#include <string.h>
#include <stdint.h>
#include <jni.h>
#include <android/log.h>
#include <android/native_window.h>
#include <android/native_window_jni.h>
#include <gst/gst.h>
#include <gst/video/video.h>
#include <gst/video/videooverlay.h>
#include <pthread.h>

GST_DEBUG_CATEGORY_STATIC (debug_category);
#define GST_CAT_DEFAULT debug_category

/*
 * These macros provide a way to store the native pointer to CustomData, which might be 32 or 64 bits, into
 * a jlong, which is always 64 bits, without warnings.
 */
#if GLIB_SIZEOF_VOID_P == 8
# define GET_CUSTOM_DATA(env, thiz, fieldID) (CustomData *)(*env)->GetLongField (env, thiz, fieldID)
# define SET_CUSTOM_DATA(env, thiz, fieldID, data) (*env)->SetLongField (env, thiz, fieldID, (jlong)data)
#else
# define GET_CUSTOM_DATA(env, thiz, fieldID) (CustomData *)(jint)(*env)->GetLongField (env, thiz, fieldID)
# define SET_CUSTOM_DATA(env, thiz, fieldID, data) (*env)->SetLongField (env, thiz, fieldID, (jlong)(jint)data)
#endif

/* Structure to contain all our information, so we can pass it to callbacks */
typedef struct _CustomData {
    jobject app;                  /* Application instance, used to call its methods. A global reference is kept. */
    GstElement *pipeline;         /* The running pipeline */
    GMainContext *context;        /* GLib context used to run the main loop */
    GMainLoop *main_loop;         /* GLib main loop */
    gboolean initialized;         /* To avoid informing the UI multiple times about the initialization */
    ANativeWindow *native_window; /* The Android native window where video will be rendered */
    GstState state;               /* Current pipeline state */
    GstState target_state;        /* Desired pipeline state, to be set once buffering is complete */
    gboolean is_live;             /* Live streams do not use buffering */
} CustomData;

/* playbin2 flags */
typedef enum {
    GST_PLAY_FLAG_TEXT = (1 << 2) /* We want subtitle output */
} GstPlayFlags;

/* These global variables cache values which are not changing during execution */
static pthread_t gst_app_thread;
static pthread_key_t current_jni_env;
static JavaVM *java_vm;
static jfieldID custom_data_field_id;
static jmethodID set_message_method_id;
static jmethodID on_gstreamer_initialized_method_id;
static jmethodID on_media_size_changed_method_id;

/*
 * Private methods
 */

/* Register this thread with the VM */
static JNIEnv *attach_current_thread(void) {
    JNIEnv *env;
    JavaVMAttachArgs args;

    GST_DEBUG ("Attaching thread %p", g_thread_self());
    args.version = JNI_VERSION_1_4;
    args.name = NULL;
    args.group = NULL;

    if ((*java_vm)->AttachCurrentThread(java_vm, &env, &args) < 0) {
        GST_ERROR ("Failed to attach current thread");
        return NULL;
    }

    return env;
}

/* Unregister this thread from the VM */
static void detach_current_thread(void *env) {
    GST_DEBUG ("Detaching thread %p", g_thread_self());
    (*java_vm)->DetachCurrentThread(java_vm);
}

/* Retrieve the JNI environment for this thread */
static JNIEnv *get_jni_env(void) {
    JNIEnv *env;

    if ((env = pthread_getspecific(current_jni_env)) == NULL) {
        env = attach_current_thread();
        pthread_setspecific(current_jni_env, env);
    }

    return env;
}

/* Change the content of the UI's TextView */
static void set_ui_message(const gchar *message, CustomData *data) {
    JNIEnv *env = get_jni_env();
    GST_DEBUG ("Setting message to: %s", message);
    jstring jmessage = (*env)->NewStringUTF(env, message);
    (*env)->CallVoidMethod(env, data->app, set_message_method_id, jmessage);
    if ((*env)->ExceptionCheck(env)) {
        GST_ERROR ("Failed to call Java method");
        (*env)->ExceptionClear(env);
    }
    (*env)->DeleteLocalRef(env, jmessage);
}

