#define _GNU_SOURCE

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <argp.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include "openbmc_intf.h"
#include "gpio.h"
#include "gpio_json.h"

#define GPIO_PORT_OFFSET 8
#define GPIO_BASE_PATH "/sys/class/gpio"

cJSON* gpio_json = NULL;

int gpio_writec(GPIO* gpio, char value)
{
	g_assert (gpio != NULL);
	int rc = GPIO_OK;
	char buf[1];
	buf[0] = value;

	if (lseek(gpio->fd, 0, SEEK_SET) == -1)
	{
		return GPIO_ERROR;
	}

	if (write(gpio->fd, buf, 1) != 1)
	{
		rc = GPIO_WRITE_ERROR;
	}
	return rc;
}

int gpio_write(GPIO* gpio, uint8_t value)
{
	g_assert (gpio != NULL);
	int rc = GPIO_OK;
	char buf[1];
	buf[0] = '0';
	if (value==1)
	{
		buf[0]='1';
	}

	if (lseek(gpio->fd, 0, SEEK_SET) == -1)
	{
		return GPIO_ERROR;
	}

	if (write(gpio->fd, buf, 1) != 1)
	{
		rc = GPIO_WRITE_ERROR;
	}
	return rc;
}

int gpio_read(GPIO* gpio, uint8_t *value)
{
	g_assert (gpio != NULL);
	char buf[1];
	int r = GPIO_OK;
	if (gpio->fd <= 0)
	{
		r = GPIO_ERROR;
	}
	else
	{
		if (lseek(gpio->fd, 0, SEEK_SET) == -1)
		{
			return GPIO_ERROR;
		}

		if (read(gpio->fd,&buf,1) != 1)
		{
			r = GPIO_READ_ERROR;
		} else {
			if (buf[0]=='1') {
				*value = 1;
			} else {
				*value = 0;
			}
		}
	}
	return r;
}
int gpio_clock_cycle(GPIO* gpio, int num_clks) {
	g_assert (gpio != NULL);
        int i=0;
	int r=GPIO_OK;
        for (i=0;i<num_clks;i++) {
                if (gpio_writec(gpio,'0') == -1) {
			r = GPIO_WRITE_ERROR;
			break;
		}
		if (gpio_writec(gpio,'1') == -1) {
			r = GPIO_WRITE_ERROR;
			break;
		}
        }
	return r;
}

int get_gpio_base()
{
	/* TODO */
	return 0;
}

/**
 * Converts the GPIO port/offset nomenclature value
 * to a number.  Supports the ASPEED method where
 * num = base + (port * 8) + offset, and the port is an
 * A-Z character that converts to 0 to 25.  The base
 * is obtained form the hardware.
 *
 * For example: "A5" -> 5,  "Z7" -> 207
 *
 * @param[in] gpio - the GPIO name
 *
 * @return int - the GPIO number or < 0 if not found
 */
int convert_gpio_to_num(const char* gpio)
{
	static int gpio_base = -1;
	if (gpio_base == -1)
	{
		gpio_base = get_gpio_base();
		if (gpio_base < 0)
		{
			return gpio_base;
		}
	}

	size_t len = strlen(gpio);
	if (len < 2)
	{
		fprintf(stderr, ("Invalid GPIO name %s\n", gpio));
		return -1;
	}

	/* Read the offset from the last character */
	if (!isdigit(gpio[len-1]))
	{
		fprintf(stderr, "Invalid GPIO offset in GPIO %s\n", gpio);
		return -1;
	}

	int offset = gpio[len-1] - '0';

	/* Read the port from the second to last character */
	if (!isalpha(gpio[len-2]))
	{
		fprintf(stderr, "Invalid GPIO port in GPIO %s\n", gpio);
		return -1;
	}
	int port = toupper(gpio[len-2]) - 'A';

	/* Check for a 2 character port, like AA */
	if ((len == 3) && isalpha(gpio[len-3]))
	{
		port += 26 * (toupper(gpio[len-3]) - 'A' + 1);
	}

	return gpio_base + (port * GPIO_PORT_OFFSET) + offset;
}

/**
 * Returns the cJSON pointer to the GPIO definition
 * for the GPIO passed in.
 *
 * @param[in] gpio_name - the GPIO name, like BMC_POWER_UP
 *
 * @return cJSON* - pointer to the cJSON object or NULL
 *				  if not found.
 */
cJSON* get_gpio_def(const char* gpio_name)
{
	if (gpio_json == NULL)
	{
		gpio_json = load_json();
		if (gpio_json == NULL)
		{
			return NULL;
		}
	}

	cJSON* gpio_defs = cJSON_GetObjectItem(gpio_json, "gpio_definitions");
	g_assert(gpio_defs != NULL);

	cJSON* def;
	cJSON_ArrayForEach(def, gpio_defs)
	{
		cJSON* name = cJSON_GetObjectItem(def, "name");
		g_assert(name != NULL);

		if (strcmp(name->valuestring, gpio_name) == 0)
		{
			return def;
		}
	}
	return NULL;
}

/**
 * Frees the gpio_json memory
 *
 * Can be called once when callers are done calling making calls
 * to gpio_init() so that the JSON only needs to be loaded once.
 */
void gpio_inits_done()
{
	if (gpio_json != NULL)
	{
		cJSON_Delete(gpio_json);
		gpio_json = NULL;
	}
}

