;;;  see next comments on how to start this

;; boat service:
(use srfi-18 medea comparse)

;; workaround for blocking on i/o when reading json from stdin
(include "nonblocking-input-ports.scm")
(current-input-port (open-input-file*/nonblock 0))

;; ==================== globals

(define state '())

(define (limit lst num)
  (take lst (min (length lst) num)))

;; ==================== boat utils

(define (geojson-mmsi geojson)
  (alist-ref 'mmsi (or (alist-ref 'properties geojson) '())))

;; (pp (extract (include "./boat.data.scm")))

;; input: alist ((pos . (lat . lon)) (mmsi . mmsi))
;; state is a map of :
(define (prj-geojson geojson state)
  ;; set properties for mmsi key:
  (alist-update (geojson-mmsi geojson) ;; key (mmsi)
                geojson ;; value (geojson feature)
                state))

;; (rect-inside? 0 0  1 -1 -1 1)
(define (rect-inside? x y top left bottom right)
  (and (>= x left)   (<= x right)
       (>= y bottom) (<= y top)))

;; (length (filter (lambda (pair) (geojson-inside? (cdr pair) 61 5 60 6)) _state))

(define (geojson-inside? geojson top left bottom right)
  (and-let* ((gm (alist-ref 'geometry geojson))
             (pos (alist-ref 'coordinates gm))
             (lon (vector-ref pos 0))
             (lat (vector-ref pos 1)))
            (and lon lat (rect-inside? lon lat top left bottom right))))

;; query boats based on region (bounding box). typical json is "[60,
;; 5, 61, 5.5]"
(define (bb-query state bbox)
  ;; bad naming here, sorry. need a rect abstraction
  (define (corner x) (vector-ref bbox x))
  (define result
    (filter (lambda (pair)
              (geojson-inside? (cdr pair)
                               (corner 0) (corner 1)
                               (corner 2) (corner 3)))
            state))

  (print "found " (length result) "/" (length state) " boats")

  (json->string
   `((type . "FeatureCollection")
     (features . ,(list->vector (limit (map cdr result) 100))))))

(define (query-handler json)
  (print "boats: got query " json)
  (bb-query state json))

;; uri to bounding-box query. ie:
;; (uri-bbq (uri-reference "?bb=1/2/3/4"))
;; (uri-bbq (uri-reference "?nothing=false"))
(define (get-bbq bb)
  (list->vector (map string->number (string-split bb "/"))))

(define (top-handler)
  (query-handler
   (get-bbq "67.1016555307692/-28.256835937499996/53.61857936489517/46.669921875")))

(define server-thread
  (thread-start!
   (lambda ()
     (let lp ()
       (thread-sleep! 0.01)
       (print "boats!" (top-handler))
       (lp)))))

(define count 0)
(let loop ((input (current-input-port)))
  (receive (json rest) (read-json input)
    (set! count (add1 count))
    (set! state (prj-geojson json state))
    (if (not (parser-input-end? rest))
        (loop rest))))