#include <libdrm/drm.h>
#include <libdrm/drm_fourcc.h>
#include <errno.h>
#include <error.h>
#include <stdio.h>
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/random.h>
#include <linux/input.h>
#include <math.h>
#include <sys/timerfd.h>
#include <sys/poll.h>


#include "basement.raw.h"




static int touchscreen_fd;

static uint32_t *fb;

#define MAX_MT_SLOTS 16
static struct mtslot {
	int x, y, touch;
	int lastx, lasty;
} mtslots[MAX_MT_SLOTS] = {0};
static struct mtslot *curslot = &mtslots[0]; // TODO: query the current value of ABS_MT_SLOT

static void poll_touchscreen() {
	struct input_event buf[64];
	int nread;
retry_read:
	nread = read(touchscreen_fd, buf, sizeof buf);
	if(nread < 0) {
		if(errno == EINTR)
			goto retry_read;
		if(errno == EAGAIN)
			return;
		error(1, errno, "read touchscreen");
	}

	if(nread % sizeof(struct input_event))
		error(1, 0, "odd size read from touchscreen");

	for(int i = 0; i < nread; i += sizeof(struct input_event)) {
		struct input_event *evt = (struct input_event*)((char*)buf + i);
		//printf("type=%d code=%d value=%d\n", evt->type, evt->code, evt->value);
		if(evt->type == EV_SYN && evt->code == SYN_DROPPED) error(0, 0, "got SYN_DROPPED"); // TODO: resynchronize
		if(evt->type == EV_SYN && evt->code == SYN_REPORT) {
			for(int j = 0; j < MAX_MT_SLOTS; j++) {
				struct mtslot *s = &mtslots[j];
				if(s->touch) {
					//printf("slot %d x=%d y=%d\n", j, s->x, s->y);
					uint32_t col;
					switch(j & 3) {
						case 0: col = 0xFFFFFFFF; break;
						case 1: col = 0xFF0000FF; break;
						case 2: col = 0x00FF00FF; break;
						case 3: col = 0x0080FFFF; break;
					}

					int segs = s->lastx<0 ? 1 : (int)(0.9 + 2*sqrt((s->lastx-s->x)*(s->lastx-s->x) + (s->lasty-s->y)*(s->lasty-s->y)));
					if(segs<1) segs=1;
					for(int f = 0; f <= segs; f++) {
						int _x, _y;
						if(s->lastx != -1) {
							_x = (s->lastx + (s->x-s->lastx)*f/segs);
							_y = (s->lasty + (s->y-s->lasty)*f/segs);
						} else {
							_x = s->x;
							_y = s->y;
						}
						for(int dy = -5; dy <= 5; dy++) {
							for(int dx = -5; dx <= 5; dx++) {
								if(dx*dx + dy*dy <= 5*5) {
									int x = dx+_x, y = dy+_y;
									if(x >= 0 && y >= 0 && x < 800 && y < 1280) {
										*(uint32_t*)(fb + (y*800 + x)) = col;
									}
								}
							}
						}
					}
					s->lastx = s->x;
					s->lasty = s->y;
				}
			}
		}
		if(evt->type == EV_ABS && evt->code == ABS_MT_SLOT) {
			if(evt->value >= 0 && evt->value < MAX_MT_SLOTS) curslot = &mtslots[evt->value];
			else curslot = NULL;
		}
		if(evt->type == EV_ABS && evt->code == ABS_MT_POSITION_X) {
			if(curslot) curslot->x = evt->value;
		}
		if(evt->type == EV_ABS && evt->code == ABS_MT_POSITION_Y) {
			if(curslot) curslot->y = evt->value;
		}
		if(evt->type == EV_ABS && evt->code == ABS_MT_TRACKING_ID) {
			if(curslot) {
				if(!curslot->touch) {
					curslot->lastx = curslot->lasty = -1;
				}
				curslot->touch = evt->value != -1;
			}
		}
	}
}




int main(int argc, char **argv) {

	if(getuid() != 0) {
		execlp("sudo", "sudo", argv[0], NULL);
		error(1, errno, "execlp");
		return 1;
	}

	int fd = open("/dev/dri/card0", O_RDWR);
	if(fd < 0) error(1, errno, "open display");
	touchscreen_fd = open("/dev/input/event1", O_RDONLY | O_NONBLOCK);
	if(touchscreen_fd < 0) error(1, errno, "open touchscreen");
	printf("opened\n");

	if(ioctl(fd, DRM_IOCTL_SET_MASTER, NULL) < 0) error(1, errno, "set master");

