;;;; 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)
  #: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 ('prefixed-name 'pname-ns))
     `(("iri" . ,(assoc-ref (parser-state-namespaces state) ""))
       ("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 (_ str)))
     (update-parser-state state
       #:result
       (cons
         (make-rdf-triple
           (parser-state-cur-subject state)
           (parser-state-cur-predicate state)
           (make-rdf-literal str "http://www.w3.org/2001/XMLSchema#string" #f))
         (parser-state-result state))))
    (('rdf-literal ('string-pat (_ str)) ('langtag lang))
     (update-parser-state state
       #:result
       (cons
         (make-rdf-triple
           (parser-state-cur-subject state)
           (parser-state-cur-predicate state)
           (make-rdf-literal
             str "http://www.w3.org/1999/02/22-rdf-syntax-ns#langString" lang))
         (parser-state-result state))))
    (('numeric-literal ('integer int))
     (update-parser-state state
       #:result
       (cons
         (make-rdf-triple
           (parser-state-cur-subject state)
           (parser-state-cur-predicate state)
           (make-rdf-literal int "http://www.w3.org/2001/XMLSchema#integer" #f))
         (parser-state-result state))))
    (('boolean-literal bool)
     (update-parser-state state
       #:result
       (cons
         (make-rdf-triple
           (parser-state-cur-subject state)
           (parser-state-cur-predicate state)
           (make-rdf-literal bool "http://www.w3.org/2001/XMLSchema#boolean" #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)))