#lang racket/base
(require "path.rkt"
         (for-syntax racket/base
                     setup/path-to-relative))

(provide delete-directory/files
         copy-directory/files
         make-directory*
         make-temporary-file

         get-preference
         put-preferences
         preferences-lock-file-mode
         make-handle-get-preference-locked
         make-lock-file-name
         call-with-file-lock/timeout

         fold-files
         find-files
         pathlist-closure

         file->string
         file->bytes
         file->value
         file->lines
         file->bytes-lines
         file->list
         display-to-file
         write-to-file
         display-lines-to-file

         user-read-bit
         user-write-bit
         user-execute-bit
         group-read-bit
         group-write-bit
         group-execute-bit
         other-read-bit
         other-write-bit
         other-execute-bit)

(require "private/portlines.rkt")

;; utility: sorted dirlist so functions are deterministic
(define (sorted-dirlist [dir (current-directory)])
  (let* ([ps (directory-list dir)]
         [ps (map (lambda (p) (cons (path->string p) p)) ps)]
         [ps (sort ps (lambda (p1 p2) (string<? (car p1) (car p2))))]
         [ps (map cdr ps)])
    ps))

(define (delete-directory/files path)
  (unless (path-string? path)
    (raise-type-error 'delete-directory/files "path or string" path))
  (cond
   [(or (link-exists? path) (file-exists? path))
    (delete-file path)]
   [(directory-exists? path)
    (for-each (lambda (e) (delete-directory/files (build-path path e)))
              (sorted-dirlist path))
    (delete-directory path)]
   [else (error 'delete-directory/files
                "encountered ~a, neither a file nor a directory"
                path)]))

(define (copy-directory/files src dest)
  (cond [(file-exists? src)
         (copy-file src dest)]
        [(directory-exists? src)
         (make-directory dest)
         (for-each (lambda (e)
                     (copy-directory/files (build-path src e)
                                           (build-path dest e)))
                   (sorted-dirlist src))]
        [else (error 'copy-directory/files
                     "encountered ~a, neither a file nor a directory"
                     src)]))

(define (make-directory* dir)
  (let-values ([(base name dir?) (split-path dir)])
    (when (and (path? base)
               (not (directory-exists? base)))
      (make-directory* base))
    (unless (directory-exists? dir)
      (make-directory dir))))

(define-syntax (make-temporary-file stx)
  (with-syntax ([app (datum->syntax stx #'#%app stx)])
    (syntax-case stx ()
      [x (identifier? #'x) #'make-temporary-file/proc]
      [(_)
       (let ()
         (define line   (syntax-line stx))
         (define col    (syntax-column stx))
         (define source (syntax-source stx))
         (define pos    (syntax-position stx))
         (define str-src
           (cond [(path? source)
                  (regexp-replace #rx"^<(.*?)>(?=/)"
                                  (path->relative-string/library source)
                                  (lambda (_ s) (string-upcase s)))]
                 [(string? source) source]
                 [else #f]))
         (define str-loc
           (cond [(and line col) (format "-~a-~a" line col)]
                 [pos (format "--~a" pos)]
                 [else ""]))
         (define combined-str (string-append (or str-src "rkttmp") str-loc))
         (define sanitized-str (regexp-replace* #rx"[<>:\"/\\|]" combined-str "-"))
         (define max-len 50) ;; must be even
         (define not-too-long-str
           (cond [(< max-len (string-length sanitized-str))
                  (string-append (substring sanitized-str 0 (- (/ max-len 2) 2))
                                 "----"
                                 (substring sanitized-str
                                            (- (string-length sanitized-str)
                                               (- (/ max-len 2) 2))))]
                 [else sanitized-str]))
         #`(app make-temporary-file/proc
                #,(string-append not-too-long-str "_~a")))]
      [(_ . whatever)
       #'(app make-temporary-file/proc . whatever)])))

