(defvar opam nil)
(defvar git-opam-url)
(defvar opam-vars '("lib" "libexec" "bin"
		    "sbin" "toplevel"
		    "share" "share_root"
		    "etc" "doc" "stublibs"))
(defvar utop nil
  "the full path of utop")

(setf git-opam-url "https://github.com/ocaml/opam.git")

(defun opam-config-var (var)
  (let ((command-string (concat "opam config var " var)))
    (substring (shell-command-to-string command-string)
		0 -1)))

(defun opam-config-env ()
  (dolist (var (car (read-from-string
		     (shell-command-to-string
		      "opam config env --sexp"))))
    (let ((var-name (car var))
	  (var-val  (cadr var)))
      (setenv var-name
	      (let ((old-v (getenv var-name)))
		(if old-v
		    (concat old-v ":" var-val)
		  var-val)))))
  (add-to-list 'load-path
	       (concat (opam-config-var "share")
		       "/emacs/site-lisp/")))

(defun check-opam ()
  (if (not (which "opam"))
      (progn (message "Please install opam")
	     nil)
    (progn (opam-config-env)
	   (setq utop (which "utop"))
	   (unless utop
	     (message "Please install utop with (opam install utop)"))
	   utop)))

(register-mypkg
 (list :name "opam"
       :enabled (check-opam)
       :packages nil
       :init #'(lambda ()
		 (setq utop-command (concat utop " -emacs"))
		 (autoload 'utop "utop" "toplevel of ocaml" t))))