;;; misc/config-publishing/async-proc-management.el -*- lexical-binding: t; -*-

(require 'cl-lib)

(defvar start-time (float-time))
(defvar exit-code 0)

(defvar apm-timeout 300
  "Give up after this many seconds")
(defvar apm-dependent-processes nil)

(cl-defmacro apm-exec (files &key then)
  (if then
      (if (listp then)
          `(apm--exec ,files :then ',then)
        `(apm--exec ,files :then ,then))
    `(apm--exec ,files)))

(cl-defun apm--exec (files &key then announce)
  (dolist (file (if (listp files) files (list files)))
    (let ((proc-name (intern (format "%s-process" (file-name-base file))))
          proc-info)
      (when announce
        (message "[0;32] Starting %s%s" file
                 (apm-space-fill-line (+ 9 (length file)))))
      (set proc-name
           (start-process (file-name-base file) nil
                          (if (file-exists-p file)
                              (expand-file-name file)
                            file)))
      (setq proc-info (list :proc (symbol-value proc-name)
                            :file file
                            :name (file-name-base file)
                            :padded-name (format "%-8s" (file-name-base file)) ; max len Active/Complete
                            :then (if (listp then) then (list then))))
      (push proc-info apm-dependent-processes)
      (apm-watch-process proc-info))))

(defun apm-watch-process (proc-info)
  (let ((file (plist-get proc-info :file)))
    (set-process-sentinel
     (plist-get proc-info :proc)
     `(lambda (process _signal)
        (when (eq (process-status process) 'exit)
          (if (= 0 (process-exit-status process))
              (progn
                (message (format "[1;35] %s finished%s"
                                 ,(file-name-base file)
                                 (apm-space-fill-line ,(length (file-name-base file)))))
                ;; start dependent processes
                (when ',(car (plist-get proc-info :then))
                  (mapcar (lambda (then)
                            (apply #'apm--exec
                                   (append
                                    (pcase (if (and (listp then)
                                                    (symbolp (car then)))
                                               (eval then) then)
                                      ((and n (pred stringp)) (list n))
                                      ((and n (pred listp)) n)
                                      (n (user-error "unrecognised :then form %s" n)))
                                    '(:announce t))))
                          ',(list (plist-get proc-info :then)))))
            ;; non-zero exit code
            (message (format "[31] %s process failed!%s"
                             ,(file-name-base (eval file))
                             (apm-space-fill-line ,(+ 16 (length (file-name-base file))))))
            (message "\033[0;31m      %s\033[0m"
                     'unmodified
                     (with-temp-buffer
                       (insert-file-contents-literally (expand-file-name ,(format "%s-log.txt" (file-name-base file))
                                                                         (file-name-directory load-file-name)))
                       (buffer-substring-no-properties (point-min) (point-max))))
            (message "[1;31] Config publishing aborted%s" (apm-space-fill-line 23))
            (kill-emacs 1)))))))

(defun apm-space-fill-line (base-length)
  "Return whitespace such that the line will be filled to overwrite the status line."
  (make-string (max 0
                    (- (apply #'+ (* 2 (1- (length apm-dependent-processes)))
                              (mapcar (lambda (dep) (length (plist-get dep :padded-name))) apm-dependent-processes))
                       base-length))
               ? ))


;;; Status info

(defun apm-process-status-table ()
  (message (concat
            "\033[1m[%4.1fs] \033[0;1m"
            (mapconcat (lambda (dep) (plist-get dep :padded-name)) apm-dependent-processes "  ")
            "\n\033[0m        "
            (mapconcat (lambda (dep)
                         (apply #'format (format "%%s%%-%ds" (length (plist-get dep :padded-name)))
                                (pcase (process-status (plist-get dep :proc))
                                  ('run '("\033[0;33m" "Active"))
                                  ('exit '("\033[0;32m" "Complete")))))
                       apm-dependent-processes
                       "  ")
            "\033[0;90m")
           'unmodified
           (- (float-time) start-time)))

;;; Await completion

(defun apm-wait-and-monitor ()
  (setq apm-all-proc-finished nil)

  (sleep-for 0.1) ; let processes start
  (while (not apm-all-proc-finished)
    (apm-process-status-table)
    (setq apm-all-proc-finished t)
    (dolist (dep apm-dependent-processes)
      (when (not (eq (process-status (plist-get dep :proc)) 'exit))
        (setq apm-all-proc-finished nil)))
    (when (< apm-timeout (- (float-time) start-time))
      (message "[0;31] Timout exceeded. Killing slow processes%s" (apm-space-fill-line 37))
      (dolist (dep apm-dependent-processes)
        (let ((proc (plist-get dep :proc)))
          (when (not (eq (process-status proc) 'exit))
            (message "[1;31] Killing %s%s" proc (apm-space-fill-line (+ 6 (length (format "%s" proc)))))
            (signal-process proc 'SIGUSR2)
            (sleep-for 0.2)
            (delete-process proc)
            (message "\n\033[0;31m      %s\033[0m"
                     'unmodified
                     (with-temp-buffer
                       (insert-file-contents-literally (expand-file-name (format "%s-log.txt" (file-name-base (plist-get dep :file)))
                                                                         (file-name-directory load-file-name)))
                       (buffer-substring-no-properties (point-min) (point-max)))))))
      (setq apm-all-proc-finished t)
      (setq exit-code 1))
    (unless apm-all-proc-finished
      (sleep-for 0.5))))