#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <X11/Xutil.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

typedef struct Key {
	char *command;
	unsigned int mod;
	KeySym keysym;
} Key;


// A horrible hack.
struct Key * parse_key(char *shortcut, char *command) {
	
	Key  *key = malloc(sizeof(struct Key));
	if(key == NULL) {
		fprintf(stderr, "could not allocate keys\n");
		exit(EXIT_FAILURE);
	}
	key->command = strndup(command, strlen(command) + 2);
	key->command[strlen(command)] = ' ';
	key->command[strlen(command) + 1] = '&';

	size_t i = 0;

	char *token;
	char **tokens = malloc(sizeof(char *) * 16);
	size_t token_nb = 0;

	int key_set = 0;
	int mod_set = 0;

	// load our tokens
	while ((token = strsep(&shortcut, "+")) != NULL) {
		tokens[token_nb] = token;
		token_nb++;
	}

	if(token_nb != 0) {
		// Modifiers

		for(i = 0; i < token_nb; i++) {
			// if it's a regular key
			if(strlen(tokens[i]) == 1) {
				if(key_set)  {
					return NULL;
				}
				key->keysym = XStringToKeysym(tokens[token_nb - 1]);
				key_set = 1;
			}
			// if it's a mod key
			else {
				int mask = 0;
				if(strcmp(tokens[i], "control") == 0)
				mask = ControlMask;
				else if(strcmp(tokens[i], "shift") == 0)
				mask = ShiftMask;
				else if(strcmp(tokens[i], "mod1") == 0)
				mask = Mod1Mask;
				else if(strcmp(tokens[i], "mod2") == 0)
					mask = Mod2Mask;
				else if(strcmp(tokens[i], "mod3") == 0)
					mask = Mod3Mask;
				else if(strcmp(tokens[i], "mod4") == 0)
					mask = Mod4Mask;
				else
					return NULL;

				
				if(mask) {
					key->mod = key->mod | mask ;
					mod_set = 1;
				}
				else {
					return NULL;
				}
			}
		}
	} 

	if(key_set && mod_set) {
		return(key);
	}
	else {
		free(key);
		return NULL;
	}
}

struct Key **load_hotkeys(FILE *fh, size_t *key_len) {
	char line[4096];
	int  line_nb = 1;

	size_t realloc_size = 1;
	*key_len = 0;

	struct Key **keys = malloc(sizeof(struct Key **));
	if(keys == NULL) {
		fprintf(stderr, "could not allocate keys\n");
		return NULL;
	}

	while((fgets(line, 4096, fh)) != NULL) { 
		int res;
		int error = 0;
		char *shortcut, *command;
		Key *key;

		res = sscanf(line, "%ms %m[^\n]+", &shortcut, &command);
		if(res == 2) {
			key = parse_key(shortcut, command);
			if(key == NULL)
				error = 1;
		}
		else {
			error = 1;
		}

		if(error) 
			fprintf(stderr, "Error:could not parse line %d: %s\n", line_nb, line);
		else {
			keys[*key_len] = key;
			*key_len = *key_len + 1;

			keys = realloc(keys, sizeof(struct Key *) * realloc_size);
			if(keys == NULL) {
				fprintf(stderr, "could not realloc keys\n");
				exit(EXIT_FAILURE);
			}

			realloc_size++;
		}
		
		line_nb++;
	}

	if(*key_len != 0)
		return keys;

	return NULL;
}

void wait_for_input(Display* dpy, Window root, struct Key **hotkeys, size_t len) {
	size_t i = 0;

	XSelectInput(dpy, root, KeyPressMask );
	while(1)	{

		XEvent ev;
		XNextEvent(dpy, &ev);

		if(ev.type == KeyPress) {
			XKeyEvent *kev = &ev.xkey;
			KeySym keysym = XKeycodeToKeysym(dpy, (KeyCode)kev->keycode, 0);

			for(i = 0; i < len; i++) {
				if(keysym == hotkeys[i]->keysym && hotkeys[i]->mod == kev->state) {
					printf("executing '%s'\n", hotkeys[i]->command);
					system(hotkeys[i]->command);
				}
			}
		}
	}
}

int main(int argc, char **argv) {
	Display*    dpy     = XOpenDisplay(0);
	Window      root    = DefaultRootWindow(dpy);


	unsigned int i = 0;

	FILE *config_fh = NULL;
	char *config_fn;
	
	size_t len = 0;

	struct Key **hotkeys = NULL;

	if(argc == 1) {
		asprintf(&config_fn, "%s%s", getenv("HOME"), "/.hotkeyrc");
		config_fh = fopen(config_fn, "r");
	}
	else if (argc == 2) {
		config_fh = fopen(argv[1], "r");
		config_fn = argv[1];
	}
	else {
		fprintf(stderr, "usage: hotkeys config_file (default is ~/.hotkeyrc)\n");
		exit(EXIT_FAILURE);
	}

	if(config_fh == NULL) {
		fprintf(stderr, "could not open %s\n", config_fn);
		exit(EXIT_FAILURE);
	}

	hotkeys = load_hotkeys(config_fh, &len);

	if(hotkeys == NULL) {
		fprintf(stderr, "Could not load any keys from %s. quitting...\n", config_fn);
		exit(EXIT_FAILURE);
	}

	for(i = 0; i < len; i++) {
		XGrabKey(dpy,  XKeysymToKeycode(dpy,hotkeys[i]->keysym), hotkeys[i]->mod, root, False, GrabModeAsync, GrabModeAsync);
	}

	wait_for_input(dpy, root, hotkeys, len);

	XCloseDisplay(dpy);
	return 0;
}