/* Retrieve errors from the bus and show them on the UI */
static void error_cb(GstBus *bus, GstMessage *msg, CustomData *data) {
    GError *err;
    gchar *debug_info;
    gchar *message_string;

    gst_message_parse_error(msg, &err, &debug_info);
    message_string =
            g_strdup_printf("Error received from element %s: %s",
                            GST_OBJECT_NAME (msg->src), err->message);
    g_clear_error(&err);
    g_free(debug_info);
    set_ui_message(message_string, data);
    g_free(message_string);
    data->target_state = GST_STATE_NULL;
    gst_element_set_state(data->pipeline, GST_STATE_NULL);
}

/* Called when the End Of the Stream is reached. Just move to the beginning of the media and pause. */
static void eos_cb(GstBus *bus, GstMessage *msg, CustomData *data) {
    data->target_state = GST_STATE_PAUSED;
    data->is_live |= (gst_element_set_state(data->pipeline,
                                            GST_STATE_PAUSED) == GST_STATE_CHANGE_NO_PREROLL);
}

/* Called when buffering messages are received. We inform the UI about the current buffering level and
 * keep the pipeline paused until 100% buffering is reached. At that point, set the desired state. */
static void buffering_cb(GstBus *bus, GstMessage *msg, CustomData *data) {
    gint percent;

    if (data->is_live)
        return;

    gst_message_parse_buffering(msg, &percent);
    if (percent < 100 && data->target_state >= GST_STATE_PAUSED) {
        gchar *message_string = g_strdup_printf("Buffering %d%%", percent);
        gst_element_set_state(data->pipeline, GST_STATE_PAUSED);
        set_ui_message(message_string, data);
        g_free(message_string);
    } else if (data->target_state >= GST_STATE_PLAYING) {
        gst_element_set_state(data->pipeline, GST_STATE_PLAYING);
    } else if (data->target_state >= GST_STATE_PAUSED) {
        set_ui_message("Buffering complete", data);
    }
}

/* Called when the clock is lost */
static void clock_lost_cb(GstBus *bus, GstMessage *msg, CustomData *data) {
    if (data->target_state >= GST_STATE_PLAYING) {
        gst_element_set_state(data->pipeline, GST_STATE_PAUSED);
        gst_element_set_state(data->pipeline, GST_STATE_PLAYING);
    }
}

/* Retrieve the video sink's Caps and tell the application about the media size */
static void check_media_size(CustomData *data) {
    JNIEnv *env = get_jni_env();
    GstElement *video_sink;
    GstPad *video_sink_pad;
    GstCaps *caps;
    GstVideoInfo info;

    /* Retrieve the Caps at the entrance of the video sink */
    g_object_get(data->pipeline, "video-sink", &video_sink, NULL);
    video_sink_pad = gst_element_get_static_pad(video_sink, "sink");
    caps = gst_pad_get_current_caps(video_sink_pad);

    if (gst_video_info_from_caps(&info, caps)) {
        info.width = info.width * info.par_n / info.par_d;
        GST_DEBUG ("Media size is %dx%d, notifying application", info.width,
                   info.height);

        (*env)->CallVoidMethod(env, data->app, on_media_size_changed_method_id,
                               (jint) info.width, (jint) info.height);
        if ((*env)->ExceptionCheck(env)) {
            GST_ERROR ("Failed to call Java method");
            (*env)->ExceptionClear(env);
        }
    }

    gst_caps_unref(caps);
    gst_object_unref(video_sink_pad);
    gst_object_unref(video_sink);
}

