/**
 ******************************************************************************
 *
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup PIOS_FLASHFS_OBJLIST Object list based flash filesystem (low ram)
 * @{
 *
 * @file       pios_flashfs_objlist.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      A file system for storing UAVObject in flash chip
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/* 
 * This program is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU 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 General Public License 
 * for more details.
 * 
 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */


#include "openpilot.h"
#include "uavobjectmanager.h"

// Private functions
static int32_t PIOS_FLASHFS_CleabObjectTableHeader();
static int32_t PIOS_FLASHFS_GetObjAddress(uint32_t objId, uint16_t instId);
static int32_t PIOS_FLASHFS_GetNewAddress(uint32_t objId, uint16_t instId);

// Private variables
static int32_t numObjects = -1;

// Private structures
// Header for objects in the file system table
struct objectHeader {
	uint32_t objMagic;
	uint32_t objId;
	uint32_t instId;
	uint32_t address;
} __attribute__((packed));;

struct fileHeader {
	uint32_t id;
	uint16_t instId;
	uint16_t size;
} __attribute__((packed));


#define OBJECT_TABLE_MAGIC 0x85FB3C33
#define OBJ_MAGIC          0x3015AE71
#define OBJECT_TABLE_START 0x00000010
#define OBJECT_TABLE_END   0x00001000
#define SECTOR_SIZE        0x00001000

/**
 * @brief Initialize the flash object setting FS
 * @return 0 if success, -1 if failure
 */
int32_t PIOS_FLASHFS_Init()
{
	
	// Check for valid object table or create one
	uint32_t object_table_magic;
	if (PIOS_Flash_W25X_ReadData(0, (uint8_t *)&object_table_magic, sizeof(object_table_magic)) != 0)
		return -1;	
	if(object_table_magic != OBJECT_TABLE_MAGIC) {
		if(PIOS_FLASHFS_CleabObjectTableHeader() < 0)
			return -1;
	}

	int32_t addr = OBJECT_TABLE_START;
	struct objectHeader header;
	numObjects = 0;
		
	// Loop through header area while objects detect to count how many saved
	while(addr < OBJECT_TABLE_END) {
		// Read the instance data
		if (PIOS_Flash_W25X_ReadData(addr, (uint8_t *)&header, sizeof(header)) != 0)
			return -1;
		
		// Counting number of valid headers	
		if(header.objMagic != OBJ_MAGIC) 
			break;
		
		numObjects++;
		addr += sizeof(header);
	}
	
	return 0;
}

/**
 * @brief Erase the headers for all objects in the flash chip
 * @return 0 if successful, -1 if not
 */
static int32_t PIOS_FLASHFS_CleabObjectTableHeader() 
{
	if(PIOS_Flash_W25X_EraseSector(OBJECT_TABLE_START) != 0)
		return -1;

	uint32_t object_table_magic = OBJECT_TABLE_MAGIC;
	if (PIOS_Flash_W25X_WriteData(0, (uint8_t *)&object_table_magic, sizeof(object_table_magic)) != 0)
		return -1;

	return 0;
}

/**
 * @brief Get the address of an object
 * @param obj UAVObjHandle for that object
 * @parma instId Instance id for that object
 * @return address if successful, -1 if not found
 */
static int32_t PIOS_FLASHFS_GetObjAddress(uint32_t objId, uint16_t instId) 
{
	int32_t addr = OBJECT_TABLE_START;
	struct objectHeader header;
		
	// Loop through header area while objects detect to count how many saved
	while(addr < OBJECT_TABLE_END) {
		// Read the instance data
		if (PIOS_Flash_W25X_ReadData(addr, (uint8_t *) &header, sizeof(header)) != 0)
			return -1;
		if(header.objMagic != OBJ_MAGIC) 
			break; // stop searching once hit first non-object header
		else if (header.objId == objId && header.instId == instId)
			break;
		addr += sizeof(header);
	}
	
	if (header.objId == objId && header.instId == instId)
		return header.address;
	
	return -1;
}

/**
 * @brief Returns an address for a new object and creates entry into object table
 * @param[in] obj Object handle for object to be saved
 * @param[in] instId The instance id of object to be saved
 * @return 0 if success or error code
 * @retval -1 Object not found
 * @retval -2 No room in object table 
 * @retval -3 Unable to write entry into object table
 * @retval -4 FS not initialized
 */
int32_t PIOS_FLASHFS_GetNewAddress(uint32_t objId, uint16_t instId)
{
	struct objectHeader header;

	if(numObjects < 0)
		return -4;
	
