;;; Copyright (c) 2006, 2007 Abdulaziz Ghuloum and Kent Dybvig
;;; 
;;; Permission is hereby granted, free of charge, to any person obtaining a
;;; copy of this software and associated documentation files (the "Software"),
;;; to deal in the Software without restriction, including without limitation
;;; the rights to use, copy, modify, merge, publish, distribute, sublicense,
;;; and/or sell copies of the Software, and to permit persons to whom the
;;; Software is furnished to do so, subject to the following conditions:
;;; 
;;; The above copyright notice and this permission notice shall be included in
;;; all copies or substantial portions of the Software.
;;; 
;;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
;;; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
;;; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
;;; THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
;;; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
;;; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
;;; DEALINGS IN THE SOFTWARE. 

(library (psyntax library-manager)
  (export imported-label->binding library-subst installed-libraries
    visit-library library-name library-exists? find-library-by-name
    install-library library-spec invoke-library extend-library-subst!
    extend-library-env! current-library-expander current-library-collection)
  (import (rnrs) (psyntax compat) (rnrs r5rs))

  (define (make-collection)
    (let ((set '()))
      (define (set-cons x ls)
        (cond
          ((memq x ls) ls)
          (else (cons x ls))))
      (case-lambda
        (() set)
        ((x) (set! set (set-cons x set))))))

  (define current-library-collection
    ;;; this works now because make-collection is a lambda
    ;;; binding and this turns into a complex binding as far
    ;;; as letrec is concerned.  It will be more ok once we do
    ;;; letrec*.
    (make-parameter (make-collection)
      (lambda (x)
        (unless (procedure? x)
          (error 'current-library-collection "~s is not a procedure" x))
        x)))

  (define-record library 
    (id name ver imp* vis* inv* subst env visit-state invoke-state visible?)
    (lambda (x p)
      (unless (library? x)
        (error 'record-type-printer "not a library"))
      (display 
        (format "#<library ~s>" (append (library-name x) (library-ver x)))
        p)))

  (define (find-dependencies ls)
    (cond
      ((null? ls) '())
      (else (error 'find-dependencies "cannot handle deps yet"))))

  (define (find-library-by pred)
    (let f ((ls ((current-library-collection))))
      (cond
        ((null? ls) #f)
        ((pred (car ls)) (car ls))
        (else (f (cdr ls))))))

  (define library-path
    (make-parameter
      '(".")
      (lambda (x)
        (if (and (list? x) (for-all string? x))
            ;(map values x)
            (map (lambda (x) x) x)
            (error 'library-path "~s is not a list of strings" x)))))
  
  (define (library-name->file-name x) 
    (let-values (((p extract) (open-string-output-port)))
      (define (display-hex n)
        (cond
          ((<= 0 n 9) (display n p))
          (else (display 
                  (integer->char 
                    (+ (char->integer #\A)
                       (- n 10)))
                  p))))
      (let f ((ls x))
        (cond
          ((null? ls) (display ".ss" p))
          (else
           (display "/" p)
           (for-each
             (lambda (c)
               (cond
                 ((or (char<=? #\a c #\z)
                      (char<=? #\A c #\Z)
                      (char<=? #\0 c #\9)
                      (memv c '(#\- #\. #\_ #\~)))
                  (display c p))
                 (else
                  (display "%" p)
                  (let ((n (char->integer c)))
                    (display-hex (quotient n 16))
                    (display-hex (remainder n 16))))))
             (string->list 
               (symbol->string (car ls))))
           (f (cdr ls)))))
      (extract)))

  (define file-locator
    (make-parameter
      (lambda (x)
        (let ((str (library-name->file-name x)))
          (let f ((ls (library-path)))
            (and (pair? ls)
                 (let ((name (string-append (car ls) str)))
                   (if (file-exists? name)
                       name
                       (f (cdr ls))))))))
      (lambda (f)
        (if (procedure? f)
            f
            (error 'file-locator "~s is not a procedure" f)))))

  (define library-locator
    (make-parameter
      (lambda (x)
        (let ((file-name ((file-locator) x)))
          (and (string? file-name)
               (with-input-from-file file-name read))))
      (lambda (f)
        (if (procedure? f)
            f
            (error 'library-locator 
                   "~s is not a procedure" f)))))

  (define current-library-expander
    (make-parameter
      (lambda (x)
        (error 'library-expander "not initialized"))
      (lambda (f)
        (if (procedure? f)
            f
            (error 'library-expander 
                   "~s is not a procedure" f)))))

