;;; chicken-doc

(include "chicken-doc-text.scm") ; local module

(module chicken-doc
;; Used by chicken-doc command
(verify-repository
 open-repository close-repository locate-repository current-repository
 describe-signatures
 search-only
 describe-contents
 describe
 doc-dwim
;; Used additionally by chicken-doc-admin.  Somewhat internal, but exported.
 repository-information repository-root repository-base open-repository*
 repository-magic +repository-version+
 repository-id-cache set-repository-id-cache!
 path->keys keys->pathname field-filename keys+field->pathname key->id
 make-id-cache id-cache-filename id-cache-table validate-id-cache!
 make-repository-placeholder
 repository-modification-time
;; Node API
 lookup-node
 match-nodes
 match-node-paths/re
 match-ids/prefix
 match-paths/prefix
 node-signature
 node-type
 node-sxml
 node-path
 node-id
 node-timestamp
 node-children
 node-child
 node-child-ids
 node-definition-ids    ;experimental
 node-definition-id?    ;experimental
;; Other API
 decompose-qualified-path
;; Parameters
 wrap-column
 chicken-doc-warnings
 )

(import scheme)
(cond-expand
  (chicken-4
   (import chicken)
   (use matchable srfi-13 posix data-structures srfi-69 extras files utils srfi-1)
   (use irregex)
   (import (only csi toplevel-command))
   (import chicken-doc-text))
  (else
   (import (chicken base))
   (import (chicken irregex))
   (import (chicken fixnum))
   (import (chicken pathname))
   (import (chicken string))
   (import (chicken sort))
   (import (chicken condition))
   (import (chicken format))
   (import (chicken file) (chicken file posix))
   (import (only (chicken platform) chicken-home feature?))
   (import (only (chicken gc) set-finalizer!))
   (import (only (chicken io) read-line))
   (import (rename (only (chicken io) read-list)
                   (read-list read-file)))  ;; chicken 4 compat
   (import (only (chicken process-context) get-environment-variable))
   (import srfi-1)
   (import srfi-13)
   (import srfi-69)
   (import matchable)
   (import chicken-doc-text)
   ;; note: do not import chicken.csi yet
   )
)

;;; Config

(define wrap-column
  (make-parameter 76))   ; 0 or #f for no wrapping
(define chicken-doc-warnings
  (make-parameter #f))

;;; Lowlevel

(define +rx:%escape+ (irregex "[%/,.*<>?!: ]"))
(define +rx:%unescape+ (irregex "%([0-9a-fA-F][0-9a-fA-F])"))

(define (id->key id)
  (define (escape str)
    (irregex-replace/all +rx:%escape+ str
                         (lambda (m) (sprintf "%~x"
                                         (char->integer
                                          (string-ref (irregex-match-substring m 0) 0))))))
  (let ((str (escape (->string id))))
    (cond ((or (string=? str ".")
               (string=? str ".."))
           (warning "Identifier must not be . or .." str)     ;; ?
           #f)
          (else
           str))))
(define (key->id key)
  (string->symbol
   (irregex-replace/all +rx:%unescape+ key
                        (lambda (m) (string
                                (integer->char
                                 (string->number (irregex-match-substring m 1)
                                                 16)))))))

(define (path->keys path)
  (map id->key path))
(define (keys->pathname keys)
  (make-pathname (cons (repository-root (current-repository)) keys) #f))
(define (field-filename name)
  (string-append "," (->string name)))
(define (pathname+field->pathname pathname field)
  (make-pathname pathname (field-filename field)))
(define (keys+field->pathname keys field)  ;; should this take a path instead of keys?
  (pathname+field->pathname (keys->pathname keys) field))

;; Turn pathspec (a path list or path string) into a path or id.
;; Path lists pass through.  Qualified path strings (contains #) become
;; path lists.  Unqualified path strings become ids (symbols).  An empty
;; path string becomes () -- i.e. toplevel.
(define (decompose-pathspec pathspec)
  (if (pair? pathspec)
      pathspec
      (let ((p (decompose-qualified-path pathspec)))
        (cond ((null? p) p)
              ((null? (cdr p)) (string->symbol (car p)))
              (else p)))))

