;;;; cl-xml.lisp

;(in-package #:cl-xml)

(declaim (optimize (debug 3)))

(defun tagp (exp)
  (symbolp (car exp)))

(defun print-contents (contents indentation stream)
  (mapc (lambda (s) (format stream "~a~a~%" indentation s)) contents))

(defun next-tags (list)
  (cond ((null list) nil)
        ((eq 'cons (type-of (car list))) list)
        (t (next-tags (cdr list)))))

(defun handle-keywords (keywords)
  (cond ((or (null keywords)
             (consp (car keywords)))
         "")
        ((keywordp (car keywords))
         (format nil " ~a=\"~a\"~a"
                 (string-downcase (symbol-name (car keywords)))
                 (cadr keywords)
                 (handle-keywords (cddr keywords))))))

(defun indentation (level)
  (labels ((create-indentation-string (count)
             (if (= count 0)
                 '()
                 (cons " " (create-indentation-string (1- count))))))
    (let ((spaces (create-indentation-string level)))
      (if (null spaces)
          ""
          (reduce (lambda (s1 s2) (concatenate 'string s1 s2))
                  spaces)))))

(defun sexp-to-xml (sexp indentation-level &optional (stream t))
  (cond ((null sexp) nil)
        ((stringp (car sexp)) (print-contents sexp (indentation indentation-level) stream))
        ((consp (car sexp))
         (sexp-to-xml (car sexp) (1+ indentation-level) stream)
         (sexp-to-xml (cdr sexp) indentation-level stream))
        ((tagp sexp)
         (let ((tag-name (string-downcase (symbol-name (car sexp))))
               (spaces (indentation indentation-level)))
           (format stream "~a<~a~a>~%"
                   spaces
                   tag-name
                   (handle-keywords (cdr sexp)))
           (let ((next-tags (next-tags (cdr sexp))))
             (unless (null next-tags)
               (sexp-to-xml next-tags (1+ indentation-level) stream)))
           (format stream "~a</~a>~%" spaces tag-name)))))

(defmacro xml (form)
  (sexp-to-xml form 0))

(defun sexp-to-xml-string (form)
  (with-open-stream (stream (make-string-output-stream))
    (sexp-to-xml form 0 stream)
    (get-output-stream-string stream)))

(defmacro xml-string (form)
  (sexp-to-xml-string form))