#include <ch32fun.h>
#include <stdint.h>
#include <stdio.h>
#include <fsusb.h>

#include "lib_i2c.h"
#include "display.h"
#include "filter.h"
#include "u8g2.h"


// Pin definitions
#define PIN_VBUS     PA0  // vbus voltage feedback
#define PIN_CURRENT  PA1  // current feedback
#define PIN_NTC      PA2  // ntc temperature sensor
#define PIN_TEMP     PA3  // thermocouple amplifier
#define PIN_12V      PA5  // 12V regulator enable
#define PIN_HEATER   PA6  // power mosfet gate control
#define PIN_ENC_A    PB3  // rotary encoder A
#define PIN_ENC_B    PB11 // rotary encoder B
#define PIN_BTN      PB1  // rotary encoder button

// Analog channel definitions
#define VBUS_ADC_CHANNEL    ANALOG_0 // PA0
#define CURRENT_ADC_CHANNEL ANALOG_1 // PA1
#define NTC_ADC_CHANNEL     ANALOG_2 // PA2
#define TEMP_ADC_CHANNEL    ANALOG_3 // PA3

#define FRAME_TIME_MS 41 // roughly 24 fps

// constants
// LUT for converting NTC readings to degrees kelvin
// Nominal: 1kOhm, Beta: 3380, Step: 64
const uint8_t ntc_step_size = 64;
const int16_t ntc_lut[] = {
	1316, 197, 155, 133, 119, 108, 100, 93, 87, 82, 77, 73, 69, 66, 63, 60,
	57, 54, 52, 50, 47, 45, 43, 41, 39, 37, 35, 34, 32, 30, 28, 27,
	25, 23, 22, 20, 19, 17, 15, 14, 12, 11, 9, 7, 6, 4, 2, 0,
	-1, -3, -5, -7, -9, -11, -14, -16, -19, -22, -25, -28, -32, -38, -44, -55,
	-55 // extra value to not have an extra if statement
};


u8g2_t *u8g2;
int16_t encoder = 0; // rotary encoder counter
uint32_t last_interrupt = 0; // last time the encoder interrupt was triggered
#define ENCODER_DEBOUNCE 6000


// Convert the raw adc reading to a temperature in kelvin with the ntc lut,
// linearly interpolating between positions
static inline int16_t get_temp_k(uint16_t adc_reading)
{
	if (adc_reading > 4095) return 0;
	uint8_t index = adc_reading / ntc_step_size;
	uint8_t remainder = adc_reading % ntc_step_size;
	int16_t temp_base = index < 64 ? ntc_lut[index] : 0;
    int16_t temp_next = ntc_lut[index + 1];
    return temp_base + ((temp_next - temp_base) * remainder)/ntc_step_size;
}


// convert the raw TPA191 adc reading to a current in milliamps
static inline int16_t get_current_ma(uint16_t adc_reading)
{
	// Rshunt = 4 milliOhm
	// Gain = 100
	u32 mv = ((u32)adc_reading * VCC_MV) / 4096;
	return (mv * 10) / 4;
}


void print_i2c_device(uint8_t addr)
{
	printf("Device found at 0x%02X\n", addr);
}


// this callback is mandatory when FUNCONF_USE_USBPRINTF is defined,
// can be empty though
void handle_usbfs_input(int numbytes, uint8_t *data)
{
	// handle single character commands
	// TODO:
	//     - 'c' to calibrate the tip temperature
	//     - 't' to test tip presence
	if(numbytes == 1) {
		switch(data[0]) {
		case 'r': // toggle the 12V regulator
			if (funDigitalRead(PIN_12V)) {
				funDigitalWrite(PIN_12V, 0);
				printf("Disabled 12V Regulator\n");
			} else {
				funDigitalWrite(PIN_12V, 1);
				printf("Enabled 12V Regulator\n");
			}
			break;
		case 'h':
			printf(
				"Available commands:\n"
				"\tr : toggle the 12V regulator\n"
				"\td : init display\n"
				"\ts : scan I2C bus\n"
			);
			break;
		case 's':
			printf("Scanning I2C bus...\n");
			i2c_scan(I2C_TARGET, print_i2c_device);
			break;
		default:
			printf("Unknown command '%c'\n", data[0]);
			break;
		}
	}
	else {
		// echo
		// _write(0, (const char*)data, numbytes);
	}
}


// triggered on the falling edge of the rotary encoder PIN_A
void EXTI15_8_IRQHandler(void) __attribute__((interrupt));
void EXTI15_8_IRQHandler(void)
{
	uint32_t now = funSysTick32();
	if (now - last_interrupt > ENCODER_DEBOUNCE) {
		last_interrupt = now;
		if (funDigitalRead(PIN_ENC_A)) {
			encoder++;
		} else {
			encoder--;
		}
	}
	EXTI->INTFR = EXTI_Line11;
}


// Procedure to get hardware I2C working on the CH32X035F8U6
static inline void setup_i2c(void)
{
	// Order here matters, first initialize the AFIO and I2C subsystems then
	// change register values, do that the other way around and the configuration
	// wont take effect
	// Enable AFIO (Alternate Function IO)
	RCC->APB2PCENR |= RCC_AFIOEN;
	// Init I2C
    i2c_init(I2C_TARGET, FUNCONF_SYSTEM_CORE_CLOCK, 100000);