;; Split path STR at #.  However, keep any #+ prefix in the first segment.
;; In other words, sys#foo#bar -> ("sys" "foo" "bar")
;; but ##sys#foo#bar -> ("##sys" "foo" "bar")
;; and #u8 -> ("#u8").  Allows # read syntax and internal namespaces.
(define (decompose-qualified-path path)
  (let ((str (if (symbol? path) (symbol->string path) path)))
    (cond ((string=? str "") '())  ;; string-skip returns #f for ""
          ((string-skip str #\#)
           => (lambda (i)
                (if (= i 0)
                    (string-split str "#")
                    (let ((S (string-split (substring str i) "#")))
                      (cons (string-append (substring str 0 i)
                                           (car S))
                            (cdr S))))))
          (else str)   ;; all #s
          )))

;;; Access

(define-record-type chicken-doc-node
  (%make-node path id md pathname definfo)
  node?
  (path node-path)            ; includes ID
  (id node-id)
  (md node-md)
  (pathname node-pathname)    ; internal; cached node pathname
  (definfo %node-definfo)    ; internal; node definitions record
  )

(define (node-definfo n)
  (force (%node-definfo n)))

(define-record-type chicken-doc-node-definfo
  (make-node-definfo index start pathname)
  node-definfo?
  (index node-definfo-index)
  (start node-definfo-start)
  (pathname node-definfo-pathname))

(define (make-empty-node-definfo)
  (make-node-definfo #f 0 #f))
(define (node-definfo-keys D)
  (let ((I (node-definfo-index D)))
    (if I
        (hash-table-keys (node-definfo-index D))
        '())))
(define (node-definfo-offset D id)
  (car (hash-table-ref/default (node-definfo-index D) id '(#f))))
(define (node-definfo-sxml D id)
  (cond ((node-definfo-offset D id)
         => (lambda (o)
              (let ((pos (+ o (node-definfo-start D))))
                (call-with-input-file*
                 (node-definfo-pathname D)
                 (lambda (p)
                   (set-file-position! p pos seek/set)
                   (read p))))))
        (else #f)))

(define (make-node path id pathname)
  (%make-node path id
              (delay (read-path-metadata pathname))
              pathname
              (delay (read-definfo pathname))))

;; Return string list of child keys (directories) directly under PATH, or #f
;; if the PATH is invalid.  FIXME: might return '() if PATH indicates a
;; definition node (or if that is otherwise indicated).

(define (node-child-keys node)
  (let ((dir (node-pathname node)))
    (if (directory? dir)
        (filter (lambda (x) (not (eqv? (string-ref x 0) #\,)))  ;; Contains hardcoded ,
                (sort (directory dir) string<?))
        '())))

(define (node-children node)   ;; FIXME: inefficient for definition children.
  (map (lambda (id) (node-child node id))
       (node-child-ids node)))

;; Returns child node of NODE with id ID, or #f if not found.
(define (node-child node id)
  (let ((path (node-path node))
        (pathname (node-pathname node)))
    (let ((child-path (append path (list id)))
          (idstr (->string id)))
      (if (node-definition-id? node idstr)
          (make-definition-node node child-path idstr)
          (let ((child-pathname (make-pathname pathname (id->key id))))  ;; otherwise regular node
            (and (directory? child-pathname)
                 (make-node child-path id child-pathname)))))))

;; Shortcut if you only need identifiers for node children.
;; Might be faster than node-children.
(define (node-child-ids node)
  (append (map key->id (node-child-keys node))
          (node-definition-ids node)))

;; (define (node-definition-ids node)
;;   (let next-def ((defs (node-definitions node))
;;                  (ids '()))
;;     (if (null? defs)
;;         ids
;;         (let next-sig ((sigs (cdadr (car defs))) (sigids '()))
;;           (if (null? sigs)
;;               (next-def (cdr defs)
;;                         (append sigids ids))
;;               (let* ((x (car sigs)) (type (car x)) (sig (cadr x)) (alist (cddr x)))
;;                 (next-sig
;;                  (cdr sigs)
;;                  (cons
;;                   (cond ((assq 'id alist) => cadr) ;; Check for pre-parsed ID.
;;                         (else
;;                          (error 'node-definition-ids "preparsed ID unavailable")))
;;                   sigids))))))))

