/* 
 *  a crude button press/long-press/shift management based on GPIO
 *
 *  (c) Philippe G. 2019, philippe_44@outlook.com
 *
 * 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/>.
 *
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/timers.h"
#include "freertos/queue.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_task.h"
#include "driver/gpio.h"
#include "buttons.h"

static const char * TAG = "audio_controls";

static int n_buttons = 0;

#define MAX_BUTTONS		16
#define DEBOUNCE		50

static struct button_s {
	int gpio, index;
	button_handler handler, long_handler, shift_handler;
	struct button_s *shifter;
	int	long_press;
	bool long_timer, shifted, shifting;
	int type, level;	
	TimerHandle_t timer;
} buttons[MAX_BUTTONS];

static xQueueHandle button_evt_queue = NULL;

static void buttons_task(void* arg);

/****************************************************************************************
 * GPIO low-level handler
 */
static void IRAM_ATTR gpio_isr_handler(void* arg)
{
	struct button_s *button = (struct button_s*) arg;
	BaseType_t woken = pdFALSE;

	if (xTimerGetPeriod(button->timer) > DEBOUNCE / portTICK_RATE_MS) xTimerChangePeriodFromISR(button->timer, DEBOUNCE / portTICK_RATE_MS, &woken); // does that restart the timer? 
	else xTimerResetFromISR(button->timer, &woken);
	// ESP_EARLY_LOGD(TAG, "INT gpio %u level %u", button->gpio, button->level);
}

/****************************************************************************************
 * Buttons debounce/longpress timer
 */
static void buttons_timer( TimerHandle_t xTimer ) {
	struct button_s *button = (struct button_s*) pvTimerGetTimerID (xTimer);
	
	button->level = gpio_get_level(button->gpio);

	if (button->long_press && !button->long_timer && button->level == button->type) {
		// detect a long press, so hold event generation
		ESP_LOGD(TAG, "setting long timer gpio:%u level:%u", button->gpio, button->level);
		xTimerChangePeriod(xTimer, button->long_press / portTICK_RATE_MS, 0);
		button->long_timer = true;
	} else {
		// send a button pressed/released event (content is copied in queue)
		ESP_LOGD(TAG, "sending event for gpio:%u level:%u", button->gpio, button->level);
		// queue will have a copy of button's context
		xQueueSend(button_evt_queue, button, 0);
		button->long_timer = false;
	}
}

/****************************************************************************************
 * Tasks that calls the appropriate functions when buttons are pressed
 */
static void buttons_task(void* arg) {
	ESP_LOGI(TAG, "starting button tasks");

    while (1) {
		struct button_s button;
		button_event_e event;
		bool shifted = false;

        if (!xQueueReceive(button_evt_queue, &button, portMAX_DELAY)) continue;

		event = (button.level == button.type) ? BUTTON_PRESSED : BUTTON_RELEASED;		

		ESP_LOGD(TAG, "received event:%u from gpio:%u level:%u (timer %u shifting %u)", event, button.gpio, button.level, button.long_timer, button.shifting);

		// find if shifting is activated
		if (button.shifter && button.shifter->type == button.shifter->level) {
			button.shifter->shifting = true;
			shifted = true;
		} 
	
		/* 
		long_timer will be set either because we truly have a long press 
		or we have a release before the long press timer elapsed, so two 
		events shall be sent
		*/
		if (button.long_timer) {
			if (event == BUTTON_RELEASED) {
				// early release of a long-press button, send press/release
				if (shifted) {
					(*button.shift_handler)(BUTTON_PRESSED, BUTTON_SHIFTED);
					(*button.shift_handler)(BUTTON_RELEASED, BUTTON_SHIFTED);
				} else if (!button.shifting) {
					(*button.handler)(BUTTON_PRESSED, BUTTON_NORMAL);
					(*button.handler)(BUTTON_RELEASED, BUTTON_NORMAL);
				}	
				// button is a copy, so need to go to real context
				buttons[button.index].shifting = false;
			} else if (!button.shifting) {
				/* 
				normal long press and not shifting so don't discard but there
				is no long-press when shifted
				*/
				if (shifted) (*button.shift_handler)(BUTTON_PRESSED, BUTTON_SHIFTED);
				else (*button.long_handler)(BUTTON_PRESSED, BUTTON_LONG);
			}  
		} else if (shifted) {
			// we are shifted
			(*button.shift_handler)(event, BUTTON_SHIFTED);
		} else {
			// normal press/release of a button or release of a long-press button
			if (!button.shifting) {
				if (button.long_press) (*button.long_handler)(event, BUTTON_LONG);
				else (*button.handler)(event, BUTTON_NORMAL);
			}
			// button is a copy, so need to go to real context
			buttons[button.index].shifting = false;
		}
    }
}	
	
