/* This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/** STM32F1 project template
 *  @file main.c
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2016
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#include <stdlib.h> // standard utilities
#include <unistd.h> // standard streams
#include <errno.h> // error number utilities
#include <string.h> // string utilities
#include <math.h> // mathematical utilities

/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/cm3/scb.h> // vector table definition
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
#include <libopencm3/cm3/nvic.h> // interrupt utilities
#include <libopencm3/stm32/exti.h> // external interrupt utilities
#include <libopencm3/stm32/rtc.h> // real time clock utilities

/* own libraries */
#include "global.h" // board definitions
#include "usart.h" // USART utilities
#include "usb_cdcacm.h" // USB CDC ACM utilities

/** @defgroup main_flags flag set in interrupts to be processed in main task
 *  @{
 */
volatile bool button_flag = false; /**< flag set when board user button has been pressed/released */
volatile bool rtc_internal_tick_flag = false; /**< flag set when internal RTC ticked */
/** @} */

/** user input command */
char command[32] = {0};
/** user input command index */
uint8_t command_i = 0;

int _write(int file, char *ptr, int len)
{
	int i; // how much data has been sent
	static char newline = 0; // what newline has been sent

	if (file == STDOUT_FILENO || file == STDERR_FILENO) {
		for (i = 0; i < len; i++) {
			if (ptr[i] == '\r' || ptr[i] == '\n') { // send CR+LF newline for most carriage return and line feed combination
				if (newline==0 || (newline==ptr[i])) { // newline has already been detected
					usart_putchar_nonblocking('\r'); // send newline over USART
					usart_putchar_nonblocking('\n'); // send newline over USART
					cdcacm_putchar('\r'); // send newline over USB
					cdcacm_putchar('\n'); // send newline over USB
					newline = ptr[i]; // remember the newline
				}
				if (ptr[i] == '\n') { // line feed are always considered to end a line (the LF+CR combination is not supported to better support the others)
					newline = 0; // clear new line
				}
			} else { // non-newline character
				usart_putchar_nonblocking(ptr[i]); // send byte over USART
				cdcacm_putchar(ptr[i]); // send byte over USB
				newline = 0; // clear new line
			}
		}
		return i;
	}
	errno = EIO;
	return -1;
}

char* b2s(uint64_t binary, uint8_t rjust)
{
	static char string[64+1] = {0}; // the string representation to return
	int8_t bit = LENGTH(string)-1; // the index of the bit to print
	string[bit--] = 0; // terminate string

	while (binary) {
		if (binary & 1) {
			string[bit--] = '1';
		} else {
			string[bit--] = '0';
		}
		binary >>= 1;
	}

	while (64-bit-1<rjust && bit>=0) {
		string[bit--] = '0';
	}

	return &string[bit+1];
}

/** process user command
 *  @param[in] str user command string (\0 ended)
 */
static void process_command(char* str)
{
	// split command
	const char* delimiter = " ";
	char* word = strtok(str,delimiter);
	if (!word) {
		goto error;
	}
	// parse command
	if (0==strcmp(word,"help")) {
		printf("available commands:\n");
		printf("led [on|off|toggle]\n");
		printf("time [HH:MM:SS]\n");
	} else if (0==strcmp(word,"led")) {
		word = strtok(NULL,delimiter);
		if (!word) {	
			goto error;
		} else if (0==strcmp(word,"on")) {
			led_on(); // switch LED on
			printf("LED switched on\n"); // notify user		
		} else if (0==strcmp(word,"off")) {
			led_off(); // switch LED off
			printf("LED switched off\n"); // notify user
		} else if (0==strcmp(word,"toggle")) {
			led_toggle(); // toggle LED
			printf("LED toggled\n"); // notify user
		} else {
			goto error;
		}
	} else if (0==strcmp(word,"time")) {
		word = strtok(NULL,delimiter);
		if (!word) {
			printf("current time: %02lu:%02lu:%02lu\n", rtc_get_counter_val()/(60*60), (rtc_get_counter_val()%(60*60))/60, (rtc_get_counter_val()%60)); // get and print time from internal RTC
		} else if (strlen(word)!=8 || word[0]<'0' || word[0]>'2' || word[1]<'0' || word[1]>'9' || word[3]<'0' || word[3]>'5' || word[4]<'0' || word[4]>'9' || word[6]<'0' || word[6]>'5' || word[7]<'0' || word[7]>'9') { // time format is incorrect
				goto error;
		} else {
			rtc_set_counter_val(((word[0]-'0')*10+(word[1]-'0')*1)*(60*60)+((word[3]-'0')*10+(word[4]-'0')*1)*60+((word[6]-'0')*10+(word[7]-'0')*1)); // set time in internal RTC counter
			printf("time set\n");
		}
	} else {
		goto error;
	}

	return; // command successfully processed
error:
	printf("command not recognized. enter help to list commands\n");
}

/** program entry point
 *  this is the firmware function started by the micro-controller
 */
int main(void)
{	
	rcc_clock_setup_in_hse_8mhz_out_72mhz(); // use 8 MHz high speed external clock to generate 72 MHz internal clock
	
