#lang scheme/base
(require mzlib/contract
         mzlib/list
         net/url
         "response-structs.ss"
         "request-structs.ss")

;; make-session-url: url (listof string) -> url
;; produce a new url for this session:
;;   Minimal path to the servlet.
;;   No query.
;;   No fragment.
(define (make-session-url uri new-path)
  (make-url
   (url-scheme uri)
   (url-user uri)
   (url-host uri)
   (url-port uri)
   #t
   (map (lambda (p) (make-path/param p empty))
        new-path)
   empty
   #f))

(define-struct session (cust namespace servlet url)
  #:mutable)

(provide/contract
 [struct session ([cust custodian?]
                  [namespace namespace?]
                  [servlet (request? . -> . response?)]
                  [url url?])]
 [lookup-session ((listof string?) . -> . (or/c session? false/c))]
 [install-session (session? (listof string?) . -> . void)]
 [new-session (custodian? namespace? url? (listof string?) . -> . session?)])
(provide current-session)  

(define current-session (make-parameter #f))

(define the-session-table (make-weak-hash))

;; new-session : namespace path uri (listof string) -> session
(define (new-session cust ns uri paths)
  (define ses (make-session
               cust
               ns
               (lambda (req) (error "session not initialized"))
               (make-session-url uri paths)))
  #;(printf "New session of ~a~n" (hash-table-count the-session-table))    
  ses)

(define (install-session ses paths)
  (hash-set! the-session-table paths ses))

;; lookup-session : (listof string) -> (union session #f)
(define (lookup-session paths)
  (hash-ref the-session-table paths 
            (lambda () #f)))