(define (node-definition-ids node)
  (sort (node-definfo-keys (node-definfo node))
        string<?))
(define (node-definition-id? node id)
  (and-let* ((D (node-definfo node))       ;; check if this node is in the definition index
             (I (node-definfo-index D)))
    (hash-table-exists? I (->string id))))

(define (make-definition-node parent path id)
  (define (find-sig def id)
    (let ((sigs (cdadr def)))
      (find (lambda (s) (cond ((assq 'id (cddr s))
                          => (lambda (idc) (equal? id (->string (cadr idc)))))
                         (else #f)))
            sigs)))
  (define (get-definition-sxml parent id)
    (node-definfo-sxml (node-definfo parent) id))
  (define (definition-sxml->metadata sxml parent id)
    (let ((s (find-sig sxml id)))
      (if s
          (let ((type (car s)) (signature (cadr s)))
            `((type ,type)
              (signature ,signature)
              (timestamp ,(node-timestamp parent))
              (sxml ,sxml)))
          (error 'definition-sxml->metadata "no match for id in signature" id))))
  (%make-node path id
              (definition-sxml->metadata (get-definition-sxml parent id) parent id)
              (pathname+field->pathname (node-pathname parent) 'defs) ;; tmp -- non-dir indicates def node
              (make-empty-node-definfo)))

;; Obtain metadata alist at node at PATHNAME.  Valid node without metadata record
;; returns '().  Invalid node throws error.
(define (read-path-metadata pathname)
  (let ((metafile (pathname+field->pathname pathname 'meta)))
    (cond ((file-exists? metafile)
           (call-with-input-file* metafile read-file)) ;; ensure binary read
          ((directory? pathname)
           ;; write-keys may create intermediate container directories
           ;; without metadata, so handle this specially.
           '())
          (else
           (error "No such metadata pathname" metafile) ;; internal error
           ))))

(define (call-with-input-file* file proc)
  (let ((p (open-input-file file #:binary)))
    (handle-exceptions exn (begin (close-input-port p)
                                  (signal exn))
      (let ((rc (proc p)))
        (close-input-port p)
        rc))))
(define (read-definfo pathname)
  (let ((deffile (pathname+field->pathname pathname 'defs)))
    (cond ((file-exists? deffile)
           (call-with-input-file* deffile
             (lambda (p)
               (let ((index (read p)))
                 (unless (and (pair? index)
                              (eq? (car index) 'index))
                   (error "Invalid file format in definition index"))
                 (make-node-definfo (alist->hash-table (cdr index) string=?)
                                    (+ (file-position p) 1) deffile)))))
          (else
           (make-empty-node-definfo)))))

(define (node-metadata-field node field)
  (cond ((assq field (node-metadata node))
         => cadr)
        (else #f)))

(define (node-metadata node)
  (force (node-md node)))         ;  load metadata as needed

(define (node-definitions node)
  (force (node-metadata-field node 'defs)))

;; Return node record at PATH or throw error if the record does
;; not exist.  It would be acceptable to return #f on failure,
;; like node-child does; the only reason we don't is to
;; signal to the caller which part of the path lookup failed,
;; which is perhaps not that useful.
(define (lookup-node path)
  (define (make-root-node)
    (make-node '() "" (keys->pathname '())))
  (let loop ((node (make-root-node))
             (P path))
    (if (null? P)
        node
        (loop (or (node-child node (car P))
                  (error 'lookup-node "node path not found"
                         `(,@(node-path node) ,(car P))))
              (cdr P)))))

;; Return string representing signature of PATH.  If no signature, return "".
(define (node-signature node)
  (or (node-metadata-field node 'signature)
      ""))

