#include <stdint.h> /* Standard Integer Types */
#include <stdio.h> /* Standard IO facilities */
#include <stdlib.h> /* General utilities */
#include <stdbool.h> /* Boolean */
#include <string.h> /* Strings */
#include <avr/io.h> /* AVR device-specific IO definitions */
#include <util/delay.h> /* Convenience functions for busy-wait delay loops */
#include <avr/interrupt.h> /* Interrupts */

#include "main.h"
#include "uart.h"
#include "ir_nec.h"

/* global variables */
#define INPUT_MAX 255 /* max length for user input string */
char input[INPUT_MAX+2]; /* user input from USART */
volatile uint8_t input_i = 0; /* user input index */
volatile uint8_t pwr_ok; /* is power ok */
volatile uint8_t fan; /* fan signal state, to measure tachometer */
volatile uint8_t timer2_ovf = 0; /* to measure fan speed using timer 2 */
uint16_t TIMER2_PRESCALE[8] = {0,1,8,32,64,128,256,1024}; /* timer 2 CS2[2:0] values */
volatile uint16_t tachometer = 0; /* the tachometer time (from timer) */
volatile uint8_t ir; /* IR signal state, to measure IR code */
uint16_t TIMER1_PRESCALE[8] = {0,1,8,64,256,1024,0,0}; /* timer 1 CS1[2:0] values */
volatile uint16_t ir_tick; /* number of counter ticks per millisecond */
volatile uint8_t pulse = 0; /* pulse index within the burst */
#define PULSE_MAX 128 /* maximum number of pulses to save */
uint16_t burst[PULSE_MAX]; /* pulse times forming a burst (from timer) */

/* channel variables */
#define LEVELS 10 /* the number of PWM levels */
uint8_t ch_tick = 0; /* the tick counter for the channel PWM */
#define OUTPUTS_1 5 /* the number of outputs for channel 1 */
#define OUTPUTS_2 5 /* the number of outputs for channel 2 */
volatile uint8_t* PORTS_1[OUTPUTS_1] = {&PORTC,&PORTC,&PORTC,&PORTC,&PORTC}; /* channel 1 output ports */
volatile uint8_t* PORTS_2[OUTPUTS_2] = {&PORTD,&PORTD,&PORTD,&PORTD,&PORTD}; /* channel 2 output ports */
uint8_t BITS_1[OUTPUTS_1] = {PC0,PC1,PC2,PC3,PC4}; /* channel 1 output bits */
uint8_t BITS_2[OUTPUTS_2] = {PD2,PD3,PD4,PD5,PD7}; /* channel 2 output bits */
uint8_t ch_1[OUTPUTS_1]; /* the level value for the channel 1 outputs */
uint8_t ch_2[OUTPUTS_2]; /* the level value for the channel 2 outputs */

/* flags, set in the interrupts and handled in the main program */
volatile bool uart_flag = false; /* an incoming activity on the UART */
volatile bool power_flag = false; /* a change in the power or fan */
volatile bool ir_flag = false; /* to process a burst */
volatile bool pwm_flag = false; /* to trigger a PWM tick */
volatile bool channel_flag = false; /* indicate a change in the channel PWM values */

/* UART receive interrupt */
ISR(USART_RX_vect) {
	input[input_i] = getchar(); /* save input */
	input[input_i+1] = 0; /* always end the string */
	if (input_i<INPUT_MAX) { /* next character, if space is available */
		input_i++;
	}
	uart_flag = true; /* set flag */
}

/* power ok interrupt */
ISR(PCINT0_vect) { /* PCI0 Interrupt Vector for PCINT[7:0] */
	if (pwr_ok!=(PINB&(1<<PWR_OK))) { /* did the PWR_OK pin state changed */
		pwr_ok = PINB&(1<<PWR_OK); /* save new state */
		power_flag = true;
	} else if (ir!=(PINB&(1<<IR))) { /* did the IR pin state changed */
		ir = PINB&(1<<IR); /* save new state */
		if (pulse>0) { /* save pulse, except the first */
			burst[pulse-1] = (TCNT1*1000UL)/ir_tick;
			burst[pulse] = 0;
		}
		if (pulse<PULSE_MAX-1) { /* prepare to save next pulse */
			pulse++;
		}
		TCNT1 = 0; /* clear timer 1 */
	}
}

/* fan tachometer interrupt */
ISR(PCINT1_vect) { /* PCI0 Interrupt Vector for PCINT[14:8] */
	if (fan!=(PINC&(1<<FAN))) { /* did the FAN pin state changed */
		fan = PINC&(1<<FAN); /* save new state */
		if (fan) { /* only react to rising edge */
			tachometer = (uint16_t)(timer2_ovf<<8)+TCNT2; /* save time */
			TCNT2 = 0; /* reset timer 2 */
			timer2_ovf = 0; /* reset timer 2 */
		}
	}
}

