(define-module (sigils home services wayland)
  #:use-module (gnu home services)
  #:use-module (gnu home services shepherd)
  #:use-module (gnu packages wm)
  #:use-module (gnu services configuration)
  #:use-module (guix packages)
  #:use-module (guix gexp)
  #:use-module (guix diagnostics)
  #:use-module (guix ui)
  #:use-module (sigils home services desktop)

  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-43)
  #:use-module (ice-9 match)

  #:export (home-kanshi-service-type
            home-kanshi-configuration))

;;;
;;; kanshi.
;;;

(define kanshi-config? list?)

(define (serialize-kanshi-config config)
  (define serialize-term
    (match-lambda
      ((? symbol? e) `(" " ,(symbol->string e)))
      ((? number? e) `(" " ,(number->string e)))
      ((? string? e) `(" " ,(format #f "~s" e)))
      (e `(" " ,e))))

  (define serialize-statement
    (match-lambda
      ((cmd . lst)
       `(,(symbol->string cmd)
         ,@(append-map serialize-term lst)))))

  (define serialize-profile
    (match-lambda
      ((name ((expressions ...) ...))
       `("profile " ,(symbol->string name) " {\n"
         ,@(append-map
            (lambda (expr) `("    " ,@(serialize-statement expr) "\n"))
            expressions)
         "}\n"))))

  (append-map serialize-profile config))

(define-configuration home-kanshi-configuration
  (kanshi
   (file-like kanshi)
   "kanshi package to use.")
  (config
   (kanshi-config
    `())
   "The kanshi configuration is a list of profiles with output and exec fields.
@lisp
'((static ((output LVDS-1 disable)
           (output \"Some Company ASDF 4242\" mode 1600x900 position 0,0)))
  (portable ((output LVDS-1 enable scale 2))))
@end lisp

serializes to

@code
profile static {
	output LVDS-1 disable
	output \"Some Company ASDF 4242\" mode 1600x900 position 0,0
}

profile portable {
	output LVDS-1 enable scale 2
}
@end code
"))

(define (add-kanshi-packages config)
  (list (home-kanshi-configuration-kanshi config)))

(define (add-kanshi-configuration config)
  `(("kanshi/config"
     ,(apply
       mixed-text-file
       "kanshi-config"
       (serialize-kanshi-config (home-kanshi-configuration-config config))))))

(define (home-kanshi-shepherd-service config)
  (let ((kanshi (home-kanshi-configuration-kanshi config)))
    (list
     (shepherd-service
      (provision '(kanshi))
      (requirement '(wayland-display))
      (modules '((srfi srfi-1)
                 (srfi srfi-26)))
      (start #~(lambda _
                 ;; This is not optimal.
                 (fork+exec-command
                  (list #$(file-append kanshi "/bin/kanshi"))
                  #:log-file (string-append
                              (getenv "XDG_STATE_HOME") "/log"
                              "/kanshi.log")
                  #:environment-variables
                  (cons (string-append "WAYLAND_DISPLAY=" (getenv "WAYLAND_DISPLAY"))
                        (remove (cut string-prefix? "WAYLAND_DISPLAY=" <>)
                                (default-environment-variables))))))
      (stop #~(make-kill-destructor))
      (documentation "Run Kanshi")))))

(define (home-kanshi-extensions cfg extensions)
  (home-kanshi-configuration
   (inherit cfg)
   (config
    (append (home-kanshi-configuration-config cfg)
            (append-map identity (reverse extensions))))))

(define home-kanshi-service-type
  (service-type (name 'home-kanshi)
                (extensions
                 (list (service-extension
                        home-profile-service-type
                        add-kanshi-packages)
                       (service-extension
                        home-shepherd-service-type
                        home-kanshi-shepherd-service)
                       (service-extension
                        home-xdg-configuration-files-service-type
                        add-kanshi-configuration)))
                (compose identity)
                (extend home-kanshi-extensions)
                (default-value (home-kanshi-configuration))
                (description "\
Install and configure kanshi, output profile manager.")))