;; Return symbol representing type of PATH, or 'unknown.
(define (node-type node)
  (let ((key (node-metadata-field node 'type)))
    (if key
        (if (string? key)
            (string->symbol key)
            key)
        'unknown)))

;; Return SXML document for node.  If small enough, it may be packed
;; into the metadata; otherwise read it from the filesystem.
(define (node-sxml node)
  (or (node-metadata-field node 'sxml)  ;; FIXME? Returns #f on (sxml #f)
      (let* ((file (pathname+field->pathname (node-pathname node)
                                             'sxml)))
        (and (file-exists? file)
             (with-input-from-file file read)))))

#|
(define (node-modification-time node)
  ;; hypothetical function returning the last update time of a node.
  ;; The most accurate result is probably obtained by returning the
  ;; mtime of the ,meta file.  Clients may also want to know when
  ;; children have been updated (or at least when the child IDs change).
  ;; It may be sufficient to check the parent directory mtime or
  ;; the max of that and ,meta since rename, add and delete of child
  ;; directories will change parent mtime.  Parent mtime is usually
  ;; not affected when ,meta or ,sxml file is overwritten, though.
  )
  
|#

;; Return timestamp of a node in seconds since UNIX epoch,
;; or #f if no timestamp was available. (Should we return 0 in that case?)
(define (node-timestamp node)
  (node-metadata-field node 'timestamp))

;;; Describe

;; Utility procedure (dropped in Chicken >= 4.3.2)
(define (for-each-line proc #!optional (port (current-input-port)))
  (do ((line (read-line port) (read-line port)))
      ((eof-object? line))
    (proc line)))

;; Display file to stdout
(define (cat file)
  (with-input-from-file file
    (lambda ()
      (for-each-line (lambda (x) (display x) (newline))))))

;; Display the "text" field of NODE to current-output-port.  Even if
;; NODE is a valid node, that doesn't mean it has text contents.
(define (describe node)
  (cond ((node-sxml node)
         => (lambda (doc)
              (write-sxml-as-text doc (wrap-column)
                                  warnings: (chicken-doc-warnings))))
        (else
         (error "No such identifier"
                (sprintf "~a" (node-path node))))))

;; Display the signature of all child keys of PATH, to stdout.
(define (maximum-string-length strs)
  (reduce max 0 (map string-length strs)))
(define (padding len s)
  (make-string (max 0 (- len (string-length s)))
               #\space))
(define (describe-contents node)
  (let ((kids (node-children node)))
    (let* ((strids (map ->string (map node-id kids)))
           (len (maximum-string-length strids)))
      (for-each (lambda (n s) (print s (padding len s)
                                "  "
                                (node-signature n)))
                kids strids))))

(define (describe-signatures nodes)
  (let* ((strpaths (map ->string (map node-path nodes)))
         (len (maximum-string-length strpaths)))
    (for-each (lambda (n s) (print s (padding len s)
                              "  "
                              (node-signature n)))
              nodes strpaths)))

(define (describe-matches nodes)
  (print "Found " (length nodes) " matches:")
  (describe-signatures nodes))

;;; ID search cache

;; Cache is unique to repository but is shared between
;; threads holding the same repository object.
(define-record-type id-cache
  (%make-id-cache table mtime filename
                  ids ; id string vector
                  paths ; path string vector
                  )
  id-cache?
  (table id-cache-table)
  (mtime id-cache-mtime)
  (filename id-cache-filename)
  (ids %id-cache-ids)
  (paths %id-cache-paths))

;; Delayed construction of id string list and paths is legal
;; because cache updates are disallowed.  Note that any
;; change to the id cache on disk will result in revalidation
;; and full recomputation of the delayed constructors.
(define (make-id-cache table mtime filename)
  (%make-id-cache table mtime filename
                  (delay (list->vector
                          (sort (map ->string (hash-table-keys table))
                                ;; ->string not symbol->string to workaround WRITE bug for integer symbols
                                string<?)))
                  (delay (list->vector
                          (sort
                           (flatten
                            (hash-table-fold
                             table
                             (lambda (k v s)
                               (cons
                                (map (lambda (x)
                                       (string-intersperse
                                        (map ->string (append x (list k))) " "))
                                     v)
                                s))
                             '()))
                           string<?)))))

