
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; MODULE      : db-users.scm
;; DESCRIPTION : Users and permissions
;; COPYRIGHT   : (C) 2015  Joris van der Hoeven
;;
;; This software falls under the GNU general public license version 3 or later.
;; It comes WITHOUT ANY WARRANTY WHATSOEVER. For details, see the file LICENSE
;; in the root directory or <http://www.gnu.org/licenses/gpl-3.0.html>.
;;
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(texmacs-module (database db-users)
  (:use (database db-format)))

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;; The current user
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(tm-define db-current-user #t)

(tm-define-macro (with-user uid . body)
  `(with-global db-current-user ,uid ,@body))

(tm-define (db-reset)
  (former)
  (set! db-current-user #t))

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;; The database for user management
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(define users-dir "$TEXMACS_HOME_PATH/users")
(define users-master (url->url (string-append users-dir "/users-master.tmdb")))

(tm-define (add-user pseudo name)
  (with-database users-master
    (db-set-entry pseudo `(("type" "user")
                           ("pseudo" ,pseudo)
                           ("name" ,name)))
    pseudo))

;; (tm-define (add-user pseudo name)
;;   (with-database users-master
;;     (db-create-entry `(("type" "user")
;;                        ("pseudo" ,pseudo)
;;                        ("name" ,name)))))

(tm-define (remove-user)
  (let* ((del (get-default-user))
         (rem (list-filter (get-users-list) (cut != <> del))))
    (when (nnull? rem)
      (set-default-user (car rem))
      (with-database users-master
        (db-remove-entry del)))))

(tm-define (pseudo->user pseudo)
  (with-database users-master
    (with ids (db-search `(("type" "user")
                           ("pseudo" ,pseudo)))
      (and (nnull? ids) (car ids)))))

(tm-define (user->pseudo uid)
  (with-database users-master
    (db-get-field-first uid "pseudo" #f)))

(tm-define (set-default-user uid)
  (with-database users-master
    (when (!= db-the-default-user uid)
      (db-set-field "root" "default-user" (list uid))
      (set! db-the-default-user uid))))

(define (search-default-user)
  (with-database users-master
    (with l (db-get-field "root" "default-user")
      (and (pair? l) (car l)))))

(tm-define (set-user-info attr val)
  (with-database users-master
    (when (!= val (get-user-info attr))
      (db-set-field (get-default-user) attr (list val)))))

(tm-define (get-user-info attr)
  (with-database users-master
    (db-get-field-first (get-default-user) attr "")))

(tm-define (get-users-list)
  (with-database users-master
    (db-search `(("type" "user")))))

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;; The default user
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define db-the-default-user #f)

(define (safe-getpwnam id)
  (catch #t
	 (lambda () (passwd:gecos (getpwnam id)))
	 (lambda err
	   (display* "Error in getpwnam: " err "\n")
	   "")))

(define (safe-getpwuid id)
  (catch #t
	 (lambda () (passwd:name (getpwuid id)))
	 (lambda err
	   (display* "Error in getpwuid: " err "\n")
	   "")))

(define (get-full-name user)
 (if (os-mingw?)
     (or (and (url-exists-in-path? "fullname")
              (var-eval-system (string-append "fullname " user)))
         "Default User")
     (safe-getpwnam user)))

(define (create-default-user)
  (let* ((pseudo (or (getlogin) (safe-getpwuid (getuid))))
         (name (get-full-name pseudo)))
    ;;(display* "pseudo= " pseudo "\n")
    ;;(display* "name= " name "\n")
    (when (== pseudo "") (set! pseudo "default"))
    (when (== name "") (set! name "Default User"))
    (list pseudo name)))

(tm-define (get-default-user)
  (when (not db-the-default-user)
    (and-with uid (search-default-user)
      (set! db-the-default-user uid)))
  (when (not db-the-default-user)
    (with info (create-default-user)
      (with (pseudo name) info
	(with me (add-user pseudo name)
	  (set-default-user me)
	  (set! db-the-default-user me)))))
  db-the-default-user)

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;; User databases
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(define dir-created-table (make-ahash-table))

(define (get-user-dir uid)
  (with dir (string-append users-dir "/" uid)
    (when (not (ahash-ref dir-created-table dir))
      (system-mkdir dir)
      (ahash-set! dir-created-table dir #t))
    dir))

(define (search-preferred-database-id uid kind)
  (with ids (db-search `(("type" "preference")
			 ("user" ,uid)
			 ("key" ,(string-append "database-" kind))))
    (and (nnull? ids) (car ids))))

(tm-define (get-preferred-database uid kind)
  (with-database users-master
    (let* ((id (search-preferred-database-id uid kind))
	   (val (and id (db-get-field-first id "value" #f))))
      (if val (system->url val)
	  (let* ((dir (get-user-dir uid))
		 (pseudo (user->pseudo uid))
		 (db* (string-append dir "/" pseudo "-" kind ".tmdb"))
		 (db (string->url db*)))
	    (set-preferred-database uid kind db)
	    db)))))

(tm-define (set-preferred-database uid kind db)
  (with-database users-master
    (with-time-stamp #t
      (with id (or (search-preferred-database-id uid kind) (db-create-id))
	(db-set-entry id `(("type" "preference")
			   ("user" ,uid)
			   ("key" ,(string-append "database-" kind))
			   ("value" ,(url->system db))))))))

