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

#include "cms_template.h"

cms_template_args* cms_template_args_create()
{
	cms_template_args* args = malloc(sizeof(cms_template_args));
	if (!args)
		return NULL;

	args->arguments = NULL;
	args->argnum = 0;
	args->allocd = 0;

	return args;
}

cms_err* cms_template_args_append(cms_template_args* args, char* key, char* val)
{
	args->argnum += 1;

	if (args->argnum > args->allocd)
	{
		args->allocd *= 2;
		args->arguments = realloc(
			args->arguments,
			sizeof(cms_template_arg) * args->allocd
		);
		if (!args->arguments)
			return cms_err_create(CMS_ERR_ALLOC, 0);
	}

	cms_template_arg arg = {key, val};
	args->arguments[args->argnum - 1] = arg;

	return cms_err_create(CMS_ERR_NONE, NULL);
}

static char* str_insert(
		char* str1,
		char* str2,
		size_t start,
		size_t end,
		size_t len)
{
	size_t len2 = strlen(str2);

	str1 = realloc(str1, len + len2 - (end - start));
	if (str1 == NULL)
		return NULL;

	memmove(str1 + end, str1 + start, len - start);
	memcpy(str1 + start, str2, len2);

	return str1;
}

static char* templatify_arg(char* str, cms_template_arg arg, size_t len)
{
	#define OFFSET i - match_start

	size_t match_start = 0;
	size_t i = 0;
	int in_match = 0;

	char c;
	while ((c = str[i]) != 0)
	{
		if (!in_match && arg.key[0] == c)
		{
			match_start = i;
			in_match = 1;
		}

		if (in_match && arg.key[OFFSET] != 0)
		{
			if (arg.key[OFFSET] != c)
				in_match = 0;
		}
		else if (in_match)
		{
			str = str_insert(str, arg.val, match_start, i, len);
			if (str == NULL)
				return NULL;

			in_match = 0;
		}

		i += 1;
	}

	#undef OFFSET

	return str;
}

char* cms_templateify(char* str, cms_template_args* args)
{
	size_t len = strlen(str);

	size_t i;
	for (i = 0; i < args->argnum; ++i)
	{
		str = templatify_arg(str, args->arguments[i], len);
		if (str == NULL)
			return NULL;
	}

	return str;
}