(define-library (gemini)
  (export gemini-error?
          gemini-error-response
          make-gemini-response
          gemini-response?
          gemini-response-code
          gemini-response-first-digit
          gemini-response-second-digit
          gemini-response-success?
          gemini-response-redirect?
          gemini-response-meta
          gemini-response-port
          gemini-response-read-bytevector-all
          gemini-response-read-string-all
          gemini-response-raise
          read-cr-lf-terminated-line)
  (import (scheme base))
  (cond-expand
    (chicken
     (import (chicken condition) (openssl) (uri-generic))))
  (cond-expand
    (chicken

     (define gemini-error?
       (condition-predicate 'gemini-error))

     (define gemini-error-response
       (condition-property-accessor 'gemini-error 'response #f))

     (define (make-gemini-error response)
       (make-property-condition 'gemini-error
                                'message "Gemini request failed"
                                'response response))))
  (begin

    (define-record-type gemini-respose
      (make-gemini-response code meta port)
      gemini-response?
      (code gemini-response-code)
      (meta gemini-response-meta)
      (port gemini-response-port))

    (define (gemini-response-first-digit response)
      (truncate-quotient (gemini-response-code response) 10))

    (define (gemini-response-second-digit response)
      (truncate-remainder (gemini-response-code response) 10))

    (define (gemini-response-success? response)
      (= 2 (gemini-response-first-digit response)))

    (define (gemini-response-redirect? response)
      (= 3 (gemini-response-first-digit response)))

    (define (gemini-response-raise response)
      (and (not (gemini-response-success? response))
           (raise (make-gemini-error response))))

    (define (gemini-response-read-bytevector-all response)
      (let ((port (gemini-response-port response)))
        (let loop ((whole (bytevector)))
          (let ((part (read-bytevector 10000 port)))
            (if (eof-object? part) whole
                (loop (bytevector-append whole part)))))))

    (define (gemini-response-read-string-all response)
      (utf8->string (gemini-response-read-bytevector-all response)))

    (define (malformed-first-line line)
      (error "Malformed first line" line))

    (define (read-cr-lf-terminated-line port)
      (let loop ((line ""))
        (let ((char (read-char port)))
          (if (eof-object? char)
              (malformed-first-line line)
              (if (char=? #\return char)
                  (let ((char (read-char port)))
                    (if (char=? #\newline char)
                        line
                        (malformed-first-line line)))
                  (loop (string-append line (string char))))))))))