(tm-define (recent-preferred-databases uid kind)
  (with-database users-master
    (with id (or (search-preferred-database-id uid kind) (db-create-id))
      (with-time :always
	(with vals (db-get-field id "value")
	  (list-remove-duplicates (map system->url (reverse vals))))))))

(tm-define (db-get-kind) "general")

(tm-define (user-database . opt-kind)
  (with kind (if (null? opt-kind) (db-get-kind) (car opt-kind))
    (get-preferred-database (get-default-user) kind)))

(tm-define (use-database db)
  (set-preferred-database (get-default-user) (db-get-kind) db)
  (revert-buffer))

(tm-define (recent-databases)
  (recent-preferred-databases (get-default-user) (db-get-kind)))

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;; Important tables
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(smart-table db-encoding-table
  (("owner" * :pseudos) :users)
  (("readable" * :pseudos) :users)
  (("writable" * :pseudos) :users)
  (("delegate-owner" * :pseudos) :users)
  (("delegate-readable" * :pseudos) :users)
  (("delegate-writable" * :pseudos) :users))

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;; Encoding and decoding of lists of users
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define (db-encode-user user)
  (if (== user "all") user
      (with l (db-search (list (list "type" "user") (list "pseudo" user)))
        (if (pair? l) (car l) "all"))))

(define (db-encode-users users)
  ;;(display* "Encode users " users "\n")
  (list-filter (map db-encode-user users) identity))

(define (db-decode-user id)
  (if (== id "all") id
      (db-get-field-first id "pseudo" "nobody")))

(define (db-decode-users ids)
  ;;(display* "Decode users " ids "\n")
  (list-filter (map db-decode-user ids) identity))

(smart-table db-encoder-table
  (,:users ,db-encode-users))

(smart-table db-decoder-table
  (,:users ,db-decode-users))

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;; Expand user list according to group membership
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(define (db-expand accu todo attr)
  (with-user #t
    (with added (make-ahash-table)
      (for (uid (ahash-set->list todo))
        (with q (list (list "type" "group")
                      (list (string-append "delegate-" attr) uid))
          (for (x (db-search q))
            (when (not (ahash-ref accu x))
              (ahash-set! accu x #t)
              (ahash-set! added x #t)))))
      (if (== (ahash-size added) 0)
          accu
          (db-expand accu added attr)))))

(tm-define (db-expand-user uid attr)
  (cond ((string? uid) (db-expand-user (list uid) attr))
        ((list? uid)
         (let* ((accu (list->ahash-set uid))
                (todo accu)
                (done (db-expand accu todo attr)))
           (rcons (sort (ahash-set->list done) string<=?) "all")))
        (else (list "all"))))

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;; Access rights
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(tm-define (db-allow? id uid attr)
  ;;(display* "Allow " id ", " uid ", " attr "\n")
  (or (== uid #t)
      (let* ((ids (db-get-field id attr))
             (exp (db-expand-user uid attr)))
        ;;(display* "Expanded " uid " -> " exp "\n")
        ;;(display* "Test " ids " -> " (nnull? (list-intersection ids exp)) "\n")
        (or (nnull? (list-intersection ids exp))
            (and (!= attr "owner")
                 (db-allow? id uid "owner"))))))

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;; Wrap basic interface to databases
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(tm-define (db-get-field id attr)
  (if (or (== db-current-user #t)
          (db-allow? id db-current-user "owner")
          (db-allow? id db-current-user "readable"))
      (with-user #t
        (former id attr))
      (list)))

(tm-define (db-set-field id attr vals)
  (when (or (== db-current-user #t)
            (db-allow? id db-current-user "owner"))
    (with-user #t
      (former id attr vals))))

(tm-define (db-get-entry id)
  (if (or (== db-current-user #t)
          (db-allow? id db-current-user "owner")
          (db-allow? id db-current-user "readable"))
      (with-user #t
        (former id))
      (list)))

(tm-define (db-set-entry id l)
  (when (or (== db-current-user #t)
            (db-allow? id db-current-user "owner"))
    (with-user #t
      (former id l))))

(tm-define (db-create-entry l)
  (if (== db-current-user #t)
      (former l)
      (let* ((old-owners (or (assoc-ref l "owner") (list)))
             (new-owners (cond ((string? db-current-user)
                                (list db-current-user))
                               ((list? db-current-user)
                                db-current-user)
                               (else (list))))
             (all-owners (list-union old-owners new-owners)))
        (and (nnull? all-owners)
             (with-user #t
               (set! l (assoc-set! (list-copy l) "owner" all-owners))
               (former l))))))

(tm-define (db-remove-entry id)
  (when (or (== db-current-user #t)
            (db-allow? id db-current-user "owner"))
    (with-user #t
      (former id))))

(tm-define (db-search l)
  (if (== db-current-user #t)
      (former l)
      (let* ((users (db-expand-user db-current-user "readable"))
             (lo (rcons l (cons "owner" users)))
             (lr (rcons l (cons "readable" users))))
        (with-user #t
          (list-union (former lo)
                      (former lr))))))
