// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later
#include "watch.h"
static GQueue changes = G_QUEUE_INIT;
static gboolean watchEnabled;
static unsigned long long watchEpoch;

void clipboard_watch_free(ClipboardChange *change) {
    if (--change->references) return;
    g_free(change->text);
    g_free(change);
}

static void text_received(GtkClipboard *clipboard, const gchar *text, gpointer data) {
    (void)clipboard;
    ClipboardChange *change = data;
    change->text = g_strdup(text);
    change->done = TRUE;
    clipboard_watch_free(change);
}

static void targets_received(GtkClipboard *clipboard, GdkAtom *targets, gint count, gpointer data) {
    ClipboardChange *change = data;
    if (!watchEnabled || watchEpoch != change->epoch || !targets ||
            gtk_targets_include_image(targets, count, FALSE) ||
            gtk_targets_include_uri(targets, count) ||
            !gtk_targets_include_text(targets, count)) {
        change->done = TRUE;
        clipboard_watch_free(change);
        return;
    }
    // No image or file payload is requested, only a text target.
    gtk_clipboard_request_text(clipboard, text_received, change);
}

static void owner_changed(GtkClipboard *clipboard, GdkEventOwnerChange *event, gpointer data) {
    (void)data;
    if (!watchEnabled) return;
    if (g_queue_get_length(&changes) >= 128)
        clipboard_watch_free(g_queue_pop_head(&changes));
    ClipboardChange *change = g_new0(ClipboardChange, 1);
    change->epoch = watchEpoch;
    change->timestamp = event->time;
    change->deadline = g_get_monotonic_time() + 3 * G_TIME_SPAN_SECOND;
    change->references = 2; // queue and asynchronous callback
    g_queue_push_tail(&changes, change);
    gtk_clipboard_request_targets(clipboard, targets_received, change);
}

int clipboard_watch_init(void) {
    if (!gtk_init_check(NULL, NULL)) return 0;
    GtkClipboard *clipboard = gtk_clipboard_get(GDK_SELECTION_CLIPBOARD);
    if (!clipboard) return 0;
    g_signal_connect(clipboard, "owner-change", G_CALLBACK(owner_changed), NULL);
    return 1;
}

void clipboard_watch_enable(int enabled, unsigned long long epoch) {
    watchEnabled = enabled;
    watchEpoch = epoch;
}
void clipboard_watch_iterate(void) {
    while (gtk_events_pending()) gtk_main_iteration_do(FALSE);
}
ClipboardChange *clipboard_watch_next(void) {
    ClipboardChange *change = g_queue_peek_head(&changes);
    if (!change || (!change->done && g_get_monotonic_time() < change->deadline)) return NULL;
    return g_queue_pop_head(&changes);
}