Scripts/parking.scm

(import medea)
(import http-client)
(import srfi-1)
(import (chicken io))
(import (chicken sort))

(define (curry fn a)
  (lambda (b)
    (fn a b)))

(define (perhaps fn a)
  (if a (fn a) a))

(define (member? a ln)
  (if (member a ln) #t #f))

(define (default b a)
  (if a a b))

(define value
  (compose (curry perhaps cdr) assoc))

(define (value-with-default k v ln)
  (default v (value k ln)))

(define (has-key? k ln)
  (member? k (map car ln)))

(define (sort-via less-than? fn ln)
  (sort ln (lambda (a b)
	     (less-than? (fn a) (fn b)))))

(define (display-newline str)
  (display str)
  (newline))

(define (->string a)
  (cond ((string? a) a)
	((symbol? a) (symbol->string a))
	((number? a) (number->string a))
	((char? a) (string a))))
    
(define (format-assoc statement ln)
  (apply string-append
	 (map (lambda (directive)
		(if (symbol? directive)
		    (->string (value directive ln))
		    directive)) statement)))

(define (simple-json-request uri)
  (with-input-from-request uri #f read-json))

(define parking-key
  (with-input-from-file "key-parking" read-line))

(define (get-parking-lots)
  (let ((result (simple-json-request (string-append "http://parkering.linkoping.se/Parkeringsdata/ParkeringsdataV1.svc/GetParkeringsYtaList/" parking-key "/0"))))
    (vector->list (value 'ParkingAreaNewList result))))

(define (computerized? lot)
  (has-key? 'ParkingSpacesAvailable lot))

(define (only-has-handicap-spots? lot)
  (equal? #(4) (value 'ParkingTypes lot)))

(define (electric-car-lot? lot)
  (member? 3 (value 'ParkingTypes lot)))

(define (main)
  (display-newline "Parking spaces available:")
  (let ((lots (sort-via string-ci<? (curry value 'Name) (get-parking-lots))))
    (map (compose display-newline (curry format-assoc '(Name ": " ParkingSpacesAvailable "/" ParkingSpaces)))
	 (filter (conjoin computerized? (complement only-has-handicap-spots?)) lots))))

(main)