	// setup LED
	rcc_periph_clock_enable(LED_RCC); // enable clock for LED
	gpio_set_mode(LED_PORT, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, LED_PIN); // set LED pin to 'output push-pull'
	led_off(); // switch off LED per default

	// setup USART and USB for user communication
    usart_setup(); // setup USART (for printing)
	cdcacm_setup(); // setup USB CDC ACM (for printing)
    setbuf(stdout, NULL); // set standard out buffer to NULL to immediately print   
    setbuf(stderr, NULL); // set standard error buffer to NULL to immediately print

	// minimal setup ready	
	printf("welcome to the STM32F1 CuVoodoo example code\n"); // print welcome message

	// setup button
#if defined(BUTTON_RCC) && defined(BUTTON_PORT) && defined(BUTTON_PIN) && defined(BUTTON_EXTI) && defined(BUTTON_IRQ)
	rcc_periph_clock_enable(BUTTON_RCC); // enable clock for button
	gpio_set_mode(BUTTON_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, BUTTON_PIN); // set button pin to input
	gpio_clear(BUTTON_PORT, BUTTON_PIN); // pull down to be able to detect button push (go high)
	rcc_periph_clock_enable(RCC_AFIO); // enable alternate function clock for external interrupt
	exti_select_source(BUTTON_EXTI, BUTTON_PORT); // mask external interrupt of this pin only for this port
	exti_set_trigger(BUTTON_EXTI, EXTI_TRIGGER_RISING); // trigger when button is pressed
	exti_enable_request(BUTTON_EXTI); // enable external interrupt
	nvic_enable_irq(BUTTON_IRQ); // enable interrupt
#endif

	// setup RTC
	printf("setup internal RTC: ");
	rtc_auto_awake(RCC_LSE, 32768-1); // ensure internal RTC is on, uses the 32.678 kHz LSE, and the prescale is set to our tick speed, else update backup registers accordingly (power off the micro-controller for the change to take effect)
	rtc_interrupt_enable(RTC_SEC); // enable RTC interrupt on "seconds"
	nvic_enable_irq(NVIC_RTC_IRQ); // allow the RTC to interrupt
	printf("OK\n");

	// get date and time
	uint32_t ticks_time = 0;
	ticks_time = rtc_get_counter_val(); // get time/date from internal RTC
	printf("current time: %02lu:%02lu:%02lu\n", ticks_time/(60*60), (ticks_time%(60*60))/60, (ticks_time%60)); // display time

	// main loop
	printf("command input: ready\n");
	bool action = false; // if an action has been performed don't go to sleep
	button_flag = false; // reset button flag
	char c = ' '; // to store received character
	bool char_flag = false; // a new character has been received
	while (true) { // infinite loop
		while (usart_received) { // data received over UART
			action = true; // action has been performed
			led_toggle(); // toggle LED
			c = usart_getchar(); // store receive character
			char_flag = true; // notify character has been received
		}
		while (cdcacm_received) { // data received over USB
			action = true; // action has been performed
			led_toggle(); // toggle LED
			c = cdcacm_getchar(); // store receive character
			char_flag = true; // notify character has been received
		}
		while (char_flag) { // user data received
			char_flag = false; // reset flag
			action = true; // action has been performed
			printf("%c",c); // echo receive character
			if (c=='\r' || c=='\n') { // end of command received
				if (command_i>0) { // there is a command to process
					command[command_i] = 0; // end string
					command_i = 0; // prepare for next command
					process_command(command); // process user command
				}
			} else { // user command input
				command[command_i] = c; // save command input
				if (command_i<LENGTH(command)-2) { // verify if there is place to save next character
					command_i++; // save next character
				}
			}
		}
		while (button_flag) { // user pressed button
			action = true; // action has been performed
			printf("button pressed\n");
			led_toggle(); // toggle LED
			for (uint32_t i=0; i<1000000; i++) { // wait a bit to remove noise and double trigger
				__asm__("nop");
			}
			button_flag = false; // reset flag
		}
		while (rtc_internal_tick_flag) { // the internal RTC ticked
			rtc_internal_tick_flag = false; // reset flag
			ticks_time = rtc_get_counter_val(); // copy time from internal RTC for processing
			action = true; // action has been performed
			if ((ticks_time%(60*60))==0) { // one minute passed
				printf("%02lu:%02lu:%02lu\n", ticks_time/(60*60), (ticks_time%(60*60))/60, (ticks_time%60)); // display external time
			}
		}
		if (action) { // go to sleep if nothing had to be done, else recheck for activity
			action = false;
		} else {
			__WFI(); // go to sleep
		}
	}

	return 0;
}

#if defined(BUTTON_ISR) && defined(BUTTON_EXTI)
/** interrupt service routine called when button is pressed */
void BUTTON_ISR(void)
{
	exti_reset_request(BUTTON_EXTI); // reset interrupt
	button_flag = true; // perform button action
}
#endif

/** @brief interrupt service routine called when tick passed on RTC */
void rtc_isr(void)
{
	rtc_clear_flag(RTC_SEC); // clear flag
	rtc_internal_tick_flag = true; // notify to show new time
}