/*
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
 * Copyright (C) 2013-2015 Sensnology AB
 * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 */

 /**
 * @file MyTransport.h
 *
 * @defgroup MyTransportgrp MyTransport
 * @ingroup internals
 * @{
 *
 * Transport-related log messages, format: [!]SYSTEM:[SUB SYSTEM:]MESSAGE
 * - [!] Exclamation mark is prepended in case of error
 * - SYSTEM: 
 *  - TSM: messages emitted by the transport state machine
 *  - TSF: messages emitted by transport support functions
 * - SUB SYSTEMS:
 *  - Transport state machine (TSM)
 *   - TSM:INIT						from <b>stInit</b> Initialize transport and radio
 *   - TSM:FPAR						from <b>stParent</b> Find parent
 *   - TSM:ID						from <b>stID</b> Check/request node ID, if dynamic node ID set
 *   - TSM:UPL						from <b>stUplink</b> Verify uplink connection by pinging GW
 *   - TSM:READY					from <b>stReady</b> Transport is ready and fully operational
 *   - TSM:FAILURE					from <b>stFailure</b> Failure in transport link or transport HW
 *  - Transport support function (TSF)
 *   - TSF:CHKUPL					from @ref transportCheckUplink(..), checks connection to GW
 *   - TSF:ASID						from @ref transportAssignNodeID(..), assigns node ID
 *   - TSF:PING						from @ref transportPingNode(..), pings a node
 *   - TSF:CRT						from @ref transportClearRoutingTable(..), clears routing table stored in EEPROM
 *   - TSF:MSG						from @ref transportProcessMessage(..), processes incoming message
 *   - TSF:SANCHK					from @ref transportInvokeSanityCheck(..), calls transport-specific sanity check
 *   - TSF:ROUTE					from @ref transportRouteMessage(..), sends message
 *   - TSF:SEND						from @ref transportSendRoute(..), sends message if transport is ready (exposed)
 *
 * TSM state <b>stInit</b> log status / errors
 * - TSM:INIT						Transition to stInit state
 * - TSM:INIT:STATID,ID=x			Node ID x is static
 * - TSM:INIT:TSP OK				Transport device configured and fully operational
 * - TSM:INIT:GW MODE				Node is set up as GW, thus omitting ID and findParent states
 * - !TSM:INIT:TSP FAIL				Transport device initialization failed
 *
 * TSM state <b>stParent</b> log status / errors
 * - TSM:FPAR						Transition to stParent state
 * - TSM:FPAR:STATP=x				Static parent x set, skip finding parent
 * - TSM:FPAR:OK					Parent node identified
 * - !TSM:FPAR:NO REPLY				No potential parents replied to find parent request, retry
 * - !TSM:FPAR:FAIL					Finding parent failed, go to failure state
 *
 * TSM state <b>stID</b> log status / errors
 * - TSM:ID							Transition to stID state
 * - TSM:ID:OK,ID=x					Node ID x is valid
 * - TSM:ID:REQ						Request node ID from controller
 * - !TSM:ID:FAIL,ID=x				ID verification failed, ID x invalid
 *
 * TSM state <b>stUplink</b> log status / errors
 * - TSM:UPL						Transition to stUplink state
 * - TSM:UPL:OK						Uplink OK, GW returned ping
 * - !TSM:UPL:FAIL					Uplink check failed, i.e. GW could not be pinged
 *
 * TSM state <b>stReady</b> log status / errors
 * - TSM:READY						Transition to stReady, i.e. transport is ready and fully operational
 * - !TSM:READY:UPL FAIL,SNP		Too many failed uplink transmissions, search new parent
 * - !TSM:READY:UPL FAIL,STATP		Too many failed uplink transmissions, no SNP, static parent enforced
 *
 * TSM state <b>stFailure</b> information / status
 * - TSM:FAILURE					Transition to stFailure state
 * - TSM:FAILURE:PDT				Power-down transport
 * - TSM:FAILURE:RE-INIT			Attempt to re-initialize transport
 *
 * TSF information / status
 * - TSF:CHKUPL:OK					Uplink OK
 * - TSF:CHKUPL:OK,FCTRL			Uplink OK, flood control prevents pinging GW in too short intervals
 * - TSF:CHKUPL:DGWC,O=x,N=y		Checking uplink revealed a changed network topology, old distance x, new distance y
 * - TSF:CHKUPL:FAIL				No reply received when checking uplink
 * - TSF:ASID:OK,ID=x				Node ID x assigned
 * - TSF:PING:SEND,TO=x				Send ping to destination x
 * - TSF:MSG:ACK REQ				ACK message requested
 * - TSF:MSG:ACK					ACK message, do not proceed but forward to callback
 * - TSF:MSG:FPAR RES,ID=x,D=y		Response to find parent received from node x with distance y to GW
 * - TSF:MSG:FPAR PREF FOUND		Preferred parent found
 * - TSF:MSG:FPAR OK,ID=x,D=y		Find parent reponse from node x is valid, distance y to GW
 * - TSF:MSG:FPAR INACTIVE			Find parent response received, but no find parent request active, skip response
 * - TSF:MSG:FPAR REQ,ID=x			Find parent request from node x
 * - TSF:MSG:PINGED,ID=x,HP=y		Node pinged by node x with y hops
 * - TSF:MSG:PONG RECV,HP=x			Pinged node replied with x hops
 * - TSF:MSG:BC						Broadcast message received
 * - TSF:MSG:GWL OK					Link to GW ok
 * - TSF:MSG:FWD BC MSG				Controlled broadcast message forwarding
 * - TSF:MSG:REL MSG				Relay message
 * - TSF:MSG:REL PxNG,HP=x			Relay PING/PONG message, increment hop counter x
 * - TSF:SANCHK:OK					Sanity check passed. This ensures radio functionality and automatically attempts to re-initialize in case of failure
 * - TSF:CRT:OK						Clearing routing table successful 
 *
 * Incoming / outgoing messages
 *
 * See <a href="https://www.mysensors.org/download/serial_api_20">here</a> for more detail on the format and definitons.
 * 
 * Receiving a message		
 * - TSF:MSG:READ,sender-last-destination,s=%d,c=%d,t=%d,pt=%d,l=%d,sg=%d:%s		
 * Sending a message		
 * - [!]TSF:MSG:SEND,sender-last-next-destination,s=%d,c=%d,t=%d,pt=%d,l=%d,sg=%d,ft=%d,st=%s:%s
 *
 * - Message fields:
 *  - s=sensor ID
 *  - c=command
 *  - t=msg type
 *  - pt=payload type
 *  - l=length
 *  - ft=failed uplink transmission counter 
 *  - sg=signing flag
 * 
 * TSF errors
 * - !TSF:ASID:FAIL,ID=x			Assigned ID x is invalid, e.g. 0 (GATEWAY)
 * - !TSF:ROUTE:FPAR ACTIVE			Finding parent active, message not sent
 * - !TSF:ROUTE:DST x UNKNOWN		Routing for destination x unkown, send message to parent
 * - !TSF:SEND:TNR					Transport not ready, message cannot be sent
 * - !TSF:MSG:PVER,x!=y				Message protocol version mismatch
 * - !TSF:MSG:SIGN VERIFY FAIL		Signing verficiation failed
 * - !TSF:MSG:REL MSG,NORP			Node received a message for relaying, but node is not a repeater, message skipped
 * - !TSF:MSG:SIGN FAIL				Signing message failed
 * - !TSF:MSG:GWL FAIL				GW uplink failed
 * - !TSF:SANCHK:FAIL				Sanity check failed, attempt to re-intialize radio
 *
 * @brief API declaration for MyTransport
 *
 */

