/* $OpenBSD$ */

/*
* Copyright (c) 2021 Will <[email protected]>
* Copyright (c) 2022 Jeff Chiang <[email protected]>
*
* 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 "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(__UNCONST(hlu->internal_id));
       free(__UNCONST(hlu->external_id));
       free(__UNCONST(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);
       }
}

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