;;; Guix --- Nix package management from Guile.         -*- coding: utf-8 -*-
;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of Guix.
;;;
;;; Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; Guix 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 General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (guix)
  #:use-module (rnrs bytevectors)
  #:use-module (rnrs io ports)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-26)
  #:use-module (ice-9 match)
  #:use-module (ice-9 rdelim)
  #:export (nix-server?
            nix-server-major-version
            nix-server-minor-version
            nix-server-socket

            open-connection
            set-build-options
            add-text-to-store
            add-to-store))

(define %protocol-version #x109)

(define %worker-magic-1 #x6e697863)
(define %worker-magic-2 #x6478696f)

(define (protocol-major magic)
  (logand magic #xff00))
(define (protocol-minor magic)
  (logand magic #x00ff))

(define-syntax define-enumerate-type
  (syntax-rules ()
    ((_ name->int (name id) ...)
     (define-syntax name->int
       (syntax-rules (name ...)
         ((_ name) id) ...)))))

(define-enumerate-type operation-id
  ;; operation numbers from worker-protocol.hh
  (quit 0)
  (valid-path? 1)
  (has-substitutes? 3)
  (query-path-hash 4)
  (query-references 5)
  (query-referrers 6)
  (add-to-store 7)
  (add-text-to-store 8)
  (build-derivations 9)
  (ensure-path 10)
  (add-temp-root 11)
  (add-indirect-root 12)
  (sync-with-gc 13)
  (find-roots 14)
  (export-path 16)
  (query-deriver 18)
  (set-options 19)
  (collect-garbage 20)
  (query-substitutable-path-info 21)
  (query-derivation-outputs 22)
  (query-valid-paths 23)
  (query-failed-paths 24)
  (clear-failed-paths 25)
  (query-path-info 26)
  (import-paths 27)
  (query-derivation-output-names 28))

(define-enumerate-type hash-algo
  ;; hash.hh
  (md5 1)
  (sha1 2)
  (sha256 3))

(define %nix-state-dir "/nix/var/nix")
(define %default-socket-path
  (string-append %nix-state-dir "/daemon-socket/socket"))


;; serialize.cc

(define (write-int n p)
  (let ((b (make-bytevector 8 0)))
    (bytevector-u32-set! b 0 n (endianness little))
    (put-bytevector p b)))

(define (read-int p)
  (let ((b (get-bytevector-n p 8)))
    (bytevector-u32-ref b 0 (endianness little))))

(define (write-long-long n p)
  (let ((b (make-bytevector 8 0)))
    (bytevector-u64-set! b 0 n (endianness little))
    (put-bytevector p b)))

(define write-padding
  (let ((zero (make-bytevector 8 0)))
    (lambda (n p)
      (let ((m (modulo n 8)))
        (or (zero? m)
            (put-bytevector p zero 0 (- 8 m)))))))

(define (write-string s p)
  (let ((b (string->utf8 s)))
    (write-int (bytevector-length b) p)
    (put-bytevector p b)
    (write-padding (bytevector-length b) p)))

(define (read-string p)
  (let* ((len (read-int p))
         (m   (modulo len 8))
         (bv  (get-bytevector-n p len))
         (str (utf8->string bv)))
    (or (zero? m)
        (get-bytevector-n p (- 8 m)))
    str))

(define (write-string-list l p)
  (write-int (length l) p)
  (for-each (cut write-string <> p) l))

(define (read-store-path p)
  (read-string p))                                ; TODO: assert path

(define (write-contents file p)
  "Write the contents of FILE to output port P."
  (define (dump in size)
    (define buf-size 65536)
    (define buf (make-bytevector buf-size))

    (let loop ((left size))
      (if (<= left 0)
          0
          (let ((read (get-bytevector-n! in buf 0 buf-size)))
            (if (eof-object? read)
                left
                (begin
                  (put-bytevector p buf 0 read)
                  (loop (- left read))))))))

