/* $OpenBSD: layout-custom.c,v 1.24 2026/04/04 16:40:27 nicm Exp $ */

/*
 * Copyright (c) 2010 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * 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 MIND, 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 <ctype.h>
#include <string.h>

#include "tmux.h"

static struct layout_cell       *layout_find_bottomright(struct layout_cell *);
static u_short                   layout_checksum(const char *);
static int                       layout_append(struct layout_cell *, char *,
                                     size_t);
static struct layout_cell       *layout_construct(struct layout_cell *,
                                     const char **);
static void                      layout_assign(struct window_pane **,
                                     struct layout_cell *);

/* Find the bottom-right cell. */
static struct layout_cell *
layout_find_bottomright(struct layout_cell *lc)
{
        if (lc->type == LAYOUT_WINDOWPANE)
                return (lc);
        lc = TAILQ_LAST(&lc->cells, layout_cells);
        return (layout_find_bottomright(lc));
}

/* Calculate layout checksum. */
static u_short
layout_checksum(const char *layout)
{
        u_short csum;

        csum = 0;
        for (; *layout != '\0'; layout++) {
                csum = (csum >> 1) + ((csum & 1) << 15);
                csum += *layout;
        }
        return (csum);
}

/* Dump layout as a string. */
char *
layout_dump(__unused struct window *w, struct layout_cell *root)
{
        char    layout[8192], *out;

        *layout = '\0';
        if (layout_append(root, layout, sizeof layout) != 0)
                return (NULL);

        xasprintf(&out, "%04hx,%s", layout_checksum(layout), layout);
        return (out);
}

/* Append information for a single cell. */
static int
layout_append(struct layout_cell *lc, char *buf, size_t len)
{
        struct layout_cell     *lcchild;
        char                    tmp[64];
        size_t                  tmplen;
        const char             *brackets = "][";

        if (len == 0)
                return (-1);

        if (lc->wp != NULL) {
                tmplen = xsnprintf(tmp, sizeof tmp, "%ux%u,%u,%u,%u",
                    lc->sx, lc->sy, lc->xoff, lc->yoff, lc->wp->id);
        } else {
                tmplen = xsnprintf(tmp, sizeof tmp, "%ux%u,%u,%u",
                    lc->sx, lc->sy, lc->xoff, lc->yoff);
        }
        if (tmplen > (sizeof tmp) - 1)
                return (-1);
        if (strlcat(buf, tmp, len) >= len)
                return (-1);

        switch (lc->type) {
        case LAYOUT_LEFTRIGHT:
                brackets = "}{";
                /* FALLTHROUGH */
        case LAYOUT_TOPBOTTOM:
                if (strlcat(buf, &brackets[1], len) >= len)
                        return (-1);
                TAILQ_FOREACH(lcchild, &lc->cells, entry) {
                        if (layout_append(lcchild, buf, len) != 0)
                                return (-1);
                        if (strlcat(buf, ",", len) >= len)
                                return (-1);
                }
                buf[strlen(buf) - 1] = brackets[0];
                break;
        case LAYOUT_WINDOWPANE:
                break;
        }

        return (0);
}

/* Check layout sizes fit. */
static int
layout_check(struct layout_cell *lc)
{
        struct layout_cell      *lcchild;
        u_int                    n = 0;

        switch (lc->type) {
        case LAYOUT_WINDOWPANE:
                break;
        case LAYOUT_LEFTRIGHT:
                TAILQ_FOREACH(lcchild, &lc->cells, entry) {
                        if (lcchild->sy != lc->sy)
                                return (0);
                        if (!layout_check(lcchild))
                                return (0);
                        n += lcchild->sx + 1;
                }
                if (n - 1 != lc->sx)
                        return (0);
                break;
        case LAYOUT_TOPBOTTOM:
                TAILQ_FOREACH(lcchild, &lc->cells, entry) {
                        if (lcchild->sx != lc->sx)
                                return (0);
                        if (!layout_check(lcchild))
                                return (0);
                        n += lcchild->sy + 1;
                }
                if (n - 1 != lc->sy)
                        return (0);
                break;
        }
        return (1);
}

/* Parse a layout string and arrange window as layout. */
int
layout_parse(struct window *w, const char *layout, char **cause)
{
        struct layout_cell      *lc, *lcchild;
        struct window_pane      *wp;
        u_int                    npanes, ncells, sx = 0, sy = 0;
        u_short                  csum;

        /* Check validity. */
        if (sscanf(layout, "%hx,", &csum) != 1) {
                *cause = xstrdup("invalid layout");
                return (-1);
        }
        layout += 5;
        if (csum != layout_checksum(layout)) {
                *cause = xstrdup("invalid layout");
                return (-1);
        }

        /* Build the layout. */
        lc = layout_construct(NULL, &layout);
        if (lc == NULL) {
                *cause = xstrdup("invalid layout");
                return (-1);
        }
        if (*layout != '\0') {
                *cause = xstrdup("invalid layout");
                goto fail;
        }

