From 8137daf4ae9fab7a5133a31a5f6adda01d321226 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hugo=20H=C3=B6rnquist?= <hugo@hornquist.se>
Date: Sun, 10 Mar 2019 23:49:18 +0100
Subject: Add serialize-vcomponent.

---
 vcalendar/output.scm | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

(limited to 'vcalendar')

diff --git a/vcalendar/output.scm b/vcalendar/output.scm
index 908dab34..e4635beb 100644
--- a/vcalendar/output.scm
+++ b/vcalendar/output.scm
@@ -1,8 +1,11 @@
 (define-module (vcalendar output)
   #:use-module (vcalendar)
+  #:use-module (vcalendar control)
   #:use-module (util)
+  #:use-module (srfi srfi-19 util)
   #:use-module (srfi srfi-26)
   #:export (print-vcomponent
+            serialize-vcomponent
             color-if
             STR-YELLOW STR-RESET))
 
@@ -31,3 +34,60 @@
                              key value))))
     (for-each-in (children comp)
                  (cut print-vcomponent <> (1+ depth)))))
+
+
+
+;;; TODO
+;; Error in CREATED /home/hugo/.calendars/b85ba2e9-18aa-4451-91bb-b52da930e977/a1a25238-d63d-46a1-87fd-d0c9334a7a30CalSync.ics:
+;; Wrong type argument in position 1 (expecting string): ("20180118T124015Z" "VALARM")
+
+(define (string->ics-safe-string str)
+  "TODO wrap at 75(?) columns."
+  (define (escape char)
+    (string #\\ char))
+
+  (string-concatenate
+   (map (lambda (c)
+          (case c
+            ((#\newline) "\\n")
+            ((#\, #\; #\\) => escape)
+            (else => string)))
+        (string->list str))))
+
+;;; TODO parameters ( ;KEY=val: )
+(define* (serialize-vcomponent comp #:optional (port (current-output-port)))
+  "Recursively write a component back to its ICS form.
+Removes the X-HNH-FILENAME attribute, and sets PRODID to
+\"HugoNikanor-calparse\" in the output."
+  (with-replaced-attrs
+   (comp (prodid "HugoNikanor-calparse"))
+
+   (format port "BEGIN:~a~%" (type comp))
+   (let ((kvs (map (lambda (key) (list key (attr comp key)))
+                   (filter (negate (cut key=? <> 'X-HNH-FILENAME))
+                           (attributes comp)))))
+     (for-each-in
+      kvs (lambda (kv)
+            (let* (((key value) kv))
+              (catch 'wrong-type-arg
+                (lambda ()
+                  (format port "~a:~a~%" key
+                          (string->ics-safe-string
+                           (case key
+                             ((DTSTART DTEND)
+                              (if (string? value)
+                                  value
+                                  (time->string value "~Y~m~dT~H~M~S")))
+
+                             ((RRULE DURATION) "Just forget it")
+
+                             (else value)))))
+
+                ;; Catch
+                (lambda (type proc fmt . args)
+                  (apply format (current-error-port) "[ERR] ~a in ~a (~a) ~a:~%~?~%"
+                         type key proc (attr comp 'X-HNH-FILENAME)
+                         fmt args))))))
+
+     (for-each (cut serialize-vcomponent <> port) (children comp)))
+   (format port "END:~a~%" (type comp))))
-- 
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