(define make-temporary-file/proc
  (let ()
    (define (make-temporary-file [template "rkttmp~a"] [copy-from #f] [base-dir #f])
      (with-handlers ([exn:fail:contract?
                       (lambda (x)
                         (raise-type-error 'make-temporary-file
                                           "format string for 1 argument"
                                           template))])
        (format template void))
      (unless (or (not copy-from)
                  (path-string? copy-from)
                  (eq? copy-from 'directory))
        (raise-type-error 'make-temporary-file
                          "path, valid-path string, 'directory, or #f"
                          copy-from))
      (unless (or (not base-dir) (path-string? base-dir))
        (raise-type-error 'make-temporary-file
                          "path, valid-path, string, or #f"
                          base-dir))
      (let ([tmpdir (find-system-path 'temp-dir)])
        (let loop ([s (current-seconds)]
                   [ms (inexact->exact (truncate (current-inexact-milliseconds)))])
          (let ([name (let ([n (format template (format "~a~a" s ms))])
                        (cond [base-dir (build-path base-dir n)]
                              [(relative-path? n) (build-path tmpdir n)]
                              [else n]))])
            (with-handlers ([exn:fail:filesystem:exists?
                             (lambda (x)
                               ;; try again with a new name
                               (loop (- s (random 10))
                                     (+ ms (random 10))))])
              (if copy-from
                  (if (eq? copy-from 'directory)
                      (make-directory name)
                      (copy-file copy-from name))
                  (close-output-port (open-output-file name)))
              name)))))
    make-temporary-file))

(define (with-pref-params thunk)
  (parameterize ([read-case-sensitive #f]
                 [read-square-bracket-as-paren #t]
                 [read-curly-brace-as-paren #t]
                 [read-accept-box #t]
                 [read-accept-compiled #f]
                 [read-accept-bar-quote #t]
                 [read-accept-graph #t]
                 [read-decimal-as-inexact #t]
                 [read-accept-dot #t]
                 [read-accept-infix-dot #t]
                 [read-accept-quasiquote #t]
                 [read-accept-reader #f]
                 [print-struct #f]
                 [print-graph #f] ; <--- FIXME: temporary solution to DrRacket-pref problem
                 [print-box #t]
                 [print-vector-length #t]
                 [current-readtable #f])
    (thunk)))

(define pref-cache (make-weak-box #f))

(define (path->key p)
  (string->symbol (bytes->string/latin-1 (path->bytes p))))

(define (pref-cache-install! fn-key fn-date f)
  (let ([table (or (weak-box-value pref-cache)
                   (make-hasheq))])
    (hash-set! table 
               (path->key fn-key)
               (cons
                (file-or-directory-modify-seconds fn-date #f (lambda () -inf.0))
                f))
    (unless (eq? table (weak-box-value pref-cache))
      (set! pref-cache (make-weak-box table)))))

(define (make-pathless-lock-file-name name)
  (bytes->path-element
   (bytes-append
    (if (eq? 'windows (system-type))
        #"_"
        #".")
    #"LOCK"
    (path-element->bytes name))))

(define make-lock-file-name
  (case-lambda
   [(path)
    (unless (path-string? path)
      (raise-type-error 'make-lock-file-name "path string" path))
    (let-values ([(dir name dir?) (split-path path)])
      (if (eq? dir 'relative)
          (make-pathless-lock-file-name name)
          (make-lock-file-name dir name)))]
   [(dir name)
    (unless (path-string? dir)
      (raise-type-error 'make-lock-file-name "path string" dir))
    (unless (path-element? name)
      (raise-type-error 'make-lock-file-name "path element" name))
    (build-path dir
                (make-pathless-lock-file-name name))]))

(define (preferences-lock-file-mode)
  (case (system-type)
    [(windows) 'file-lock]
    [else 'exists]))

(define (call-with-file-lock/timeout fn kind thunk failure-thunk
                                     #:lock-file [lock-file #f]
                                     #:delay [delay 0.01]
                                     #:max-delay [max-delay 0.2])
  
  (unless (or (path-string? fn) (eq? fn #f))
    (raise-type-error 'call-with-file-lock/timeout "path-string? or #f" fn))
  (unless (or (eq? kind 'shared) (eq? kind 'exclusive))
    (raise-type-error 'call-with-file-lock/timeout "'shared or 'exclusive" kind))
  (unless (and (procedure? thunk) (= (procedure-arity thunk) 0))
    (raise-type-error 'call-with-file-lock/timeout "procedure (arity 0)" thunk))
  (unless (and (procedure? thunk) (= (procedure-arity failure-thunk) 0))
    (raise-type-error 'call-with-file-lock/timeout "procedure (arity 0)" failure-thunk))
  (unless (or (not lock-file) (path-string? lock-file))
    (raise-type-error 'call-with-file-lock/timeout "path-string? or #f" lock-file))
  (unless (and (real? delay) (not (negative? delay)))
    (raise-type-error 'call-with-file-lock/timeout "non-negative real" delay))
  (unless (and (real? max-delay) (not (negative? max-delay)))
    (raise-type-error 'call-with-file-lock/timeout "non-negative real" max-delay))
  
