#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/uinput.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>
#include <termios.h>

//List of button definitons and whatnot
#define START 0x01
#define WEST 0x02
#define EAST 0x08
#define SOUTH 0x04
#define DPAD_LEFT 0x10
#define DPAD_RIGHT 0x20
#define DPAD_DOWN 0x40
#define DPAD_UP 0x80
#define SELECT 0x100
#define LEFT_TRIGGER 0x200
#define NORTH 0x400
#define RIGHT_TRIGGER 0x800
//#define DEBUG_MODE 0x1337
//#define CONTROLLER_MODE 0x420

//A list that will hold the button offsets in a sequential order
int buttons_list[] = {
    START,WEST,EAST,SOUTH, // 0 - 3
    DPAD_LEFT,DPAD_RIGHT,DPAD_DOWN,DPAD_UP, // 4 - 7
    SELECT,LEFT_TRIGGER,NORTH,RIGHT_TRIGGER // 8 - 11
};


#ifdef DEBUG_MODE
//1-letter names for buttons
char debug_names[] = "TWESLRDUMZNC";
#endif

//Actual mappings for the buttons, in the same order as in buttons_list
#ifdef CONTROLLER_MODE
//Mappings that are binding the controller as a joystick instead of a keyboard
int mappings[] = {
    BTN_START,BTN_WEST,BTN_EAST,BTN_SOUTH,
    BTN_DPAD_LEFT,BTN_DPAD_RIGHT,BTN_DPAD_DOWN,BTN_DPAD_UP,
    BTN_SELECT,BTN_TL,BTN_NORTH,BTN_TR
};
#else
//Mappings that correspond to a particular subset of keyboard keys
int mappings[] = {
    KEY_ESC,KEY_A,KEY_D,KEY_S,
    KEY_LEFT,KEY_RIGHT,KEY_DOWN,KEY_UP,
    KEY_X,KEY_Z,KEY_W,KEY_C
};
#endif


int input;
int uinput_fd;

//a bit of stolen code to make things work
void emit(int fd, int type, int code, int val) {
   struct input_event ie;

   ie.type = type;
   ie.code = code;
   ie.value = val;
   /* timestamp values below are ignored */
   ie.time.tv_sec = 0;
   ie.time.tv_usec = 0;

   write(fd, &ie, sizeof(ie));
}

void bye(int signum) {
    //wait some more just because we want all the events that are happening to happen before we close everything.
    sleep(1);
    printf("Exit signal received - destroying the uinput device.\n");
    close(input);
    ioctl(uinput_fd, UI_DEV_DESTROY);
    sleep(1);
    close(uinput_fd);
    exit(0);
};

int set_interface_attribs(int fd, int speed, int parity) {
    struct termios tty;
    if (tcgetattr(fd, &tty) != 0) {
        printf("Error %d from tcget",errno);
        return -1;
    }

    cfsetospeed(&tty, speed);
    cfsetispeed(&tty, speed);
    tty.c_lflag = 0;
    tty.c_cflag |= CRTSCTS | CS8 | CLOCAL | CREAD;
    tty.c_iflag = IGNPAR;
    tty.c_oflag = 0;
    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 0;
    tcflush(fd, TCIFLUSH);
    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        printf("Error %d when setting up tty", errno);
        return -1;
    }
    return 0;
}

int set_blocking(int fd, int should_block) {
    struct termios tty;
    memset (&tty, 0, sizeof(tty));
    if(tcgetattr(fd, &tty) != 0) {
        printf("Error %d from tcget", errno);
        return -1;
    }
    tty.c_cc[VMIN] = should_block ? 1 : 0;
    tty.c_cc[VTIME] = 0;

    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        printf("Error %d from tcset", errno);
        return -1;
    }
    return 0;
}

int main(int argc, char* argv[]) {
    if (argc < 2) {
        printf("Usage: driver <input device>\n");
        return 1;
    }
    
    //Open tty device for reading
    input = open(argv[1], O_RDWR | O_NOCTTY | O_SYNC);
    if (!input) {
        printf("Unable to open device %s for reading: %s\n",argv[1],strerror(errno));
        return errno;
    }
    set_interface_attribs(input, B9600, 0);
    set_blocking(input, 1);

    //Create uinput configuration struct and open /dev/uinput
    struct uinput_setup usetup;
    uinput_fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
    
    //Add this to gracefully close uinput_fd and input
    signal(SIGINT, bye);

    ioctl(uinput_fd, UI_SET_EVBIT, EV_KEY);
    for (int k = 0; k < 12; k++) {
        ioctl(uinput_fd, UI_SET_KEYBIT, mappings[k]);
    }

    //Clear struct, set vendor and product.
    memset(&usetup, 0, sizeof(usetup));
    usetup.id.bustype = BUS_USB;
    usetup.id.vendor = 0x041e;
    usetup.id.product = 0x1003;
    strcpy(usetup.name,"Macrohard YBox 2pi LPT2USB controller");

    //Call setup 
    if (ioctl(uinput_fd, UI_DEV_SETUP, &usetup)) {
        perror("UI_DEV_SETUP");
        printf("Note: This might have been the result of not running the program as root\n");
        return 1;
    }
    if (ioctl(uinput_fd, UI_DEV_CREATE)) {
        perror("UI_DEV_CREATE");
        return 1;
    }

    //Wait for some time so that uinput has time to setup stuff
    sleep(1);
    short unsigned int buffer[2];
    short unsigned int prev_state = 0x0;
    short unsigned int changes = 0x0;
    short unsigned int current_state = 0x0;
    //Main loop
    while(1) {
        read(input, buffer, 2);
        current_state = ~buffer[0];
        changes = prev_state ^ current_state;
        if (changes != 0) {
#ifdef DEBUG_MODE
            printf("State hash: %u\n",current_state);
            printf("Recieved message: %u\n",buffer[0]);
#endif
            for (int k = 0; k < 12; k++) {
                if (changes & buttons_list[k]) {
                    emit(uinput_fd, EV_KEY, mappings[k], (current_state & buttons_list[k]) > 0);
                    emit(uinput_fd, EV_SYN, SYN_REPORT, 0);
#ifdef DEBUG_MODE
                    printf("Internal key name: %c\n",debug_names[k]);
                    printf("Key state: %u\n",(current_state & buttons_list[k]) > 0);
                    printf("Key mapping: %u\n",mappings[k]);
#endif
                }
            }
#ifdef DEBUG_MODE
            printf("-------\n");
            fflush(stdout);
#endif
        }
        prev_state = current_state;
    }
    //haha what a loser can't even get here because while true do loop
    return 0;
}