/* Notify UI about pipeline state changes */
static void state_changed_cb(GstBus *bus, GstMessage *msg, CustomData *data) {
    GstState old_state, new_state, pending_state;
    gst_message_parse_state_changed(msg, &old_state, &new_state, &pending_state);
    /* Only pay attention to messages coming from the pipeline, not its children */
    if (GST_MESSAGE_SRC (msg) == GST_OBJECT (data->pipeline)) {
        data->state = new_state;
        gchar *message = g_strdup_printf("State changed to %s", gst_element_state_get_name(new_state));
        set_ui_message(message, data);
        g_free(message);

        if (new_state == GST_STATE_NULL || new_state == GST_STATE_READY)
            data->is_live = FALSE;

        /* The Ready to Paused state change is particularly interesting: */
        if (old_state == GST_STATE_READY && new_state == GST_STATE_PAUSED) {
            /* By now the sink already knows the media size */
            check_media_size(data);
        }
    }
}

/* Check if all conditions are met to report GStreamer as initialized.
 * These conditions will change depending on the application */
static void check_initialization_complete(CustomData *data) {
    JNIEnv *env = get_jni_env();
    if (!data->initialized && data->native_window && data->main_loop) {
        GST_DEBUG("Initialization complete, notifying application. native_window:%p main_loop:%p", data->native_window, data->main_loop);

        /* The main loop is running and we received a native window, inform the sink about it */
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY (data->pipeline),
                                            (guintptr) data->native_window);

        (*env)->CallVoidMethod(env, data->app, on_gstreamer_initialized_method_id);
        if ((*env)->ExceptionCheck(env)) {
            GST_ERROR ("Failed to call Java method");
            (*env)->ExceptionClear(env);
        }
        data->initialized = TRUE;
    }
}

/* Main method for the native code. This is executed on its own thread. */
static void *app_function(void *userdata) {
    JavaVMAttachArgs args;
    GstBus *bus;
    CustomData *data = (CustomData *) userdata;
    GSource *timeout_source;
    GSource *bus_source;
    GError *error = NULL;
    guint flags;

    GST_DEBUG ("Creating pipeline in CustomData at %p", data);

    /* Create our own GLib Main Context and make it the default one */
    data->context = g_main_context_new();
    g_main_context_push_thread_default(data->context);

    /* Build pipeline */
    data->pipeline = gst_parse_launch("playbin", &error);
    if (error) {
        gchar *message = g_strdup_printf("Unable to build pipeline: %s", error->message);
        g_clear_error(&error);
        set_ui_message(message, data);
        g_free(message);
        return NULL;
    }

    /* Disable subtitles */
    g_object_get(data->pipeline, "flags", &flags, NULL);
    flags &= ~GST_PLAY_FLAG_TEXT;
    g_object_set(data->pipeline, "flags", flags, NULL);

    /* Set the pipeline to READY, so it can already accept a window handle, if we have one */
    data->target_state = GST_STATE_READY;
    gst_element_set_state(data->pipeline, GST_STATE_READY);

    /* Instruct the bus to emit signals for each received message, and connect to the interesting signals */
    bus = gst_element_get_bus(data->pipeline);
    bus_source = gst_bus_create_watch(bus);
    g_source_set_callback(bus_source, (GSourceFunc) gst_bus_async_signal_func,
                          NULL, NULL);
    g_source_attach(bus_source, data->context);
    g_source_unref(bus_source);
    g_signal_connect (G_OBJECT(bus), "message::error", (GCallback) error_cb,
                      data);
    g_signal_connect (G_OBJECT(bus), "message::eos", (GCallback) eos_cb, data);
    g_signal_connect (G_OBJECT(bus), "message::state-changed", (GCallback) state_changed_cb, data);
    g_signal_connect (G_OBJECT(bus), "message::buffering", (GCallback) buffering_cb, data);
    g_signal_connect (G_OBJECT(bus), "message::clock-lost", (GCallback) clock_lost_cb, data);
    gst_object_unref(bus);