	// Don't worry about max size of flash chip here, other code will catch that
	header.objMagic = OBJ_MAGIC;
	header.objId = objId;
	header.instId = instId;
	header.address = OBJECT_TABLE_END + SECTOR_SIZE * numObjects;
	
	int32_t addr = OBJECT_TABLE_START + sizeof(header) * numObjects;

	// No room for this header in object table
	if((addr + sizeof(header)) > OBJECT_TABLE_END) 
		return -2;		
	
	if(PIOS_Flash_W25X_WriteData(addr, (uint8_t *) &header, sizeof(header)) != 0)
		return -3;
		
	// This numObejcts value must stay consistent or there will be a break in the table
	// and later the table will have bad values in it
	numObjects++;	
	return header.address;	
}


/**
 * @brief Saves one object instance per sector
 * @param[in] obj UAVObjHandle the object to save
 * @param[in] instId The instance of the object to save
 * @return 0 if success or -1 if failure
 * @note This uses one sector on the flash chip per object so that no buffering in ram
 * must be done when erasing the sector before a save
 */
int32_t PIOS_FLASHFS_ObjSave(UAVObjHandle obj, uint16_t instId, uint8_t * data) 
{
	uint32_t objId = UAVObjGetID(obj);

	int32_t addr = PIOS_FLASHFS_GetObjAddress(objId, instId);
	
	// Object currently not saved
	if(addr < 0) 
		addr = PIOS_FLASHFS_GetNewAddress(objId, instId);
	
	// Could not allocate a sector
	if(addr < 0)
		return -1;
	
	struct fileHeader header = {
		.id = objId,
		.instId = instId,
		.size = UAVObjGetNumBytes(obj)
	};
	
	if(PIOS_Flash_W25X_EraseSector(addr) != 0)
		return -2;

	// Save header
	// This information IS redundant with the object table id.  Oh well.  Better safe than sorry.	
	
	if(PIOS_Flash_W25X_WriteData(addr, (uint8_t *) &header, sizeof(header)) != 0)
		return -3;
		
	// Save data
	if(PIOS_Flash_W25X_WriteData(addr + sizeof(header), data, UAVObjGetNumBytes(obj)) != 0)
		return -4;
	
	return 0;
}

/**
 * @brief Load one object instance per sector
 * @param[in] obj UAVObjHandle the object to save
 * @param[in] instId The instance of the object to save
 * @return 0 if success or error code
 * @retval -1 if object not in file table
 * @retval -2 if unable to retrieve object header
 * @retval -3 if loaded data instId or objId don't match
 * @retval -4 if unable to retrieve instance data
 * @note This uses one sector on the flash chip per object so that no buffering in ram
 * must be done when erasing the sector before a save
 */
int32_t PIOS_FLASHFS_ObjLoad(UAVObjHandle obj, uint16_t instId, uint8_t * data)
{
	uint32_t objId = UAVObjGetID(obj);
	
	int32_t addr = PIOS_FLASHFS_GetObjAddress(objId, instId);
		
	// Object currently not saved
	if(addr < 0) 
		return -1;

	struct fileHeader header;
	
	// Load header
	// This information IS redundant with the object table id.  Oh well.  Better safe than sorry.
	if(PIOS_Flash_W25X_ReadData(addr, (uint8_t *) &header, sizeof(header)) != 0)
		return -2;
	
	if((header.id != objId) || (header.instId != instId))
		return -3;
	
	// Read the instance data
	if (PIOS_Flash_W25X_ReadData(addr + sizeof(header), data, UAVObjGetNumBytes(obj)) != 0)
		return -4;
	
	return 0;
}

/**
 * @brief Delete object from flash
 * @param[in] obj UAVObjHandle the object to save
 * @param[in] instId The instance of the object to save
 * @return 0 if success or error code
 * @retval -1 if object not in file table
 * @retval -2 Erase failed
 * @note To avoid buffering the file table (1k ram!) the entry in the file table 
 * remains but destination sector is erased.  This will make the load fail as the 
 * file header won't match the object.  At next save it goes back there.
 */
int32_t PIOS_FLASHFS_ObjDelete(UAVObjHandle obj, uint16_t instId)
{
	uint32_t objId = UAVObjGetID(obj);
	
	int32_t addr = PIOS_FLASHFS_GetObjAddress(objId, instId);
	
	// Object currently not saved
	if(addr < 0) 
		return -1;

	if(PIOS_Flash_W25X_EraseSector(addr) != 0)
		return -2;
	
	return 0;
}