/* timer 2 interrupt used to measure fan speed based on tachometer */
ISR(TIMER2_OVF_vect) { /* timer 2 overflow interrupt vector */
	if (timer2_ovf<0xff) { /* prevent overflow */
		timer2_ovf++; /* increase tachometer counter */
	} else {
		tachometer = 0; /* indicate no speed can be measured */
		if (pwr_ok) { /* warn the fan is dead while the power in on */
			power_flag = true;
		}
		timer2_ovf = 0;
	}
}

/* timer 1 interrupt used to timeout IR burst */
ISR(TIMER1_COMPA_vect) { /* timer 1 OCR1A match interrupt vector */
	if (pulse>0 && !ir_flag) { /* warm an burst is ready when the timeout triggered */
		ir_flag = true;
	}
}

/* timer 0 interrupt used generate a PWM for the channels */
ISR(TIMER0_COMPA_vect) { /* timer 0 OCR0A match interrupt vector */
	ch_tick = (ch_tick+1)%LEVELS;
	pwm_flag = true;
}

static void ioinit(void)
{
	/* configure power */
	DDRB |= (1<<nPS_ON); /* nPS_ON is output */
	PORTB |= (1<<nPS_ON); /* switch off power supply */
	DDRB &= ~(1<<PWR_OK); /* PWR_ON (PB1/PCINT1) is input */
	pwr_ok = PINB&(1<<PWR_OK); /* save state */
	PCIFR &= ~(1<<PCIF0); /* clear interrupt flag */
	PCICR |= (1<<PCIE0); /* enable interrupt for PCINT[7:0] */
	PCMSK0 |= (1<<PCINT1); /* enable interrupt for PCINT1 */

	/* configure LED (on PD6/OC0A) */
	DDRD |= (1<<LED); /* LED is output */
	PORTD &= ~(1<<LED); /* switch LED on */
	
	/* configure FAN */
	DDRC &= ~(1<<FAN); /* FAN (PC5/PCINT13) is input */
	fan = PINC&(1<<FAN); /* save state */
	PCIFR &= ~(1<<PCIF1); /* clear interrupt flag */
	PCICR |= (1<<PCIE1); /* enable interrupt for PCINT[14:8] */
	PCMSK1 |= (1<<PCINT13); /* enable interrupt for PCINT1 */
	/* use timer 2 to measure the tachometer */
	/* use normal mode */
	TCCR2A &= ~((1<<WGM20)|(1<<WGM21));
	TCCR2B &= ~(1<<WGM22);
	/* clock/64 prescaler */
	TCCR2B |= (1<<CS22);
	TCCR2B &= ~((1<<CS21)|(1<<CS20));
	TIFR2 &= ~(1<<TOV2); /* clear timer 2 overflow interrupt flag */
	TIMSK2 |= (1<<TOIE2); /* enable timer 2 overflow interrupt */

	/* configure IR receiver */
	DDRB &= ~(1<<IR); /* IR (PB0/PCINT0) receiver is input */
	ir = PINB&(1<<IR); /* save state */
	PCIFR &= ~(1<<PCIF0); /* clear interrupt flag */
	PCICR |= (1<<PCIE0); /* enable interrupt for PCINT[7:0] */
	PCMSK0 |= (1<<PCINT0); /* enable interrupt for PCINT0 */
	/* use timer 1 to measure IR pulse */
	/* use CTC mode */
	TCCR1A &= ~((1<<WGM10)|(1<<WGM11));
	TCCR1B |= (1<<WGM12);
	TCCR1B &= ~(1<<WGM13);
	/* clock/8 prescaler, offers most precision for 15ms (up to 28.5ms) */
	TCCR1B |= (1<<CS11);
	TCCR1B &= ~((1<<CS12)|(1<<CS10));
	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10]; /* timer 1 presacler */
	if (0!=prescale) {
		ir_tick = F_CPU/(1000*prescale); /* ticks per ms */
		OCR1A = (uint32_t)(15*F_CPU)/(1000*prescale); /* set clear time to 15 ms (no IR toggle should be longer) */
	}
	TIFR1 &= ~(1<<OCF1A); /* clear timer 1 compare interrupt flag */
	TIMSK1 |= (1<<OCIE1A); /* enable timer 1 compare interrupt */