  (let ((size (stat:size (lstat file))))
    (write-string "contents" p)
    (write-long-long size p)
    (call-with-input-file file
      (lambda (p)
        (dump p size)))
    (write-padding size p)))

(define (write-file f p)
  (define %archive-version-1 "nix-archive-1")

  (let ((s (lstat f)))
    (write-string %archive-version-1 p)
    (write-string "(" p)
    (case (stat:type s)
      ((regular)
       (write-string "type" p)
       (write-string "regular" p)
       (if (not (zero? (logand (stat:mode s) #o100)))
           (begin
             (write-string "executable" p)
             (write-string "" p)))
       (write-contents f p)
       (write-string ")" p))
      ((directory)
       (write-string "type" p)
       (write-string "directory" p)
       (error "ENOSYS"))
      (else
       (error "ENOSYS")))))

(define-syntax write-arg
  (syntax-rules (integer boolean file string string-list)
    ((_ integer arg p)
     (write-int arg p))
    ((_ boolean arg p)
     (write-int (if arg 1 0) p))
    ((_ file arg p)
     (write-file arg p))
    ((_ string arg p)
     (write-string arg p))
    ((_ string-list arg p)
     (write-string-list arg p))))

(define-syntax read-arg
  (syntax-rules (integer boolean string store-path)
    ((_ integer p)
     (read-int p))
    ((_ boolean p)
     (not (zero? (read-int p))))
    ((_ string p)
     (read-string p))
    ((_ store-path p)
     (read-store-path p))))


;; remote-store.cc

(define-record-type <nix-server>
  (%make-nix-server socket major minor)
  nix-server?
  (socket nix-server-socket)
  (major  nix-server-major-version)
  (minor  nix-server-minor-version))

(define* (open-connection #:optional (file %default-socket-path))
  (let ((s (with-fluids ((%default-port-encoding #f))
             ;; This trick allows use of the `scm_c_read' optimization.
             (socket PF_UNIX SOCK_STREAM 0)))
        (a (make-socket-address PF_UNIX file)))
    (connect s a)
    (write-int %worker-magic-1 s)
    (let ((r (read-int s)))
      (and (eqv? r %worker-magic-2)
           (let ((v (read-int s)))
             (and (eqv? (protocol-major %protocol-version)
                        (protocol-major v))
                  (begin
                    (write-int %protocol-version s)
                    (let ((s (%make-nix-server s
                                               (protocol-major v)
                                               (protocol-minor v))))
                      (process-stderr s)
                      s))))))))

(define (process-stderr server)
  (define p
    (nix-server-socket server))

  ;; magic cookies from worker-protocol.hh
  (define %stderr-next  #x6f6c6d67)
  (define %stderr-read  #x64617461)               ; data needed from source
  (define %stderr-write #x64617416)               ; data for sink
  (define %stderr-last  #x616c7473)
  (define %stderr-error #x63787470)

  (let ((k (read-int p)))
    (cond ((= k %stderr-write)
           (read-string p))
          ((= k %stderr-read)
           (let ((len (read-int p)))
             (read-string p)                      ; FIXME: what to do?
             ))
          ((= k %stderr-next)
           (let ((s (read-string p)))
             (display s (current-error-port))
             s))
          ((= k %stderr-error)
           (let ((error  (read-string p))
                 (status (if (>= (nix-server-minor-version server) 8)
                             (read-int p)
                             1)))
             (format (current-error-port) "error: ~a (status: ~a)~%"
                     error status)
             error))
          ((= k %stderr-last)
           #t)
          (else
           (error "invalid standard error code" k)))))

(define* (set-build-options server
                            #:key keep-failed? keep-going? try-fallback?
                            (verbosity 0)
                            (max-build-jobs (current-processor-count))
                            (max-silent-time 3600)
                            (use-build-hook? #t)
                            (build-verbosity 0)
                            (log-type 0)
                            (print-build-trace #t))
  ;; Must be called after `open-connection'.

