/* vedit.c - buffer editing for the c64 vim clone: insert, delete, save. */

extern char *bfr;
extern unsigned blen;
extern unsigned lptr[];
extern int nlines, cy, cx, top, leftcol, mode, dirty;
extern char *note;
extern char fname[];
extern char ybuf[];
extern int ylen, yok;

/* end offset (exclusive of the $0d) of line ln */
linend(ln)
int ln;
{
    if (ln + 1 < nlines) return lptr[ln + 1] - 1;
    return blen;
}

/* keep cx inside the current line */
clampx()
{
    int len;

    len = linend(cy) - lptr[cy];
    if (cx > len) cx = len;
    if (cx < 0) cx = 0;
    return 0;
}

/* ------------------------------------------------------------- editing */

/* insert byte ch at buffer offset pos. 1 on success, 0 if the buffer is full */
bins(pos, ch)
unsigned pos;
int ch;
{
    unsigned i;

    if (blen >= 18999) return 0;
    for (i = blen; i > pos; i--) bfr[i] = bfr[i - 1];
    bfr[pos] = ch;
    blen++;
    dirty = 1;
    return 1;
}

/* remove n bytes at offset pos */
delrange(pos, n)
unsigned pos, n;
{
    unsigned i;

    for (i = pos; i + n < blen; i++) bfr[i] = bfr[i + n];
    blen = blen - n;
    dirty = 1;
    return 0;
}

/* type one character at the cursor */
inschar(ch)
int ch;
{
    int l;

    if (bins(lptr[cy] + cx, ch) == 0) return 0;
    for (l = cy + 1; l < nlines; l++) lptr[l]++;
    cx++;
    return 1;
}

/* split the line at the cursor */
newline()
{
    int l;
    unsigned pos;

    if (nlines >= 599) return 0;
    pos = lptr[cy] + cx;
    if (bins(pos, 13) == 0) return 0;
    for (l = nlines; l > cy + 1; l--) lptr[l] = lptr[l - 1];
    lptr[cy + 1] = pos + 1;
    nlines++;
    for (l = cy + 2; l < nlines; l++) lptr[l]++;
    cy++;
    cx = 0;
    return 1;
}

/* delete the character under the cursor */
delchar()
{
    int l;

    if (cx >= linend(cy) - lptr[cy]) return 0;
    delrange(lptr[cy] + cx, 1);
    for (l = cy + 1; l < nlines; l++) lptr[l]--;
    return 1;
}

/* backspace: delete before the cursor, or join onto the previous line */
bkspace()
{
    int l, pl;

    if (cx > 0) {
        cx--;
        delchar();
        return 0;
    }
    if (cy == 0) return 0;
    pl = linend(cy - 1) - lptr[cy - 1];
    delrange(lptr[cy] - 1, 1);
    for (l = cy; l < nlines - 1; l++) lptr[l] = lptr[l + 1];
    nlines--;
    for (l = cy; l < nlines; l++) lptr[l]--;
    cy--;
    cx = pl;
    return 0;
}

/* dd: yank the current line and remove it */
delline()
{
    int l, i;
    unsigned s, e, n;

    s = lptr[cy];
    e = linend(cy);
    ylen = e - s;
    if (ylen > 159) ylen = 159;
    for (i = 0; i < ylen; i++) ybuf[i] = bfr[s + i];
    yok = 1;

    if (nlines == 1) {
        blen = 0;
        dirty = 1;
    } else if (cy + 1 < nlines) {
        n = lptr[cy + 1] - s;
        delrange(s, n);
        for (l = cy; l < nlines - 1; l++) lptr[l] = lptr[l + 1];
        nlines--;
        for (l = cy; l < nlines; l++) lptr[l] -= n;
    } else {                                    /* last line: take its leading $0d */
        delrange(s - 1, blen - s + 1);
        nlines--;
        cy--;
    }
    cx = 0;
    return 0;
}

/* p: put the yanked line below the cursor line */
paste()
{
    int i;

    if (yok == 0) return 0;
    cx = linend(cy) - lptr[cy];
    if (newline() == 0) return 0;
    for (i = 0; i < ylen; i++) inschar(ybuf[i]);
    cx = 0;
    return 0;
}

/* cursor keys, the same in both modes. 1 if k was one of them */
arrow(k)
int k;
{
    if (k == 17) {
        if (cy + 1 < nlines) {
            cy++;
            clampx();
        }
        return 1;
    }
    if (k == 145) {
        if (cy > 0) {
            cy--;
            clampx();
        }
        return 1;
    }
    if (k == 29) {
        cx++;
        clampx();
        return 1;
    }
    if (k == 157) {
        if (cx > 0) cx--;
        return 1;
    }
    return 0;
}

/* write the buffer to fname, replacing any old copy. 1 on success */
savef()
{
    char on[32];
    int i, f;
    unsigned j;

    on[0] = 64;                                 /* @ */
    on[1] = 48;                                 /* 0 */
    on[2] = 58;                                 /* : */
    i = 3;
    j = 0;
    while (fname[j] && j < 20) on[i++] = fname[j++];
    on[i++] = 44;                               /* , */
    on[i++] = 83;                               /* S  (petscii, not ascii) */
    on[i++] = 44;                               /* , */
    on[i++] = 87;                               /* W */
    on[i] = 0;

    f = open(5, 8, 3, on);
    if (f == 0) return 0;
    for (j = 0; j < blen; j++) putc(bfr[j], 5);
    if (blen > 0) {
        if (bfr[blen - 1] != 13) putc(13, 5);
    }
    close(5);
    return 1;
}