  (define real-lock-file (or lock-file (make-lock-file-name fn)))
  (let loop ([delay delay])
    (call-with-file-lock 
     kind 
     real-lock-file
     thunk
     (lambda ()
       (if (delay . < . max-delay)
           (begin
             (sleep delay)
             (loop (* 2 delay)))
           (failure-thunk))))))
    
(define (call-with-preference-file-lock who kind get-lock-file thunk lock-there)
  (define lock-style (preferences-lock-file-mode))
  (define lock-file (get-lock-file))
  (define failure-thunk 
    (if lock-there 
        (lambda () (lock-there lock-file))
        (lambda ()
          (case lock-style
            [(file-lock) (error who
                                "~a ~a: ~e"
                                "some other process has a lock"
                                "on the preferences lock file"
                                lock-file)]
            [else (error who
                         "~a, ~a: ~e"
                         "some other process has the preference-file lock"
                         "as indicated by the existence of the lock file"
                         lock-file)]))))
                                  
  (call-with-file-lock kind lock-file thunk failure-thunk #:lock-style lock-style))

(define (call-with-file-lock kind lock-file thunk failure-thunk #:lock-style [lock-style 'file-lock])
  (case lock-style
    [(file-lock)
      ;; Create the lock file if it doesn't exist:
      (unless (file-exists? lock-file)
        (with-handlers ([exn:fail:filesystem:exists? (lambda (exn) 'ok)])
          (close-output-port (open-output-file lock-file #:exists 'error))))
      (((if (eq? kind 'exclusive)
            (lambda (fn proc) (call-with-output-file fn proc #:exists 'update))
            call-with-input-file*)
        lock-file
        (lambda (p)
          (if (port-try-file-lock? p kind)
              ;; got lock:
              (let ([v (dynamic-wind
                           void
                           thunk
                           (lambda ()
                             (port-file-unlock p)))])
                (lambda () v))
              ;; didn't get lock:
              (lambda () (failure-thunk))))))]
    [else ; = 'exists
     ;; Only a write lock is needed, and the file lock 
     ;; is implemented by the presence of the file:
     (case kind
       [(shared) (thunk)]
       [(exclusive)
        (with-handlers ([exn:fail:filesystem:exists? 
                         (lambda (x) (failure-thunk))])
          ;; Grab lock:
          (close-output-port (open-output-file lock-file #:exists 'error)))
        (dynamic-wind 
            void
            thunk
            (lambda ()
              ;; Release lock:
              (delete-file lock-file)))])]))