(define (make-invalid-id-cache repo-base)
  (make-id-cache #f 0
                 (make-pathname repo-base "id.idx")))

(define (current-id-cache)  ; access current id cache hash table; legacy
  (repository-id-cache (current-repository)))
(define (id-cache-ref c id)
  (hash-table-ref/default (id-cache-table c) id '()))
(define (id-cache-keys c)
  (hash-table-keys (id-cache-table c)))

;; Validate and update the shared id cache in repository R.
(define (validate-id-cache! r)
  (define (read-id-cache! r c)
    (define (read-id-cache c)
      (let ((fn (id-cache-filename c)))
        (call-with-input-file fn
          (lambda (in)
            ;; Convert all incoming keys to symbols; they are stored as strings
            ;; but much code expects symbolic keys. They were formerly stored as symbols (even
            ;; integers) but this caused r/w invariance issues with read syntax.
            ;; Values are still stored as lists of symbols, but we stipulate read syntax should
            ;; never have child nodes.
            (define (->symbol x)
              (string->symbol (->string x)))
            (let ((idx-alist (map (lambda (p)
                                    (cons (->symbol (car p)) (cdr p)))
                                  (read in))))
              (make-id-cache
               (alist->hash-table idx-alist eq?)
               (file-modification-time (port->fileno in))
               fn))))))
    (set-repository-id-cache! r (read-id-cache c)))

  ;; We don't currently lock id-cache validations with a mutex.
  ;; All that (should) happen is that when the cache is (rarely)
  ;; updated, if two threads validate at the same time both will
  ;; read the entire cache in.
  (let* ((c (repository-id-cache r)))
    (when (< (id-cache-mtime c)
             (file-modification-time (id-cache-filename c)))
      (read-id-cache! r c))))

;; Not currently needed.  Also not tested and not thread-safe
;; (define (invalidate-id-cache!)
;;   (set-repository-id-cache! (current-repository) (make-invalid-id-cache)))

;; Return a list of sorted IDs as strings, suitable for regex node matching.
;; Construction is lazy because it is not that cheap.
(define (id-cache-ids c)
  (force (%id-cache-ids c)))
;; This one's pretty expensive (time and space wise).
(define (id-cache-paths c)
  (force (%id-cache-paths c)))

;;; ID search

;; Returns list of nodes matching identifier ID.
;; ID may be a symbol or string.  LIMIT is an integer
;; indicating the maximum number of results to return,
;; or #f for no limit.
(define (match-nodes/id id #!optional limit)
  (define (lookup id)
    (id-cache-ref (current-id-cache) id))
  (define (take-up-to lim L)
    (let loop ((i 0) (L L) (acc '()))
      (if (or (>= i lim) (null? L))
          (reverse acc)
          (loop (add1 i) (cdr L) (cons (car L) acc)))))
  (validate-id-cache! (current-repository))
  (let ((id (if (string? id) (string->symbol id) id)))
    (map (lambda (x)
           (lookup-node (append x (list id))))
         (if limit
             (take-up-to limit (lookup id))
             (lookup id)))))

(define (vector-filter-map f v #!optional (limit -1))
  ;; filter-map vector V to list.  this is here because
  ;; we converted the id-cache-ids to a vector.  If limit is
  ;; given and non-negative, limits returned results.
  (let ((len (vector-length v)))
    (let lp ((i 0) (L '()) (left limit))
      (if (or (fx>= i len)
              (= 0 left))
          (reverse L)
          (let ((x (f i (vector-ref v i))))
            (if x
                (lp (fx+ i 1) (cons x L) (fx- left 1))
                (lp (fx+ i 1) L left)))))))
(define (vector-copy v #!optional (start 0) (end (vector-length v)) (fill (void)))
  ;; SRFI-43 vector-copy.  Why is vector-lib's implementation so verbose?
  (let ((len (vector-length v)))
    (when (> start end) (error 'vector-copy "start > end" start end))
    (when (< start 0)   (error 'vector-copy "start < 0" start))
    (when (> start len) (error 'copy-vec "start > len" start len))
    (let ((c (make-vector (- end start))))
      (let ((end (min end len)))
        (let loop ((vi start)
                   (ci 0))
          (cond ((< vi end)
                 (vector-set! c ci (vector-ref v vi))
                 (loop (+ vi 1) (+ ci 1)))
                (else c)))))))