  (define external-pending-libraries 
    (make-parameter '()))

  (define (find-external-library name)
    (when (member name (external-pending-libraries))
      (error #f "circular attempt to import library ~s detected"
             name))
    (parameterize ((external-pending-libraries
                    (cons name (external-pending-libraries))))
      (let ((lib-expr ((library-locator) name)))
        (unless lib-expr 
          (error #f "cannot find library ~s" name))
        ((current-library-expander) lib-expr)
        (or (find-library-by
              (lambda (x) (equal? (library-name x) name)))
            (error #f "handling external library of ~s did not yield the currect library" name)))))
          
  (define (find-library-by-name name)
    (or (find-library-by
          (lambda (x) (equal? (library-name x) name)))
        (find-external-library name)))

  (define (library-exists? name)
    (and (find-library-by
           (lambda (x) (equal? (library-name x) name)))
         #t))

  (define (find-library-by-spec/die spec)
    (let ((id (car spec)))
      (or (find-library-by
            (lambda (x) (eq? id (library-id x))))
          (error #f "cannot find library with spec ~s" spec))))

  (define label->binding-table (make-hashtable))

  (define (install-library-record lib)
    (let ((exp-env (library-env lib)))
      (for-each 
        (lambda (x) 
          (let ((label (car x)) (binding (cdr x)))
            (let ((binding 
                   (case (car binding)
                     ((global) 
                      (cons 'global (cons lib (cdr binding))))
                     ((global-macro)
                      (cons 'global-macro (cons lib (cdr binding))))
                     ((global-macro!)
                      (cons 'global-macro! (cons lib (cdr binding))))
                     (else binding))))
              (hashtable-set! label->binding-table label binding))))
        exp-env))
    ((current-library-collection) lib))

  (define (install-library id name ver imp* vis* inv* 
            exp-subst exp-env visit-code invoke-code visible?)
    (let ((imp-lib* (map find-library-by-spec/die imp*))
          (vis-lib* (map find-library-by-spec/die vis*))
          (inv-lib* (map find-library-by-spec/die inv*)))
      (unless (and (symbol? id) (list? name) (list? ver))
        (error 'install-library "invalid spec ~s ~s ~s" id name ver))
      (when (library-exists? name)
        (error 'install-library "~s is already installed" name))
      (let ((lib (make-library id name ver imp-lib* vis-lib* inv-lib* 
                    exp-subst exp-env visit-code invoke-code 
                    visible?)))
        (install-library-record lib))))

  (define extend-library-subst!
    (lambda (lib sym label)
      (set-library-subst! lib 
        (cons (cons sym label) (library-subst lib)))))

  (define extend-library-env!
    (lambda (lib label binding)
      (set-library-env! lib
        (cons (cons label binding) (library-env lib)))
      (hashtable-set! label->binding-table label binding)))

  (define (imported-label->binding lab)
    (hashtable-ref label->binding-table lab #f))

  (define (invoke-library lib)
    (let ((invoke (library-invoke-state lib)))
      (when (procedure? invoke)
        (set-library-invoke-state! lib 
          (lambda () (error 'invoke "circularity detected for ~s" lib)))
        (for-each invoke-library (library-inv* lib))
        (set-library-invoke-state! lib 
          (lambda () (error 'invoke "first invoke did not return for ~s" lib)))
        (invoke)
        (set-library-invoke-state! lib #t))))


  (define (visit-library lib)
    (let ((visit (library-visit-state lib)))
      (when (procedure? visit)
        (set-library-visit-state! lib 
          (lambda () (error 'visit "circularity detected for ~s" lib)))
        (for-each invoke-library (library-vis* lib))
        (set-library-visit-state! lib 
          (lambda () (error 'invoke "first visit did not return for ~s" lib)))
        (visit)
        (set-library-visit-state! lib #t))))


  (define (invoke-library-by-spec spec)
    (invoke-library (find-library-by-spec/die spec)))

  (define installed-libraries 
    (case-lambda
      ((all?)
       (let f ((ls ((current-library-collection))))
         (cond
           ((null? ls) '())
           ((or all? (library-visible? (car ls)))
            (cons (car ls) (f (cdr ls))))
           (else (f (cdr ls))))))
      (() (installed-libraries #f))))

  (define library-spec       
    (lambda (x) 
      (unless (library? x)
        (error 'library-spec "~s is not a library" x))
      (list (library-id x) (library-name x) (library-ver x)))) 
  )