;;; Guix Build Coordinator
;;;
;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
;;;
;;; This file is part of the guix-build-coordinator.
;;;
;;; The Guix Build Coordinator 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.
;;;
;;; The Guix Build Coordinator 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 the guix-data-service.  If not, see
;;; <http://www.gnu.org/licenses/>.

(define-module (guix-build-coordinator agent)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 futures)
  #:use-module (ice-9 atomic)
  #:use-module (ice-9 threads)
  #:use-module (ice-9 exceptions)
  #:use-module (rnrs bytevectors)
  #:use-module (web http)
  #:use-module (oop goops)
  #:use-module (logging logger)
  #:use-module (logging port-log)
  #:use-module (prometheus)
  #:use-module (guix store)
  #:use-module (guix derivations)
  #:use-module (guix base32)
  #:use-module (guix-build-coordinator utils)
  #:use-module (guix-build-coordinator agent-messaging http)
  #:export (run-agent))

(define (run-agent uuid coordinator-uri password
                   systems
                   max-parallel-builds
                   derivation-substitute-urls
                   non-derivation-substitute-urls
                   metrics-file
                   max-1min-load-average)
  (define lgr (make <logger>))
  (define port-log (make <port-log>
                     #:port (current-output-port)
                     #:formatter
                     (lambda (lvl time str)
                       (format #f "~a (~5a): ~a~%"
                               (strftime "%F %H:%M:%S" (localtime time))
                               lvl
                               str))))

  (define metrics-enabled?
    (and (not (string-null? metrics-file))
         (let ((directory (dirname metrics-file)))
           (or (file-exists? directory)
               (begin
                 (simple-format (current-error-port)
                                "skipping writing metrics as ~A does not exist\n"
                                directory)
                 #f)))
         (with-exception-handler
             (lambda (exn)
               (simple-format
                (current-error-port)
                "skipping writing metrics, encountered exception ~A\n"
                exn)
               #f)
           (lambda ()
             (let ((test-file (string-append metrics-file "-tmp")))
               (call-with-output-file test-file
                 (lambda (port)
                   (display "test" port)))
               (delete-file test-file)
               #t))
           #:unwind? #t)))

  (define metrics-registry
    (make-metrics-registry
     #:namespace "guixbuildcoordinator_agent"))

  (define (write-metrics)
    (when metrics-enabled?
      (write-textfile metrics-registry
                      metrics-file)))

  (define (wait-for-low-load build-id)
    (let ((current-load (get-load-average #:period 1)))
      (when (>= current-load max-1min-load-average)
        (log-msg lgr 'INFO
                 build-id
                 ": holding build start due to high load")
        (sleep 30)
        (wait-for-low-load build-id))))

  (define (process-job build)
    (let ((build-id (assoc-ref build "uuid"))
          (derivation-name (assoc-ref build "derivation-name")))
      (log-msg lgr 'INFO
               build-id
               ": setting up to build: "
               derivation-name)
      (with-store store
        (let ((pre-build-status
               (call-with-duration-metric
                metrics-registry
                "pre_build_duration_seconds"
                (lambda ()
                  (pre-build-process lgr
                                     store
                                     build-id
                                     derivation-substitute-urls
                                     non-derivation-substitute-urls
                                     derivation-name))
                #:buckets (list 1 2.5 5 10 25 50 100 200 500 1000 (inf)))))
          (write-metrics)
          (if (eq? (assq-ref pre-build-status 'result) 'success)
              (begin
                (wait-for-low-load build-id)
                (log-msg lgr 'INFO
                         build-id
                         ": setup successful, building: "
                         derivation-name)
                (report-build-start coordinator-uri uuid password
                                    build-id
                                    #:log (build-log-procedure lgr build-id))
                (let* ((result (perform-build lgr store build-id derivation-name))
                       ;; TODO Check this handles timezones right
                       (end-time (localtime (current-time) "UTC")))

                  (agent-submit-log-file lgr uuid coordinator-uri password
                                         build-id derivation-name)

                  ((if result
                       post-build-success
                       post-build-failure)
                   lgr
                   uuid coordinator-uri password
                   build-id
                   derivation-name
                   end-time)))
              (begin
                (log-msg lgr 'INFO
                         build-id
                         ": setup failure: "
                         (assq-ref pre-build-status 'failure_reason))
                (report-setup-failure coordinator-uri uuid password
                                      build-id
                                      pre-build-status
                                      #:log (build-log-procedure lgr
                                                                 build-id))))))))

  (add-handler! lgr port-log)
  (open-log! lgr)