	/* configure channels (used for powering LEDs using an nMOS) */
	DDRC |= (1<<CH1_1)|(1<<CH1_2)|(1<<CH1_3)|(1<<CH1_4)|(1<<CH1_5); /* CH1_x is output */
	PORTC &= ~((1<<CH1_1)|(1<<CH1_2)|(1<<CH1_3)|(1<<CH1_4)|(1<<CH1_5)); /* switch off CH1_x */
	DDRD |= (1<<CH2_1)|(1<<CH2_2)|(1<<CH2_3)|(1<<CH2_4)|(1<<CH2_5); /* CH2_x is output */
	PORTD &= ~((1<<CH2_1)|(1<<CH2_2)|(1<<CH2_3)|(1<<CH2_4)|(1<<CH2_5)); /* switch off CH2_x */

	/* use timer 0 as source for the channel PWM */
	/* use CTC mode */
	TCCR0A |= (1<<WGM01);
	TCCR0A &= ~(1<<WGM00);
	TCCR0B &= ~(1<<WGM02);
	/* /64 prescale timer */
	TCCR0B &= ~(1<<CS02);
	TCCR0B |= (1<<CS01)|(1<<CS00);
	OCR0A = 0xff; /* set PWM speed */
	TIFR0 &= ~(1<<OCF0A); /* clear timer 0 compare interrupt flag */
	TIMSK0 |= (1<<OCIE0A); /* enable timer 0 compare interrupt */

	/* use UART as terminal */
	uart_init();
	stdout = &uart_output;
	stdin  = &uart_input;

	sei(); /* enable interrupts */
}

int main(void)
{
	ioinit(); /* initialize IOs */

	uint8_t command_i = 0; /* command index */
	struct nec ir_data; /* last IR data */
	ir_data.valid = false;
	ir_data.repeat = false;
	ir_data.address = 0;
	ir_data.command = 0;
	uint8_t ir_repeat = 0; /* number of times the IR data has been repeated */

	/* initialize channel output PWM values */
	for (uint8_t i=0; i<OUTPUTS_1; i++) {
		ch_1[i] = 0;
	}
	for (uint8_t i=0; i<OUTPUTS_2; i++) {
		ch_2[i] = 0;
	}
	uint8_t on_1[5] = {0,0,0,0,0}; /* times when to switch on the outputs for channel 1 */
	uint8_t on_2[5] = {0,0,0,0,0}; /* times when to switch on the outputs for channel 2 */
	uint8_t off_1[5] = {0,0,0,0,0}; /* times when to switch off the outputs for channel 1 */
	uint8_t off_2[5] = {0,0,0,0,0}; /* times when to switch off the outputs for channel 2 */
	channel_flag = true; /* calculate above values later */

	puts("LED dimmer up & running");
	while (true) {
		/* calculated PWM values */
		while (channel_flag) {
			uint8_t start = 0;
			for (uint8_t i=0; i<OUTPUTS_1; i++) {
				on_1[i] = (start)%LEVELS;
				off_1[i] = (on_1[i]+ch_1[i])%LEVELS;
				start = (start+ch_1[i])%LEVELS;
			}
			start = 0;
			for (uint8_t i=0; i<OUTPUTS_2; i++) {
				on_2[i] = (start)%LEVELS;
				off_2[i] = (on_2[i]+ch_2[i])%LEVELS;
				start = (start+ch_2[i])%LEVELS;
			}
			channel_flag = false;
		}
		/* generate PWM for channel */
		while (pwm_flag) {
			if (pwr_ok) {
				for (int i=0; i<OUTPUTS_1; i++) {
					if (on_1[i]==ch_tick) {
						if (on_1[i]!=off_1[i]) {
							*(PORTS_1[i]) |= (1<<BITS_1[i]);
						} else if (ch_1[i]==0) {
							*(PORTS_1[i]) &= ~(1<<BITS_1[i]);
						} else {
							*(PORTS_1[i]) |= (1<<BITS_1[i]);
						}
					} else if (off_1[i]==ch_tick) {
						*(PORTS_1[i]) &= ~(1<<BITS_1[i]);
					}
				}
				for (int i=0; i<OUTPUTS_2; i++) {
					if (on_2[i]==ch_tick) {
						if (on_2[i]!=off_2[i]) {
							*(PORTS_2[i]) |= (1<<BITS_2[i]);
						} else if (ch_2[i]==0) {
							*(PORTS_2[i]) &= ~(1<<BITS_2[i]);
						} else {
							*(PORTS_2[i]) |= (1<<BITS_2[i]);
						}
					} else if (off_2[i]==ch_tick) {
						*(PORTS_2[i]) &= ~(1<<BITS_2[i]);
					}
				}
				PIND |= (1<<LED);
			}
			pwm_flag = false;
		}
		/* handle UART input */
		while (uart_flag) {
			/* echo back */
			char c = 0;
			while (command_i<input_i) {
				c = input[command_i++];
				putchar(c);
			}
			uart_action(c);
			uart_flag = false;
		}
		/* handle power state */
		while (power_flag) {
			if (pwr_ok) {
				puts("power ok");
				/* verify if FAN is present */
				_delay_ms(500);
				if (0==tachometer) {
					puts("FAN not on, switching power off");
					PORTB |= (1<<nPS_ON);
				}
			} else {
				puts("power off");
			}
			power_flag = false;
		}
		/* handle IR input */
		while (ir_flag) {
			time2nec(burst,pulse-1); /* convert raw time burst in NEC format */
			struct nec ir_tmp = nec2data(burst,pulse-1); /* decode NEC burst */
			if (ir_tmp.valid) {
				if (ir_tmp.repeat) {
					if (ir_repeat<0xff) {
						ir_repeat++;
					}
				} else {
					ir_data = ir_tmp;
					ir_repeat = 0;
				}
				if (ir_repeat==0 || ir_repeat>3) {
					ir_action(ir_data.address,ir_data.command);
				}
			}
			pulse = 0; /* reset burst */
			ir_flag = false;
		}
	}
	return 0;
}

