtle-doc parse-tree state))

(define (turtle->rdf str-or-file base)

  (define str

    (cond

      ((file-exists? str-or-file) (call-with-input-file str-or-file get-string-all))

      ((string? str-or-file) str-or-file)))

  (let ((parse-tree (parse-turtle str)))

    (tordf parse-tree base)))