;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;; Copyright © 2015, 2016 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 ng0 <ng0@we.make.ritual.n0.is>
;;; Copyright © 2016 Julien Lepiller <julien@lepiller.eu>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU 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.
;;;
;;; GNU 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 GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu services web)
  #:use-module (gnu services)
  #:use-module (gnu services shepherd)
  #:use-module (gnu system shadow)
  #:use-module (gnu packages admin)
  #:use-module (gnu packages web)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 match)
  #:export (nginx-configuration
            nginx-configuration?
            nginx-block-server
            nginx-access
            nginx-option
            nginx-listen
            nginx-service
            nginx-service-type))

;;; Commentary:
;;;
;;; Web services.
;;;
;;; Code:

(define-record-type* <nginx-configuration>
  nginx-configuration make-nginx-configuration
  nginx-configuration?
  (nginx          nginx-configuration-nginx)         ;<package>
  (log-directory  nginx-configuration-log-directory) ;string
  (run-directory  nginx-configuration-run-directory) ;string
  (http-configs   nginx-configuration-http-configs)
  (events-configs nginx-configuration-events-configs)
  (blocks         nginx-configuration-blocks)
  (file           nginx-configuration-file))         ;string | file-like

(define-record-type* <nginx-option>
  nginx-option make-nginx-option
  nginx-option?
  (type  nginx-option-type)
  (value nginx-option-value))

(define-record-type* <nginx-block-server>
  nginx-block-server make-nginx-block-server
  nginx-block-server?
  (blocks  nginx-block-server-blocks)
  (configs nginx-block-server-configs))

(define-record-type* <nginx-listen>
  nginx-listen make-nginx-listen
  nginx-listen?
  (port    nginx-listen-port
           (default 80))
  (address nginx-listen-address
           (default #f))
  (socket  nginx-listen-socket
           (default #f))
  (ssl?    nginx-listen-ssl?
           (default #f))
  (http2?  nginx-listen-http2?
           (default #f))
  (spdy?   nginx-listen-spdy?
           (default #f))
  (proxy?  nginx-listen-proxy?
           (default #f)))

(define-record-type* <nginx-error-page>
  nginx-error-page make-nginx-error-page
  nginx-error-page?
  (codes    nginx-error-page-codes
            (default (list 404)))
  (response nginx-error-page-response
            (default #f))
  (uri      nginx-error-page-uri
            (default "/404.html")))

(define-record-type* <nginx-access>
  nginx-access make-nginx-access
  nginx-access?
  (deny?  nginx-access-restriction
          (default #t))
  (to     nginx-access-to
          (default 'all))
  (except nginx-access-except
          (default '())))

(define (config-domain-strings names)
 "Return a string denoting the nginx config representation of NAMES, a list
of domain names."
 (string-concatenate
    (map (match-lambda
          ('default "_ ")
          ((? string? str) (string-append str " ")))
         names)))

(define (config-index-strings names)
 "Return a string denoting the nginx config representation of NAMES, a list
of index files."
 (string-concatenate
    (map (match-lambda
          ((? string? str) (string-append str " ")))
         names)))

(define (config-code-strings codes)
 "Return a string denoting the nginx config representation of CODES, a list
of HTTP response code."
 (string-concatenate
    (map (match-lambda
          ((? number? n) (string-append (number->string n) " ")))
         codes)))

(define (nginx-listen-config listen)
  (match listen
   (($ <nginx-listen> port address socket ssl? http2? spdy? proxy?)
     #~(string-append "listen "
        #$(if address
              (if port
                  (string-append address ":" (number->string port))
                  address)
              (if port
                  (number->string port)
                  (string-append "unix:" socket)))
        #$(if ssl? "http2 " (if spdy? "spdy " " "))
        #$(if proxy? "proxy_protocol" "")
        ";"))))

(define (nginx-error-page-config error)
  (match error
    (($ <nginx-error-page> codes response uri)
      #~(string-append "error_page " #$(config-code-strings codes)
                       #$(match response
                           (#f "")
                           ('proxy "=")
                           ((? number? n) (string-append "=" (number->string n))))
                       #$uri ";"))))

(define (nginx-access-config access)
  (match access
    (($ <nginx-access> deny? to except)
      #~(string-append
          #$(let ((except-list
                    (map nginx-access-config except)))
              (do ((except-list except-list (cdr except-list))
                   (block "" #~(string-append #$(car except-list) "\n" #$block )))
                  ((null? except-list) block)))
          #$(if deny? "deny " "allow ")
          #$(match to
              ('all "all")
              ('unix "unix:")
              (_ to))
          ";"))))
          