  (log-msg lgr 'INFO "starting agent " uuid)
  (log-msg lgr 'INFO "connecting to coordinator " coordinator-uri)
  (let-values (((process-job-with-queue count-jobs list-jobs)
                (create-work-queue max-parallel-builds
                                   process-job)))
    (let ((details (submit-status coordinator-uri uuid password 'idle
                                  #:log (build-log-procedure
                                         lgr
                                         (assoc-ref build "uuid")))))
      (for-each
       (lambda (job-args)
         (process-job-with-queue job-args))
       (vector->list (assoc-ref details "builds")))

      (while #t
        (if (< (count-jobs) max-parallel-builds)
            (let* ((queued-build-ids
                    (map (lambda (job-args)
                           (assoc-ref (car job-args) "uuid"))
                         (list-jobs)))
                   (fetched-builds
                    (fetch-builds-for-agent coordinator-uri uuid password
                                            systems
                                            max-parallel-builds
                                            #:log (build-log-procedure lgr)))
                   (new-builds
                    (remove (lambda (build)
                              (member (assoc-ref build "uuid")
                                      queued-build-ids))
                            fetched-builds)))

              (log-msg lgr 'INFO
                       "max " max-parallel-builds
                       " builds, currently allocated "
                       (length fetched-builds))
              (log-msg lgr 'INFO
                       "starting " (length new-builds)
                       " new "
                       (if (eq? (length new-builds) 1) "build" "builds"))
              (for-each
               (lambda (job-args)
                 (process-job-with-queue job-args))
               new-builds)

              (when (null? new-builds)
                (sleep 30)))
            (sleep 3))))))

(define* (build-log-procedure lgr #:optional build-id)
  (lambda (level . components)
    (apply log-msg
           lgr
           level
           (if build-id
               (cons*
                build-id
                ": "
                components)
               components))))

(define (agent-submit-log-file lgr uuid coordinator-uri password
                               build-id derivation-name)
  (retry-on-error
   (lambda ()
     (let ((log-file (derivation-log-file derivation-name)))
       (unless log-file
         (raise-exception
          (make-exception-with-message
           (simple-format #f "log file missing for ~A (~A)"
                          derivation-name build-id))))

       (log-msg lgr 'INFO
                build-id ": uploading log file "
                log-file)
       (submit-log-file
        coordinator-uri uuid password
        build-id
        log-file
        #:log (build-log-procedure lgr build-id))))
   #:times 6
   #:delay 30))

(define (pre-build-process lgr
                           store
                           build-id
                           derivation-substitute-urls
                           non-derivation-substitute-urls
                           derivation-name)
  (define (find-missing-inputs derivation inputs)
    (log-msg lgr 'DEBUG
             build-id ": checking the availability of build inputs")
    (let* ((output-paths
            (append-map derivation-input-output-paths inputs))
           (missing-paths
            (remove (lambda (path)
                      (valid-path? store path))
                    output-paths))
           (path-substitutes
            (begin
              (with-store store
                (apply set-build-options
                       store
                       `(,@(if non-derivation-substitute-urls
                               (list #:substitute-urls
                                     non-derivation-substitute-urls)
                               '())
                         #:max-silent-time 60
                         #:timeout ,(* 10 60)))

                (unless non-derivation-substitute-urls
                  (log-msg lgr 'WARN
                           "non-derivation-substitute-urls unset,
unable to query substitute servers without caching"))

                (map (lambda (file)
                       (let ((substitute-urls-with-substitute
                              (if (list? non-derivation-substitute-urls)
                                  (has-substiutes-no-cache?
                                   non-derivation-substitute-urls
                                   file)
                                  #f)))
                         (and
                          (if (eq? substitute-urls-with-substitute #f)
                              #t        ; keep going
                              (not (null? substitute-urls-with-substitute)))
                          (let ((log-port (open-output-string)))
                            ;; TODO Do something with the logged output
                            (parameterize ((current-build-output-port log-port))
                              (if (has-substitutes? store file)
                                  #t
                                  (begin
                                    (log-msg
                                     lgr 'WARN
                                     "a substitute should be available for " file ",
but the guix-daemon claims it's unavailable"
                                     (if substitute-urls-with-substitute
                                         (string-append
                                          ":\n"
                                          (string-join substitute-urls-with-substitute "\n"))
                                         ""))
                                    #f)))))))
                     missing-paths)))))