#ifndef MyTransport_h
#define MyTransport_h

#include "MySensorsCore.h"

#if defined(MY_REPEATER_FEATURE)
	#define TRANSMISSION_FAILURES  10		//!< search for a new parent node after this many transmission failures, higher threshold for repeating nodes
#else
	#define TRANSMISSION_FAILURES  5		//!< search for a new parent node after this many transmission failures, lower threshold for non-repeating nodes
#endif
#define TIMEOUT_FAILURE_STATE 10000			//!< duration failure state
#define STATE_TIMEOUT 2000					//!< general state timeout
#define STATE_RETRIES 3						//!< retries before switching to FAILURE
#define AUTO 255							//!< ID 255 is reserved for auto initialization of nodeId.
#define BROADCAST_ADDRESS ((uint8_t)255)	//!< broadcasts are addressed to ID 255
#define DISTANCE_INVALID ((uint8_t)255)		//!< invalid distance when searching for parent
#define MAX_HOPS ((uint8_t)254)				//!< maximal mumber of hops for ping/pong
#define INVALID_HOPS ((uint8_t)255)			//!< invalid hops
#define MAX_SUBSEQ_MSGS 5					//!< Maximum number of subsequentially processed messages in FIFO (to prevent transport deadlock if HW issue)
#define CHKUPL_INTERVAL ((uint32_t)10000)	//!< Minimum time interval to re-check uplink

#define _autoFindParent (bool)(MY_PARENT_NODE_ID == AUTO)				//!<  returns true if static parent id is undefined
#define isValidDistance(distance) (bool)(distance!=DISTANCE_INVALID)	//!<  returns true if distance is valid
#define isValidParent(parent) (bool)(parent != AUTO)					//!<  returns true if parent is valid

 /**
 * @brief SM state
 *
 * This structure stores SM state definitions
 */
struct transportState {
	void(*Transition)();					//!< state transition function
	void(*Update)();						//!< state update function
};

