/*
	e screen editor

	(C) G. Nigel Gilbert, MICROLOGY, 1981

	August-December 1981

	FILE: e2

	FUNCTIONS: movechar,moveline, maovepage, moveword, insertchar,
			deletechar,crdelete,deleteword,crinsert,adjustc,
			sync.

	PURPOSE: perform text changing commands

*/

#include "e.h"

movechar(move)	/*move cursor by 'move' columns to the right
		  return YES unless going off text*/
int move;
{
	int cp, len, result;

	cp=charn+move;
	result=YES;
	if (cp < 0) {
		result=moveline(-1); 
		if (result) {
			cursorx=adjustc(LLIM); 
			movechar(cp+1);
			}
		else sync(0);
		}
	else if (cp > (len=strlen(text))) {
		result=moveline(1); 
		if (result) {
			sync(0);
			movechar(cp-len-1);			
			}
		else cursorx=adjustc(LLIM);
		}
	else sync(cp);
	return result;
}

moveline(move)	/*move cursor by 'move' lines down 
		 return YES if Ok, NO if going off text*/
int move;
{
	int line;

	puttext();
	if ( (move<0?-move:move) > SHEIGHT) gotoxy(WAITPOS,0);
	line=cline;
	if ((cline=loc(cline,move)) == line) return NO;
	gettext(cline);
	if (cline < pfirst || cline > plast) {
		if (move == 1 || move == -1) scroll(move);
		else putpage();
		}
	else {
		putline(line,cursory);
		cursory+=cline-line;
		cursorx=adjustc(cursorx);
		putline(cline,cursory);
		}
	return YES;
}

scroll(move)	/*scroll up (move==1) or down 1 line*/
int move;
{
	if (move == 1) {
		linedelete(topline);
		putline(cline-1,SHEIGHT-1);
		}
	else {
		insertline();
		putline(cline+1,topline+1);
		}
	cursorx=adjustc(cursorx);
	putline(cline,cursory);
	if (plast-pfirst == (SHEIGHT-topline)) plast+=move;
	pfirst+=move;
}

jumpline(move)	/*move current line by move lines down, checking for
			interrupt from user (if interrupted, do nothing,
			and return NO) */
int move;
{
	int line, dest;

	puttext();
	dest=cline+move;
	dest-=dest%100;
	if (dest > lastread) {
		gotoxy(WAITPOS,0);
		line=cline;
		while (line < dest && loc(line,100) != line) {
			line+=100;
			if (testkey() == ESCKEY) {
				error("Interrupted");
				return NO;
				}
			}
		}
	moveline(move);
	return YES;
}

movepage(dir)	/*move current line by a page down (dir==0) or up (-1)*/
int dir;
{
	int move, line;

	puttext();
	move=(SHEIGHT-topline)/2 - PAGEOVERLAP;
	if (dir) move=pfirst-cline-move;
	else move=plast-cline+move;
	if ( (cline=loc((line=cline),move) ) != line) {
		gettext(cline);  
		putpage();
		}
}

moveword(move)	/*move 1 word to the right (move -ve: left)*/
int move;
{
	if (charn+move < 0) {
		moveline(-1); 
		charn=strlen(text);
		}
	else if (charn+move >= strlen(text)) {
		moveline(1); 
		sync(0);
		if (inword(text[0])) return;
		}
	while ((move<0 || text[charn]) && inword(text[charn]) && (charn+=move));
	while ((move<0 || text[charn]) && !inword(text[charn]) && (charn+=move));
	if (move < 0 && charn) {
		while(inword(text[charn]) && --charn);
		if (charn || !inword(text[charn]) ) charn++;
		}
	sync(charn);
}

insertchar(c)	/*inserts 'c' at charn, moves cursor up  one */
char c;
{
	int cx,cp,temp;
	char *t;

	if ( (cp=strlen(text)+1) >= (LLIM-1))
		error("Line to long");
	else {
		for (; cp >= charn; cp--) text[cp+1]=text[cp];
		text[charn]=c;
		altered=YES;
		rewrite(charn,cursorx);
		sync(charn+1);
		}
}