(define (get-prefs flush-mode filename use-lock? lock-there)
  (define (read-prefs default-pref-file)
    (with-handlers ([exn:fail:filesystem? (lambda (x) null)])
      (let-values ([(pref-file use-lock?)
                    (if filename
                        (values filename use-lock?)
                        (let ([f default-pref-file])
                          (if (file-exists? f)
                              ;; Using `file-exists?' means there's technically a
                              ;; race condition, but something has gone really wrong
                              ;; if the file disappears.
                              (values f use-lock?)
                              ;; Look for old PLT Scheme pref file:
                              (let ([alt-f 
                                     (case (system-type)
                                       [(windows)
                                        (build-path (find-system-path 'pref-dir)
                                                    'up "PLT Scheme" "plt-prefs.ss")]
                                       [(macosx)
                                        (build-path (find-system-path 'pref-dir)
                                                    "org.plt-scheme.prefs.ss")]
                                       [(unix)
                                        (expand-user-path "~/.plt-scheme/plt-prefs.ss")])])
                                (if (file-exists? alt-f)
                                    (values alt-f #f)
                                    ;; Last chance: check for a "defaults" collection:
                                    ;; (error here in case there's no "defaults"
                                    ;;  bails out through above `with-handlers')
                                    (values
                                     (collection-file-path "racket-prefs.rktd"
                                                           "defaults")
                                     #f))))))])
        (let ([prefs (with-pref-params
                      (lambda ()
                        (with-handlers ([exn:fail:read? (lambda (exn)
                                                          (log-error 
                                                           (format "error reading preferences: ~a"
                                                                   (exn-message exn)))
                                                          null)])
                          (if use-lock? 
                              (call-with-preference-file-lock
                               'get-preference
                               'shared
                               (lambda ()
                                 (make-lock-file-name pref-file))
                               (lambda ()
                                 (with-input-from-file pref-file read))
                               lock-there)
                              (with-input-from-file pref-file read)))))])
          ;; Make sure file content had the right shape:
          (if (and (list? prefs)
                   (andmap (lambda (x)
                             (and (pair? x) 
                                  (symbol? (car x))
                                  (pair? (cdr x)) 
                                  (null? (cddr x))))
                           prefs))
              prefs
              (begin
                (log-error "preference file content is not a list of symbol--value lists")
                null))))))
  (let* ([fn (path->complete-path
              (or filename
                  (find-system-path 'pref-file)))]
         [cache (let ([table (weak-box-value pref-cache)])
                  (and table (hash-ref table (path->key fn) #f)))])
    (if (and cache
             (or (not flush-mode)
                 (and (eq? flush-mode 'timestamp)
                      (= (car cache)
                         (file-or-directory-modify-seconds fn #f (lambda () -inf.0))))))
        (cdr cache)
        (let ([ts (file-or-directory-modify-seconds fn  #f (lambda () -inf.0))]
              [f (read-prefs fn)])
          (pref-cache-install! fn fn f)
          f))))

(define (make-handle-get-preference-locked delay 
                                           name 
                                           [fail-thunk (lambda () #f)]
                                           [refresh-cache? 'timestamp]
                                           [filename #f]
                                           #:lock-there [lock-there #f]
                                           #:max-delay [max-delay 0.2])
  (lambda (lock-filename)
    (sleep delay)
    (get-preference name fail-thunk refresh-cache? filename 
                    #:lock-there (let ([new-delay (* 2 delay)])
                                   (if (new-delay . < . max-delay)
                                       (make-handle-get-preference-locked
                                        new-delay
                                        name fail-thunk refresh-cache? filename
                                         #:lock-there lock-there
                                         #:max-delay max-delay)
                                       lock-there)))))

(define (get-preference name [fail-thunk (lambda () #f)]
                        [refresh-cache? 'timestamp]
                        [filename #f]
                        #:timeout-lock-there [timeout-lock-there #f]
                        #:lock-there [lock-there 
                                      (make-handle-get-preference-locked
                                       0.01
                                       name
                                       fail-thunk
                                       refresh-cache?
                                       filename
                                       #:lock-there timeout-lock-there)]
                        #:use-lock? [use-lock? #t])
  (unless (symbol? name)
    (raise-type-error 'get-preference "symbol" name))
  (unless (and (procedure? fail-thunk)
               (procedure-arity-includes? fail-thunk 0))
    (raise-type-error 'get-preference "procedure (arity 0)" fail-thunk))
  ((let/ec esc
     (let ([f (get-prefs refresh-cache? filename use-lock? 
                         (and lock-there
                              (lambda (file)
                                (esc (lambda () (lock-there file))))))])
       (lambda ()
         (let ([m (assq name f)])
           (if m (cadr m) (fail-thunk))))))))