/**
* @brief Status variables and SM state
*
* This structure stores transport status and SM variables
*/ 
typedef struct {
	transportState* currentState;			//!< pointer to current fsm state
	uint32_t stateEnter;					//!< state enter timepoint
	uint32_t lastUplinkCheck;				//!< last uplink check, required to prevent GW flooding
	uint32_t lastSanityCheck;				//!< last sanity check
	// 8 bits
	bool findingParentNode : 1;				//!< flag finding parent node is active
	bool preferredParentFound : 1;			//!< flag preferred parent found
	bool uplinkOk : 1;						//!< flag uplink ok
	bool pingActive : 1;					//!< flag ping active
	bool transportActive : 1;				//!< flag transport active
	uint8_t reserved : 3;					//!< reserved
	// 8 bits
	uint8_t retries : 4;					//!< retries / state re-enter
	uint8_t failedUplinkTransmissions : 4;	//!< counter failed uplink transmissions
	// 8 bits
	uint8_t pingResponse;					//!< stores hops received in I_PONG
} __attribute__((packed)) transportSM;


// PRIVATE functions

/**
* @brief Initialize SM variables and transport HW
*/
void stInitTransition();
/**
* @brief Find parent
*/
void stParentTransition();
/**
* @brief Verify find parent responses
*/
void stParentUpdate();
/**
* @brief Send ID request
*/
void stIDTransition();
/**
* @brief Verify ID response and GW link
*/
void stIDUpdate();
/**
* @brief Send uplink ping request
*/
void stUplinkTransition();
/**
* @brief Set transport OK
*/
void stReadyTransition();
/**
* @brief Monitor transport link
*/
void stReadyUpdate();
/**
* @brief Transport failure and power down radio 
*/
void stFailureTransition();
/**
* @brief Re-initialize transport after timeout
*/
void stFailureUpdate();
/**
* @brief Switch SM state
* @param newState New state to switch SM to
*/
void transportSwitchSM(transportState& newState);
/**
* @brief Update SM state
*/
void transportUpdateSM();
/**
* @brief Request time in current SM state
* @return ms in current state
*/
uint32_t transportTimeInState();
/**
* @brief Call transport driver sanity check
*/
void transportInvokeSanityCheck();
/**
* @brief Process all pending messages in RX FIFO
*/
void transportProcessFIFO();
/**
* @brief Receive message from RX FIFO and process
*/
void transportProcessMessage();
/**
* @brief Assign node ID
* @param newNodeId New node ID
* @return true if node ID valid and successfully assigned
*/
bool transportAssignNodeID(uint8_t newNodeId);
/**
* @brief Wait and process messages for a defined amount of time until specified message received
* @param ms Time to wait and process incoming messages in ms
* @param cmd Specific command
* @param msgtype Specific message type 
* @return true if specified command received within waiting time
*/
bool transportWait(uint32_t ms, uint8_t cmd, uint8_t msgtype);
/**
* @brief Ping node
* @param targetId Node to be pinged
* @return hops from pinged node or 255 if no answer received within 2000ms
*/
uint8_t transportPingNode(uint8_t targetId);
/**
* @brief Send and route message according to destination
* 
* This function is used in MyTransport and omits the transport state check, i.e. message can be sent even if transport is not ready
*
* @param message
* @return true if message sent successfully
*/
bool transportRouteMessage(MyMessage &message);
/**
* @brief Send and route message according to destination with transport state check
* @param message
* @return true if message sent successfully and false if sending error or transport !OK
*/
bool transportSendRoute(MyMessage &message);
/**
* @brief Send message to recipient
* @param to Recipient of message
* @param message
* @return true if message sent successfully 
*/
bool transportSendWrite(uint8_t to, MyMessage &message);
/**
* @brief Check uplink to GW, includes flooding control
* @param force to override flood control timer
* @return true if uplink ok
*/
bool transportCheckUplink(bool force);

// PUBLIC functions

/**
* @brief Initialize transport and SM
*/
void transportInitialize();
/**
* @brief Process FIFO msg and update SM
*/
void transportProcess();
/**
* @brief Flag transport ready
* @return true if transport is initialize and ready
*/
bool isTransportReady();
/**
* @brief Flag searching parent ongoing
* @return true if transport is searching for parent
*/
bool isTransportSearchingParent();
/**
* @brief Clear routing table
*/
void transportClearRoutingTable();
/**
* @brief Return heart beat, i.e. ms in current state
*/
uint32_t transportGetHeartbeat();

// interface functions for radio driver

/**
* @brief Initialize transport HW
* @return true if initalization successful
*/
bool transportInit();
/**
* @brief Set node address
*/
void transportSetAddress(uint8_t address);
/**
* @brief Retrieve node address
*/
uint8_t transportGetAddress();
/**
* @brief Send message
* @param to recipient
* @param data message to be sent
* @param len length of message (header + payload)
* @return true if message sent successfully
*/
bool transportSend(uint8_t to, const void* data, uint8_t len);
/**
* @brief Verify if RX FIFO has pending messages
* @return true if message available in RX FIFO
*/
bool transportAvailable();
/**
* @brief Sanity check for transport: is transport still responsive?
* @return true transport ok
*/
bool transportSanityCheck();
/**
* @brief Receive message from FIFO
* @return length of recevied message (header + payload)
*/
uint8_t transportReceive(void* data); 
/**
* @brief Power down transport HW
*/
void transportPowerDown();


#endif // MyTransport_h
/** @}*/