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

#include <url.h>

#ifdef TESTURLLIB

int
main (int    argc,
      char **argv)
{
	Url *url;
	char url_str[1025];

	url = urllib_init ();

	if (argc == 2)
	{
		if (urllib_parse (url, argv[1]))
			return 1;
	}
	if (argc >= 3)
	{
		if (urllib_parse (url, argv[1]))
			return 1;

		if (urllib_join (url, argv[2]))
			return 1;
	}
	else
	{
		printf ("Enter a url : ");
		scanf ("%s", url_str);

		if (urllib_parse (url, url_str))
			return 1;

		printf ("Enter a path : ");
		scanf ("%s", url_str);

		if (urllib_join (url, url_str))
			return 1;
	}

	urllib_tostring (url, url_str);

	printf ("=> %s\n", url_str);

	urllib_free (url);

	return 0;
}

#endif

Url*
urllib_init (void)
{
	Url *url = malloc (sizeof (Url));

	url->scheme = NULL;
	url->host = NULL;
	url->port = NULL;
	url->path = NULL;

	return url;
}

void
urllib_free (Url *url)
{
	free (url->scheme);
	free (url->host);
	free (url->port);
	free (url->path);
	free (url);
}

int
urllib_parse (Url        *url,
              const char *url_string)
{
	const char *cursor = url_string;
	char *tmpcursor = NULL;
	int len, i;

	/* get scheme */
	tmpcursor = strchr (cursor, ':');
	if (tmpcursor == NULL)
		return 1;//error if not found

	len = tmpcursor - cursor;

	/* Verify scheme syntax */
	if (!isalpha (cursor[0]))
		return 1;
	for (i = 1; i < len; i++)
		if (!(isalnum(cursor[i]) || cursor[i] == '+' || cursor[i] == '-' || cursor[i] == '.'))
			return 1;

	url->scheme = malloc (sizeof (char) * (len + 1));
	if (url->scheme == NULL)
		return 1;

	strncpy (url->scheme, cursor, len);
	url->scheme[len] = '\0';

	//Move after first ':'
	cursor = tmpcursor + 1;
	if (strlen (cursor) <= 2)
		return 1;//There must be 2 '/' and an host
	if (cursor[0] != '/' || cursor[1] != '/')
		return 1;

	//parse IPv6, IPv4 or hostname
	
	cursor += 2;
	if (cursor[0] == '[') // IPv6
	{
		tmpcursor = strchr (cursor, ']');

		if (tmpcursor == NULL)
			return 1;

		len = tmpcursor - cursor;

		for (i = 1; i < len; i++)//verify
			if (!isdigit (cursor[i]) && !(tolower(cursor[i]) >= 'a' && tolower(cursor[i]) <= 'f') && !(cursor[i] == ':'))
				return 1;
	}
	else // IPv4 or hostname
	{
		tmpcursor = strchr (cursor, ':');

		if (tmpcursor == NULL)
			tmpcursor = strchr (cursor, '/');

		if (tmpcursor == NULL)
			len = strlen (cursor);
		else
			len = tmpcursor - cursor;

		for (i = 0; i < len; i++)
			if (!isalnum (cursor[i]) && !(cursor[i] == '.'))
				return 1;
	}

	url->host = malloc (sizeof (char) * (len + 1));
	if (url->host == NULL)
		return 1;

	strncpy (url->host, cursor, len);
	url->host[len] = '\0';

	//parse port (or not)
	
	cursor += len;
	if (cursor[0] == ':')
	{
		tmpcursor = strchr (cursor, '/');
		if (tmpcursor == NULL)
			len = strlen (cursor);
		else
			len = tmpcursor - cursor;

		for (i = 1; i < len; i++)
			if (!isdigit (cursor[i]))
				return 1;

		url->port = malloc (sizeof (char) * len);
		if (url->port == NULL)
			return 1;

		strncpy (url->port, cursor + 1, len - 1);

		cursor += len;
	}

	//parse path
	
	len = strlen (cursor);

	if (len > 0)
	{
		url->path = malloc (sizeof (char) * (len + 1));
		if (url->path == NULL)
			return 1;

