#include <Arduino.h>
#include <ArduinoJson.h>
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <EEPROM.h>
#include <Ticker.h>

const char *WIFI_SSID PROGMEM = "Protospace";
const char *WIFI_PASS PROGMEM = "yycmakers";
char wifiMACAddr[20] = "";
const String SOCKET_URL = String("http://tools-socket.protospace.ca/api/lockout/");
const String CARD_URL = String("http://tools-auth.protospace.ca/cards/");

Ticker ticker;

#define CARD_BUFFER_LENGTH 14
char cardBuffer[CARD_BUFFER_LENGTH];

#define CARD_DATA_LENGTH 10
#define CARD_CHECK_LENGTH 2
typedef struct __attribute__((packed)) cardData {
	char head;
	char data[CARD_DATA_LENGTH];
	char checksum[CARD_CHECK_LENGTH];
	char tail;
} cardData_t;

#define LOGGING true

#define RELAY_PIN D1
#define GREEN_BUTTON_PIN D3
#define RED_BUTTON_PIN D4
#define GREEN_LED_PIN D6
#define RED_LED_PIN D7

#define RELAY_CLOSED HIGH
#define RELAY_OPEN !RELAY_CLOSED
#define BUTTON_CLOSED LOW
#define BUTTON_OPEN !BUTTON_CLOSED
#define LED_PIN_ON HIGH
#define LED_PIN_OFF !LED_PIN_ON

#define DELAY_TIME 10
#define LOCK_ARMED_TIMEOUT 1000
#define COMM_LOCK_IDLE_TIME 50
#define COMM_CARD_IDLE_TIME 1000
#define LED_ARMED_BLINK_TIME 50
#define LED_ERROR_BLINK_TIME 50

#define EEPROM_SIZE 4095

enum wifiStates
{
	WIFI_DISCONNECTED,
	WIFI_CONNECTING,
	WIFI_CONNECTED,
} wifiState = WIFI_DISCONNECTED;

enum LEDStates
{
	LED_OFF,
	LED_ARMED,
	LED_ON,
	LED_ERROR,
} LEDState = LED_OFF;

enum lockStates
{
	LOCK_OFF,
	LOCK_PREARM,
	LOCK_ARMED,
	LOCK_ON_PRESSED, // to wait until button is released
	LOCK_ON,
} lockState = LOCK_OFF;

enum commStates
{
	COMM_INIT,
	COMM_IDLE,
	COMM_LOCK,
	COMM_CARD,
} commState = COMM_INIT;

void setup()
{
	Serial.begin(9600);
	if (LOGGING) Serial.println("[INFO] Serial started.");

	pinMode(RELAY_PIN, OUTPUT);
	pinMode(GREEN_BUTTON_PIN, INPUT_PULLUP);
	pinMode(RED_BUTTON_PIN, INPUT_PULLUP);
	pinMode(GREEN_LED_PIN, OUTPUT);
	pinMode(RED_LED_PIN, OUTPUT);

	EEPROM.begin(EEPROM_SIZE);

	byte ar[6];
	WiFi.macAddress(ar);
	sprintf(wifiMACAddr, "%02X%02X%02X%02X%02X%02X", ar[0], ar[1], ar[2], ar[3], ar[4], ar[5]);
	if (LOGGING) Serial.print("[INFO] Wifi MAC Address: ");
	if (LOGGING) Serial.println(wifiMACAddr);

	ticker.attach_ms(DELAY_TIME, tickerLoop);
}

// The stuff in this loop must not be blocked by network delay
void tickerLoop()
{
	processLockState();
	processLEDState();

	if (Serial.available() >= CARD_BUFFER_LENGTH) {
		uint8_t bufPos = 0;

		while (true) {
			char readChar = Serial.read();

			if (readChar == -1) {
				break;
			} else if (readChar == 0x2) {
				bufPos = 0;
			}

			if (bufPos >= CARD_BUFFER_LENGTH) {
				break;
			}

			cardBuffer[bufPos++] = readChar;

			if (readChar == 0x3 && bufPos == CARD_BUFFER_LENGTH) {
				if (lockState == LOCK_OFF && LEDState == LED_OFF) checkCard();
				break;
			}
		}
	}
}

void loop()
{
	processWifiState();
	processCommState();

	delay(DELAY_TIME);
}

int8_t charToNum(char input)
{
	return String("0123456789ABCDEF").indexOf(input);
}

bool checksum(cardData_t *cardData)
{
	// checksum is each hex data byte xord'd together.
	// each char is a hex nibble, so we have to work in pairs.

