#!/bin/sh
exec guile -e main -s $0 $@
!#

;; Copyright (C) 2012 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
;;
;; This program is free software; you can redistribute it and/or modify it
;; under the terms of the GNU General Public License as published by the
;; Free Software Foundation; either version 3, or (at your option) any
;; later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.
;;

;; You should have received a copy of the GNU General Public License
;; along with this program; if not, write to the Free Software Foundation,
;; Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

(use-modules (ice-9 getopt-long) (ice-9 format))
(use-modules (sxml simple))

(define (mapconcat func lst sepa)
  "Apply FUNC to elements of LST, concat the result as strings
separated by SEPA."
  (if (null? lst)
    ""
    (string-append
      (func (car lst))
      (if (null? (cdr lst))
	""
	(string-append sepa (mapconcat func (cdr lst) sepa))))))

(define (property-list? obj)
  "Is OBJ a elisp-style property list (ie. a list of the
form (:symbol1 something :symbol2 somethingelse), as in an elisp
proplilst."
  (and (list? obj)
    (not (null? obj))
    (symbol? (car obj))
    (string= ":" (substring (symbol->string (car obj)) 0 1))))

(define (plist->pairs plist)
  "Convert an elisp-style property list; e.g:
   (:prop1 foo :prop2: bar ...)
into a list of pairs
   ((prop1 . foo) (prop2 . bar) ...)."
  (if (null? plist)
    '()
    (cons
      (cons
	(substring (symbol->string (car plist)) 1)
	(cadr plist))
      (plist->pairs (cddr plist)))))

(define (string->xml str)
  "XML-encode STR."
  (call-with-output-string (lambda (port) (sxml->xml str port))))

(define (etime->time_t t)
  "Convert elisp time object T into a time_t value."
  (logior (ash (car t) 16) (car t)))

(define (output-xml)
  "Convert string INPUT to XML and print on stdout."
  (letrec ((convert-xml
	     (lambda* (expr #:optional parent)
	    (cond
	      ((property-list? expr)
		(mapconcat
		  (lambda (pair)
		    (format #f "\t<~a>~a</~a>\n"
		      (car pair) (convert-xml (cdr pair) (car pair)) (car pair)))
		  (plist->pairs expr) " "))
	      ((list? expr)
		(cond
		  ((member parent '("from" "to" "cc" "bcc"))
		    (mapconcat (lambda (addr)
				 (format #f "<address>~a~a</email>"
				   (if (string? (car addr))
				     (format #f "<name>~a</name>" (string->xml (car addr))) "")
				   (if (string? (cdr addr))
				     (format #f "<email>~a</email>" (string->xml (cdr addr))) "")))
		      expr " "))
		  ((string= parent "parts") "<!-- message parts -->") ;; for now, ignore
		  ;; convert the crazy emacs time thingy to time_t...
		  ((string= parent "date") (format #f "~a" (etime->time_t expr)))
		  ((string= parent "flags")
		    (mapconcat (lambda (flag)  (format #f "<flag>~a</flag>" flag)) expr ""))))
	      ((or (string? expr) (symbol? expr)) (string->xml expr))
	      ((number? expr) (number->string expr))
	      (#t ".")))))
    (let ((expr (read)))
      (if (not (eof-object? expr))
	(begin
	  (format #t "<message>\n~a</message>\n" (convert-xml expr))
	  (output-xml))))))


(define (output-json)
  "Convert string INPUT to JSON and print on stdout."
  (letrec ((convert-json
	     (lambda* (expr #:optional parent)
	    (cond
	      ((property-list? expr)
		(mapconcat
		  (lambda (pair)
		    (format #f "\n\t\"~a\":~a"
		      (car pair) (convert-json (cdr pair) (car pair))))
		  (plist->pairs expr) ", "))
	      ((list? expr)
		(cond
		  ((member parent '("from" "to" "cc" "bcc"))
		    (string-append "["
		      (mapconcat (lambda (addr)
				   (format #f "{~a~a}"
				     (if (string? (car addr))
				       (format #f "\"name\":\"~a\"," (string->xml (car addr))) "")
				     (if (string? (cdr addr))
				       (format #f "\"email\":\"~a\"" (string->xml (cdr addr))) "")))
			expr " ")
		      "]"))
		  ((string= parent "parts") "[<!-- message parts -->]") ;; for now, ignore
		  ;; convert the crazy emacs time thingy to time_t...
		  ((string= parent "date") (format #f "~a" (format #f "~a" (etime->time_t expr))))
		  ((string= parent "flags")
		    (string-append "["
		      (mapconcat (lambda (flag)  (format #f "\"flag\":\"~a\"" flag)) expr ", ")
		      "]"))))
	      ((or (string? expr) (symbol? expr)) (format #f "\"~a\"" (string->xml expr)))
	      ((number? expr) (number->string expr))
	      (#t ".")))))
    (let ((expr (read)))
      (if (not (eof-object? expr))
	(begin
	  (format #t "{~a\n},\n" (convert-json expr))
	  (output-json))))))

(define (main args)
  (let* ((optionspec '((format  (value #t))))
	  (options (getopt-long args optionspec))
	  (msg (string-append
		 "usage: mu-sexp-convert "
		 "--format=<xml|json>\n"
		 "reads from standard-input and prints to standard output\n"))
	  (outformat (or (option-ref options 'format #f)
		       (begin (display msg) (exit 1)))))
    (cond
      ((string= outformat "xml")
	(output-xml))
      ((string= outformat "json")
	(output-json))
      (#t (begin
	    (display msg)
	    (exit 1))))))

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