/* $OpenBSD: hyperlinks.c,v 1.4 2024/08/27 07:49:07 nicm Exp $ */

/*
 * Copyright (c) 2021 Will <author@will.party>
 * Copyright (c) 2022 Jeff Chiang <pobomp@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 <stdlib.h>
#include <string.h>
#include <vis.h>

#include "tmux.h"

/*
 * OSC 8 hyperlinks, described at:
 *
 *     https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
 *
 * Each hyperlink and ID combination is assigned a number ("inner" in this
 * file) which is stored in an extended grid cell and maps into a tree here.
 *
 * Each URI has one inner number and one external ID (which tmux uses to send
 * the hyperlink to the terminal) and one internal ID (which is received from
 * the sending application inside tmux).
 *
 * Anonymous hyperlinks are each unique and are not reused even if they have
 * the same URI (terminals will not want to tie them together).
 */

#define MAX_HYPERLINKS 5000

static long long hyperlinks_next_external_id = 1;
static u_int global_hyperlinks_count;

struct hyperlinks_uri {
        struct hyperlinks       *tree;

        u_int                    inner;
        const char              *internal_id;
        const char              *external_id;
        const char              *uri;

        TAILQ_ENTRY(hyperlinks_uri) list_entry;
        RB_ENTRY(hyperlinks_uri)    by_inner_entry;
        RB_ENTRY(hyperlinks_uri)    by_uri_entry; /* by internal ID and URI */
};
RB_HEAD(hyperlinks_by_uri_tree, hyperlinks_uri);
RB_HEAD(hyperlinks_by_inner_tree, hyperlinks_uri);

TAILQ_HEAD(hyperlinks_list, hyperlinks_uri);
static struct hyperlinks_list global_hyperlinks =
    TAILQ_HEAD_INITIALIZER(global_hyperlinks);

struct hyperlinks {
        u_int                           next_inner;
        struct hyperlinks_by_inner_tree by_inner;
        struct hyperlinks_by_uri_tree   by_uri;
        u_int                           references;
};

static int
hyperlinks_by_uri_cmp(struct hyperlinks_uri *left, struct hyperlinks_uri *right)
{
        int     r;

        if (*left->internal_id == '\0' || *right->internal_id == '\0') {
                /*
                 * If both URIs are anonymous, use the inner for comparison so
                 * that they do not match even if the URI is the same - each
                 * anonymous URI should be unique.
                 */
                if (*left->internal_id != '\0')
                        return (-1);
                if (*right->internal_id != '\0')
                        return (1);
                return (left->inner - right->inner);
        }

        r = strcmp(left->internal_id, right->internal_id);
        if (r != 0)
                return (r);
        return (strcmp(left->uri, right->uri));
}
RB_PROTOTYPE_STATIC(hyperlinks_by_uri_tree, hyperlinks_uri, by_uri_entry,
    hyperlinks_by_uri_cmp);
RB_GENERATE_STATIC(hyperlinks_by_uri_tree, hyperlinks_uri, by_uri_entry,
    hyperlinks_by_uri_cmp);

static int
hyperlinks_by_inner_cmp(struct hyperlinks_uri *left,
    struct hyperlinks_uri *right)
{
        return (left->inner - right->inner);
}
RB_PROTOTYPE_STATIC(hyperlinks_by_inner_tree, hyperlinks_uri, by_inner_entry,
    hyperlinks_by_inner_cmp);
RB_GENERATE_STATIC(hyperlinks_by_inner_tree, hyperlinks_uri, by_inner_entry,
    hyperlinks_by_inner_cmp);

/* Remove a hyperlink. */
static void
hyperlinks_remove(struct hyperlinks_uri *hlu)
{
        struct hyperlinks       *hl = hlu->tree;

        TAILQ_REMOVE(&global_hyperlinks, hlu, list_entry);
        global_hyperlinks_count--;