	int8_t even = 0, odd = 0;

	for (int8_t i = 0; i < CARD_DATA_LENGTH; i++) {
		int8_t num = charToNum(cardData->data[i]);

		if (num == -1) return false;
		if (i % 2 == 0) even ^= num;
		if (i % 2 == 1) odd ^= num;
	}

	int8_t checksum_even = charToNum(cardData->checksum[0]);
	int8_t checksum_odd = charToNum(cardData->checksum[1]);

	if (even == checksum_even && odd == checksum_odd) {
		return true;
	} else {
		return false;
	}
}

void checkCard()
{
	cardData_t *cardData = (cardData_t *) cardBuffer;

	if (cardData->head == 0x2 && cardData->tail == 0x3 && checksum(cardData)) {
		String cardStr = String();
		String authorizedCards = String();

		for (uint8_t i = 0; i < CARD_DATA_LENGTH; i++) {
			cardStr += cardData->data[i];
		}

		for (uint16_t i = 0; i < EEPROM_SIZE; i++) {
			char tmp = EEPROM.read(i);
			authorizedCards += tmp;
			if (tmp == '$') break;
		}

		if (LOGGING) Serial.println("[INFO] Good scan from card: " + cardStr);

		if (authorizedCards.indexOf(cardStr) >= 0) {
			if (LOGGING) Serial.println("[INFO] Card is authorized on machine.");
			if (lockState == LOCK_OFF) {
				lockState = LOCK_PREARM;
			}
		} else {
			if (LOGGING) Serial.println("[INFO] Card not authorized on machine.");
			LEDState = LED_ERROR;
		}
	}
}

void processWifiState()
{
	switch(wifiState) {
		case WIFI_DISCONNECTED:
			commState = COMM_INIT;

			if (LOGGING) Serial.println("[INFO] Wifi is disconnected. Attempting to connect...");
			WiFi.begin(WIFI_SSID, WIFI_PASS);

			wifiState = WIFI_CONNECTING;
			break;
		case WIFI_CONNECTING:
			commState = COMM_INIT;

			if (WiFi.status() == WL_CONNECTED) {
				if (LOGGING) Serial.println("[INFO] Wifi is connected.");

				if (LOGGING) Serial.print("[INFO] Wifi IP Address: ");
				if (LOGGING) Serial.println(WiFi.localIP());

				wifiState = WIFI_CONNECTED;
			}
			break;
		case WIFI_CONNECTED:
			if (WiFi.status() != WL_CONNECTED) {
				wifiState = WIFI_DISCONNECTED;
			}
			break;
		default:
			if (LOGGING) Serial.println("[ERROR] Invalid wifi state.");
			wifiState = WIFI_DISCONNECTED;
			break;
	}
}

bool greenButton() { return digitalRead(GREEN_BUTTON_PIN) == BUTTON_CLOSED; }
bool redButton() { return digitalRead(RED_BUTTON_PIN) == BUTTON_CLOSED; }

void relayOn() { digitalWrite(RELAY_PIN, RELAY_CLOSED); }
void relayOff() { digitalWrite(RELAY_PIN, RELAY_OPEN); }

void processLockState()
{
	static uint16_t lockArmedTimeoutCount;

	if (lockState != LOCK_ARMED) lockArmedTimeoutCount = 0;

	switch (lockState) {
		case LOCK_OFF:
			if (LEDState != LED_ERROR) LEDState = LED_OFF;

			relayOff();
			break;
		case LOCK_PREARM:
			if (!greenButton() && !redButton()) {
				if (LOGGING) Serial.println("[INFO] Arming interlock.");
				lockState = LOCK_ARMED;
			} else {
				lockState = LOCK_OFF;
				LEDState = LED_ERROR;
			}
			break;
		case LOCK_ARMED:
			if (LEDState != LED_ERROR) LEDState = LED_ARMED;

			relayOff();
			lockArmedTimeoutCount++;