static void uart_action(char c)
{
	switch (c) {
		case 'l':
			PIND |= (1<<LED);
			printf("LED: ");
			if (PIND&(1<<LED)) {
				puts("off");
			} else {
				puts("on");
			}
			break;
		case 'a':
			printf("switching power supply ");
			if (PINB&(1<<nPS_ON)) {
				puts("on");
			} else {
				puts("off");
			}
			PINB |= (1<<nPS_ON);
			break;
		case 's':
			printf("power: ");
			if (PINB&(1<<PWR_OK)) {
				puts("ok");
			} else {
				puts("ko");
			}
			break;
		case '1':
			ch_1[0] = (ch_1[0]+1)%(LEVELS+1);
			channel_flag = true;
			break;
		case '2':
			PINC |= (1<<CH1_2);
			printf("CH1_2: ");
			if (PINC&(1<<CH1_2)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '3':
			PINC |= (1<<CH1_3);
			printf("CH1_3: ");
			if (PINC&(1<<CH1_3)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '4':
			PINC |= (1<<CH1_4);
			printf("CH1_4: ");
			if (PINC&(1<<CH1_4)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '5':
			PINC |= (1<<CH1_5);
			printf("CH1_5: ");
			if (PINC&(1<<CH1_5)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '6':
			PIND |= (1<<CH2_1);
			printf("CH2_1: ");
			if (PIND&(1<<CH2_1)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '7':
			PIND |= (1<<CH2_2);
			printf("CH2_2: ");
			if (PIND&(1<<CH2_2)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '8':
			PIND |= (1<<CH2_3);
			printf("CH2_3: ");
			if (PIND&(1<<CH2_3)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '9':
			PIND |= (1<<CH2_4);
			printf("CH2_4: ");
			if (PIND&(1<<CH2_4)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '0':
			PIND |= (1<<CH2_5);
			printf("CH2_5: ");
			if (PIND&(1<<CH2_5)) {
				puts("on");
			} else {
				puts("off");
			}
			break;
		case '-':
			if (OCR0A>0) {
				OCR0A--;
			}
			printf("decreasing LED: %u\n",OCR0A);
			break;
		case '+':
			if (OCR0A<0xff) {
				OCR0A++;
			}
			printf("increasing LED: %u\n",OCR0A);
			break;
		case 't':
			if (tachometer) {
				uint16_t prescale = TIMER2_PRESCALE[TCCR2B&((1<<CS22)|(1<<CS21)|(1<<CS20))];
				if (prescale) {
					if (timer2_ovf<0xff) {
						uint32_t speed = ((60*F_CPU)/(prescale*(uint32_t)tachometer))/2; /* calculate speed. 2 pulses per revolution */
						printf("fan speed: %lurpm\n",speed);
					} else {
						printf("fan off (or not detected)\n");
					}
				} else {
					printf("fan speed measurement not started\n");
				}
			} else {
				printf("fan off (or not detected)\n");
			}
			break;
	}
}

static void ir_action(uint8_t address, uint8_t command)
{
	if (0==address && 72==command) {
		printf("switching power supply ");
		if (PINB&(1<<nPS_ON)) {
			puts("on");
		} else {
			puts("off");
		}
		PINB |= (1<<nPS_ON);
	} else {
		printf("IR addr: %u, command: %u\n", address, command);
	}
}