#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>
#include <poll.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <getopt.h>

#include <linux/usbdevice_fs.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <linux/gpio.h>

#define BIT(n) (1u << (n))

#define KB_ADDR 0x15
#define POWER_ADDR 0x75

static bool verbose;
#define debug(args...) { if (verbose) printf(args); }

static void syscall_error(int is_err, const char* fmt, ...)
{
	va_list ap;

	if (!is_err)
		return;

	fprintf(stderr, "ERROR: ");
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fprintf(stderr, ": %s\n", strerror(errno));

	exit(1);
}

static void error(const char* fmt, ...)
{
	va_list ap;

	fprintf(stderr, "ERROR: ");
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	fprintf(stderr, "\n");

	exit(1);
}

static bool read_file(const char* path, char* buf, size_t size)
{
	int fd;
	ssize_t ret;

	fd = open(path, O_RDONLY);
	if (fd < 0)
		return false;

	ret = read(fd, buf, size);
	close(fd);
	if (ret < 0)
		return false;

	if (ret < size) {
		buf[ret] = 0;
		return true;
	} else {
		buf[size - 1] = 0;
		return false;
	}
}

static int open_usb_dev(uint16_t vid, uint16_t pid)
{
	char path[256], buf[256];
	struct dirent *e;
	unsigned e_vid, e_pid, bus, dev;
	int fd = -1, ret;
	DIR* d;

        d = opendir("/sys/bus/usb/devices");
	syscall_error(d == NULL, "opendir(/sys/bus/usb/devices) failed");

	while (true) {
		errno = 0;
		e = readdir(d);
		syscall_error(e == NULL && errno, "readdir(/sys/bus/usb/devices) failed");
		if (!e)
			break;

                if (!strcmp(e->d_name, ".") || !strcmp(e->d_name, ".."))
			continue;

		snprintf(path, sizeof path,
			 "/sys/bus/usb/devices/%s/idVendor", e->d_name);
		if (!read_file(path, buf, sizeof buf))
			continue;

		ret = sscanf(buf, "%x", &e_vid);
		if (ret != 1)
			error("Failed to parse %s", path);

		snprintf(path, sizeof path,
			 "/sys/bus/usb/devices/%s/idProduct", e->d_name);
		if (!read_file(path, buf, sizeof buf))
			continue;

		ret = sscanf(buf, "%x", &e_pid);
		if (ret != 1)
			error("Failed to parse %s", path);

		if (e_vid == vid && e_pid == pid) {
			snprintf(path, sizeof path,
				 "/sys/bus/usb/devices/%s/busnum", e->d_name);
			if (!read_file(path, buf, sizeof buf))
				error("Failed to read %s", path);

			ret = sscanf(buf, "%u", &bus);
			if (ret != 1)
				error("Failed to parse %s", path);

			snprintf(path, sizeof path,
				 "/sys/bus/usb/devices/%s/devnum", e->d_name);
			if (!read_file(path, buf, sizeof buf))
				error("Failed to read %s", path);

			ret = sscanf(buf, "%u", &dev);
			if (ret != 1)
				error("Failed to parse %s", path);

			snprintf(path, sizeof path,
				 "/dev/bus/usb/%03u/%03u", bus, dev);

			debug("Found %04x:%04x at %s\n", e_vid, e_pid, path);

			fd = open(path, O_RDWR);
			syscall_error(fd < 0, "open(%s) failed", path);
			break;
		}
	}

	errno = ENOENT;
	closedir(d);
	return fd;
}

static int handle_urb(int usb_fd, struct usbdevfs_urb* urb, int timeout)
{
	int ret;
	struct usbdevfs_urb* reaped_urb;
	int retries = 0;

retry:
        ret = ioctl(usb_fd, USBDEVFS_SUBMITURB, urb);
        if (ret < 0)
        	return ret;

	struct pollfd fd = {
		.fd = usb_fd,
		.events = POLLOUT,
	};

	ret = poll(&fd, 1, timeout);
	if (ret <= 0) {
		if (ret == 0)
			errno = ETIMEDOUT;

		int save_errno = errno;

		// on timeout or other poll error, we need to discard and reap the submitted URB
		ret = ioctl(usb_fd, USBDEVFS_DISCARDURB, urb);

		// even if discard fails, URB may still be reapable, we need to try reaping anyway
		ret = ioctl(usb_fd, USBDEVFS_REAPURBNDELAY, &reaped_urb);

