;;;; Copyright (C) 2019, 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)

  #:use-module (jsonld compaction)

  #:use-module (jsonld context)

  #:use-module (jsonld context-processing)

  #:use-module (jsonld download)

  #:use-module (jsonld expansion)

  #:use-module (jsonld flattening)

  #:use-module (jsonld inverse-context-creation)

  #:use-module (jsonld iri)

  #:use-module (jsonld iri-compaction)

  #:use-module (jsonld json)

  #:use-module (jsonld options)

  #:export (compact

            expand

            flatten))

(define* (compact input context #:key (options (new-jsonld-options)))

  (call-with-values

    (lambda ()

      ;; TODO: set ordered to #f

      (expand-with-base input #:options options))

    ;; 2 and 3

    (lambda (expanded-input context-base)

      (when (string? context)

        (set! context

          (json-document-document

            ((jsonld-options-document-loader options)

             context))))

      ;; 4

      (when (json-has-key? context "@context")

        (set! context (assoc-ref context "@context")))

      (let* ((base-iri (or (jsonld-options-base options)

                           (and (jsonld-options-compact-to-relative? options)

                                (string? input)

                                input)))

             (active-context (context-processing (new-active-context

                                                   #:base base-iri)

                                                 context context-base

                                                 #:options options))

             (inverse-context (inverse-context-creation active-context))

             (compacted-output

               (compaction active-context inverse-context

                           #nil ;; active-property

                           expanded-input ;; element

                           #:compact-arrays? (jsonld-options-compact-arrays? options)

                           #:ordered? (jsonld-options-ordered? options)

                           #:processing-mode

                           (jsonld-options-processing-mode options))))

        (if (equal? compacted-output #())

            (set! compacted-output '())

            (when (json-array? compacted-output)

              (set! compacted-output `((,(iri-compaction active-context

                                                         inverse-context

                                                         "@graph"

                                                         #:vocab? #t

                                                         #:reverse? #f) .

                                         ,compacted-output)))))

        (when (and context (not (null? compacted-output)) (not (null? context)))

          (set! compacted-output

            (cons (cons "@context" context) compacted-output)))

        compacted-output))))

(define* (expand-with-base input #:key (options (new-jsonld-options)))

  (let ((document input)

        (remote-document #f)

        (active-context (new-active-context

                          #:base (jsonld-options-base options)

                          #:original-base (jsonld-options-base options)))

        (document-base (jsonld-options-base options)))

    (when (string? input)

      ;; 2

      (catch #t

        (lambda ()

          (set! remote-document

            ((jsonld-options-document-loader options)

             input

             #:extract-all-scripts? (jsonld-options-extract-all-scripts? options))))

        (lambda (key . value)

          (cond

            ((member key '(loading-document-failed multiple-context-link-headers

                           invalid-script-element))

             (apply throw key value))

            (else

              (apply throw 'loading-document-failed key value)))))

      ;; 3

      (set! document (json-document-document remote-document))

      (set! document-base (json-document-document-url remote-document))

      ;; 4

      (set! active-context

        (update-active-context active-context

                               #:base (or (jsonld-options-base options)

                                          (json-document-document-url remote-document))

                               #:original-base

                               (or (json-document-document-url remote-document)

                                   (jsonld-options-base options)))))

    ;; 5

    (when (jsonld-options-expand-context options)

      (set! active-context

        (let* ((local-context (jsonld-options-expand-context options))

               (local-context (if (json-has-key? local-context "@context")

                                  (assoc-ref local-context "@context")

                                  local-context)))

          (context-processing active-context local-context

                              (active-context-original-base active-context)))))

    ;; 6

    (when (and remote-document (json-document-context-url remote-document))

      (let ((context-url (json-document-context-url remote-document)))

        (set! active-context

          (context-processing active-context context-url context-url))))

    ;; 7

    (let ((expanded-output (expansion active-context #nil document

                                      (if remote-document

                                          (or (json-document-document-url remote-document)

                                              (jsonld-options-base options))

                                          (jsonld-options-base options))

                                      #:options options)))

      (when (and

              (json-object? expanded-output)

              (json-has-key? expanded-output "@graph")

              (null? (filter

                       (lambda (kv)

                         (not (equal? (car kv) "@graph")))

                       expanded-output)))

        (set! expanded-output (assoc-ref expanded-output "@graph")))

      (when (equal? expanded-output #nil)

        (set! expanded-output #()))

      (unless (json-array? expanded-output)

        (set! expanded-output `#(,expanded-output)))

      ;; 8

      (values expanded-output document-base))))

(define* (expand input #:key (options (new-jsonld-options)))

  (call-with-values

    (lambda ()

      (expand-with-base input #:options options))

    (lambda (out base)

      out)))

(define* (flatten input #:key (context #f) (options (new-jsonld-options)))

  ;; 2

  (let* ((expanded-input

           (expand input #:options (update-jsonld-options

                                     options #:ordered? #t)))

         ;; 3

         (base-iri (or (jsonld-options-base options)

                       (and (jsonld-options-compact-to-relative? options)

                            (string? input)

                            input)))

         ;; 4

         (identifier-map '())

         ;; 5

         (flattened-output (flattening expanded-input

                                       #:ordered?

                                       (jsonld-options-ordered? options))))

    ;; 5.1

    (when context

      ;; TODO

      (set! flattened-output (compact flattened-output context #:options options)))

    flattened-output))