(in-package :pkgmgr-except)

;; Define an 'extended' condition that satisfies what I would personally
;; consider a minimal base condition - in other words, being able to
;; specify a generic human-readable error message aswell as specify
;; an underlying cause for the condition (in the form of another
;; condition).
(define-condition extended-condition (condition)
  ((message :accessor extended-condition-message :initarg :message :initform nil)
   (cause :accessor extended-condition-cause :initarg :cause :initform nil)
   (kvlist :accessor extended-condition-kvlist :initarg :kvlist :initform nil))
  (:report (lambda (condition stream)
	     (format stream "~a" (extended-condition-report condition)))))

(defmethod extended-condition-report (condition)
  (with-accessors ((message extended-condition-message)
		   (cause extended-condition-cause)
		   (kvlist extended-condition-kvlist))
    condition
    (format nil
	    "Condition of type ~a: ~a (cause: ~a)"
	    (class-name (class-of condition))
	    (if (and (typep condition 'extended-condition)
		     (extended-condition-extended-message condition))
		(extended-condition-extended-message condition)
		(format nil "~a, ~a" message kvlist))
	    cause)))

(define-condition extended-error (extended-condition error)
  ())

;; Method to be overrided for classes that want to include more information
;; than just the message given using :message. Implementors must also
;; print :message if is to be shown, as this message is printed instead
;; of the message.
(defmethod extended-condition-extended-message ((c condition))
  nil)