  (define socket
    (nix-server-socket server))

  (let-syntax ((send (syntax-rules ()
                       ((_ option ...)
                        (for-each (lambda (i)
                                    (cond ((boolean? i)
                                           (write-int (if i 1 0) socket))
                                          ((integer? i)
                                           (write-int i socket))
                                          (else
                                           (error "invalid build option"
                                                  i))))
                                  (list option ...))))))
    (send (operation-id set-options)
          keep-failed? keep-going? try-fallback? verbosity
          max-build-jobs max-silent-time)
    (if (>= (nix-server-minor-version server) 2)
        (send use-build-hook?))
    (if (>= (nix-server-minor-version server) 4)
        (send build-verbosity log-type print-build-trace))
    (process-stderr server)))

(define-syntax define-operation
  (syntax-rules ()
    ((_ (name (type arg) ...) docstring return)
     (define (name server arg ...)
       docstring
       (let ((s (nix-server-socket server)))
         (write-int (operation-id name) s)
         (write-arg type arg s)
         ...
         (process-stderr server)
         (read-arg return s))))))

(define-operation (add-text-to-store (string name) (string text)
                                     (string-list references))
  "Add TEXT under file NAME in the store."
  store-path)

(define-operation (add-to-store (string basename)
                                (integer algo)
                                (boolean sha256-and-recursive?)
                                (boolean recursive?)
                                (file file-name))
  "Add the contents of FILE-NAME under BASENAME to the store."
  store-path)

(define-operation (build-derivations (string-list derivations))
  "Build DERIVATIONS; return #t on success."
  boolean)


;; derivations

(define-record-type <derivation>
  (make-derivation outputs inputs sources system builder args env-vars)
  derivation?
  (outputs  derivation-outputs)      ; list of name/<derivation-output> pairs
  (inputs   derivation-inputs)       ; list of <derivation-input>
  (sources  derivation-sources)      ; list of store paths
  (system   derivation-system)       ; string
  (builder  derivation-builder)      ; store path
  (args     derivation-builder-arguments)         ; list of strings
  (env-vars derivation-builder-environment-vars)) ; list of name/value pairs

(define-record-type <derivation-output>
  (make-derivation-output path hash-algo hash)
  derivation-output?
  (path       derivation-output-path)             ; store path
  (hash-algo  derivation-output-hash-algo)        ; symbol | #f
  (hash       derivation-output-hash))            ; symbol | #f

(define-record-type <derivation-input>
  (make-derivation-input path sub-derivations)
  derivation-input?
  (path            derivation-input-path)             ; store path
  (sub-derivations derivation-input-sub-derivations)) ; list of strings

(define (fixed-output-derivation? drv)
  "Return #t if DRV is a fixed-output derivation, such as the result of a
download with a fixed hash (aka. `fetchurl')."
  (match drv
    (($ <derivation>
        (($ <derivation-output> _ (? symbol?) (? string?))))
     #t)
    (_ #f)))

(define (read-derivation drv-port)
  "Read the derivation from DRV-PORT and return the corresponding
<derivation> object."

  (define comma (string->symbol ","))

  (define (ununquote x)
    (match x
      (('unquote x) (ununquote x))
      ((x ...)      (map ununquote x))
      (_            x)))

  (define (outputs->alist x)
    (fold-right (lambda (output result)
                  (match output
                    ((name path "" "")
                     (alist-cons name
                                 (make-derivation-output path #f #f)
                                 result))
                    ((name path hash-algo hash)
                     ;; fixed-output
                     (let ((algo (string->symbol hash-algo)))
                       (alist-cons name
                                   (make-derivation-output path algo hash)
                                   result)))))
                '()
                x))

  (define (make-input-drvs x)
    (fold-right (lambda (input result)
                  (match input
                    ((path (sub-drvs ...))
                     (cons (make-derivation-input path sub-drvs)
                           result))))
                '()
                x))