/****************************************************************************************
 * dummy button handler
 */	
void dummy_handler(button_event_e event, button_press_e press) {
	ESP_LOGW(TAG, "should not be here");
}

/****************************************************************************************
 * Create buttons 
 */
void button_create(int gpio, int type, bool pull, button_handler handler, ...) { 
	char *param;
	va_list args;
	
	if (n_buttons >= MAX_BUTTONS) return;

	ESP_LOGI(TAG, "creating button using GPIO %u, type %u, pull-up/down %u", gpio, type, pull);

	if (!n_buttons) {
		button_evt_queue = xQueueCreate(10, sizeof(struct button_s));
		gpio_install_isr_service(0);
		xTaskCreate(buttons_task, "buttons_task", 2048, NULL, ESP_TASK_PRIO_MIN + 1, NULL);
	}
	
	// just in case this structure is allocated later
	memset(buttons + n_buttons, 0, sizeof(struct button_s));

	// set mandatory parameters
 	buttons[n_buttons].gpio = gpio;
	buttons[n_buttons].handler = handler;
	buttons[n_buttons].level = -1;
	buttons[n_buttons].type = type;
	buttons[n_buttons].timer = xTimerCreate("buttonTimer", DEBOUNCE / portTICK_RATE_MS, pdFALSE, (void *) &buttons[n_buttons], buttons_timer);
	// little trick to find ourselves from queued copy
	buttons[n_buttons].index = n_buttons;

	va_start(args, handler);
	
	// set optional parameters
	while ((param = va_arg(args, char*)) != NULL) {
		if (!strcasecmp(param, "long")) {
			buttons[n_buttons].long_handler = (button_handler) va_arg(args, void*);
			buttons[n_buttons].long_press = va_arg(args, int);
			ESP_LOGI(TAG, "adding long press %u (ms)", buttons[n_buttons].long_press);
		} else if (!strcasecmp(param, "shift")) {
			buttons[n_buttons].shift_handler = (button_handler) va_arg(args, void*);
			int shifter_gpio = va_arg(args, int);
			for (int i = 0; i < n_buttons; i++) {
				if (buttons[i].gpio == shifter_gpio) {
					buttons[n_buttons].shifter = buttons + i;
					// a shifter must have a long-press handler
					if (!buttons[i].long_press) {
						buttons[i].long_press = 60*60*1000;
						buttons[i].long_handler = dummy_handler;
					} 
					break;
				}
			}	
			ESP_LOGI(TAG, "adding shifter %u", buttons[n_buttons].shifter->gpio);
		}
	}

	va_end(args);
	
	gpio_set_direction(gpio, GPIO_MODE_INPUT);

	// we need any edge detection
	gpio_set_intr_type(gpio, GPIO_INTR_ANYEDGE);

	// do we need pullup or pulldown
	if (pull) {
		if (type == BUTTON_LOW) gpio_set_pull_mode(gpio, GPIO_PULLUP_ONLY);
		else gpio_set_pull_mode(gpio, GPIO_PULLDOWN_ONLY);
	}
 
	gpio_isr_handler_add(gpio, gpio_isr_handler, (void*) &buttons[n_buttons]);
	gpio_intr_enable(gpio);

	n_buttons++;
}