        /* Check this window will fit into the layout. */
        for (;;) {
                npanes = window_count_panes(w);
                ncells = layout_count_cells(lc);
                if (npanes > ncells) {
                        xasprintf(cause, "have %u panes but need %u", npanes,
                            ncells);
                        goto fail;
                }
                if (npanes == ncells)
                        break;

                /* Fewer panes than cells - close the bottom right. */
                lcchild = layout_find_bottomright(lc);
                layout_destroy_cell(w, lcchild, &lc);
        }

        /*
         * It appears older versions of tmux were able to generate layouts with
         * an incorrect top cell size - if it is larger than the top child then
         * correct that (if this is still wrong the check code will catch it).
         */
        switch (lc->type) {
        case LAYOUT_WINDOWPANE:
                break;
        case LAYOUT_LEFTRIGHT:
                TAILQ_FOREACH(lcchild, &lc->cells, entry) {
                        sy = lcchild->sy + 1;
                        sx += lcchild->sx + 1;
                }
                break;
        case LAYOUT_TOPBOTTOM:
                TAILQ_FOREACH(lcchild, &lc->cells, entry) {
                        sx = lcchild->sx + 1;
                        sy += lcchild->sy + 1;
                }
                break;
        }
        if (lc->type != LAYOUT_WINDOWPANE && (lc->sx != sx || lc->sy != sy)) {
                log_debug("fix layout %u,%u to %u,%u", lc->sx, lc->sy, sx,sy);
                layout_print_cell(lc, __func__, 0);
                lc->sx = sx - 1; lc->sy = sy - 1;
        }

        /* Check the new layout. */
        if (!layout_check(lc)) {
                *cause = xstrdup("size mismatch after applying layout");
                goto fail;
        }

        /* Resize to the layout size. */
        window_resize(w, lc->sx, lc->sy, -1, -1);

        /* Destroy the old layout and swap to the new. */
        layout_free_cell(w->layout_root);
        w->layout_root = lc;

        /* Assign the panes into the cells. */
        wp = TAILQ_FIRST(&w->panes);
        layout_assign(&wp, lc);

        /* Update pane offsets and sizes. */
        layout_fix_offsets(w);
        layout_fix_panes(w, NULL);
        recalculate_sizes();

        layout_print_cell(lc, __func__, 0);

        notify_window("window-layout-changed", w);

        return (0);

fail:
        layout_free_cell(lc);
        return (-1);
}

/* Assign panes into cells. */
static void
layout_assign(struct window_pane **wp, struct layout_cell *lc)
{
        struct layout_cell      *lcchild;

        switch (lc->type) {
        case LAYOUT_WINDOWPANE:
                layout_make_leaf(lc, *wp);
                *wp = TAILQ_NEXT(*wp, entry);
                return;
        case LAYOUT_LEFTRIGHT:
        case LAYOUT_TOPBOTTOM:
                TAILQ_FOREACH(lcchild, &lc->cells, entry)
                        layout_assign(wp, lcchild);
                return;
        }
}

/* Construct a cell from all or part of a layout tree. */
static struct layout_cell *
layout_construct(struct layout_cell *lcparent, const char **layout)
{
        struct layout_cell     *lc, *lcchild;
        u_int                   sx, sy, xoff, yoff;
        const char             *saved;

        if (!isdigit((u_char) **layout))
                return (NULL);
        if (sscanf(*layout, "%ux%u,%u,%u", &sx, &sy, &xoff, &yoff) != 4)
                return (NULL);

        while (isdigit((u_char) **layout))
                (*layout)++;
        if (**layout != 'x')
                return (NULL);
        (*layout)++;
        while (isdigit((u_char) **layout))
                (*layout)++;
        if (**layout != ',')
                return (NULL);
        (*layout)++;
        while (isdigit((u_char) **layout))
                (*layout)++;
        if (**layout != ',')
                return (NULL);
        (*layout)++;
        while (isdigit((u_char) **layout))
                (*layout)++;
        if (**layout == ',') {
                saved = *layout;
                (*layout)++;
                while (isdigit((u_char) **layout))
                        (*layout)++;
                if (**layout == 'x')
                        *layout = saved;
        }

        lc = layout_create_cell(lcparent);
        lc->sx = sx;
        lc->sy = sy;
        lc->xoff = xoff;
        lc->yoff = yoff;

        switch (**layout) {
        case ',':
        case '}':
        case ']':
        case '\0':
                return (lc);
        case '{':
                lc->type = LAYOUT_LEFTRIGHT;
                break;
        case '[':
                lc->type = LAYOUT_TOPBOTTOM;
                break;
        default:
                goto fail;
        }

        do {
                (*layout)++;
                lcchild = layout_construct(lc, layout);
                if (lcchild == NULL)
                        goto fail;
                TAILQ_INSERT_TAIL(&lc->cells, lcchild, entry);
        } while (**layout == ',');

        switch (lc->type) {
        case LAYOUT_LEFTRIGHT:
                if (**layout != '}')
                        goto fail;
                break;
        case LAYOUT_TOPBOTTOM:
                if (**layout != ']')
                        goto fail;
                break;
        default:
                goto fail;
        }
        (*layout)++;

        return (lc);

fail:
        layout_free_cell(lc);
        return (NULL);
}