/**
 * Fills in the dev, direction, and num elements in
 * the GPIO structure.
 *
 * @param gpio - the GPIO structure to fill in
 *
 * @return GPIO_OK if successful
 */
int gpio_get_params(GPIO* gpio)
{
	gpio->dev = g_strdup(GPIO_BASE_PATH);

	const cJSON* def = get_gpio_def(gpio->name);
	if (def == NULL)
	{
		fprintf(stderr, "Unable to find GPIO %s in the JSON\n",
				gpio->name);
		return GPIO_LOOKUP_ERROR;
	}

	const cJSON* dir = cJSON_GetObjectItem(def, "direction");
	g_assert(dir != NULL);
	gpio->direction = g_strdup(dir->valuestring);

	/* Must use either 'num', like 87, or 'pin', like "A5" */
	const cJSON* num = cJSON_GetObjectItem(def, "num");
	if ((num != NULL) && cJSON_IsNumber(num))
	{
		gpio->num = num->valueint;
	}
	else
	{
		const cJSON* pin = cJSON_GetObjectItem(def, "pin");
		g_assert(pin != NULL);

		gpio->num = convert_gpio_to_num(pin->valuestring);
		if (gpio->num < 0)
		{
			return GPIO_LOOKUP_ERROR;
		}
	}
	return GPIO_OK;
}

// Gets the gpio device path from gpio manager object
int gpio_init(GDBusConnection *connection, GPIO* gpio)
{
	int rc = gpio_get_params(gpio);
	if (rc != GPIO_OK)
	{
	    return rc;
	}

	g_print("GPIO Lookup:  %s = %d,%s\n",gpio->name,gpio->num,gpio->direction);

	//export and set direction
	char dev[254];
	char data[4];
	int fd;
	do {
		struct stat st;

		sprintf(dev,"%s/gpio%d/value",gpio->dev,gpio->num);
		//check if gpio is exported, if not export
    		int result = stat(dev, &st);
    		if (result)
		{
			sprintf(dev,"%s/export",gpio->dev);
			fd = open(dev, O_WRONLY);
			if (fd == GPIO_ERROR) {
				rc = GPIO_OPEN_ERROR;
				break;
			}
			sprintf(data,"%d",gpio->num);
			rc = write(fd,data,strlen(data));
			close(fd);
			if (rc != strlen(data)) {
				rc = GPIO_WRITE_ERROR;
				break;
			}
		}
		const char* file = "edge";
		const char* direction = gpio->direction;
		if (strcmp(direction, "in") == 0)
		{
			file = "direction";
		}
		else if (strcmp(direction, "out") == 0)
		{
			file = "direction";

			// Read current value, so we can set 'high' or 'low'.
			// Setting direction directly to 'out' is the same as
			// setting to 'low' which can change the value in the
			// GPIO.
			uint8_t value = 0;
			rc = gpio_open(gpio);
			if (rc) break;
			rc = gpio_read(gpio, &value);
			if (rc) break;
			gpio_close(gpio);

			direction = (value ? "high" : "low");
		}
		sprintf(dev,"%s/gpio%d/%s",gpio->dev,gpio->num,file);
		fd = open(dev,O_WRONLY);
		if (fd == GPIO_ERROR) {
			rc = GPIO_WRITE_ERROR;
			break;
		}
		rc = write(fd,direction,strlen(direction));
		if (rc != strlen(direction)) {
			rc = GPIO_WRITE_ERROR;
			break;
		}

		close(fd);
		rc = GPIO_OK;
	} while(0);

	return rc;
}


char* get_gpio_dev(GPIO* gpio)
{
	char* buf;
	asprintf(&buf, "%s/gpio%d/value", gpio->dev, gpio->num);
	return buf;
}

int gpio_open_interrupt(GPIO* gpio, GIOFunc func, gpointer user_data)
{
	int rc = GPIO_OK;
	char buf[255];
	sprintf(buf, "%s/gpio%d/value", gpio->dev, gpio->num);
	gpio->fd = open(buf, O_RDONLY | O_NONBLOCK );
	gpio->irq_inited = false;
	if (gpio->fd == -1)
	{
		rc = GPIO_OPEN_ERROR;
	}
	else
	{
		GIOChannel* channel = g_io_channel_unix_new( gpio->fd);
		guint id = g_io_add_watch( channel, G_IO_PRI, func, user_data );
	}
	return rc;
}

int gpio_open(GPIO* gpio)
{
	g_assert (gpio != NULL);
	// open gpio for writing or reading
	char buf[254];
	int rc = 0;
	gpio->fd = -1;
	if (gpio->direction == NULL) {
		return GPIO_OPEN_ERROR;
	}
	if (strcmp(gpio->direction,"in")==0)
	{
		sprintf(buf, "%s/gpio%d/value", gpio->dev, gpio->num);
		gpio->fd = open(buf, O_RDONLY);
	}
	else
	{
		sprintf(buf, "%s/gpio%d/value", gpio->dev, gpio->num);
		gpio->fd = open(buf, O_RDWR);

	}
	if (gpio->fd == -1) {
		return GPIO_OPEN_ERROR;
	}
	return GPIO_OK;
}

void gpio_close(GPIO* gpio)
{
	close(gpio->fd);
}