        RB_REMOVE(hyperlinks_by_inner_tree, &hl->by_inner, hlu);
        RB_REMOVE(hyperlinks_by_uri_tree, &hl->by_uri, hlu);

        free((void *)hlu->internal_id);
        free((void *)hlu->external_id);
        free((void *)hlu->uri);
        free(hlu);
}

/* Store a new hyperlink or return if it already exists. */
u_int
hyperlinks_put(struct hyperlinks *hl, const char *uri_in,
    const char *internal_id_in)
{
        struct hyperlinks_uri    find, *hlu;
        char                    *uri, *internal_id, *external_id;

        /*
         * Anonymous URI are stored with an empty internal ID and the tree
         * comparator will make sure they never match each other (so each
         * anonymous URI is unique).
         */
        if (internal_id_in == NULL)
                internal_id_in = "";

        utf8_stravis(&uri, uri_in, VIS_OCTAL|VIS_CSTYLE);
        utf8_stravis(&internal_id, internal_id_in, VIS_OCTAL|VIS_CSTYLE);

        if (*internal_id_in != '\0') {
                find.uri = uri;
                find.internal_id = internal_id;

                hlu = RB_FIND(hyperlinks_by_uri_tree, &hl->by_uri, &find);
                if (hlu != NULL) {
                        free (uri);
                        free (internal_id);
                        return (hlu->inner);
                }
        }
        xasprintf(&external_id, "tmux%llX", hyperlinks_next_external_id++);

        hlu = xcalloc(1, sizeof *hlu);
        hlu->inner = hl->next_inner++;
        hlu->internal_id = internal_id;
        hlu->external_id = external_id;
        hlu->uri = uri;
        hlu->tree = hl;
        RB_INSERT(hyperlinks_by_uri_tree, &hl->by_uri, hlu);
        RB_INSERT(hyperlinks_by_inner_tree, &hl->by_inner, hlu);

        TAILQ_INSERT_TAIL(&global_hyperlinks, hlu, list_entry);
        if (++global_hyperlinks_count == MAX_HYPERLINKS)
                hyperlinks_remove(TAILQ_FIRST(&global_hyperlinks));

        return (hlu->inner);
}

/* Get hyperlink by inner number. */
int
hyperlinks_get(struct hyperlinks *hl, u_int inner, const char **uri_out,
    const char **internal_id_out, const char **external_id_out)
{
        struct hyperlinks_uri   find, *hlu;

        find.inner = inner;

        hlu = RB_FIND(hyperlinks_by_inner_tree, &hl->by_inner, &find);
        if (hlu == NULL)
                return (0);
        if (internal_id_out != NULL)
                *internal_id_out = hlu->internal_id;
        if (external_id_out != NULL)
                *external_id_out = hlu->external_id;
        *uri_out = hlu->uri;
        return (1);
}

/* Initialize hyperlink set. */
struct hyperlinks *
hyperlinks_init(void)
{
        struct hyperlinks       *hl;

        hl = xcalloc(1, sizeof *hl);
        hl->next_inner = 1;
        RB_INIT(&hl->by_uri);
        RB_INIT(&hl->by_inner);
        hl->references = 1;
        return (hl);
}

/* Copy hyperlink set. */
struct hyperlinks *
hyperlinks_copy(struct hyperlinks *hl)
{
        hl->references++;
        return (hl);
}

/* Free all hyperlinks but not the set itself. */
void
hyperlinks_reset(struct hyperlinks *hl)
{
        struct hyperlinks_uri   *hlu, *hlu1;

        RB_FOREACH_SAFE(hlu, hyperlinks_by_inner_tree, &hl->by_inner, hlu1)
                hyperlinks_remove(hlu);
}

/* Free hyperlink set. */
void
hyperlinks_free(struct hyperlinks *hl)
{
        if (--hl->references == 0) {
                hyperlinks_reset(hl);
                free(hl);
        }
}