/*
 * Copyright (c) 2010-2022 Belledonne Communications SARL.
 *
 * This file is part of Liblinphone
 * (see https://gitlab.linphone.org/BC/public/liblinphone).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "bctoolbox/charconv.h"
#include <bctoolbox/defs.h>

#include "sqlite3_bctbx_vfs.h"
#include <sqlite3.h>

#ifndef _WIN32_WCE
#include <errno.h>
#endif /*_WIN32_WCE*/

#include "private.h"

/**
 * Closes the file whose file descriptor is stored in the file handle p.
 * @param  p 	sqlite3_file file handle pointer.
 * @return      SQLITE_OK if successful,  SQLITE_IOERR_CLOSE otherwise.
 */
static int sqlite3bctbx_Close(sqlite3_file *p) {

	int ret;
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;

	ret = bctbx_file_close(pFile->pbctbx_file);
	if (!ret) {
		return SQLITE_OK;
	} else {
		free(pFile);
		return SQLITE_IOERR_CLOSE;
	}
}

/**
 * Read count bytes from the open file given by p, starting at offset and puts them in
 * the buffer pointed by buf.
 * Calls bctbx_file_read.
 *
 * @param  p  		sqlite3_file file handle pointer.
 * @param  buf    	buffer to write the read bytes to.
 * @param  count  	number of bytes to read
 * @param  offset 	file offset where to start reading
 * @return 			SQLITE_OK if read bytes equals count,
 *                  SQLITE_IOERR_SHORT_READ if the number of bytes read is inferior to count
 *                  SQLITE_IOERR_READ if an error occurred.
 */
static int sqlite3bctbx_Read(sqlite3_file *p, void *buf, int count, sqlite_int64 offset) {
	int ret;
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;
	if (pFile) {
		ret = (int)bctbx_file_read(pFile->pbctbx_file, buf, (size_t)count, (off_t)offset);
		if (ret == count) {
			return SQLITE_OK;
		} else if (ret >= 0) {
			/*fill in unread portion of buffer, as requested by sqlite3 documentation*/
			memset(((uint8_t *)buf) + ret, 0, (size_t)(count - ret));
			return SQLITE_IOERR_SHORT_READ;
		} else {

			return SQLITE_IOERR_READ;
		}
	}
	return SQLITE_IOERR_READ;
}

/**
 * Writes directly to the open file given through the p argument.
 * Calls bctbx_file_write .
 * @param  p       sqlite3_file file handle pointer.
 * @param  buf     Buffer containing data to write
 * @param  count   Size of data to write in bytes
 * @param  offset  File offset where to write to
 * @return         SQLITE_OK on success, SQLITE_IOERR_WRITE if an error occurred.
 */
static int sqlite3bctbx_Write(sqlite3_file *p, const void *buf, int count, sqlite_int64 offset) {
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;
	int ret;
	if (pFile) {
		ret = (int)bctbx_file_write(pFile->pbctbx_file, buf, (size_t)count, (off_t)offset);
		if (ret > 0) return SQLITE_OK;
		else {
			return SQLITE_IOERR_WRITE;
		}
	}
	return SQLITE_IOERR_WRITE;
}

/**
 * TRuncates or extends a file depending on the size provided.
 * @param  p    sqlite3_file file handle pointer.
 * @param  size New file size.
 * @return  SQLITE_OK on success, SQLITE_IOERR_TRUNCATE if an error occurred during truncate,
 *          SQLITE_ERROR if ther was a problem on the file descriptor.
 */
static int sqlite3bctbx_Truncate(sqlite3_file *p, sqlite_int64 size) {
	int rc;
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;
	if (pFile->pbctbx_file) {
		rc = bctbx_file_truncate(pFile->pbctbx_file, size);
		if (rc < 0) {
			return SQLITE_IOERR_TRUNCATE;
		}
		if (rc == 0) {
			return SQLITE_OK;
		}
	}
	return SQLITE_ERROR;
}

/**
 * Saves the file size associated with the file handle p into the argument pSize.
 * @param  p 	sqlite3_file file handle pointer.
 * @return 		SQLITE_OK if read bytes equals count,
 *              SQLITE_IOERR_FSTAT if the file size returned is negative
 *              SQLITE_ERROR if an error occurred.
 */
static int sqlite3bctbx_FileSize(sqlite3_file *p, sqlite_int64 *pSize) {

	int64_t rc; /* Return code from fstat() call */
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;
	if (pFile->pbctbx_file) {
		rc = bctbx_file_size(pFile->pbctbx_file);
		if (rc < 0) {
			return SQLITE_IOERR_FSTAT;
		}
		if (pSize) {
			*pSize = rc;
			return SQLITE_OK;
		}
	}
	return SQLITE_ERROR;
}

/************************ PLACE HOLDER FUNCTIONS ***********************/
/** These functions were implemented to please the SQLite VFS
implementation. Some of them are just stubs, some do a very limited job. */

