;;; 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-messaging http)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-19)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 threads)
  #:use-module (ice-9 exceptions)
  #:use-module (ice-9 textual-ports)
  #:use-module (ice-9 binary-ports)
  #:use-module (system repl error-handling)
  #:use-module (rnrs bytevectors)
  #:use-module (oop goops)
  #:use-module (logging logger)
  #:use-module (json)
  #:use-module (web http)
  #:use-module (web client)
  #:use-module (web request)
  #:use-module (web response)
  #:use-module (web uri)
  #:use-module (gcrypt base16)
  #:use-module (gcrypt hash)
  #:use-module (lzlib)
  #:use-module ((gnutls) #:select (gnutls-version))
  #:use-module ((guix config) #:select (%guix-version))
  #:use-module ((guix utils) #:select (version>=?))
  #:use-module (prometheus)
  #:use-module (guix store)
  #:use-module (guix base64)
  #:use-module (guix serialization)
  #:use-module (guix build utils)
  #:use-module (guix-build-coordinator utils)
  #:use-module (guix-build-coordinator agent-messaging abstract)
  #:export (make-http-agent-interface

            fetch-session-credentials

            submit-status
            submit-log-file
            submit-build-result
            report-build-start
            report-setup-failure
            submit-output
            fetch-builds-for-agent))

(define-class <http-agent-interface> ()
  (coordinator-uri #:init-keyword #:coordinator-uri)
  (agent-uuid #:init-keyword #:agent-uuid)
  (password #:init-keyword #:password))

(define (make-http-agent-interface coordinator-uri
                                   agent-uuid
                                   password)
  (let* ((gnutls-ver (gnutls-version))
         (guix-ver   %guix-version)
         (gnutls-probably-retries-on-gc?
          (or (version>=? gnutls-ver "3.7.3")
              ;; guix patched gnutls to retry when interrupted by gc before
              ;; gnutls released the change
              (version>=? guix-ver "1.3.0-14"))))
    (simple-format (current-error-port)
                   "gc protection ~A (gnutls version: ~A, guix version: ~A)\n"
                   (if gnutls-probably-retries-on-gc?
                       "disabled"
                       "enabled")
                   gnutls-ver
                   guix-ver)
    (use-gc-protection? (not gnutls-probably-retries-on-gc?)))

  (make <http-agent-interface>
    #:coordinator-uri coordinator-uri
    #:agent-uuid agent-uuid
    #:password password))

(define* (coordinator-uri-for-path base-uri-string agent-path
                                   #:key query)
  (let* ((base-uri (string->uri base-uri-string))
         (scheme (uri-scheme base-uri))
         (host   (uri-host base-uri))
         (port   (uri-port base-uri))
         (path   (uri-path base-uri)))
    (build-uri scheme
               #:host host
               #:port port
               #:path
               (string-append
                path
                (if (string-suffix? path "/")
                    agent-path
                    (string-drop agent-path 1)))
               #:query query)))

(define (default-log level . components)
  (apply log-msg level components))

(define* (coordinator-handle-failed-request log method path response body
                                            #:key first-request-failed?)
  (log 'ERROR
       "coordinator-http-request: "
       method " " path " "
       (response-code response))

  (catch #t
    (lambda ()
      (if (equal? '(application/json (charset . "utf-8"))
                  (response-content-type response))
          (json-string->scm (utf8->string body))
          (utf8->string body)))
    (lambda (key . args)
      (log 'ERROR
           "error decoding body " key " " args)
      #f)))

(define* (coordinator-http-request log
                                   interface
                                   path
                                   #:key method body (headers '())
                                   succeed-on-access-denied-retry?)
  (define auth-value
    (string-append
     "Basic "
     (base64-encode
      (string->utf8
       (string-append (slot-ref interface 'agent-uuid)
                      ":"
                      (slot-ref interface 'password))))))

  (define uri
    (coordinator-uri-for-path (slot-ref interface 'coordinator-uri)
                              path))

  (define first-request-failed? #f)

  (define (make-request)
    (let-values (((response body)
                  (http-request uri
                                #:method method
                                #:body (scm->json-string body)
                                #:decode-body? #f
                                #:headers
                                `((Authorization . ,auth-value)
                                  ,@headers))))
      (let ((code (response-code response)))
        (cond
         ((eq? code 400)
          (and=> (coordinator-handle-failed-request log
                                                    method
                                                    path
                                                    response
                                                    body)
                 (lambda (error)
                   (raise-exception
                    (make-agent-error-from-coordinator
                     (assoc-ref error "error"))))))

         ((eq? code 404)
          (values
           (and body (json-string->scm (utf8->string body)))
           response))