	// attach CRTC 51, connector 56, to a new framebuffer with a new dumbbuffer

	struct drm_mode_create_dumb createdumb = {
		.height = 1280,
		.width = 800,
		.bpp = 32,
		.flags = 0,
	};
	if(ioctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &createdumb) < 0) error(1, errno, "create dumb buffer");

	struct drm_mode_fb_cmd2 addfb = {
		.width = 800,
		.height = 1280,
		.pixel_format = DRM_FORMAT_XRGB8888,
		.flags = 0,
		.handles = {createdumb.handle, 0, 0, 0},
		.pitches = {createdumb.pitch, 0, 0, 0},
		.offsets = {0, 0, 0, 0},
	};
	if(ioctl(fd, DRM_IOCTL_MODE_ADDFB2, &addfb) < 0) error(1, errno, "add framebuffer");

	struct drm_mode_map_dumb mapdumb = {
		.handle = createdumb.handle
	};
	if(ioctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &mapdumb) < 0) error(1, errno, "map dumb buffer");

	fb = (uint32_t*)mmap(NULL, createdumb.size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, mapdumb.offset);
	if(!fb) error(1, errno, "mmap dumb buffer");

	//getrandom(fb, createdumb.size, 0);
	memset(fb, 0, createdumb.size);

	memcpy(fb, basement.pixel_data, createdumb.size);

	uint32_t connectors[1] = {56};
	struct drm_mode_crtc crtc = {.crtc_id = 51};
	if(ioctl(fd, DRM_IOCTL_MODE_GETCRTC, &crtc) < 0) error(1, errno, "get crtc");
	//struct drm_mode_crtc oldcrtc = crtc;
	crtc.set_connectors_ptr = (uint64_t)connectors;
	crtc.count_connectors=1;
	crtc.fb_id = addfb.fb_id;
	if(ioctl(fd, DRM_IOCTL_MODE_SETCRTC, &crtc) < 0) error(1, errno, "set crtc");

	int timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
	if(timerfd < 0) error(1, errno, "timerfd_create");
	{
		struct itimerspec tspec = {.it_interval = {.tv_nsec = 250000000}, .it_value = {.tv_nsec=250000000}};
		if(timerfd_settime(timerfd, 0, &tspec, NULL) < 0) error(1, errno, "timerfd_settime");
	}

	printf("ready\n");

	for(;;) {
		struct pollfd polls[] = {
			{.fd = touchscreen_fd, .events = POLLIN},
			{.fd = timerfd, .events = POLLIN},
		};
		int npoll = poll(polls, sizeof(polls)/sizeof(polls[0]), 0);
		if(npoll < 0) error(1, errno, "poll");

		// POLLERR, POLLHUP, POLLNVAL can always be returned
		if((polls[0].revents | polls[1].revents) & POLLNVAL) error(1, 0, "poll: got POLLNVAL");

		if(polls[0].revents & POLLERR) error(1, 0, "got POLLERR on touchscreen");
		if(polls[0].revents & POLLHUP) error(1, 0, "got POLLHUP on touchscreen");
		if(polls[1].revents & POLLERR) error(1, 0, "got POLLERR on animation timer");
		if(polls[1].revents & POLLHUP) error(1, 0, "got POLLHUP on animation timer");

		if(polls[0].revents & POLLIN) {
			poll_touchscreen();
		}
		if(polls[1].revents & POLLIN) {
			uint64_t dummy; // don't care about expiration count
			if(read(timerfd, &dummy, sizeof dummy) < 0) error(1, errno, "read (timerfd)");
			printf("animation frame\n");
		}
	}

	//if(ioctl(fd, DRM_IOCTL_MODE_SETCRTC, &oldcrtc) < 0) error(1, errno, "restore crtc"); // doesn't work: EINVAL (maybe because framebuffer id is local to our connection)
}