		strncpy (url->path, cursor, len);
	}

	return 0;
}

void
urllib_tostring (Url  *url,
                 char *dest)
{
	if (url->port == NULL)
		if (url->path == NULL)
			sprintf (dest, "%s://%s\r\n", url->scheme, url->host);
		else
			sprintf (dest, "%s://%s%s\r\n", url->scheme, url->host, url->path);
	else
		if (url->path == NULL)
			sprintf (dest, "%s://%s:%s\r\n", url->scheme, url->host, url->port);
		else
			sprintf (dest, "%s://%s:%s%s\r\n", url->scheme, url->host, url->port, url->path);
}

int
urllib_join (Url        *url,
             const char *path)
{// view RFC 3986, section 5.2.4
	int len = strlen (path);
	char *base, *result, *inputcursor;

	if (len == 0)//nothing to merge
		return 0;

	if (url->path == NULL)//no current path, path = '/' 
	{
		url->path = malloc (sizeof (char) * 2);
		if (url->path == NULL)
			return 1;

		url->path[0] = '/';
		url->path[1] = '\0';
	}

	if (path[0] != '/') //relative path
	{
		int url_path_len = strlen (path);

		if (url->path[url_path_len - 1] != '/')//we are on a file
		{
			char *tmpcursor = strrchr (url->path, '/');
			if (tmpcursor == NULL)
				return -1;

			tmpcursor[1] = '\0';
		}

		len += url_path_len;
		base = malloc (sizeof (char) * (len + 1));
		if (base == NULL)
			return 1;
		result = malloc (sizeof (char) * (len + 1));
		if (result == NULL)
		{
			free (base);
			return 1;
		}
	
		sprintf (base, "%s%s", url->path, path);
		result[0] = '\0';
	}
	else //absolute path
	{
		base = malloc (sizeof (char) * (len + 1));
		if (base == NULL)
			return 1;
		result = malloc (sizeof (char) * (len + 1));
		if (result == NULL)
		{
			free (base);
			return 1;
		}

		strncpy (base, path, len);
		base[len] = '\0';
		result[0] = '\0';
	}

	inputcursor = base;
	len = strlen (inputcursor);
	while (len > 0) //while input buffer is not empty
	{
		char *tmpcursor;

		if (len >= 3 && inputcursor[0] == '.' && inputcursor[1] == '.' && inputcursor[2] == '/')
		{
			inputcursor += 3;
			len = strlen (inputcursor);
		}
		else if (len >= 2 && inputcursor[0] == '.' && inputcursor[1] == '/')
		{
			inputcursor += 2;
			len = strlen (inputcursor);
		}
		else if (len >= 3 && inputcursor[0] == '/' && inputcursor[1] == '.' && inputcursor[2] == '/')
		{
			inputcursor += 2;
			len = strlen (inputcursor);
		}
		else if (len == 2 && inputcursor[0] == '/' && inputcursor[1] == '.')
		{
			inputcursor += 1;
			inputcursor[0] = '/';
			len = strlen (inputcursor);
		}
		else if (len >= 4 && inputcursor[0] == '/' && inputcursor[1] == '.' && inputcursor[2] == '.' && inputcursor[3] == '/')
		{
			inputcursor += 3;
			len = strlen (inputcursor);
			//remove result last segment
			tmpcursor = strrchr (result, '/');
			if (tmpcursor != NULL)
				*tmpcursor = '\0';
		}
		else if (len == 3 && inputcursor[0] == '/' && inputcursor[1] == '.' && inputcursor[2] == '.')
		{
			inputcursor += 2;
			inputcursor[0] = '/';
			len = strlen (inputcursor);
			//remove result last segment
			tmpcursor = strrchr (result, '/');
			if (tmpcursor != NULL)
				*tmpcursor = '\0';
		}
		else if ((len == 2 && inputcursor[0] == '.' && inputcursor[1] == '.') || (len == 1 && inputcursor[0] == '.'))
		{
			inputcursor[0] = '\0';
			len = strlen (inputcursor);
		}
		else
		{
			//get first segment of inputcursor then append it to result and delete it
			tmpcursor = strchr (inputcursor + 1, '/');
			if (tmpcursor == NULL)//last segment in input buffer
			{
				sprintf (result, "%s%s", result, inputcursor);
				*inputcursor = '\0';
			}
			else
			{
				len = tmpcursor - inputcursor;
				strncpy (result + strlen (result), inputcursor, len);
				inputcursor = tmpcursor;
			}

			len = strlen (inputcursor);
		}
	}

	free (url->path);
	url->path = result;
	free (base);

	return 0;
}