deletechar(dir)	/*deletes char before (dir=-1) or at (dir=0) cursor */
int dir;
{
	char c;
	int cp;

	cp=charn+dir;
	if (cp < 0) {
		if (cline > 1) crdelete(-1);
		}
	else if (text[cp] == '\0') {
		if (cline < lastl) crdelete(0);
		}
	else {
		do { 
			c=text[cp]=text[cp+1]; 
			cp++; 
			} 
		while(c);
		altered=YES;
		sync(charn+dir);
		if (calcoffset() != lastoff)rewrite(0,0);
		else rewrite(charn,cursorx);
		}
}

crdelete(dir)	/*delete a [CR] before (dir==-1)or at (dir==0) cursor */
int dir;
{
	int delline, len, *t;
	char textb[LLIM];

	altered=YES;
	if (dir == 0) {
		delline=cline+1;
		strcpy(textb,getline(delline));
		cursory++;
		}
	else {
		delline=cline;
		strcpy(textb,text);
		if (cline > 1) gettext(cline-1);
		else puttext();
		}
	sync((len=strlen(text)));
	if (len+strlen(textb) >= LLIM) {
		textb[LLIM-len]='\0';
		error("Line too long - cut short");
		}
	strcat(text,textb);
	deltp(delline,1);
	if (delline > plast || delline <= pfirst) {
		puttext(); 
		putpage();
		}
	else {
		linedelete(cursory--);
		rewrite(0,0);
		if (plast <= lastl && lastl-pfirst > SHEIGHT - topline)
			putline(plast, SHEIGHT);
		else plast=lastl;
		}
}

deleteword()
{
	int pend, cp;
	char c;

	for (pend=charn; (c=text[pend]) && ( !inword(c)); pend++);
	while ( (c=text[pend]) && inword(c)) pend++;
	for (cp=charn; (text[cp]=text[pend]); pend++, cp++);
	rewrite(charn,cursorx);
	altered=YES;
}

crinsert(dir)	/*insert a [CR] behind (dir==0) or in front of (-1) cursor*/
{
	char textb[LLIM], c;
	int charnb;

	charnb=0;
	if (autoin && !isspace(text[charn]))
		while(isspace( (c=text[charnb]) )) textb[charnb++]=c;
	strcpy(&textb[charnb],&text[charn]);
	text[charn]='\0';
	altered=YES; 
	if (dir == 0) puttext();
	if ((cline=inject(cline,textb)+dir) == FAIL) return;
	if (dir == 0) {
		gettext(cline); 
		sync(charnb); 
		}
	if (cursory >= SHEIGHT) { 
		puttext(); 
		putpage(); 
		}
	else {
		insertline();
		if (dir == 0) putline(cline-1,cursory++);
		else putline(cline+1,cursory+1);
		if (plast-pfirst < SHEIGHT-topline)plast++;
		rewrite(0,0);
		}
}

oops()	/*undoes edits on current line*/
{
	if (altered) {
		if (cline <= lastl) gettext(cline);
		else text[0]='\0';
		altered=NO;
		cursorx=adjustc(cursorx);
		rewrite(0,0);
		}
}

adjustc(x)	/*return x coord. for cursor nearest to col. 'x' so that
		  cursor isn't in the middle of a tab or off the end of the
		  current line*/
int x;
{
	int cpos;
	char c;

	for(charn=0, cpos=0; cpos < x && (c=text[charn]); charn++, cpos++)
		if (c == '\t') cpos=cpos+tabwidth-1-(cpos%tabwidth);
	return cpos;
}

sync(cp)	/*put cursorx and charn onto character 'cp' of current line*/
int cp;
{
	for(charn=0, cursorx=0; charn < cp; cursorx++, charn++)
		if (text[charn] == '\t') cursorx=cursorx+tabwidth-1-(cursorx%tabwidth);
}
extb[LLIM-len]='\0';