/* $OpenBSD: term_tab.c,v 1.7 2025/07/16 14:23:55 schwarze Exp $ */
/*
 * Copyright (c) 2017, 2021, 2025 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/types.h>

#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#include "mandoc_aux.h"
#include "out.h"
#include "term.h"

struct tablist {
        size_t  *t;     /* Allocated array of tab positions [BU]. */
        size_t   s;     /* Allocated number of positions. */
        size_t   n;     /* Currently used number of positions. */
};

static struct {
        struct tablist   a;     /* All tab positions for lookup. */
        struct tablist   p;     /* Periodic tab positions to add. */
        struct tablist  *r;     /* Tablist currently being recorded. */
        size_t           d;     /* Default tab width in basic units. */
} tabs;


void
term_tab_set(const struct termp *p, const char *arg)
{
        struct roffsu    su;
        struct tablist  *tl;
        size_t           pos;
        int              add;

        /* Special arguments: clear all tabs or switch lists. */

        if (arg == NULL) {
                tabs.a.n = tabs.p.n = 0;
                tabs.r = &tabs.a;
                if (tabs.d == 0) {
                        a2roffsu(".8i", &su, SCALE_IN);
                        tabs.d = term_hspan(p, &su);
                }
                return;
        }
        if (arg[0] == 'T' && arg[1] == '\0') {
                tabs.r = &tabs.p;
                return;
        }

        /* Parse the sign, the number, and the unit. */

        if (*arg == '+') {
                add = 1;
                arg++;
        } else
                add = 0;
        if (a2roffsu(arg, &su, SCALE_EM) == NULL)
                return;

        /* Select the list, and extend it if it is full. */

        tl = tabs.r;
        if (tl->n >= tl->s) {
                tl->s += 8;
                tl->t = mandoc_reallocarray(tl->t, tl->s, sizeof(*tl->t));
        }

        /* Append the new position. */

        pos = term_hspan(p, &su);
        tl->t[tl->n] = pos;
        if (add && tl->n)
                tl->t[tl->n] += tl->t[tl->n - 1];
        tl->n++;
}

size_t
term_tab_next(size_t prev)
{
        size_t   i, j;

        for (i = 0;; i++) {
                if (i == tabs.a.n) {
                        if (tabs.p.n == 0)
                                return prev;
                        tabs.a.n += tabs.p.n;
                        if (tabs.a.s < tabs.a.n) {
                                tabs.a.s = tabs.a.n;
                                tabs.a.t = mandoc_reallocarray(tabs.a.t,
                                    tabs.a.s, sizeof(*tabs.a.t));
                        }
                        for (j = 0; j < tabs.p.n; j++)
                                tabs.a.t[i + j] = tabs.p.t[j] +
                                    (i ? tabs.a.t[i - 1] : 0);
                }
                if (prev < tabs.a.t[i])
                        return tabs.a.t[i];
        }
}

void
term_tab_free(void)
{
        free(tabs.a.t);
        free(tabs.p.t);
        memset(&tabs, 0, sizeof(tabs));
        tabs.r = &tabs.a;
}