(define (authorized-option-type type)
  (match type
    ('http (list 'access 'error_page 'etag 'index 'if_modified_since
                 'ignore_invalid_headers 'log_not_found 'log_subrequest
                 'merge_slashes 'port_in_redirect 'recursive_error_pages 'root
                 'server_name_in_redirect 'server_tokens))
    ('server (list 'access 'error_page 'etag 'index 'if_modified_since
                   'ignore_invalid_headers 'listen 'log_not_found 'log_subrequest
                   'merge_slashes 'port_in_redirect 'recursive_error_pages 'root
                   'server_name 'server_name_in_redirect 'server_tokens 'try_files))
    ('location (list 'access 'alias 'error_page 'etag 'if_modified_since 'index
                     'internal 'log_not_found 'log_subrequest 'port_in_redirect
                     'recursive_error_pages 'root 'server_name_in_redirect
                     'server_tokens 'try_files))
    ('if (list 'error_page 'root))
    ('limit_except (list 'access))
    ('events (list))))

(define (assert-good-type conf-type block-type)
  (if (not (memq conf-type (authorized-option-type block-type)))
      (throw 'bad-conf-type
             (string-append (symbol->string conf-type)
                            " is not allowed in a " 
                            (symbol->string block-type)
                            " block."))))

(define (default-nginx-option-config name value)
  #~(string-append #$(symbol->string name) " " #$value ";"))

(define (nginx-option-config option parent-block-type)
  (assert-good-type (nginx-option-type option) parent-block-type)
  (match option
    (($ <nginx-option> type value)
      (match type
        ('access (nginx-access-config value))
        ('error_page (nginx-error-page-config value))
        ('if_modified_since (match value
                             (#f "if_modified_since off;")
                             ('exact "if_modified_since exact;")
                             ('before "if_modified_since before;")))
        ('internal (if value "internal;" ""))
        ('listen (nginx-listen-config value))
        ('server_name #~(string-append "server_name "
                                       #$(config-domain-strings value) ";"))
        ('index #~(string-append "index " #$(config-index-strings value) ";"))
        ('try_files #~(string-append "try_files "
                                     #$(config-index-strings value)) ";")
        (_ (match value
             ((? number? n) (default-nginx-option-config type (number->string n)))
             (#t default-nginx-option-config type "on")
             (#f default-nginx-option-config type "off")
             (_ (default-nginx-option-config type value))))))))

(define (authorized-block-type type)
  (match type
    ('http (list 'server 'types))
    ('location (list 'if 'limit_except 'location 'types))
    ('server (list 'location 'types))))

(define (assert-good-block-type block-type parent-type)
  (if (not (memq block-type (authorized-block-type parent-type)))
      (throw 'bad-block-type
             (string-append (symbol->string block-type)
                            " is not allowed in a " 
                            (symbol->string parent-type)
                            " block."))))

(define (nginx-block-server-config blocks options parent-type)
  (assert-good-block-type 'server parent-type)
  #~(string-append
     "    server {\n"
     #$(let ((config-list
               (map (lambda (option)
                            (nginx-option-config option 'server))
                    options)))
         (do ((config-list config-list (cdr config-list))
              (block "" #~(string-append #$(car config-list) "\n" #$block )))
             ((null? config-list) block)))
     #$(let ((block-list
               (map (lambda (block)
                            (nginx-block-config block 'server)) blocks)))
         (do ((block-list block-list (cdr block-list))
              (block "" #~(string-append #$(car block-list) "\n" #$block )))
             ((null? block-list) block)))
    ; #$(if (eq? options '())
    ;       ""
    ;       #~(string-concatenate
    ;                 #$(map (lambda (option)
    ;                              (nginx-option-config option 'server))
    ;                      options)))
    ; #$(if (eq? blocks '())
    ;       ""
    ;       (string-concatenate
    ;                 (map (lambda (block)
    ;                              (nginx-block-config block 'server))
    ;                      blocks)))
     "    }\n"))

(define (nginx-block-config block parent-type)
  (match block
    (($ <nginx-block-server> blocks options)
      (nginx-block-server-config blocks options parent-type))
    (_ "")))