    /* Create a GLib Main Loop and set it to run */
    GST_DEBUG ("Entering main loop... (CustomData:%p)", data);
    data->main_loop = g_main_loop_new(data->context, FALSE);
    check_initialization_complete(data);
    g_main_loop_run(data->main_loop);
    GST_DEBUG ("Exited main loop");
    g_main_loop_unref(data->main_loop);
    data->main_loop = NULL;

    /* Free resources */
    g_main_context_pop_thread_default(data->context);
    g_main_context_unref(data->context);
    data->target_state = GST_STATE_NULL;
    gst_element_set_state(data->pipeline, GST_STATE_NULL);
    gst_object_unref(data->pipeline);

    return NULL;
}

/*
 * Java Bindings
 */

/* Instruct the native code to create its internal data structure, pipeline and thread */
static void gst_native_init(JNIEnv *env, jobject thiz) {
    CustomData *data = g_new0 (CustomData, 1);
    SET_CUSTOM_DATA (env, thiz, custom_data_field_id, data);
    GST_DEBUG_CATEGORY_INIT (debug_category, "player", 0, "HI SHARP DX RTSP Player");
    gst_debug_set_threshold_for_name("player", GST_LEVEL_DEBUG);
    GST_DEBUG ("Created CustomData at %p", data);
    data->app = (*env)->NewGlobalRef(env, thiz);
    GST_DEBUG ("Created GlobalRef for app object at %p", data->app);
    pthread_create(&gst_app_thread, NULL, &app_function, data);
}

/* Quit the main loop, remove the native thread and free resources */
static void gst_native_finalize(JNIEnv *env, jobject thiz) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data)
        return;
    GST_DEBUG ("Quitting main loop...");
    g_main_loop_quit(data->main_loop);
    GST_DEBUG ("Waiting for thread to finish...");
    pthread_join(gst_app_thread, NULL);
    GST_DEBUG ("Deleting GlobalRef for app object at %p", data->app);
    (*env)->DeleteGlobalRef(env, data->app);
    GST_DEBUG ("Freeing CustomData at %p", data);
    g_free(data);
    SET_CUSTOM_DATA (env, thiz, custom_data_field_id, NULL);
    GST_DEBUG ("Done finalizing");
}

/* Set playbin2's URI */
void gst_native_set_uri(JNIEnv *env, jobject thiz, jstring uri) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data || !data->pipeline)
        return;
    const gchar *char_uri = (*env)->GetStringUTFChars(env, uri, NULL);
    GST_DEBUG ("Setting URI to %s", char_uri);
    if (data->target_state >= GST_STATE_READY)
        gst_element_set_state(data->pipeline, GST_STATE_READY);
    g_object_set(data->pipeline, "uri", char_uri, NULL);
    (*env)->ReleaseStringUTFChars(env, uri, char_uri);
    g_object_set(data->pipeline, "latency", 250, NULL);
    data->is_live = (gst_element_set_state(data->pipeline, data->target_state) == GST_STATE_CHANGE_NO_PREROLL);
}

/* Set pipeline to PLAYING state */
static void gst_native_play(JNIEnv *env, jobject thiz) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data)
        return;
    GST_DEBUG ("Setting state to PLAYING");
    data->is_live = (gst_element_set_state(data->pipeline, GST_STATE_PLAYING) == GST_STATE_CHANGE_NO_PREROLL);
    data->target_state = GST_STATE_PLAYING;
}

/* Set pipeline to PAUSED state */
static void gst_native_pause(JNIEnv *env, jobject thiz) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data)
        return;
    GST_DEBUG ("Setting state to PAUSED");
    data->is_live = (gst_element_set_state(data->pipeline, GST_STATE_PAUSED) == GST_STATE_CHANGE_NO_PREROLL);
    data->target_state = GST_STATE_PAUSED;
}