;; Like append-map, but caps returned list length at LIM, an integer.
;; Negative LIM means unlimited.  Also passes the remaining LIM to F
;; so F may optionally limit its own output to save computation.
;; Note this algorithm is iterative (in both the inner and outer loop)
;; unlike SRFI 1 append-map.
(define (append-map/limit f L lim)
  (let loop ((lim lim) (R '()) (L L))
    (if (or (null? L)
            (= lim 0))
        (reverse R)
        (let inner ((lim lim)
                    (R R)
                    (M (f (car L) lim)))
          (if (or (null? M)
                  (= lim 0))
              (loop lim R (cdr L))
              (inner (- lim 1)
                     (cons (car M) R)
                     (cdr M)))))))

;; Returns list of nodes whose identifiers match regex RE.
;; Optional LIMIT is an integer indicating maximum number of results to
;; return, or #f for unlimited.
(define (match-nodes/re re #!optional limit)
  (let ((rx (irregex re)))
    (validate-id-cache! (current-repository))
    (append-map/limit
     (lambda (id lim) (match-nodes/id id (if (< lim 0) #f lim)))
     (vector-filter-map (lambda (i k)   ; was filter-map
                          (and (irregex-search rx k) k))
                        (id-cache-ids (current-id-cache))
                        ;; Upper bound on results we need, since match-nodes
                        ;; will return 1 or more per call.  Thus we do some
                        ;; regex work here that may be thrown away.
                        (if limit limit -1))
     (if limit limit -1))))

;; Match against full node paths with RE.  Optional LIMIT is
;; an integer indicating maximum number of results to
;; return, or #f for unlimited.
(define (match-node-paths/re re #!optional limit)
  (let ((rx (irregex re)))
    (validate-id-cache! (current-repository))
    (map (lambda (path)
           (lookup-node (string-split path))) ; stupid resplit
         (vector-filter-map (lambda (i k)
                              (and (irregex-search rx k) k))
                            (id-cache-paths (current-id-cache))
                            (if limit limit -1)))))

;; Search for "nearest" VAL in vector V at start or end of a range.
;; START? is a boolean indicating whether this is the start or end of
;; the range.  INCLUSIVE? is a boolean indicating whether VAL itself
;; should be included in the results.  CMP is a procedure of two
;; arguments x y which returns < 0 if x < y, 0 if x = y, or > 0 if x >
;; y.  Returns a vector index of the nearest value; in "start" mode
;; this is inclusive, in "end" mode it is exclusive.
(define (binary-search-nearest v val cmp start? inclusive?)
  (let ((len (vector-length v)))
    (let lp ((L 0)
             (R len))
      (let ((M (fx/ (fx+ R L) 2)))
        (let ((item (vector-ref v M)))
          ;;(printf "item: ~a L: ~a M: ~a R: ~a\n" item L M R)
          (let ((dir (cmp val item)))
            (cond ((fx= dir 0)
                   (if inclusive?
                       (if start? M (fx+ M 1))
                       (if start? (fx+ M 1) M)))
                  ((fx< dir 0)
                   (if (fx> M L)
                       (lp L M)
                       M))           ; not sure this can happen
                  (else
                   (if (fx< M (- R 1))
                       (lp M R)
                       (fx+ M 1))))))))))

;; Return a vector (??) of identifier name strings or full path
;; strings which match the prefix STR.
(define match-ids/prefix)     ; probably not the best name
(define match-paths/prefix)