    // To utilize the I2C bus we need to disable SWD first, since the pins overlap
	AFIO->PCFR1 &= ~(0b0111 << 24);
	AFIO->PCFR1 |=   0b0100 << 24;

	// Map SCL to PC18 and SDA to PC19
	AFIO->PCFR1 |= 0b0101 << 2;
	// Manually set the I2C pins to Alternate Function IO,  CNF=10b, MODE=10b
	GPIOC->CFGXR &= ~((0xF << 8) | (0xF << 12)); // first clear the bits
	// then set them
	GPIOC->CFGXR |= 0b1010 << 8; // PC18
	GPIOC->CFGXR |= 0b1010 << 12; // PC19
}


__attribute__((noreturn)) int main(void)
{
	SystemInit();
	funGpioInitAll();
	funAnalogInit();
	USBFSSetup();

	funPinMode(PIN_VBUS, GPIO_CFGLR_IN_ANALOG);
	funPinMode(PIN_CURRENT, GPIO_CFGLR_IN_ANALOG);
	funPinMode(PIN_NTC, GPIO_CFGLR_IN_ANALOG);
	funPinMode(PIN_TEMP, GPIO_CFGLR_IN_ANALOG);

	funPinMode(PIN_12V, GPIO_CFGLR_OUT_10Mhz_PP);
	funDigitalWrite(PIN_12V, 0);
	funPinMode(PIN_HEATER, GPIO_CFGLR_OUT_10Mhz_PP);
	funDigitalWrite(PIN_HEATER, 0);
	funPinMode(PIN_DISP_RST, GPIO_CFGLR_OUT_10Mhz_PP);
	funDigitalWrite(PIN_DISP_RST, 1); // start with display disabled

	funPinMode(PIN_ENC_A, GPIO_CFGLR_IN_PUPD); // enable pull-up/down
	funDigitalWrite(PIN_ENC_A, 1); // specify pull-up
	funPinMode(PIN_ENC_B, GPIO_CFGLR_IN_PUPD); // enable pull-up/down
	funDigitalWrite(PIN_ENC_B, 1); // specify pull-up
	funPinMode(PIN_BTN, GPIO_CFGLR_IN_FLOAT);

	setup_i2c();

 	// Configure the IO as an interrupt.
 	// PIN_ENC_B is on port B, channel 11
    AFIO->EXTICR1 = AFIO_EXTICR1_EXTI11_PB; // Port B channel (pin) 11
    EXTI->INTENR = EXTI_INTENR_MR11; // Enable EXT11
    EXTI->FTENR = EXTI_FTENR_TR11;  // Falling edge trigger
    // enable interrupt
    NVIC_EnableIRQ(EXTI15_8_IRQn);

	Delay_Ms(500);

	u8g2 = display_init();

	for (;;) {
		static uint16_t tip_mv, vbus_mv, current_ma;
		static int16_t temp_k;

		poll_input(); // usb
	    u32 start = funSysTick32();

		vbus_mv = U16_FP_EMA_K2(vbus_mv, ((u32)funAnalogRead(VBUS_ADC_CHANNEL)*VCC_MV*11)/4096);
		current_ma = U16_FP_EMA_K2(current_ma, get_current_ma(funAnalogRead(CURRENT_ADC_CHANNEL)));
		temp_k = U16_FP_EMA_K2(temp_k, get_temp_k(funAnalogRead(NTC_ADC_CHANNEL)));
		tip_mv = U16_FP_EMA_K2(tip_mv, (u32)(funAnalogRead(TEMP_ADC_CHANNEL)*VCC_MV)/4096);

		u8g2_ClearBuffer(u8g2);
		u8g2_SetBitmapMode(u8g2, 1);
		u8g2_SetFontMode(u8g2, 1);
		u8g2_SetFont(u8g2, u8g2_font_5x8_tr);
#define x_off 0
#define y_off 8
		u8g2_DrawStr(u8g2, x_off+0, y_off+7, "TIP:");
		u8g2_DrawStr(u8g2, x_off+20, y_off+7, u8x8_u16toa(tip_mv, 4));
		u8g2_DrawStr(u8g2, x_off+0, y_off+15, "VBUS:");
		u8g2_DrawStr(u8g2, x_off+25, y_off+15, u8x8_u16toa(vbus_mv, 4));
		u8g2_DrawStr(u8g2, x_off+51, y_off+7, "TEMP:");
		u8g2_DrawStr(u8g2, x_off+75, y_off+7, u8x8_u16toa(temp_k, 2));
		u8g2_SendBuffer(u8g2);


		printf("VBUS=%d, CURRENT=%d, TEMP=%d, TIP=%d, COUNTER=%d\n", vbus_mv, current_ma, temp_k, tip_mv, encoder);

		u32 elapsed = funSysTick32() - start;
		if (elapsed < Ticks_from_Ms(FRAME_TIME_MS)) {
		    DelaySysTick(Ticks_from_Ms(FRAME_TIME_MS) - elapsed);
		} else {
		    printf("Frame took too long: %ld ms\n", elapsed/DELAY_MS_TIME);
		}
	}
}