//#define _GNU_SOURCE // for canonicalize_file_name

#include <stdio.h>
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include "fileutil.h"

/////////////////////////////////////////////////////////////////////////////

size_t GetFileSize(FILE *fd)
{
	long nRet = 0;
	long nCur = ftell(fd);

	if(!fseek(fd, 0, SEEK_END))
	{
		if((nRet = ftell(fd)) < 0)
			nRet = 0;
		fseek(fd, nCur, SEEK_SET);
	}

	return (size_t)nRet;
}

/////////////////////////////////////////////////////////////////////////////

int FileExist(const char *file)
{
	if(!file || !*file)
		return 0;
	struct stat s;
	memset(&s, 0, sizeof(s));
	return !stat(file, &s) && S_ISREG(s.st_mode);
}

/////////////////////////////////////////////////////////////////////////////

int DirectoryExist(const char *dir)
{
	if(!dir || !*dir)
		return 0;
	struct stat s;
	memset(&s, 0, sizeof(s));
	return !stat(dir, &s) && S_ISDIR(s.st_mode);
}

/////////////////////////////////////////////////////////////////////////////
// creates a directory with read/write/search permissions for owner and group,
// and with read/search permissions for others

int CreateDirectory(const char *pszDir)
{
	if(mkdir(pszDir, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH) < 0)
	{
		if(errno != EEXIST)
			return 0;
	}

	return 1;
}

/////////////////////////////////////////////////////////////////////////////

const char* GetAppPath(char *pszPath, size_t nCChPath)
{
	char szTmp[32];
	if(!pszPath || !nCChPath)
	{
		errno = EINVAL;
        return NULL;
    }
	sprintf(szTmp, "/proc/%d/exe", getpid());
	ssize_t nLen = readlink(szTmp, pszPath, nCChPath - 1);
	if(nLen < 0)
	{
		*pszPath = '\0';
        return NULL;
    }
	pszPath[nLen] = '\0';
	return pszPath;
}

/////////////////////////////////////////////////////////////////////////////

const char* GetAppDirectory(char *pszDir, size_t nCChDir)
{
	char *pszSl;
	if(!GetAppPath(pszDir, nCChDir))
		return NULL;
	if((pszSl = strrchr(pszDir, '/')))
	{
		if(pszSl != pszDir)
			*pszSl = '\0';
		else
			*(pszSl + 1) = '\0';
	}
	return pszDir;
}

/////////////////////////////////////////////////////////////////////////////

const char*	BuildCanonicalFilePath(const char *pszDir, const char *pszFilespec, char *pszPath, size_t nCChPath)
{
	size_t nLen;
	char szDir[PATH_MAX];
	char *pszCanPath, szFilePath[PATH_MAX];

	if(!pszFilespec || !*pszFilespec || !pszPath || !nCChPath)
	{
		errno = EINVAL;
        return NULL;
    }

	if(!pszDir)
	{
		memset(szDir, 0, sizeof(szDir));
		if(!GetAppDirectory(szDir, sizeof(szDir)))
	        return NULL;
		pszDir = szDir;
	}

	snprintf(szFilePath, sizeof(szFilePath), "%s/%s", pszDir, pszFilespec);

	if(!(pszCanPath = canonicalize_file_name(szFilePath)))
		return NULL;

	nLen = strlen(pszCanPath);

	if(nLen < nCChPath)
		strcpy(pszPath, pszCanPath);
	else
	{
		errno = ENOMEM;
		pszPath = NULL;
	}

	free(pszCanPath);
	return pszPath;
}