         ((>= (response-code response) 400)
          (let ((body
                 (coordinator-handle-failed-request log
                                                    method
                                                    path
                                                    response
                                                    body)))
            (if (and first-request-failed?
                     succeed-on-access-denied-retry?
                     (equal? body
                             '(("error" . "access denied"))))
                (begin
                  (log 'WARN
                       "treating access denied response as success")
                  (values body response))
                (begin
                  (set! first-request-failed? #t)
                  (raise-exception
                   (make-exception-with-message
                    body))))))
         (else
          (values
           (and body (json-string->scm (utf8->string body)))
           response))))))

  (retry-on-error (lambda ()
                    (with-port-timeouts
                     (lambda ()
                       (with-gc-protection make-request))))
                  #:times 9
                  #:delay 10
                  #:ignore agent-error-from-coordinator?))

(define* (fetch-session-credentials coordinator
                                    name
                                    token
                                    #:key (log default-log))
  (define method 'POST)
  (define path "/agent/fetch-session-credentials")
  (define uri (coordinator-uri-for-path coordinator path
                                        #:query
                                        (simple-format #f "name=~A&token=~A"
                                                       name token)))

  (let-values (((response body)
                (http-request uri
                              #:method method
                              #:decode-body? #f)))
    (let ((code (response-code response)))
      (cond
       ((eq? code 400)
        (and=> (coordinator-handle-failed-request log
                                                  method
                                                  path
                                                  response
                                                  body)
               (lambda (error)
                 (raise-exception
                  (make-agent-error-from-coordinator
                   (assoc-ref error "error"))))))

       ((>= (response-code response) 400)
        (let ((body
               (coordinator-handle-failed-request log
                                                  method
                                                  path
                                                  response
                                                  body)))
          (raise-exception
           (make-exception-with-message
            body))))
       (else
        (values
         (json-string->scm (utf8->string body))
         response))))))

(define-method (submit-status
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (status #:key (log default-log))
     (coordinator-http-request
      log
      interface
      (string-append "/agent/" (slot-ref interface 'agent-uuid))
      #:method 'PUT                     ; TODO Should be PATCH
      #:body `((status . ,status))))
   args))

(define-method (submit-output
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (build-id output-name file
                      #:key
                      (log default-log)
                      report-bytes-sent)
     (define file-size
       (stat:size (stat file)))

     (define file-md5-hash-promise
       (delay
         (bytevector->base16-string
          (file-hash (hash-algorithm md5) file))))

     (define (get-partial-upload-bytes)
       (let-values (((body response)
                     (coordinator-http-request
                      log
                      interface
                      (string-append "/build/" build-id
                                     "/output/" output-name
                                     "/partial")
                      #:method 'HEAD)))
         (if (eq? (response-code response)
                  404)
             #f
             (response-content-length response))))

     (define (get-completed-upload-bytes)
       (let-values (((body response)
                     (coordinator-http-request
                      log
                      interface
                      (string-append "/build/" build-id
                                     "/output/" output-name)
                      #:method 'HEAD)))
         (if (eq? (response-code response)
                  404)
             #f
             (response-content-length response))))

     (define auth-value
       (string-append
        "Basic "
        (base64-encode
         (string->utf8
          (string-append (slot-ref interface 'agent-uuid)
                         ":"
                         (slot-ref interface 'password))))))

     (define %force-full-upload #t)

     (define (perform-upload)
       (define reset-timeout/throttled
         (throttle
           120
           (lambda ()
             (reset-timeout (* 5 60)))))

       (let* ((partial-upload-bytes (get-partial-upload-bytes))
              (completed-upload-bytes (get-completed-upload-bytes))
              (bytes (if %force-full-upload
                         #f
                         (or partial-upload-bytes
                             completed-upload-bytes))))
         ;; Check if the server has all the bytes
         (if (and bytes
                  (eq? bytes file-size))
             (begin
               (log 'DEBUG "perform upload: server has all the bytes"
                    " (partial-upload-bytes: " partial-upload-bytes
                    ",completed-upload-bytes: " completed-upload-bytes ")")

               (unless completed-upload-bytes
                 (let loop ((retry 1))
                   (sleep 30)

                   (if (get-completed-upload-bytes)
                       (log 'DEBUG "upload completed")
                       (if (< retry 30)
                           (begin
                             (log 'DEBUG "upload not yet completed, "
                                  "rechecking in 30 seconds")

                             (loop (+ 1 retry)))
                           (begin
                             (log 'DEBUG "upload not yet completed, giving up waiting")

                             (raise-exception
                              (make-exception-with-message "upload not completed"))))))))

             (begin
               (if bytes
                   (log 'DEBUG "still more to send (bytes: " file-size
                        ", partial upload bytes: " bytes ")")
                   (begin
                     (log 'DEBUG "starting sending file from start")
                     (set! %force-full-upload #f)
                     (report-bytes-sent 'reset)))