(let ()
  (define (strcmp x y)
    (cond ((string<? x y) -1)
          ((string=? x y) 0)
          (else 1)))
  ;; finds strings in v in range [str1,str2) and returns indices [start . end)
  (define (binary-search-range v str1 str2)
    (cons (binary-search-nearest v str1 strcmp #t #t)
          (binary-search-nearest v str2 strcmp #f #f)))
  (define (next-string str)
    ;; ASSUMING BYTE SEMANTICS!
    ;; Note that src char #\xff will fail and wrap around.
    (let ((len (string-length str))
          (new (string-copy str)))
      (string-set! new (- len 1)
                   (integer->char (+ 1 (char->integer
                                        (string-ref str (- len 1))))))
      new))
  (define (match-vector v str limit)
    (if (= 0 (string-length str))
        '#()
        (match (binary-search-range v str (next-string str))
               ((start . end)
                (if limit
                    (vector-copy v start (min (+ start limit) end))
                    (vector-copy v start end))))))

  (set! match-ids/prefix
        (lambda (str #!optional (limit #f))
          (validate-id-cache! (current-repository))
          (match-vector (id-cache-ids (current-id-cache))
                        str limit)))
  (set! match-paths/prefix
        (lambda (str #!optional (limit #f))
          (validate-id-cache! (current-repository))          
          (match-vector (id-cache-paths (current-id-cache))
                        str limit))))

;; ,t (validate-id-cache!)
;;    0.123 seconds elapsed
;;    0.024 seconds in (major) GC
;;    47942 mutations
;;        3 minor GCs
;;        5 major GCs
;; after id cache loaded, disk cache warm
;; ,t (match-nodes (irregex "posix"))
;;    0.065 seconds elapsed                (0.06 - 0.10 sec)
;;        0 seconds in (major) GC
;;    68054 mutations
;;      832 minor GCs
;;        0 major GCs
;; after id-cache-ids cache
;; ,t (match-nodes (irregex "posix"))
;;    0.036 seconds elapsed
;;        0 seconds in (major) GC
;;     9642 mutations
;;       83 minor GCs
;;        0 major GCs
;; ,t (match-nodes (irregex "."))
;;    1.978 seconds elapsed           ; actually about 10-15 seconds on disk
;;    0.057 seconds in (major) GC
;;   147205 mutations
;;      404 minor GCs
;;        4 major GCs
;; time chicken-doc -m . >/dev/null    ; presuming totally warm disk cache
;; real    0m0.960s
;; ,t (match-nodes (irregex "."))
;;    0.321 seconds                    ; if metadata read is delayed, but dir checked
;;    0.133 seconds                    ; if metadata read delayed and dir not checked
;;    0.250 seconds                    ; if metadata read delayed and dir not checked, but path->pathname still computed



;; Return list of nodes whose identifiers match
;; symbol, string or re.
(define (match-nodes idre #!optional limit)
  (if (or (irregex? idre))
      (match-nodes/re idre limit)
      (match-nodes/id idre limit)))

(define (search-and-describe id)
  (let ((nodes (match-nodes id)))
    (cond ((null? nodes)
           (error "No such identifier" id))
          ((null? (cdr nodes))
           (print "path: " (node-path (car nodes)))
           (describe (car nodes)))
          (else
           (describe-matches nodes)))))
(define (search-only id)
  (let ((nodes (match-nodes id)))
    (describe-signatures nodes)))
(define (search-and-describe-contents id)
  (let ((nodes (match-nodes id)))
    (cond ((null? nodes)
           (void))
          ((null? (cdr nodes))
           (print "path: " (car nodes))
           (describe-contents (car nodes)))
          (else
           (describe-matches nodes)))))

(define (doc-dwim pathspec)
  (let ((p (decompose-pathspec pathspec)))
    (if (or (pair? p) (null? p))
        (describe (lookup-node p))
        (search-and-describe p))))

;;; Repository

(define +repository-version+ 4)

;; The repository object is a new concept (formerly all fields
;; were global parameters) so our API does not expect a
;; repository object to be passed in.  Therefore, we make
;; current-repository a global parameter.

