;;;; The dev agent, as Flan sees it. Three calls, and the shape of them is the
;;;; design: loading a redefinition and installing it are separate, because
;;;; only the program knows when it is between frames.
;;;;
;;;;   (agent/start)        listen somewhere sensible; once, at startup
;;;;   (agent/start path)   listen on that unix socket instead
;;;;   (agent/poll)         install whatever has arrived; returns how many
;;;;   (agent/wait ms)      the same, but waits for something first
;;;;
;;;; A game loop calls poll at the top of the frame and ignores the result.
;;;; wait is for a headless test, where waiting is what makes a reload
;;;; deterministic rather than a race against the frame rate.
;;;;
;;;; The path was the ceremony. Under [flan dev] the daemon has already decided
;;;; where it wants to talk to the program and says so in FLAN_AGENT_SOCKET, so
;;;; whatever the source named was being overridden anyway; outside the daemon
;;;; any path will do as long as the program says which one it picked. So the
;;;; argument is now optional, and the zero-argument form is the one to write.
;;;; The explicit form stays for a program that wants to choose — a fixed path
;;;; something else is already configured to connect to.
;;;;
;;;; No aggregate crosses this boundary, so there is no shim: a Flan string is
;;;; already ptr+len and flan_agent_start takes it that way.
(declare start-at-raw [path string] i32 "flan_agent_start")
(declare start-auto-raw [] i32 "flan_agent_start_auto")
(declare poll-raw [] i32 "flan_agent_poll")
(declare wait-raw [ms i32] i32 "flan_agent_wait")

;;; Both answer 0 for "listening" and -1 for "could not". Starting twice is not
;;; an error and not a second listener: the C side answers 0 and leaves the
;;; first socket alone, so a program that gets a listener from somewhere else
;;; and also calls start is a program with one listener.
(defn start-at [path string] i32 (start-at-raw path))
(defn start-auto [] i32 (start-auto-raw))

;;; The optional argument, which Flan has no other spelling for: a function
;;; takes the arity it declares, so the choice between the two above is made
;;; before the checker ever sees a call. Extra arguments are not silently
;;; dropped — they are spliced into [start-at], which then refuses them by its
;;; own arity, at the call site, in the usual words.
(defmacro start [& args]
  (if (= (len args) 0)
    `(start-auto)
    `(start-at ~@args)))

(defn poll [] i32 (poll-raw))
(defn wait [ms i32] i32 (wait-raw ms))