/******************************
 * Read Center.FPL.README!    *
 * Written by Daniel Stenberg *
 ******************************/

/* We should accept a line number to this function! */
export int CenterLine(int line_number) {
  int lpos;
  int rpos;
  int lcpos;
  int rcpos;
  int max;
  string line;
  int tab = ReadInfo("tab_size");
  int ch;
  int lmargin;
  int left_wall = ReadInfo("wall_left");
  int right_wall = ReadInfo("wall_right");
  int ID = GetEntryID();
  int NewID;

  if(!right_wall) {
    ReturnStatus("The 'wall_right' setting must have a non-zero value");
    DisplayBeep();
    return(1);
  }

  if(right_wall-left_wall <= 0) {
    ReturnStatus("'wall_right' must be bigger than 'wall_left'");
    return(2);
  }

  if(!line_number)
    line_number = ReadInfo("line");
  line = GetLine(line_number);
  max = strlen(line);

  for(lpos=0; lpos<max; lpos++) {
    ch = line[lpos];
    if( ch != ' ' && ch != '\t' && ch != '\n') {
      break;
    }
  }

  if(lpos<max) {
    if(! (NewID = DuplicateEntry(ID)) ) /* duplicate entry */
      return(4); /* failed */

    CurrentBuffer(NewID); /* make the new one the current */
    lcpos = GetCursor(lpos, line_number); /* get column instead of byte position */
    for(rpos=max-1; rpos>=0; rpos--) {
      ch = line[rpos];
      if( ch != ' ' && ch != '\t' && ch != '\n') {
        rpos++; /* get back on the latest whitespace */
        break;
      }
    }
    rcpos = GetCursor(rpos, line_number);
    lmargin = (right_wall - left_wall - rcpos + lcpos)/2;
  
    if(lmargin>=0)
      lmargin += left_wall;
    else
      lmargin = left_wall;
  
    GotoLine(line_number, 0); /* column 0 */
    Delete(lpos);

    while(lmargin>tab) {
      Output("\t");
      lmargin-=tab;
    }

    while(lmargin--)
      Output(" ");

    Kill(NewID);
    CurrentBuffer(ID);

  } else
    return(3);

  return (0);
}

export int CenterBlock()
{
  /* there is a block marked! */
  int start=ReadInfo("block_begin_y");
  int end=ReadInfo("block_end_y");
  int vis = Visible();
  Status(0, "Centering block...");
  Visible(0);
  do {
    CenterLine(start++);
  } while(start<end);
  Visible(vis);
  ReturnStatus("Centering block...done!");
}

ConstructInfo("wall_left", "", "", "IL", "", 0, 999, 0);
ConstructInfo("wall_right", "", "", "IL", "", 0, 999, 79);

AssignKey("CenterLine(0);", "amiga -", "!block_exist");
AssignKey("CenterBlock();", "amiga -", "block_exist");