(define (put-preferences names vals [lock-there #f] [filename #f])
  (unless (and (list? names) (andmap symbol? names))
    (raise-type-error 'put-preferences "list of symbols" names))
  (unless (list? vals)
    (raise-type-error 'put-preferences "list" vals))
  (unless (= (length names) (length vals))
    (raise-mismatch-error
     'put-preferences
     (format "the size of the name list (~a) does not match the size of the value list (~a): "
             (length names) (length vals))
     vals))
  (let-values ([(pref-file lock-file pref-dir)
                (let ([filename (or filename (find-system-path 'pref-file))])
                  (let-values ([(base name dir?) (split-path filename)])
                    (let ([dir (if (symbol? base)
                                   (current-directory)
                                   base)])
                      (unless (directory-exists? dir)
                        (make-directory* dir))
                      (values
                       filename
                       (make-lock-file-name dir name)
                       dir))))])
    (call-with-preference-file-lock
     'put-preferences
     'exclusive
     (lambda () lock-file)
     (lambda ()
       (let ([f (get-prefs #t filename #f #f)])
         (set! f (let loop ([f f][a null])
                   (cond
                    [(null? f) (reverse
                                (append (map list names vals)
                                        a))]
                    [else (if (memq (caar f) names)
                              (loop (cdr f) a)
                              (loop (cdr f) (cons (car f) a)))])))
         ;; To write the file, copy the old one to a temporary name
         ;; (preserves permissions, etc), write to the temp file,
         ;; then move (atomicly) the temp file to the normal name.
         (let ([tmp-file (make-temporary-file
                          "TMPPREF~a"
                          (and (file-exists? pref-file) pref-file)
                          pref-dir)])
           ;; If something goes wrong, try to delete the temp file.
           (with-handlers ([exn:fail? (lambda (exn)
                                        (with-handlers ([exn:fail:filesystem? void])
                                          (delete-file tmp-file))
                                        (raise exn))])
             ;; Write to temp file...
             (with-output-to-file tmp-file
               #:exists 'truncate/replace
               (lambda ()
                 (with-pref-params
                  (lambda ()
                    ;; If a pref value turns out to be unreadable, raise
                    ;;  an exception instead of creating a bad pref file.
                    (parameterize ([print-unreadable #f])
                      ;; Poor man's pretty-print: one line per entry.
                      (printf "(\n")
                      (for-each (lambda (a)
                                  (if (and (list? (cadr a))
                                           (< 4 (length (cadr a))))
                                      (begin
                                        (printf " (~s\n  (\n" (car a))
                                        (for-each (lambda (i) (printf "   ~s\n" i)) (cadr a))
                                        (printf "  ))\n"))
                                      (printf " ~s\n" a)))
                                f)
                      (printf ")\n"))))))
             ;; Install the new table in the cache. It's possible that this
             ;; cache entry will be replaced by a reading thread before we
             ;; move the file, but that's ok. It just means that a future
             ;; reading thread will have to read again.
             (pref-cache-install! (path->complete-path
                                   (or filename
                                       (find-system-path 'pref-file)))
                                  tmp-file
                                  f)
             (rename-file-or-directory tmp-file pref-file #t)))))
     lock-there)))

;; fold-files : (pathname sym alpha -> alpha) alpha pathname/#f -> alpha
(define (fold-files f init [path #f] [follow-links? #t])
  (define-syntax-rule (keep-fst e)
    (call-with-values (lambda () e) (case-lambda [(v) v] [(v _) v])))
  (define (do-path path acc)
    (cond [(and (not follow-links?) (link-exists? path))
           (keep-fst (f path 'link acc))]
          [(directory-exists? path)
           (call-with-values (lambda () (f path 'dir acc))
               (lambda (acc [descend? #t])
                 (if descend?
                   (do-paths (map (lambda (p) (build-path path p))
                                  (sorted-dirlist path))
                             acc)
                   acc)))]
          [(file-exists? path) (keep-fst (f path 'file acc))]
          [(link-exists? path) (keep-fst (f path 'link acc))] ; dangling links
          [else (error 'fold-files "path disappeared: ~e" path)]))
  (define (do-paths paths acc)
    (cond [(null? paths) acc]
          [else (do-paths (cdr paths) (do-path (car paths) acc))]))
  (if path (do-path path init) (do-paths (sorted-dirlist) init)))

(define (find-files f [path #f])
  (reverse
   (fold-files (lambda (path kind acc) (if (f path) (cons path acc) acc))
               null path)))

