/* A Screen Editer Subsystem */
#define TURBOC
#include <stdio.h>
#include <dos.h>
#include <string.h>
#include <bios.h>
#include <conio.h>


#define BUF_SIZE 32000
#define LINE_LEN 79-2
#define MAX_LINES 24-1
#define KILL_BUF_SIZE 4*LINE_LEN

/***********************************************************/
char buf[BUF_SIZE];
char *curloc,*endloc;
int scrnx,scrny;
char killbuf[KILL_BUF_SIZE];
char *helpline="F1:save F2:load F3:find F4:replace ^K:kill line ^Y:Yank ^Z:qiut";
/*************************************************************/
void edit(char *fname),help(void);
void gotoxy(int x,int y),clrline(int y);
void edit_clr_col(int x,int y),clrscr(void);
void printline(char *p),delete_char(void);
void search(void),kill_line(void);
void scrolldn(int x,int y);
void scrollup(int topx,int topy,int endx,int endy);
void upline(void);
void downline(void),left(void),right(void);
void display_scrn(int x,int y,char *p);
void pagedown(void),pageup(void),replace(void);
void home(void),gotoend(void),yank(void);
int load(char *fname),save(char *fname);
void edit_gets(char *str);
void draw_border(int,int,int,int,int);


/***************************************************/
main(int argc,char *argv[])
{
union REGS r;
char fname[80];
if(argc<2)
{
  draw_border(0,0,78,24,0x1f);
  draw_border(20,12,60,14,0x2f);
  gotoxy(20,11);
  printf("\7FILE NAME:");
  gotoxy(21,13);
  gets(fname);
  edit(fname);
}
if(argc==2)
{
  strupr(argv[1]);
  if(strstr(argv[1],".EXE")||strstr(argv[1],".COM")||\
   strstr(argv[1],".OBJ")||strstr(argv[1],".LIB"))
  {
   printf("\7Can't edit file :%s",argv[1]);
   exit(1);
  }
  else edit(argv[1]);
}
r.h.ah=6;
r.h.al=0;
r.h.ch=0;
r.h.cl=0;
r.h.dh=24;
r.h.dl=79;
r.h.bh=7;
int86(0x10,&r,&r);
gotoxy(1,1);
}


/******************************************************************/
void edit(char *fname)
{
union k
{
  char ch[2];
  unsigned i;
}key;
char name[80];
/* try to load the file */
if(!load(fname))curloc=endloc=buf;
strcpy(name,fname);
/* set initial values to X,Y coordinate vars */
scrnx=scrny=0;
display_scrn(0,0,curloc);
help();
gotoxy(1,1);
/* editer main loop . */
do{
  #ifdef TURBOC
  key.i=bioskey(0);
  #endif
  if(!key.ch[0])
  {
   switch(key.ch[1])
   {
    case 59:      /*F1 :save file */
     save(name);
     break;
    case 60:    /*F2: load file */
     clrline(MAX_LINES);
     gotoxy(1,MAX_LINES);
     printf("Enter filename :");
     edit_gets(name);
     strupr(name);
     if(strstr(name,".EXE")||strstr(name,".COM")||\
      strstr(name,".OBJ")||strstr(name,".LIB"))
     {
      gotoxy(1,MAX_LINES);
      printf("\7Can't edit file: %s",name);
      getch();
      help();
      break;
     }
     if( * name) load(name);
     help();
     display_scrn(0,0,curloc);
     scrnx=scrny=0;
     break;
    case 61:
     search();
     break;
    case 62:
     replace();
     break;
    case 71:
     home();
     break;
    case 79:
     gotoend();
     break;
    case 75:  /*left*/
     left();
     break;
    case 77:
     right();
     break;
    case 72:
     upline();
     break;
    case 80:
     downline();
     break;
    case 73:
     pageup();
     break;
    case 81:
     pagedown();
     break;
    case 83:   /*Del*/
     if(curloc<endloc) delete_char();
     break;
   }
   if(curloc<buf)
   {
    scrnx=scrny=0;
    curloc=buf;
   }
   gotoxy(scrnx+1,scrny+1);        /*postion cursor */
  }
  else
  {
   switch(key.ch[0])
   {
    case '\r':
     /*see if buffer is full */
     if(endloc==buf+BUF_SIZE-2) break;
     /* move contents of file below current location down
        one byte to make room for the RETURN.*/
     memmove(curloc+1,curloc,endloc-curloc+1);
     *curloc=key.ch[0]; /*put RETURN in file */
     curloc++;
     /*clear rest of line */
     edit_clr_col(scrnx,scrny);
     scrnx=0;
     scrny++;
     /*move text on screen down */
     if(scrny==MAX_LINES-1)
     {
      /*at bottom of page */
      scrny=MAX_LINES-2;
      scrollup(1,1,LINE_LEN,scrny+1);
     }
     else scrolldn(scrnx+1,scrny+1);
     gotoxy(scrnx+1,scrny+1);
     printline(curloc);
     endloc++;
     /* advance the end of file pointer */
     break;
    case '\b':
     if(curloc==buf) break;
     left();
     delete_char();
     break;
    case 11:
     kill_line();
     break;
    case 25:
     yank();
     break;
    case 26:
     clrline(MAX_LINES);
     gotoxy(1,MAX_LINES);
     printf("If saved file,press[Y]exit\7");
     if(tolower(getch())=='y') goto end;
     help();
     break;
    default:     /* enter keystroke into file */
     /*see if buf is full */
     if(endloc==buf+BUF_SIZE-2) break;
     /*can't type past end of line */
     if(scrnx==LINE_LEN) break;
     memmove(curloc+1,curloc,endloc-curloc+1);
     *curloc=key.ch[0];
     putch(*curloc);
     scrnx++;
     gotoxy(scrnx+1,scrny+1);
     printline(curloc+1);
     curloc++;
     endloc++;
    }
    gotoxy(scrnx+1,scrny+1);
   }
}while(1);
end:
printf("\n");
}