/**
 * Returns the device characteristics for the file. Stub function
 * to fill the SQLite VFS function pointer structure .
 * @param  p 	sqlite3_file file handle pointer.
 * @return		value 4096.
 */
static int sqlite3bctbx_DeviceCharacteristics(BCTBX_UNUSED(sqlite3_file *p)) {
	int rc = 0x00001000;
	return rc;
}

/**
 * Stub function for information and control over the open file.
 * @param  p    sqlite3_file file handle pointer.
 * @param  op   operation
 * @param  pArg unused
 * @return      SQLITE_OK on success, SALITE_NOTFOUND otherwise.
 */
static int sqlite3bctbx_FileControl(BCTBX_UNUSED(sqlite3_file *p), BCTBX_UNUSED(int op), BCTBX_UNUSED(void *pArg)) {
#ifdef SQLITE_FCNTL_MMAP_SIZE
	if (op == SQLITE_FCNTL_MMAP_SIZE) return SQLITE_OK;
#endif
	return SQLITE_NOTFOUND;
}

/**
 * The lock file mechanism is not used with this VFS : checking
 * the reserved lock is always OK.
 * @param  pUnused sqlite3_file file handle pointer.
 * @param  pResOut set to 0 since there is no lock mechanism.
 * @return         SQLITE_OK
 */
static int sqlite3bctbx_nolockCheckReservedLock(BCTBX_UNUSED(sqlite3_file *pUnused), int *pResOut) {
	*pResOut = 0;
	return SQLITE_OK;
}

/**
 * The lock file mechanism is not used with this VFS : locking the file
 * is always OK.
 * @param  pUnused sqlite3_file file handle pointer.
 * @param  unused  unused
 * @return         SQLITE_OK
 */
static int sqlite3bctbx_nolockLock(BCTBX_UNUSED(sqlite3_file *pUnused), BCTBX_UNUSED(int unused)) {
	return SQLITE_OK;
}

/**
 * The lock file mechanism is not used with this VFS : unlocking the file
 * is always OK.
 * @param  pUnused sqlite3_file file handle pointer.
 * @param  unused  unused
 * @return         SQLITE_OK
 */
static int sqlite3bctbx_nolockUnlock(BCTBX_UNUSED(sqlite3_file *pUnused), BCTBX_UNUSED(int unused)) {
	return SQLITE_OK;
}

/**
 * Simply sync the file contents given through the file handle p
 * to the persistent media.
 * @param  p 	 sqlite3_file file handle pointer.
 * @param  flags unused
 * @return       SQLITE_OK on success, SLITE_IOERR_FSYNC if an error occurred.
 */
static int sqlite3bctbx_Sync(sqlite3_file *p, BCTBX_UNUSED(int flags)) {
	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p;
	int ret = bctbx_file_sync(pFile->pbctbx_file);
	return (ret == BCTBX_VFS_OK ? SQLITE_OK : SQLITE_IOERR_FSYNC);
}

/************************ END OF PLACE HOLDER FUNCTIONS ***********************/

/**
 * Opens the file fName and populates the structure pointed by p
 * with the necessary io_methods
 * Methods not implemented for version 1 : xTruncate, xSectorSize.
 * Initializes some fields in the p structure, some of which where already
 * initialized by SQLite.
 * @param  pVfs      sqlite3_vfs VFS pointer.
 * @param  fName     filename
 * @param  p         file handle pointer
 * @param  flags     db file access flags
 * @param  pOutFlags flags used by SQLite
 * @return           SQLITE_CANTOPEN on error, SQLITE_OK on success.
 */
static int
sqlite3bctbx_Open(BCTBX_UNUSED(sqlite3_vfs *pVfs), const char *fName, sqlite3_file *p, int flags, int *pOutFlags) {
	static const sqlite3_io_methods sqlite3_bctbx_io = {
	    1,                     /* iVersion         Structure version number */
	    sqlite3bctbx_Close,    /* xClose */
	    sqlite3bctbx_Read,     /* xRead */
	    sqlite3bctbx_Write,    /* xWrite */
	    sqlite3bctbx_Truncate, /* xTruncate */
	    sqlite3bctbx_Sync,
	    sqlite3bctbx_FileSize,
	    sqlite3bctbx_nolockLock,
	    sqlite3bctbx_nolockUnlock,
	    sqlite3bctbx_nolockCheckReservedLock,
	    sqlite3bctbx_FileControl,
	    NULL, /* xSectorSize */
	    sqlite3bctbx_DeviceCharacteristics
	    /*other function points follows, all NULL but not present in all sqlite3 versions.*/
	};

	sqlite3_bctbx_file_t *pFile = (sqlite3_bctbx_file_t *)p; /*File handle sqlite3_bctbx_file_t*/
	int openFlags = 0;
	char *wFname;

	/*returns error if filename is empty or file handle not initialized*/
	if (pFile == NULL || fName == NULL) {
		return SQLITE_IOERR;
	}