(define (pathlist-closure paths)
  (let loop ([paths
              (map (lambda (p)
                     (simplify-path
                      (if (link-exists? p)
                        (let ([p2 (resolve-path p)])
                          (if (relative-path? p2)
                            (let-values ([(base name dir?) (split-path p)])
                              (build-path base p2))
                            p2))
                        p)
                      #f))
                   paths)]
             [r '()])
    (if (null? paths)
      (reverse r)
      (let loop2 ([path (car paths)]
                  [new (cond [(file-exists? (car paths))
                              (list (car paths))]
                             [(directory-exists? (car paths))
                              (find-files void (car paths))]
                             [else (error 'pathlist-closure
                                          "file/directory not found: ~a"
                                          (car paths))])])
        (let-values ([(base name dir?) (split-path path)])
          (if (path? base)
            (loop2 base (if (or (member base r) (member base paths))
                          new (cons base new)))
            (loop (cdr paths) (append (reverse new) r))))))))

(define (check-path who f)
  (unless (path-string? f)
    (raise-type-error who "path string" f)))

(define (check-file-mode who file-mode)
  (unless (memq file-mode '(binary text))
    (raise-type-error who "'binary or 'text" file-mode)))

(define (file->x who f file-mode read-x x-append)
  (check-path who f)
  (check-file-mode who file-mode)
  (let ([sz (file-size f)])
    (call-with-input-file* f #:mode file-mode
      (lambda (in)
        ;; There's a good chance that `file-size' gets all the data:
        (let ([s (read-x sz in)])
          ;; ... but double-check:
          (let ([more (let loop ()
                        (let ([l (read-x 4096 in)])
                          (if (eof-object? l) null (cons l (loop)))))])
            (if (null? more) s (apply x-append (cons s more)))))))))

(define (file->string f #:mode [mode 'binary])
  (file->x 'file->string f mode read-string string-append))

(define (file->bytes f #:mode [mode 'binary])
  (file->x 'file->bytes f mode read-bytes bytes-append))

(define (file->value f #:mode [file-mode 'binary])
  (check-path 'file->value f)
  (check-file-mode 'file->value file-mode)
  (call-with-input-file* f #:mode file-mode read))

(define (file->list f [r read] #:mode [file-mode 'binary])
  (check-path 'file->list f)
  (check-file-mode 'file->list file-mode)
  (unless (and (procedure? r) (procedure-arity-includes? r 1))
    (raise-type-error 'file->list "procedure (arity 1)" r))
  (call-with-input-file* f #:mode file-mode
    (lambda (p) (for/list ([v (in-port r p)]) v))))

(define (file->x-lines who f line-mode file-mode read-line)
  (check-path who f)
  (check-mode who line-mode)
  (check-file-mode who file-mode)
  (call-with-input-file* f #:mode file-mode
    (lambda (p) (port->x-lines who p line-mode read-line))))

(define (file->lines f #:line-mode [line-mode 'any] #:mode [file-mode 'binary])
  (file->x-lines 'file->lines f line-mode file-mode read-line))

(define (file->bytes-lines f #:line-mode [line-mode 'any] #:mode [file-mode 'binary])
  (file->x-lines 'file->bytes-lines f line-mode file-mode read-bytes-line))

(define (->file who f mode exists write)
  (unless (path-string? f)
    (raise-type-error who "path string" f))
  (unless (memq mode '(binary text))
    (raise-type-error who "'binary or 'text" mode))
  (unless (memq exists '(error append update replace truncate truncate/replace))
    (raise-type-error who "'error, 'append, 'update, 'replace, 'truncate, or 'truncate/replace" exists))
  (call-with-output-file* f #:mode mode #:exists exists write))

(define (display-to-file s f #:mode [mode 'binary] #:exists [exists 'error])
  (->file 'display-to-file f mode exists (lambda (p) (display s p))))

(define (write-to-file s f #:mode [mode 'binary] #:exists [exists 'error])
  (->file 'write-to-file f mode exists (lambda (p) (write s p))))

(define (display-lines-to-file l f
                               #:mode [mode 'binary]
                               #:exists [exists 'error]
                               #:separator [newline #"\n"])
  (unless (list? l)
    (raise-type-error 'display-lines-to-file "list" l))
  (->file 'display-lines-to-file f mode exists
          (lambda (p) (do-lines->port l p newline))))

(define user-read-bit     #o400)
(define user-write-bit    #o200)
(define user-execute-bit  #o100)
(define group-read-bit    #o040)
(define group-write-bit   #o020)
(define group-execute-bit #o010)
(define other-read-bit    #o004)
(define other-write-bit   #o002)
(define other-execute-bit #o001)