/****************************************************************************
    Display a line pointed to by p.
****************************************************************************/
void printline(register char *p)
{
register int i;
i=scrnx+1;
while(*p!='\r'&&*p&&i<LINE_LEN)
{
  putch(*p);
  p++;
  i++;
}
}

/****************************************************************************
    Insert previously killled line.
****************************************************************************/
void yank(void)
{
char *p;
p=killbuf;
while(*p)
{
  memmove(curloc+1,curloc,endloc-curloc+1);
  *curloc=*p;
  if(scrnx<LINE_LEN)
  {
   putch(*curloc);
   scrnx++;
  }
  curloc++;
  endloc++;
  p++;
}
}
/*******************************************************/
/*  Delete the line at the current location */
void kill_line(void)
{
register int i;
char *p,*killbufptr;
if(*curloc=='\r')
{
  delete_char();
  return;
}
edit_clr_col(scrnx,scrny);  /*clear to CR */
/* find out hoe many characters are in the line */
p=curloc;
i=0;
killbufptr=killbuf;
while(*p!='r'&&p<endloc)
{
  i++;
  *killbufptr=*p;
  p++;
  if(killbufptr<killbuf+KILL_BUF_SIZE-2) killbufptr++;
}
*killbufptr='\0';
/* remove the line */
memmove(curloc,curloc+i,endloc-curloc);
endloc-=i;
}
/***********************************************************************
   Global search and replace
***********************************************************************/
void replace(void)
{
register int len1;
char str1[80],str2[80];
char *p,*p2;
clrline(MAX_LINES);
gotoxy(1,MAX_LINES);
printf("enter string to replace :");
edit_gets(str1);
clrline(MAX_LINES);
gotoxy(1,MAX_LINES);
printf("enter replacement:");
edit_gets(str2);
p=curloc;
len1=strlen(str1);
while(*str1)
{
  /*search for the string */
  while(*p && strncmp(str1,p,len1)) p++;
  if(!*p)
  {
   clrline(MAX_LINES);
   gotoxy(1,MAX_LINES);
   printf("No found string %s",str1);
   getch();
   help();
   break;
  } /* not found */
  /* remove old string */
  memmove(p,p+len1,endloc-p);
  endloc-=len1;
  /*insert new string */
  p2=str2;
  while(*p2)
  {
   memmove(p+1,p,endloc-p+1);
   *p=*p2;
   p++;
   endloc++;
   p2++;
  }
}
clrscr();
/* find location of top screen */
p=curloc;
for(len1=scrny;len1>=0&&p<buf;)
{
  p--;
  if(*p=='r') len1--;
}
if(*p=='r') p++;
/* redisplay current screen */
display_scrn(0,0,p);
help();
}
/**************************************************************************
   Delete character at the current location .
**************************************************************************/
void delete_char(void)
{
gotoxy(scrnx+1,scrny+1);
if(*curloc=='r')
{
  scrollup(1,scrny+1+1,LINE_LEN,MAX_LINES-1);
  memmove(curloc,curloc+1,endloc-curloc);
  endloc--;
  display_scrn(scrnx,scrny,curloc);
  help();
}
else
{
  memmove(curloc,curloc+1,endloc-curloc);
  endloc--;
  printline(curloc);
  printf("");
}
}

/*************************************************************************
   Display help line.
*************************************************************************/
void help(void)
{
gotoxy(1,MAX_LINES);
printf(helpline);
}

/*************************************************************************
   Move cuuren location left
*************************************************************************/
void left(void)
{
if(curloc==buf) return;
scrnx--;
if(scrnx<0)
{
  scrnx=0;
  upline();         /*go up to next line */
  /* find end of line */
  while(*curloc!='r')
  {
   curloc++;
   scrnx++;
  }
}
else curloc--;
}

/**********************************************************************
   Move current position right.
**********************************************************************/
void right(void)
{
if(curloc+1>endloc) return;
scrnx++;
/* if at the end of line,go to the next one. */
if(scrnx>LINE_LEN||*curloc=='\r')
{
  scrnx=0;
  scrny++;
  if(scrny==MAX_LINES-1)  /* at end of screen */
  {
   scrny=MAX_LINES-2;
   downline();
   /* move cursor and current loc to start of new line */
   curloc--;
   while(*curloc!='\r') curloc--;
   curloc++;
   scrnx=0;
  }
  else curloc++;
}
else curloc++;
}

/**********************************************************************/
void search(void)
{