	/* Set flags  to open the file with */
	if (flags & SQLITE_OPEN_EXCLUSIVE) openFlags |= O_EXCL;
	if (flags & SQLITE_OPEN_CREATE) openFlags |= O_CREAT;
	if (flags & SQLITE_OPEN_READONLY) openFlags |= O_RDONLY;
	if (flags & SQLITE_OPEN_READWRITE) openFlags |= O_RDWR;

#if defined(_WIN32)
	openFlags |= O_BINARY;
#endif
	/* sqlite3 requires an UTF-8 encoded path, but UTF-8 may not be the
	 * process current locale. */
	wFname = bctbx_utf8_to_locale(fName);
	if (wFname != NULL) {
		pFile->pbctbx_file = bctbx_file_open2(bctbx_vfs_get_default(), wFname, openFlags);
		bctbx_free(wFname);
	} else {
		pFile->pbctbx_file = NULL;
	}

	if (pFile->pbctbx_file == NULL) {
		return SQLITE_CANTOPEN;
	}

	if (pOutFlags) {
		*pOutFlags = flags;
	}
	pFile->base.pMethods = &sqlite3_bctbx_io;

	return SQLITE_OK;
}

sqlite3_vfs *sqlite3_bctbx_vfs_create(void) {
	static sqlite3_vfs bctbx_vfs = {
	    1,                            /* iVersion */
	    sizeof(sqlite3_bctbx_file_t), /* szOsFile */
	    MAXPATHNAME,                  /* mxPathname */
	    NULL,                         /* pNext */
	    BCTBX_SQLITE3_VFS,            /* zName */
	    NULL,                         /* pAppData */
	    sqlite3bctbx_Open,            /* xOpen */
	    NULL,                         /* xDelete */
	    NULL,                         /* xAccess */
	    NULL                          /* xFullPathname */
	};
	return &bctbx_vfs;
}

/*static int sqlite3bctbx_winFullPathname(
                                        sqlite3_vfs *pVfs,            // Pointer to vfs object
                                        const char *zRelative,        // Possibly relative input path
                                        int nFull,                    // Size of output buffer in bytes
                                        char *zFull){
    //LPWSTR zTemp;
    //DWORD nByte;
    // If this path name begins with "/X:", where "X" is any alphabetic
    // character, discard the initial "/" from the pathname.
    //
    //if (zRelative[0] == '/' && sqlite3Isalpha(zRelative[1]) && zRelative[2] == ':'){
    //	zRelative++;
    //}

     nByte = GetFullPathNameW((LPCWSTR)zRelative, 0, 0, 0);
     if (nByte == 0){
        return SQLITE_CANTOPEN_FULLPATH;
     }
     nByte += 3;
     zTemp = bctbx_malloc(nByte*sizeof(zTemp[0]));
     memset(zTemp, 0, nByte*sizeof(zTemp[0]));
     if (zTemp == 0){
        return SQLITE_IOERR_NOMEM;
     }
     nByte = GetFullPathNameW((LPCWSTR)zRelative, nByte, zTemp, 0);
     if (nByte == 0){
        bctbx_free(zTemp);
        return SQLITE_CANTOPEN_FULLPATH;
     }
     if (zTemp){
        sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s", zTemp);
        bctbx_free(zTemp);
        return SQLITE_OK;
     }
     else{
        return SQLITE_IOERR_NOMEM;
     }
    sqlite3_snprintf(MIN(nFull, pVfs->mxPathname), zFull, "%s", zRelative);
    return SQLITE_OK;
}*/

void sqlite3_bctbx_vfs_register(int makeDefault) {
	sqlite3_vfs *pVfsToUse = sqlite3_bctbx_vfs_create();
#if _WIN32
	sqlite3_vfs *pDefault = sqlite3_vfs_find("win32");
#else
	sqlite3_vfs *pDefault = sqlite3_vfs_find("unix-none");
#endif
	pVfsToUse->xCurrentTime = pDefault->xCurrentTime;

	pVfsToUse->xAccess = pDefault->xAccess;
	pVfsToUse->xFullPathname = pDefault->xFullPathname;

	pVfsToUse->xDelete = pDefault->xDelete;
	pVfsToUse->xSleep = pDefault->xSleep;
	pVfsToUse->xRandomness = pDefault->xRandomness;
	pVfsToUse->xGetLastError = pDefault->xGetLastError; /* Not implemented by sqlite3 :place holder */
	/*Functions below should not be a problem sincve we are declaring ourselves
	 in version 1 */

	/* used in version 2
	xCurrentTimeInt64;*/
	/* used in version 3
	xGetSystemCall
	xSetSystemCall
	xNextSystemCall*/

	sqlite3_vfs_register(pVfsToUse, makeDefault);
}

void sqlite3_bctbx_vfs_unregister(void) {
	sqlite3_vfs *pVfs = sqlite3_vfs_find(BCTBX_SQLITE3_VFS);
	sqlite3_vfs_unregister(pVfs);
}