			if (redButton()) {
				if (LOGGING) Serial.println("[INFO] Unarming interlock.");
				lockState = LOCK_OFF;
			} else if (greenButton()) {
				if (LOGGING) Serial.println("[INFO] On button pressed.");
				lockState = LOCK_ON_PRESSED;
			}

			if (lockArmedTimeoutCount > LOCK_ARMED_TIMEOUT) {
				if (LOGGING) Serial.println("[INFO] Arming timed out, disarming.");
				lockState = LOCK_OFF;
				LEDState = LED_ERROR;
			}
			break;
		case LOCK_ON_PRESSED:
			if (redButton()) {
				if (LOGGING) Serial.println("[ERROR] Off button pressed, aborting.");
				lockState = LOCK_OFF;
			} else if (!greenButton()) {
				if (LOGGING) Serial.println("[INFO] Turning machine on.");
				lockState = LOCK_ON;
			}
			break;
		case LOCK_ON:
			if (LEDState != LED_ERROR) LEDState = LED_ON;

			relayOn();

			if (redButton()) {
				if (LOGGING) Serial.println("[INFO] Off button pressed.");
				lockState = LOCK_OFF;
			}
			break;
		default:
			if (LOGGING) Serial.println("[ERROR] Invalid lock state.");
			lockState = LOCK_OFF;
			break;
	}
}

void greenLEDOn() { digitalWrite(GREEN_LED_PIN, LED_PIN_ON); }
void greenLEDOff() { digitalWrite(GREEN_LED_PIN, LED_PIN_OFF); }
void redLEDOn() { digitalWrite(RED_LED_PIN, LED_PIN_ON); }
void redLEDOff() { digitalWrite(RED_LED_PIN, LED_PIN_OFF); }

void processLEDState()
{
	static uint16_t LEDArmedBlinkCount, LEDErrorBlinkCount;

	if (LEDState != LED_ARMED) LEDArmedBlinkCount = 0;
	if (LEDState != LED_ERROR) LEDErrorBlinkCount = 0;

	switch (LEDState) {
		case LED_OFF:
			greenLEDOff();
			redLEDOn();

			break;
		case LED_ARMED:
			LEDArmedBlinkCount++;

			if (LEDArmedBlinkCount < LED_ARMED_BLINK_TIME) {
				greenLEDOn();
				redLEDOn();
			} else if (LEDArmedBlinkCount < LED_ARMED_BLINK_TIME * 2) {
				greenLEDOff();
				redLEDOn();
			} else {
				LEDArmedBlinkCount = 0;
			}
			break;
		case LED_ON:
			greenLEDOn();
			redLEDOn();

			break;
		case LED_ERROR:
			LEDErrorBlinkCount++;

			if (LEDErrorBlinkCount < LED_ERROR_BLINK_TIME) {
				greenLEDOff();
				redLEDOff();
			} else if (LEDErrorBlinkCount < LED_ERROR_BLINK_TIME * 2) {
				greenLEDOff();
				redLEDOn();
			} else {
				LEDState = LED_OFF;
			}
			break;
		default:
			if (LOGGING) Serial.println("[ERROR] Invalid LED state.");
			LEDState = LED_OFF;
			break;
	}
}

// JSON functions to prevent memory leaking see:
// https://arduinojson.org/v5/faq/i-found-a-memory-leak-in-the-library/
String serializeLockJson(uint8_t lockState)
{
	// Generated with: https://arduinojson.org/assistant/
	const size_t bufferSize = JSON_OBJECT_SIZE(1) + 50;
	StaticJsonBuffer<bufferSize> jsonBuffer;

	JsonObject& root = jsonBuffer.createObject();
	root["lockState"] = (uint8_t) lockState;
	String postData = String();
	root.printTo(postData);

	return postData;
}

String deserializeLockJson(String input)
{
	// Generated with: https://arduinojson.org/assistant/
	const size_t bufferSize = JSON_OBJECT_SIZE(1) + 50;
	StaticJsonBuffer<bufferSize> jsonBuffer;
	JsonObject& root = jsonBuffer.parseObject(input);

	String action = root["action"];

	return action;
}

void postState()
{
	HTTPClient lockHTTP;

