/* 
   TERMatrix 0.2
   Copyright 2006 Flavio Chierichetti
   Licence GPL 2
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/time.h>
#include <sys/ioctl.h>

#define TERMINAL_DEVICE "/dev/tty"

#define min(x, y) ((x) < (y) ? (x) : (y))

#define termCursorOff() printf("\x1b[?25l");
#define termMoveTo(r, c) printf("\x1b[%d;%dH", r + 1, c + 1)
#define termSetAttr(fore, back, attr) printf("\x1b[%d;%d;%dm", attr, fore + 30, back + 40)
#define termPutChar(c) printf("%c", c)
#define termErase() printf("\x1b[2J")
#define termReset() printf("\x1b%c", 'c')

typedef struct s {
  int start, end, n, speed, counter;
  char last;
  struct s *next;
} seq;

enum { usecDelay = 8000, speedMin = 3 , speedMax = 8 , darkProb = 75 , newSeqProb = 20 , letterChangeProb = 25 };

enum { black = 0, red, green, yellow, blue, magenta, cyan, white };
enum { normalAttr = 1 , boldAttr = 22 };

void initTerm(int signum);
void initSigActions();
void print(int signum);
void end(int signum);

char *V = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz<>()[]{}.,:;!@#$%^&*-_=+|?/`~'\"\\";
int Length, R, C;
seq **S;

char *quotes[] = {
  "Wake up, Neo.",
  "There is no spoon.",
  "Follow the white rabbit.",
  "What is the matrix?",
  "Welcome to the real world.",
  "Don't think you are. Know you are.",
  "It is inevitable.",
  "Only human.",
  "Deja vu...",
  NULL
};

int main() {
  initTerm(0);

  srand(time(NULL) % RAND_MAX);

  Length = strlen(V);

  initSigActions();

  while (1)
    pause();

  return 0;
}

void initTerm(int signum) {
  int fd;
  struct winsize ws;
  int i;

  if ( (fd = open(TERMINAL_DEVICE, O_RDWR)) == -1 )
    exit(1);

  if ( ioctl(fd, TIOCGWINSZ, &ws) != 0 )
    exit(1);

  close(fd);

  R = ws.ws_row;
  C = ws.ws_col;

  /* If this function is called more than once, there would be a little memory leak here */

  S = (seq**) calloc (C, sizeof(seq*));

  for ( i = 0 ; i < C ; i++ )
    S[i] = NULL;

  termCursorOff();
  termSetAttr(green, black, normalAttr);
  termErase();
}

void initSigActions() {
  struct sigaction sigintAction, sigalrmAction, sigwinchAction;
  struct itimerval timer;

  sigfillset(&sigwinchAction.sa_mask);
  sigwinchAction.sa_flags = 0;
  sigwinchAction.sa_handler = initTerm;
  sigaction(SIGWINCH, &sigwinchAction, NULL);

  sigfillset(&sigalrmAction.sa_mask);
  sigalrmAction.sa_flags = 0;
  sigalrmAction.sa_handler = print;
  sigaction(SIGALRM, &sigalrmAction, NULL);

  sigfillset(&sigintAction.sa_mask);
  sigintAction.sa_flags = 0;
  sigintAction.sa_handler = end;
  sigaction(SIGINT, &sigintAction, NULL);

  timer.it_interval.tv_sec = timer.it_value.tv_sec = 0;
  timer.it_interval.tv_usec = timer.it_value.tv_usec = usecDelay;
  setitimer(ITIMER_REAL, &timer, NULL); 
}

void print(int signum) {
  int c, r;

  for ( c = 0 ; c < C ; c++ )
    if ( S[c] ) {
      S[c]->counter = (S[c]->counter + 1) % S[c]->speed;
      if ( S[c]->counter == 0 ) {
	for ( r = S[c]->start ; r < min(R, S[c]->end) ; r++ ) 
	  if ( rand() % 100 < letterChangeProb || r == S[c]->end - 1 ) {
	    if ( rand() % 100 < darkProb )
	      termSetAttr(green, black, boldAttr);
	    else
	      termSetAttr(green, black, normalAttr);
	    
	    termMoveTo(r, c);
	    termPutChar(V[rand() % Length]);
	  }

	if ( S[c]->end == R )
	  S[c]->end++;

	if ( S[c]->n == 0 ) {
	  termMoveTo(S[c]->start, c);
	  termPutChar(' ');
	  
	  S[c]->start++;
	}
	
	if ( S[c]->end < R ) {
	  S[c]->last = V[rand() % Length];

	  termSetAttr(white, black, normalAttr);
	  termMoveTo(S[c]->end, c);
	  termPutChar(S[c]->last);
	  
	  S[c]->end++;
	}
	
	if ( S[c]->n > 0 )
	  S[c]->n--;

	if ( S[c]->start == S[c]->end ) {
	  free(S[c]);
	  S[c] = NULL;
	}
      }
    } else
      if ( rand() % 100 < newSeqProb ) {
	S[c] = (seq*) malloc ( sizeof(seq) );

	S[c]->start = 0;
	S[c]->end = 0;
	S[c]->speed = rand() % (speedMax - speedMin + 1) + speedMin;
	S[c]->counter = 0;
	S[c]->n = rand() % R + 1;
	
	S[c]->last = 0;
      }

  fflush(stdout);
}

void end(int signum) {
  int i;

  termReset();

  for ( i = 0 ; quotes[i] != NULL ; i++ );
  i = rand() % i;
 
  printf("%s\n", quotes[i]);

  exit(0);
}