/* Static class initializer: retrieve method and field IDs */
static jboolean gst_native_class_init(JNIEnv *env, jclass klass) {
    custom_data_field_id = (*env)->GetFieldID(env, klass, "native_custom_data", "J");
    set_message_method_id = (*env)->GetMethodID(env, klass, "setMessage", "(Ljava/lang/String;)V");
    on_gstreamer_initialized_method_id = (*env)->GetMethodID(env, klass, "onGStreamerInitialized", "()V");
    on_media_size_changed_method_id = (*env)->GetMethodID(env, klass, "onMediaSizeChanged", "(II)V");

    if (!custom_data_field_id || !set_message_method_id
        || !on_gstreamer_initialized_method_id || !on_media_size_changed_method_id) {
        /* We emit this message through the Android log instead of the GStreamer log because the later
         * has not been initialized yet.
         */
        __android_log_print(ANDROID_LOG_ERROR, "tutorial-4",
                            "The calling class does not implement all necessary interface methods");
        return JNI_FALSE;
    }
    return JNI_TRUE;
}

static void gst_native_surface_init(JNIEnv *env, jobject thiz, jobject surface) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data)
        return;
    ANativeWindow *new_native_window = ANativeWindow_fromSurface(env, surface);
    GST_DEBUG ("Received surface %p (native window %p)", surface,
               new_native_window);

    if (data->native_window) {
        ANativeWindow_release(data->native_window);
        if (data->native_window == new_native_window) {
            GST_DEBUG ("New native window is the same as the previous one %p",
                       data->native_window);
            if (data->pipeline) {
                gst_video_overlay_expose(GST_VIDEO_OVERLAY (data->pipeline));
            }
            return;
        } else {
            GST_DEBUG ("Released previous native window %p", data->native_window);
            data->initialized = FALSE;
        }
    }
    data->native_window = new_native_window;

    check_initialization_complete(data);
}

static void gst_native_surface_finalize(JNIEnv *env, jobject thiz) {
    CustomData *data = GET_CUSTOM_DATA (env, thiz, custom_data_field_id);
    if (!data)
        return;
    GST_DEBUG ("Releasing Native Window %p", data->native_window);

    if (data->pipeline) {
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY (data->pipeline),
                                            (guintptr) NULL);
        gst_element_set_state(data->pipeline, GST_STATE_READY);
    }

    ANativeWindow_release(data->native_window);
    data->native_window = NULL;
    data->initialized = FALSE;
}

/* List of implemented native methods */
static JNINativeMethod native_methods[] = {
        {"nativeInit",            "()V",                   (void *) gst_native_init},
        {"nativeFinalize",        "()V",                   (void *) gst_native_finalize},
        {"nativeSetUri",          "(Ljava/lang/String;)V", (void *) gst_native_set_uri},
        {"nativePlay",            "()V",                   (void *) gst_native_play},
        {"nativePause",           "()V",                   (void *) gst_native_pause},
        {"nativeSurfaceInit",     "(Ljava/lang/Object;)V",
                                                           (void *) gst_native_surface_init},
        {"nativeSurfaceFinalize", "()V",                   (void *) gst_native_surface_finalize},
        {"nativeClassInit",       "()Z",                   (void *) gst_native_class_init}
};

/* Library initializer */
jint JNI_OnLoad(JavaVM *vm, void *reserved) {
    JNIEnv *env = NULL;

    java_vm = vm;

    if ((*vm)->GetEnv(vm, (void **) &env, JNI_VERSION_1_4) != JNI_OK) {
        __android_log_print(ANDROID_LOG_ERROR, "player", "Could not retrieve JNIEnv");
        return 0;
    }
    jclass klass = (*env)->FindClass(env, "com/hisharp/gstreamer_player/GstLibrary");
    (*env)->RegisterNatives(env, klass, native_methods,
                            G_N_ELEMENTS (native_methods));

    pthread_key_create(&current_jni_env, detach_current_thread);

    return JNI_VERSION_1_4;
}