               ;; Still more to send
               (call-with-input-file file
                 (lambda (file-port)
                   (when bytes
                     (seek file-port bytes SEEK_SET)
                     (log 'INFO "resuming upload from byte " bytes))

                   (let ((upload-uri
                          (coordinator-uri-for-path
                           (slot-ref interface 'coordinator-uri)
                           (string-append "/build/" build-id "/output/" output-name
                                          (if (integer? bytes)
                                              "/partial"
                                              "")))))

                     (with-timeout (* 5 60) ; 5 minutes
                       (raise-exception
                        (make-exception-with-message "timeout submitting output"))
                       (let-values (((response body)
                                     (call-with-streaming-http-request
                                      upload-uri
                                      (lambda (port)
                                        (with-time-logging
                                            (simple-format #f "sending ~A" file)
                                          (dump-port file-port port
                                                     #:buffer-size 65536)))
                                      #:headers `((Authorization . ,auth-value))
                                      #:method (if bytes 'POST 'PUT)
                                      #:report-bytes-sent
                                      (lambda args
                                        (reset-timeout/throttled)
                                        (apply report-bytes-sent args)))))
                         (log 'DEBUG "perform upload " file ", response code: "
                              (response-code response))

                         (when (>= (response-code response) 400)
                           (raise-exception
                            (make-exception-with-message
                             (coordinator-handle-failed-request
                              log
                              'PUT
                              (uri-path upload-uri)
                              response
                              body)))))))))))))

       (unless (and=>
                (get-completed-upload-bytes)
                (lambda (uploaded-bytes)
                  (eq? uploaded-bytes file-size)))
         (retry-on-error perform-upload
                         #:times 100
                         #:delay 40
                         #:error-hook
                         (lambda _
                           (log 'DEBUG
                                "perform-upload " file
                                " (bytes: " file-size ", "
                                "md5: " (force file-md5-hash-promise)
                                ")")))))
   args))

(define-method (submit-log-file
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (build-id file #:key (log default-log))
     (define auth-value
       (string-append
        "Basic "
        (base64-encode
         (string->utf8
          (string-append (slot-ref interface 'agent-uuid)
                         ":"
                         (slot-ref interface 'password))))))

     (define format
       (cond
        ((string-suffix? ".bz2" file) "bzip2")
        ((string-suffix? ".gz" file)  "gzip")
        (else
         (error "unsupported log format for" file))))

     (define uri
       (coordinator-uri-for-path
        (slot-ref interface 'coordinator-uri)
        (string-append "/build/" build-id "/log/" format)))

     (retry-on-error
      (lambda ()
        (let-values (((response body)
                      (call-with-streaming-http-request
                       uri
                       (lambda (request-port)
                         (call-with-input-file file
                           (lambda (file-port)
                             (dump-port file-port request-port
                                        #:buffer-size (expt 2 20)))
                           #:binary #t))
                       #:headers `((Authorization . ,auth-value)))))
          (if (>= (response-code response) 400)
              (raise-exception
               (make-exception-with-message
                (coordinator-handle-failed-request log
                                                   'PUT
                                                   (uri-path uri)
                                                   response
                                                   body)))
              (begin
                (log 'INFO
                     "successfully uploaded log file ("
                     (response-code response)
                     ")")
                #t))))
      #:times 12
      #:delay (random 15)))
   args))

(define-method (submit-build-result
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (build-id result #:key (log default-log))
     (coordinator-http-request
      log
      interface
      (string-append "/build/" build-id)
      #:method 'PUT                     ; TODO Should be PATCH
      #:body result))
   args))

(define-method (report-build-start
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (build-id #:key (log default-log))
     (coordinator-http-request
      log
      interface
      (string-append "/build/" build-id "/report-build-start")
      #:method 'POST))
   args))

(define-method (report-setup-failure
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (build-id report #:key (log default-log))
     (coordinator-http-request
      log
      interface
      (string-append "/build/" build-id "/report-setup-failure")
      #:method 'POST
      #:body report
      #:succeed-on-access-denied-retry? #t))
   args))

(define-method (fetch-builds-for-agent
                (interface <http-agent-interface>)
                .
                args)
  (apply
   (lambda* (systems target-count #:key (log default-log))
     (vector->list
      (assoc-ref (coordinator-http-request
                  log
                  interface
                  (string-append "/agent/"
                                 (slot-ref interface 'agent-uuid)
                                 "/fetch-builds")
                  #:body `((target_count . ,target-count)
                           (systems      . ,(list->vector systems)))
                  #:method 'POST)
                 "builds")))
   args))