//required for posix_openpt to work
#define _XOPEN_SOURCE 600
#define _DEFAULT_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <termios.h>
//#include <asm/termbits.h>
#include <string.h>
#include <signal.h>
#include "im.h"
int running = 1;
//hook for when the pty child process dies
void childhook(int a) {
	running = 0;
}
int pty_slave = -1;
//terminal rows and cols
int trows = 0;
int tcols = 0;
//hook for SIGWINCH
void winchhook(int a) {
	struct winsize sz;
	ioctl(STDIN_FILENO, TIOCGWINSZ, &sz);
	trows = sz.ws_row;
	tcols = sz.ws_col;
	//trick programs into thinking the terminal is smaller than it is
	if (sz.ws_row >= 1) {
		sz.ws_row--;
	}
	ioctl(pty_slave, TIOCSWINSZ, &sz);

}
void disp_im() {
	//3 spaces for the im indicator +1 for automargin
	int im_col = tcols - IM_TABLE_ENTRY_LEN - 4;
	char pos_str[32] = "";
	int l = sprintf(pos_str, "\033[%d;%df",trows, im_col);
	//printf("\0337");
	//printf("\033[%d;%df",trows,im_col);
	//printf("\033[0;0f",trows,im_col);
	//printf("\033[7m");
	//if (im_on) {
	//	printf("漢");
	//} else {
	//	printf("英");
	//}
	//printf("%s",im_buffer);
	//printf("\033[0m");
	//printf("\0338");
	write(STDOUT_FILENO,"\0337",2);
	//also writes to top left the current im buffer
	//write(STDOUT_FILENO,"\033[33;14f",8);
	//write(STDOUT_FILENO,"\033[0;4f",6);
	//write to the bottom left corner
	write(STDOUT_FILENO, pos_str,l);
	//invert video
	write(STDOUT_FILENO,"\033[7m",4);
	//overwrite what was there previously
	write(STDOUT_FILENO,"                            ",
		IM_TABLE_ENTRY_LEN+4);
	write(STDOUT_FILENO, pos_str,l);
	//im mode indicator
	if (im_on) {
		write(STDOUT_FILENO,"漢:",4);
	} else {
		write(STDOUT_FILENO,"英:",4);
	}
	//actual buffer
	write(STDOUT_FILENO,im_buffer,im_buffer_pos);
	//restore cursor pos and attrbutes
	write(STDOUT_FILENO,"\033[0m",4);
	write(STDOUT_FILENO,"\0338",2);
}
int main (int argc, char * argv[], char * envp[]) {
	//creates the pty master
	int pty_master = posix_openpt(O_RDWR);
	if (pty_master < 0) {
		fprintf(stderr, "errno: %d, failed to create pty master", errno);
		return errno;
	}
	//makes it nonblocking
	fcntl(pty_master, F_SETFL,O_NONBLOCK);
	//make it raw
	struct termios stdin_termio;
	struct termios stdin_termio_bk;
	tcgetattr(STDIN_FILENO,&stdin_termio);
	tcgetattr(STDIN_FILENO,&stdin_termio_bk);
	cfmakeraw(&stdin_termio);
	tcsetattr(STDIN_FILENO,TCSANOW,&stdin_termio);
	//make it nonblocking
	fcntl(STDIN_FILENO, F_SETFL,O_NONBLOCK);


	if ( unlockpt(pty_master) <0) {
		fprintf(stderr, "errno: %d, failed to unlock pty slave", errno);
		return errno;
	}
	//gets slave path
	char * pty_slave_fn = ptsname(pty_master);
	//tries to open pty slave
	pty_slave = open(pty_slave_fn, O_RDWR);
	if (pty_slave < 0) {
		fprintf(stderr, "errno: %d, failed to open pty slave '%s'",\
			errno, pty_slave_fn);
		return errno;
	}
	//make the pty slave the same line discipline stdin was
	tcsetattr(pty_slave,TCSANOW,&stdin_termio_bk);
	//syncs the window sizes for the first time
	winchhook(0);
	//forks for running bash
	pid_t mypid = fork();
	if (mypid == 0) {

		//set self to be session leader
		if (setsid() <0) {
			fprintf(stderr, "failed to make new session\n");
		}
		//all the stand streams
		freopen(pty_slave_fn, "r", stdin);
		freopen(pty_slave_fn, "w", stdout);
		freopen(pty_slave_fn, "w", stderr);
		//must be a session leader to set the controlling terminal
		if (ioctl(pty_slave, TIOCSCTTY, 0)) {
			fprintf(stderr, "errno: %d, failed to set controlling tty\n", errno);
		}


		
		/*
		 *  Opens up the Shell now
		 */
		
		//opens up the slave pty
		//needs to fork
		//then set its own process group
		//need to set the terminal
		//exec bash then
		//gets the shell to use, order is
		// argument 1, then $SHELL< then /bin/sh
		char * shellpath = "/bin/sh";
		if (argc >1) {
			shellpath = argv[1];
		} else if (getenv("SHELL") != NULL) {
			shellpath = getenv("SHELL");
		}
		//gets the terminal environmental variabke, 32 should be enough
		char env_term[32] = "TERM="; 
		strcat(env_term, getenv("TERM"));
		char env_home[32] = "HOME="; 
		strcat(env_home, getenv("HOME"));
		char * shell_envs[3] = {env_term,env_home, NULL};
		char * shell_args[2] = {shellpath, NULL};
		//if (execve(shellpath,shell_args, shell_envs) == -1) {
		if (execve(shellpath,shell_args, envp) == -1) {
			fprintf(stderr, "errno: %d, Failed to start shell '%s'\n", errno, shellpath);
			return errno;
		}
		//should automatically close any file descriptors
		_exit(0);
	} else {
		signal(SIGCHLD, childhook);
		signal(SIGWINCH, winchhook);
		char readbuffer[1] = {0};
		int chars_read = 0;
		//open
		while (running) {
			//just relay everything for now
			//read uses file descriptors and is a system call
			chars_read = read(pty_master,readbuffer,1);
			if (chars_read >0) {
				write(STDOUT_FILENO,readbuffer,1);
			}

			chars_read = read(STDIN_FILENO, readbuffer, 1);
			if (chars_read > 0) {
				//write(pty_master,readbuffer,1);
				//relays input from stdin
				char input_buffer[IM_TABLE_ENTRY_LEN] = {0};
				int im_chars = update_im_state(readbuffer[0],
						input_buffer);
				input_buffer[im_chars] = 0;
				if (im_chars >0) {
					write(pty_master,input_buffer,im_chars);
				}
				disp_im();
			}
		}
	}
	close(pty_master);
	tcsetattr(STDIN_FILENO,TCSANOW,&stdin_termio_bk);
	//close(pty_slave);
	return 0;
}