      (if (null? missing-paths)
          '()
          (if (member #f path-substitutes)
              (fold (lambda (file substitute-available? result)
                      (if substitute-available?
                          result
                          (cons file result)))
                    '()
                    missing-paths
                    path-substitutes)
              (begin
                (retry-on-error
                 (lambda ()
                   (with-timeout (* 1000 60 11) ; 11 minutes
                     (raise-exception
                      (make-exception-with-message "timeout fetching inputs"))
                     (begin
                       (with-store store
                         ;; Download the substitutes
                         (apply set-build-options
                                store
                                `(,@(if non-derivation-substitute-urls
                                        (list #:substitute-urls
                                              non-derivation-substitute-urls)
                                        '())
                                  #:max-silent-time 60
                                  #:timeout ,(* 10 60)))

                         (let ((log-port (open-output-string)))
                           (with-throw-handler #t
                             (lambda ()
                               (parameterize ((current-build-output-port log-port))
                                 (build-things store missing-paths)))
                             (lambda (key . args)
                               (display (get-output-string log-port))
                               (close-output-port log-port))))))))
                 #:times 6
                 #:delay (+ 15 (random 30)))

                ;; Double check everything is actually present.
                (let ((missing-files (remove (lambda (path)
                                               (valid-path? store path))
                                             output-paths)))
                  (if (null? missing-files)
                      '()
                      (begin
                        (log-msg lgr 'WARN
                                 "failed to fetch substitutes for "
                                 missing-files)

                        (let ((unavailable-outputs
                               (delete-duplicates
                                (append-map
                                 (lambda (missing-output)
                                   (find-missing-substitutes-for-output
                                    store
                                    non-derivation-substitute-urls
                                    missing-output))
                                 missing-files))))

                          (log-msg lgr 'WARN
                                   "the following outputs are missing: "
                                   (string-join
                                    (map (lambda (output)
                                           (string-append
                                            " - " output))
                                         unavailable-outputs)))

                          (if (null? unavailable-outputs) ; TODO This probably
                                                          ; shouldn't happen
                              missing-files
                              unavailable-outputs))))))))))

  (define (delete-outputs derivation)
    (let* ((outputs (derivation-outputs derivation))
           (output-file-names
            (map derivation-output-path (map cdr outputs))))
      (if (any file-exists? output-file-names)
          (let ((log-port (open-output-string)))
            (catch
              #t
              (lambda ()
                (log-msg lgr 'DEBUG build-id ": deleting "
                         (if (eq? (length output-file-names) 1)
                             "output"
                             "outputs"))
                ;; There can be issues deleting links when collecting garbage
                ;; from multiple threads
                (monitor
                 (with-store store
                   ;; TODO Do something with the logged output
                   (parameterize ((current-build-output-port log-port))
                     (delete-paths store output-file-names))))
                #t)
              (lambda (key args)
                (display (get-output-string log-port))
                (log-msg lgr 'ERROR
                         "delete-outputs: "
                         key args)
                #f)))
          #t)))

  (let ((derivation
         (if (valid-path? store derivation-name)
             (read-derivation-from-file derivation-name)
             (and
              (with-exception-handler
                  (lambda (exn)
                    (log-msg lgr 'ERROR
                             "exception when reading/fetching derivation: "
                             exn)
                    #f)
                (lambda ()
                  (log-msg lgr 'DEBUG
                           build-id ": substituting derivation")
                  (retry-on-error
                   (lambda ()
                     (substitute-derivation derivation-name
                                            #:substitute-urls
                                            derivation-substitute-urls))
                   #:times 20
                   #:delay (+ 5 (random 25)))
                  #t)
                #:unwind? #t)
              (read-derivation-from-file derivation-name)))))
    (if derivation
        (begin
          (log-msg lgr 'DEBUG
                   build-id ": derivation read from file")
          (match (delete-outputs derivation)
            (#t
             (let ((missing-inputs
                    (find-missing-inputs derivation (derivation-inputs derivation))))
               (if (null? missing-inputs)
                   '((result . success))
                   `((result         . failure)
                     (failure_reason . missing_inputs)
                     (missing_inputs . ,(list->vector missing-inputs))))))
            (failure
             '((result         . failure)
               (failure_reason . could_not_delete_outputs)))))
        '((result         . failure)
          (failure_reason . error_fetching_derivation)))))

(define (perform-build lgr store build-id derivation-name)
  (set-build-options store
                     #:use-substitutes? #f)

  (parameterize ((current-build-output-port (%make-void-port "w")))
    (with-exception-handler
        (lambda (exn)
          (if (store-protocol-error? exn)
              (cond
               ((eq? (store-protocol-error-status exn) 100)
                (log-msg lgr 'INFO build-id ": build failed"))
               ((eq? (store-protocol-error-status exn) 101)
                (log-msg lgr 'INFO build-id ": build failed due to a timeout"))
               (else
                (log-msg lgr 'ERROR build-id ": unknown error status "
                         (store-protocol-error-status exn))))
              (log-msg lgr 'ERROR build-id ": unknown exception " exn))
          #f)
      (lambda ()
        (build-things store (list derivation-name))
        #t)
      #:unwind? #t)))

