; feed/normalize — coerce arbitrary input into the canonical activity record.
; An activity is a small dict {:actor :verb :object :at :tags}; a stream is an
; APL vector of such dicts (see stream.sx). Extra keys on the raw input survive
; (e.g. :visible-to for ACL, peer metadata for federation) — :tags is the
; flexible bag but the record is not closed.

(define feed/activity-keys (list :actor :verb :object :at :tags))

(define
  feed/normalize
  (fn
    (raw)
    (let
      ((d (if (= (type-of raw) "dict") raw {})))
      (merge d {:actor (get d :actor "") :object (get d :object nil) :at (get d :at 0) :tags (let ((t (get d :tags (list)))) (if (list? t) t (list t))) :verb (get d :verb "post")}))))

(define
  feed/activity
  (fn (actor verb object at tags) (feed/normalize {:actor actor :object object :at at :tags tags :verb verb})))

(define feed/actor (fn (a) (get a :actor)))
(define feed/verb (fn (a) (get a :verb)))
(define feed/object (fn (a) (get a :object)))
(define feed/at (fn (a) (get a :at)))
(define feed/tags (fn (a) (get a :tags)))

(define
  feed/activity?
  (fn
    (a)
    (and (= (type-of a) "dict") (has-key? a :actor) (has-key? a :verb))))