(define-record-type chicken-doc-repository
  (make-repository base root magic info id-cache)
  repository?
  (base repository-base)
  (root repository-root)
  (magic repository-magic)
  (info repository-information)
  (id-cache repository-id-cache set-repository-id-cache!))

;; Current repository for node lookup API.
(define current-repository (make-parameter #f))

;; Return standard location of repository.  Does not
;; guarantee it exists.
(define (locate-repository)
  (or (get-environment-variable "CHICKEN_DOC_REPOSITORY")
      (make-pathname (chicken-home) "chicken-doc")))

;; Open the repository found in the standard location
;; and set the current repository for the thread.
(define (verify-repository)  ; legacy name; should be changed
  (current-repository
   (open-repository
    (locate-repository))))

;; Internal; make a fake repository object containing
;; all the fields a valid object would have.
(define (make-repository-placeholder base)
  (make-repository base
                   (make-pathname base "root")
                   (make-pathname base ".chicken-doc-repo")
                   `((version . ,+repository-version+))
                   (make-invalid-id-cache base)))

;; Open repository and return new repository object or
;; throw error if nonexistent or unknown format.  May accept
;; some old repository formats, so this repo MUST only be
;; passed to procedures which explicitly handle old formats.
;; Currently, that is only destroy-repository!.
(define (open-repository* base)
  (let ((rp (make-repository-placeholder base)))
    (let ((magic (repository-magic rp)))
      (if (file-exists? magic)
          (let ((info (with-input-from-file magic read)))
            (let ((r (make-repository (repository-base rp)
                                      (repository-root rp)
                                      magic
                                      info
                                      (repository-id-cache rp))))
              (set-finalizer! r close-repository)
              r))
          (error "No chicken-doc repository found at" base)))))
;; Open repository like open-repository*, but only permit the
;; current repository format.  Unless otherwise stated, procedures can only
;; handle the current format, and rely on the check happening at open time.
(define (open-repository base)
  (let ((r (open-repository* base)))
    (let ((version (or (alist-ref 'version (repository-information r)) 0)))
      (cond ((= version +repository-version+)
             r)
            (else (error (sprintf "Invalid repository version number ~a, expected ~a\n"
                                          version +repository-version+)))))))
(define (close-repository r)
  (void))

;; Last modification time of entire repository.  We just use the mtime
;; of the id cache, as update operations do not modify any global timestamp.
;; This means stale data may be returned until the cache is refreshed.
(define (repository-modification-time r)
  (validate-id-cache! r)  ;; may be wasteful, but we need the current mtime
  (id-cache-mtime (repository-id-cache r)))

;;; REPL

(define repl-doc-dwim doc-dwim)
(define repl-toc-dwim            ;; FIXME: ignore # paths for now
  (lambda (pathspec)
    (let ((p (decompose-pathspec pathspec)))
      (cond ((or (null? p)
                 (pair? p))
             (describe-contents (lookup-node p)))
            (else
             (search-and-describe-contents p))))))
(define repl-wtf
  (lambda (re)
    (search-only (irregex re))))

(when (feature? 'csi)
  ;; Warning -- will execute if called from a script.
  ;; We really only want this to execute at the REPL.

  (cond-expand
   ;; Load csi library at runtime here in Chicken 5 only after we confirm
   ;; csi is running. Otherwise chicken.csi load fails.
   (chicken-5 (import (only (chicken csi) toplevel-command)))
   (else))
  
  (verify-repository)

  
  (toplevel-command 'wtf (lambda () (repl-wtf (string-trim-both
                                          (read-line))))
                    ",wtf RE           Regex search with chicken-doc (\"where to find\")")
  (toplevel-command 'toc (lambda () (repl-toc-dwim (read)))
                    ;; TOC should look up if this is a relative path
                    ",toc PATHSPEC     List contents of path with chicken-doc")
  (toplevel-command 'doc (lambda () (repl-doc-dwim (read)))
                    ",doc PATHSPEC     Describe identifier or path with chicken-doc"))

)  ;; end module