	//lockHTTP.begin("https://url", "7a 9c f4 db 40 d3 62 5a 6e 21 bc 5c cc 66 c8 3e a1 45 59 38"); //HTTPS
	lockHTTP.begin(SOCKET_URL + wifiMACAddr);
	lockHTTP.addHeader("Content-Type", "application/json");

	if (LOGGING) Serial.println("[INFO] Lock state HTTP begin.");

	if (LOGGING) Serial.print("[INFO] HTTP POST: ");
	String postData = serializeLockJson(lockState);
	if (LOGGING) Serial.println(postData);
	int16_t lockHTTPCode = lockHTTP.POST(postData);

	if (lockHTTPCode > 0) {
		if (LOGGING) Serial.printf("[INFO] POST success, code: %d\n", lockHTTPCode);

		if (lockHTTPCode == HTTP_CODE_OK) {
			if (LOGGING) Serial.print("[INFO] Resource found, parsing response: ");
			String lockPayload = lockHTTP.getString();
			if (LOGGING) Serial.println(lockPayload);
			String action = deserializeLockJson(lockPayload);

			if (action == "arm"  && lockState == LOCK_OFF && LEDState == LED_OFF) {
				lockState = LOCK_PREARM;
			} else if (action == "disarm") {
				lockState = LOCK_OFF;
			}

			if (LOGGING) Serial.println("[INFO] action: " + action);
		} else {
			if (LOGGING) Serial.println("[ERROR] Resource not found.");
		}
	} else {
		if (LOGGING) Serial.printf("[ERROR] POST failed, error: %s\n", lockHTTP.errorToString(lockHTTPCode).c_str());
	}

	lockHTTP.end();
}

void getCards()
{
	HTTPClient cardHTTP;

	//cardHTTP.begin("https://url", "7a 9c f4 db 40 d3 62 5a 6e 21 bc 5c cc 66 c8 3e a1 45 59 38"); //HTTPS
	cardHTTP.begin(CARD_URL + wifiMACAddr + "/");
	cardHTTP.addHeader("Content-Type", "application/json");

	if (LOGGING) Serial.println("[INFO] Card state HTTP begin.");

	if (LOGGING) Serial.println("[INFO] HTTP GET");
	int16_t cardHTTPCode = cardHTTP.GET();

	if (cardHTTPCode > 0) {
		if (LOGGING) Serial.printf("[INFO] GET success, code: %d\n", cardHTTPCode);

		if (cardHTTPCode == HTTP_CODE_OK) {
			if (LOGGING) Serial.print("[INFO] Resource found, parsing response: ");
			String cardPayload = cardHTTP.getString();
			cardPayload += "$"; // Mark the end
			if (LOGGING) Serial.println(cardPayload);

			noInterrupts(); // commit() disables interrupts, but we want an atomic EEPROM buffer write
			for (int i = 0; i < cardPayload.length(); i++) {
				if (i >= EEPROM_SIZE) break;
				EEPROM.write(i, cardPayload.charAt(i));
			}
			EEPROM.commit();
			interrupts();

			if (LOGGING) Serial.println("[INFO] Finished getting card data.");
		} else {
			if (LOGGING) Serial.println("[ERROR] Resource not found.");
		}
	} else {
		if (LOGGING) Serial.printf("[ERROR] POST failed, error: %s\n", cardHTTP.errorToString(cardHTTPCode).c_str());
	}

	cardHTTP.end();
}

void processCommState()
{
	static uint16_t commLockIdleCount, commCardIdleCount;

	switch (commState) {
		case COMM_INIT:
			commLockIdleCount = 0;
			commCardIdleCount = 0;

			commState = COMM_IDLE;
			break;
		case COMM_IDLE:
			commLockIdleCount++;
			commCardIdleCount++;

			if (commLockIdleCount >= COMM_LOCK_IDLE_TIME) {
				commState = COMM_LOCK;
			} else if (commCardIdleCount >= COMM_CARD_IDLE_TIME) {
				commState = COMM_CARD;
			}
			break;
		case COMM_LOCK:
			{
				postState();

				commLockIdleCount = 0;

				commState = COMM_IDLE;
			}
			break;
		case COMM_CARD:
			{
				getCards();

				commCardIdleCount = 0;

				commState = COMM_IDLE;
			}
			break;
	}
}