/*
   Copyright 2019 stickbreaker@github

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this software and associated documentation files (the "Software"), to deal
   in the Software without restriction, including without limitation the rights
   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   copies of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE.
   */

#include "XGZP.h"
#include <Wire.h>

#define I2C_ERROR_OK 0

XGZP::XGZP(void):
	_devID(0)
{}

bool XGZP::begin(uint8_t devID) {
	_devID=0;
	Wire.begin();
	Wire.beginTransmission(devID);
	Wire.write(0xA5); // Sys Config Register
	Wire.endTransmission();
	uint8_t count = Wire.requestFrom(devID, (uint8_t) 1);
	if (count == 1) {
		uint8_t reg = Wire.read();
		Serial.printf(" Read System Configuration register = 0x%02X\n", reg);

		Wire.beginTransmission(devID);
		Wire.write(0xA5); // sys configuration register
						  // DAC ON, Single Conversion, Vout=Fixed by Vext*1.5, Vext=3.6V, Calibrated Output, Diag=on
		Wire.write(0xFD); //
		uint8_t err = Wire.endTransmission();
		if(err != 0){
			Serial.printf("Writing to register 0xA5 value 0xFD failed = %d\n", err);
			return false; // fail
		}

		bool ready = false;
		uint32_t tick = millis(); // timout
		while (!ready && (millis() - tick < 1000)) {
			Wire.beginTransmission(devID);
			ready = I2C_ERROR_OK == Wire.endTransmission();
		}
		if (ready) {
			Wire.beginTransmission(devID);
			Wire.write(0xA5);
			Wire.write(0x0A);
			err = Wire.endTransmission();
			if(err != 0){
				Serial.printf("Writing to register 0xA5 value 0x0A failed = %d\n", err);
				return false; // fail
			}
		}
		else {
			Serial.println("Timeout, Sensor did not respond after first config set.");
			return false;
		}
	}
	else {
		Serial.println("Reading from 0xA5 failed");
		return false;
	}
	_devID = devID;    
	return true;
}

bool XGZP::read(float * reading) {
	if ((! _devID ) || ( *reading == NULL )) {
		Serial.println("Not initialized or no return value location, returning");
		if (*reading != NULL) *reading = NAN;
		return false;
	}

	float XGZPC_Value = 0;
	bool ready = false;
	uint32_t tick = millis();
	while (!ready && (millis() - tick < 1000)) { // Wait upto 1sec for conversion to complete
		Wire.beginTransmission(_devID);
		Wire.write(0x02); // status register
		uint8_t err = Wire.endTransmission(); 
		if (err == I2C_ERROR_OK) {
			uint8_t count = Wire.requestFrom(_devID, (uint8_t) 1); // get status byte
			if (count==1) { // got data
				uint8_t status = Wire.read();
				ready = (status & 0x01) == 0x01; // data ready!
			}
		}
	}

	if (ready) {
		Wire.beginTransmission(_devID);
		Wire.write(0x06); // data register
		uint8_t err = Wire.endTransmission(); 
		if (err == I2C_ERROR_OK) {
			uint8_t count = Wire.requestFrom(_devID, (uint8_t) 3); // get data
			if (count == 3) { // got data
				XGZPC_Value = Wire.read() * 65536.0 + Wire.read() * 256.0 + Wire.read();
				XGZPC_Value = XGZPC_Value / 8.0;
				Serial.print("Pa Value: ");
				Serial.println(XGZPC_Value);

				XGZPC_Value = XGZPC_Value / 6895.0;

				*reading = XGZPC_Value;
				Wire.beginTransmission(_devID); // start next sample?
				Wire.write(0x30);
				Wire.write(0x0a); // Data and Temp conversion, Single shot, immediate
				uint8_t err = Wire.endTransmission();
				if (err != 0) {
					Serial.printf(" next Sample start failed? i2cError = %d\n", err);
					return true; // data valid, next sample will be a problem.
				}
				else {
					return true;
				}
			}
			else{
				Serial.println("Read data failed");
				return false;
			}
		}
		else {
			Serial.println("setData address failed");
			return false;
		}
	}
	else{
		Wire.beginTransmission(_devID); // start next sample?
		Wire.write(0x30);
		Wire.write(0x0a); // Data and Temp conversion, Single shot, immediate
		uint8_t err = Wire.endTransmission();
		if (err != 0) {
			Serial.printf(" Next Sample start failed? i2cError = %d\n", err);
		}
		return false;
	}
}