(define (post-build-failure lgr uuid coordinator-uri password
                            build-id derivation end-time)
  (log-msg lgr 'INFO build-id ": build failed")
  (with-exception-handler
      (lambda (exn)
        (unless (agent-error-from-coordinator? exn)
          (raise-exception exn))

        (let ((details
               (agent-error-from-coordinator-details exn)))
          (if (string? details)
              (cond
               ((string=? details "build_already_processed")
                (log-msg lgr 'WARN
                         build-id ": coordinator indicates this build is already marked as processed")
                #t)
               (else
                (raise-exception
                 (make-exception
                  (make-exception-with-message
                   "unrecognised error from coordinator")
                  (make-exception-with-irritants
                   details)))))
              (raise-exception
               (make-exception
                (make-exception-with-message
                 "unrecognised error from coordinator")
                (make-exception-with-irritants
                 details))))))
    (lambda ()
      (submit-build-result coordinator-uri uuid password
                           build-id
                           `((result   . failure)
                             (end_time . ,(strftime "%F %T" end-time)))
                           #:log (build-log-procedure lgr build-id)))
    #:unwind? #t))

(define (post-build-success lgr uuid coordinator-uri password
                            build-id derivation end-time)
  (define output-details
    (map
     (match-lambda
       ((output-name . output)
        (let ((path-info (with-store store
                           (query-path-info
                            store
                            (derivation-output-path output)))))
          `((name       . ,output-name)
            (hash       . ,(bytevector->nix-base32-string
                            (path-info-hash path-info)))
            (size       . ,(path-info-nar-size path-info))
            (references . ,(list->vector
                            (map basename
                                 (path-info-references path-info))))))))

     (derivation-outputs (read-derivation-from-file derivation))))

  (define (attempt-submit-build-result)
    (with-exception-handler
      (lambda (exn)
        (unless (agent-error-from-coordinator? exn)
          (raise-exception exn))

        (let ((details
               (agent-error-from-coordinator-details exn)))
          (if (string? details)
              (cond
               ((string=? details "build_already_processed")
                (log-msg lgr 'WARN
                         build-id ": coordinator indicates this build is already marked as processed")
                #t)
               ((string=? details "cannot_store_result_for_canceled_build")
                (log-msg lgr 'WARN
                         build-id ": coordinator indicates this build is now canceled")
                #t)
               ((string=? details "missing_build_log_file")
                ;; Retry submitting the log file
                (agent-submit-log-file lgr uuid coordinator-uri password
                                       build-id derivation)

                (attempt-submit-build-result))
               (else
                (raise-exception
                 (make-exception
                  (make-exception-with-message
                   "unrecognised error from coordinator")
                  (make-exception-with-irritants
                   details)))))
              (or
               (and=> (assoc-ref details "missing_output")
                      (lambda (missing-output-name)
                        (let ((missing-output
                               (any (match-lambda
                                      ((name . output)
                                       (if (string=? name missing-output-name)
                                           output
                                           #f)))
                                    (derivation-outputs
                                     (read-derivation-from-file derivation)))))
                          (unless missing-output
                            (raise-exception
                             (make-exception
                              (make-exception-with-message
                               "unknown missing output")
                              (make-exception-with-irritants
                               missing-output-name))))

                          (submit-one-output missing-output-name
                                             missing-output))

                        (attempt-submit-build-result)))
               (raise-exception
                (make-exception
                 (make-exception-with-message
                  "unrecognised error from coordinator")
                 (make-exception-with-irritants
                  details)))))))
      (lambda ()
        (submit-build-result
         coordinator-uri uuid password build-id
         `((result   . success)
           (end_time . ,(strftime "%F %T" end-time))
           (outputs  . ,(list->vector output-details)))
         #:log (build-log-procedure lgr build-id)))
      #:unwind? #t))

  (define (submit-one-output output-name output)
    (log-msg lgr 'INFO
             build-id ": submitting output "
             (derivation-output-path output))
    (submit-output coordinator-uri uuid password
                   build-id output-name
                   (derivation-output-path output)
                   #:log (build-log-procedure lgr build-id)))

  (log-msg lgr 'INFO build-id ": build successful, submitting outputs")
  (for-each (match-lambda
              ((output-name . output)
               (submit-one-output output-name output)))
            (derivation-outputs (read-derivation-from-file derivation)))

  (log-msg lgr 'INFO
           build-id ": finished submitting outputs, reporting build success")
  (attempt-submit-build-result))