  (let loop ((exp    (read drv-port))
             (result '()))
    (match exp
      ((? eof-object?)
       (let ((result (reverse result)))
         (match result
           (('Derive ((outputs ...) (input-drvs ...)
                      (input-srcs ...)
                      (? string? system)
                      (? string? builder)
                      ((? string? args) ...)
                      ((var value) ...)))
            (make-derivation (outputs->alist outputs)
                             (make-input-drvs input-drvs)
                             input-srcs
                             system builder args
                             (fold-right alist-cons '() var value)))
           (_
            (error "failed to parse derivation" drv-port result)))))
      ((? (cut eq? <> comma))
       (loop (read drv-port) result))
      (_
       (loop (read drv-port)
             (cons (ununquote exp) result))))))

(define (write-derivation drv port)
  "Write the ATerm-like serialization of DRV to PORT."
  (define (list->string lst)
    (string-append "[" (string-join lst ",") "]"))

  (define (write-list lst)
    (display (list->string lst) port))

  (match drv
    (($ <derivation> outputs inputs sources
        system builder args env-vars)
     (display "Derive(" port)
     (write-list (map (match-lambda
                       ((name . ($ <derivation-output> path hash-algo hash))
                        (format #f "(~s,~s,~s,~s)"
                                name path (or hash-algo "")
                                (or hash ""))))
                      outputs))
     (display "," port)
     (write-list (map (match-lambda
                       (($ <derivation-input> path sub-drvs)
                        (format #f "(~s,~a)" path
                                (list->string (map object->string sub-drvs)))))
                      inputs))
     (display "," port)
     (write-list sources)
     (format port ",~s,~s," system builder)
     (write-list (map object->string args))
     (display "," port)
     (write-list (map (match-lambda
                       ((name . value)
                        (format #f "(~s,~s)" name value)))
                      env-vars))
     (display ")" port))))

(define (sha256 bv)
  "Return the SHA256 of BV as an string of hexadecimal digits."
  ;; XXX: Poor programmer's implementation that uses Coreutils.
  (let ((in  (pipe))
        (out (pipe))
        (pid (primitive-fork)))
    (if (= 0 pid)
        (begin                                      ; child
          (close (cdr in))
          (close (car out))
          (close 0)
          (close 1)
          (dup2 (fileno (car in)) 0)
          (dup2 (fileno (cdr out)) 1)
          (execlp "sha256sum" "sha256sum"))
        (begin                                      ; parent
          (close (car in))
          (close (cdr out))
          (put-bytevector (cdr in) bv)
          (close (cdr in))                        ; EOF
          (let ((line (car (string-tokenize (read-line (car out))))))
            (close (car out))
            (and (and=> (status:exit-val (cdr (waitpid pid)))
                        zero?)
                 line))))))

(define (derivation-hash drv)      ; `hashDerivationModulo' in derivations.cc
  (match drv
    (($ <derivation> ((_ . ($ <derivation-output> path
                              (? symbol? hash-algo) (? string? hash)))))
     ;; A fixed-output derivation.
     (sha256
      (string->utf8
       (string-append "fixed:out:" hash-algo ":" hash ":" path))))
    (($ <derivation> outputs inputs sources
        system builder args env-vars)
     ;; A regular derivation: replace that path of each input with that
     ;; inputs hash; return the hash of serialization of the resulting
     ;; derivation.
     (let* ((inputs (map (match-lambda
                          (($ <derivation-input> path sub-drvs)
                           (let ((hash (call-with-input-file path
                                         (compose derivation-hash
                                                  read-derivation))))
                             (make-derivation-input hash sub-drvs))))
                         inputs))
            (drv     (make-derivation outputs inputs sources
                                      system builder args env-vars)))
       (sha256
        (string->utf8 (call-with-output-string
                       (cut write-derivation drv <>))))))))

(define (instantiate server derivation)
  #f
  )