(define (default-nginx-config log-directory run-directory http-configs
                              events-configs blocks)
  (computed-file "nginx.conf"
    #~(call-with-output-file #$output
        (lambda (port)
          (format port
            (string-append
             "user nginx nginx;\n"
             "pid " #$run-directory "/pid;\n"
             "error_log " #$log-directory "/error.log info;\n"
             "http {\n"
             "    client_body_temp_path " #$run-directory "/client_body_temp;\n"
             "    proxy_temp_path " #$run-directory "/proxy_temp;\n"
             "    fastcgi_temp_path " #$run-directory "/fastcgi_temp;\n"
             "    uwsgi_temp_path " #$run-directory "/uwsgi_temp;\n"
             "    scgi_temp_path " #$run-directory "/scgi_temp;\n"
             "    access_log " #$log-directory "/access.log;\n"
             #$(let ((config-list
                       (map (lambda (option)
                                    (nginx-option-config option 'http))
                            http-configs)))
                 (do ((config-list config-list (cdr config-list))
                      (block "" #~(string-append #$(car config-list) "\n" #$block )))
                     ((null? config-list) block)))
             #$(let ((block-list
                       (map (lambda (block)
                                    (nginx-block-config block 'http)) blocks)))
                 (do ((block-list block-list (cdr block-list))
                      (block "" #~(string-append #$(car block-list) "\n" #$block )))
                     ((null? block-list) block)))
             "}\n"
             "events {\n"
             #$(let ((config-list
                       (map (lambda (option)
                                    (nginx-option-config option 'http))
                            events-configs)))
                 (do ((config-list config-list (cdr config-list))
                      (block "" #~(string-append #$(car config-list) "\n" #$block )))
                     ((null? config-list) block)))
             "}\n"))))))

(define %nginx-accounts
  (list (user-group (name "nginx") (system? #t))
        (user-account
         (name "nginx")
         (group "nginx")
         (system? #t)
         (comment "nginx server user")
         (home-directory "/var/empty")
         (shell (file-append shadow "/sbin/nologin")))))

(define nginx-activation
  (match-lambda
    (($ <nginx-configuration> nginx log-directory run-directory http-configs
                              events-configs blocks file)
     #~(begin
         (use-modules (guix build utils))

         (format #t "creating nginx log directory '~a'~%" #$log-directory)
         (mkdir-p #$log-directory)
         (format #t "creating nginx run directory '~a'~%" #$run-directory)
         (mkdir-p #$run-directory)
         (format #t "creating nginx temp directories '~a/{client_body,proxy,fastcgi,uwsgi,scgi}_temp'~%" #$run-directory)
         (mkdir-p (string-append #$run-directory "/client_body_temp"))
         (mkdir-p (string-append #$run-directory "/proxy_temp"))
         (mkdir-p (string-append #$run-directory "/fastcgi_temp"))
         (mkdir-p (string-append #$run-directory "/uwsgi_temp"))
         (mkdir-p (string-append #$run-directory "/scgi_temp"))
         ;; Check configuration file syntax.
         (system* (string-append #$nginx "/sbin/nginx")
                  "-t" "-c" #$(or file
                                  (default-nginx-config log-directory run-directory
                                    http-configs events-configs blocks)))))))

(define nginx-shepherd-service
  (match-lambda
    (($ <nginx-configuration> nginx log-directory run-directory http-configs
                              events-configs blocks file)
     (let* ((nginx-binary (file-append nginx "/sbin/nginx"))
            (nginx-action
             (lambda args
               #~(lambda _
                   (zero?
                    (system* #$nginx-binary "-c"
                      #$(or file
                            (default-nginx-config log-directory run-directory
                              http-configs events-configs blocks))
                      #$@args))))))

       ;; TODO: Add 'reload' action.
       (list (shepherd-service
              (provision '(nginx))
              (documentation "Run the nginx daemon.")
              (requirement '(user-processes loopback))
              (start (nginx-action "-p" run-directory))
              (stop (nginx-action "-s" "stop"))))))))

(define nginx-service-type
  (service-type (name 'nginx)
                (extensions
                 (list (service-extension shepherd-root-service-type
                                          nginx-shepherd-service)
                       (service-extension activation-service-type
                                          nginx-activation)
                       (service-extension account-service-type
                                          (const %nginx-accounts))))
                (compose concatenate)
                (extend (lambda (config blocks)
                          (nginx-configuration
                            (inherit config)
                            (blocks (append (nginx-configuration-blocks config)
                                            blocks)))))))

(define* (nginx-service #:key (nginx nginx)
                        (log-directory "/var/log/nginx")
                        (run-directory "/var/run/nginx")
                        (http-configs '())
                        (events-configs '())
                        (blocks '())
                        (config-file #f))
  "Return a service that runs NGINX, the nginx web server.

The nginx daemon loads its runtime configuration from CONFIG-FILE, stores log
files in LOG-DIRECTORY, and stores temporary runtime files in RUN-DIRECTORY."
  (service nginx-service-type
           (nginx-configuration
            (nginx nginx)
            (log-directory log-directory)
            (run-directory run-directory)
            (http-configs http-configs)
            (events-configs events-configs)
            (blocks blocks)
            (file config-file))))