#include "ded.h"
#include "char.h"
#include "ter.h"

/************************************************************************
 *                                                                      *
 *                      copyright Richard Bornat 1981                   *
 *                                                                      *
 ************************************************************************/

/************************************************************************
 *                                                                      *
 *    a procedure to insert a line-break in THE CURRENT line. It        *
 *    finds the most convenient place (to the left of scol              *
 *    if possible)                                                      *
 ************************************************************************/

line_break(scol, ctype)
register int scol;
int ctype;
 {  register int col;
    int r_break, l_break;
    int make_br = !txin;   /* insert a line-break marker when not text mode */
    int lcol = lastcol(virt_c.row);

    /* convenience dictates that spaces and tabs force a break
     * just where they are typed. Also, a character typed to the right of
     * the last non-space character forces a break where it is typed.
     */
    if ((ctype==SPACE || ctype==TAB || scol>lcol+1) &&
	  scol>leftcol && scol<=rightcol)
      r_break = l_break = scol;
    else
     {  r_break = b_right(scol);
	l_break = b_left(scol);
     }

    /* prefer r_break if it is in a reasonable place */
    if ((r_break==scol && r_break<=rightcol) || r_break<BELLMARGIN)
      col = r_break;
    else
    if (l_break>leftcol) col = l_break;
    else
    if (r_break<rightcol) col = r_break;
    else
     {  col = (scol>=rightcol ? rightcol-1 : scol);
	make_br=true;
     }

    if (col>scol && col>lcol)
     {  col = scol; make_br = true; }

    r_break = col;
    split_row(&virt_c.row, &r_break);
    /* insert a line-break character if necessary */
    if (make_br) redisplay(virt_c.row-1, col, c_CONTROL);
    /* move the cursor to the correct position */
    if (virt_c.col==col && make_br && col*2<rightcol)
      virt_c.row--;
    else
    if (virt_c.col>=col)
     { virt_c.col = virt_c.col-col+r_break; make_br = true; }
    else
      virt_c.row--;

    if (make_br) complain();

    return(true);
 }

int b_ok(rp)
register char *rp;
 { return(*rp!=c_SPACE && *--rp==c_SPACE); }

/* find next suitable word boundary under cursor or to right */
int b_right(scol)
register int scol;
 {  register char *rp = rowmap[virt_c.row];

    if (scol>rightcol) scol=rightcol+1;
    else
     {  if (scol<=leftcol) scol=leftcol;
	else scol--;
	do
	  scol=r_word(rp, scol, leftcol, rightcol);
	while (scol<=rightcol && !b_ok(rp+scol));
     }

    return(scol);
 }

/* find next suitable boundary under cursor or to left */
int b_left(scol)
register int scol;
 {  register char *rp = rowmap[virt_c.row];

    if (scol<=leftcol) scol=leftcol;
    else
     {  if (scol>=rightcol) scol=rightcol;
	else scol++;
	do
	  scol=l_word(rp, scol, leftcol, rightcol);
	while (scol>leftcol && !b_ok(rp+scol));
     }

    return(scol);
 }