#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "xml.h"

static void check(char **str, int *len, int *used, int n);

char *encode(map_t *map, int len) {
	int slen = 128, used = 0;
	char *str = calloc(slen, sizeof(char));

	char buf[64];
	for (int i = 0; i < len; ++i) {
		check(&str, &slen, &used, snprintf(buf, 64, "<%s", map[i].tag));
		strcat(str, buf);
		if (map[i].attrs != NULL) {
			for (int j = 0; j < map[i].n_attrs; ++j) {
				check(&str, &slen, &used,
					  snprintf(buf, 64, " %s='%s'", map[i].attrs[j].id,
							   map[i].attrs[j].value));
				strcat(str, buf);
			}
		}
		check(&str, &slen, &used, 1);
		strcat(str, ">");
		if (map[i].size == sizeof(map_t)) {
			char *rt = encode((map_t *)map[i].payload, map[i].n);
			if (rt == NULL)
				return NULL;
			check(&str, &slen, &used, strlen(rt));
			strcat(str, rt);
			free(rt);
		} else if (map[i].size == sizeof(char)) {
			check(&str, &slen, &used, map[i].n);
			strcat(str, map[i].payload);
		} else
			return NULL;
		check(&str, &slen, &used, snprintf(buf, 64, "</%s>", map[i].tag));
		strcat(str, buf);
	}
	return str;
}

static void check(char **str, int *len, int *used, int n) {
	if (*used + n >= *len)
		*str = realloc(*str, (*len *= 2));
	*used += n;
}