		// reap must immediately succeed, otherwise this is fatal
		syscall_error(ret < 0, "USBDEVFS_REAPURBNDELAY failed");

		errno = save_errno;
		return -1;
	}

	// hopefully POLLERR means we get some error immediately on reap

	ret = ioctl(usb_fd, USBDEVFS_REAPURB, &reaped_urb);
        if (ret < 0)
        	return ret;

	// EPROTO errors are recoverable
	if (urb->status == -71 && retries < 3) {
		retries++;
		goto retry;
	}

	if (urb->status != 0) {
		errno = -urb->status;
		return -1;
	}

	return 0;
}

static int pogo_i2c_open(void)
{
	int ret;
	char path[256], buf[1024];
	int fd = -1;

	for (int i = 0; i < 8; i++) {
		snprintf(path, sizeof path, "/sys/class/i2c-adapter/i2c-%d/uevent", i);
		if (!read_file(path, buf, sizeof buf))
			continue;
		
		if (!strstr(buf, "OF_FULLNAME=/soc/i2c@1c2b400"))
			continue;
		
		snprintf(path, sizeof path, "/dev/i2c-%d", i);
		
		int fd = open(path, O_RDWR);
		syscall_error(fd < 0, "open(%s) failed");

		return fd;		
	}
	
	error("Can't find POGO I2C adapter");
	return -1;
}

ssize_t xwrite(int fd, uint8_t* buf, size_t len)
{
	size_t off = 0;
	
	while (off < len) {
		ssize_t ret = write(fd, buf + off, len - off);
		if (ret < 0)
			return ret;
		
		off += ret;
	}
	
	return off;
}

static const uint8_t crc8_0x7_table[] = {
	0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
	0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
	0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
	0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
	0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5,
	0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
	0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85,
	0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
	0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
	0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
	0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2,
	0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
	0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32,
	0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
	0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
	0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
	0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c,
	0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
	0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec,
	0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
	0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
	0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
	0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c,
	0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
	0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b,
	0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
	0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
	0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
	0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb,
	0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
	0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb,
	0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
};

static uint8_t crc8(const uint8_t *pdata, size_t nbytes)
{
	unsigned int idx;
	uint8_t crc = 0;

	while (nbytes--) {
		idx = (crc ^ *pdata);
		crc = (crc8_0x7_table[idx]) & 0xff;
		pdata++;
	}

	return crc;
}

uint64_t time_abs(void)
{
	struct timespec tmp;
	int ret;

	ret = clock_gettime(CLOCK_MONOTONIC, &tmp);
	if (ret < 0)
		return 0;

	return tmp.tv_sec * 1000000000ull + tmp.tv_nsec;
}

static int gpiochip_open(const char* match)
{
	int ret;
	char path[256], buf[1024];
	int fd = -1;

	for (int i = 0; i < 8; i++) {
		snprintf(path, sizeof path, "/sys/bus/gpio/devices/gpiochip%d/uevent", i);
		if (!read_file(path, buf, sizeof buf))
			continue;

		if (!strstr(buf, match))
			continue;

		snprintf(path, sizeof path, "/dev/gpiochip%d", i);

		int fd = open(path, O_RDWR);
		syscall_error(fd < 0, "open(%s) failed");

		return fd;
	}

	error("Can't find %s gpiochip", match);
	return -1;
}

static int gpio_setup_pl12(unsigned flags)
{
	int ret;
	struct gpio_v2_line_request req = {
		.num_lines = 1,
		.offsets[0] = 12,
		.config.flags = flags,
		.consumer = "ppkbd",
	};

	int fd = gpiochip_open("OF_FULLNAME=/soc/pinctrl@1f02c00");

	ret = ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req);
	syscall_error(ret < 0, "GPIO_V2_GET_LINE_IOCTL failed");

	close(fd);

	return req.fd;
}

static int gpio_get_value(int lfd)
{
	int ret;
	struct gpio_v2_line_values vals = {
		.mask = 1,
	};

	ret = ioctl(lfd, GPIO_V2_LINE_GET_VALUES_IOCTL, &vals);
	syscall_error(ret < 0, "GPIO_V2_GET_LINE_IOCTL failed");

	return vals.bits & 0x1;
}

static int gpio_set_value(int lfd, int val)
{
	int ret;
	struct gpio_v2_line_values vals = {
		.mask = 1,
	};

	ret = ioctl(lfd, GPIO_V2_LINE_GET_VALUES_IOCTL, &vals);
	syscall_error(ret < 0, "GPIO_V2_GET_LINE_IOCTL failed");

	return vals.bits & 0x1;
}