/*
 *  gstvaapidisplay_drm.c - VA/DRM display abstraction
 *
 *  Copyright (C) 2012 Intel Corporation
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2.1
 *  of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301 USA
 */

/**
 * SECTION:gstvaapidisplay_drm
 * @short_description: VA/DRM display abstraction
 */

#include "sysdeps.h"
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <libudev.h>
#include <xf86drm.h>
#include <va/va_drm.h>
#include "gstvaapiutils.h"
#include "gstvaapidisplay_priv.h"
#include "gstvaapidisplay_drm.h"
#include "gstvaapidisplay_drm_priv.h"

#define DEBUG 1
#include "gstvaapidebug.h"

#define NAME_PREFIX "DRM:"
#define NAME_PREFIX_LENGTH 4

static inline gboolean
is_device_path(const gchar *device_path)
{
    return strncmp(device_path, NAME_PREFIX, NAME_PREFIX_LENGTH) == 0;
}

static gboolean
compare_device_path(gconstpointer a, gconstpointer b, gpointer user_data)
{
    const gchar *cached_name = a;
    const gchar *tested_name = b;

    if (!cached_name || !is_device_path(cached_name))
        return FALSE;
    g_return_val_if_fail(tested_name && is_device_path(tested_name), FALSE);

    cached_name += NAME_PREFIX_LENGTH;
    tested_name += NAME_PREFIX_LENGTH;
    return strcmp(cached_name, tested_name) == 0;
}

/* Get default device path. Actually, the first match in the DRM subsystem */
static const gchar *
get_default_device_path(GstVaapiDisplay *display)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);
    const gchar *syspath, *devpath;
    struct udev *udev = NULL;
    struct udev_device *device, *parent;
    struct udev_enumerate *e = NULL;
    struct udev_list_entry *l;
    int fd;

    if (!priv->device_path_default) {
        udev = udev_new();
        if (!udev)
            goto end;

        e = udev_enumerate_new(udev);
        if (!e)
            goto end;

        udev_enumerate_add_match_subsystem(e, "drm");
        udev_enumerate_scan_devices(e);
        udev_list_entry_foreach(l, udev_enumerate_get_list_entry(e)) {
            syspath = udev_list_entry_get_name(l);
            device  = udev_device_new_from_syspath(udev, syspath);
            parent  = udev_device_get_parent(device);
            if (strcmp(udev_device_get_subsystem(parent), "pci") != 0) {
                udev_device_unref(device);
                continue;
            }

            devpath = udev_device_get_devnode(device);
            fd = open(devpath, O_RDWR|O_CLOEXEC);
            if (fd < 0) {
                udev_device_unref(device);
                continue;
            }

            priv->device_path_default = g_strdup(devpath);
            close(fd);
            udev_device_unref(device);
            break;
        }

    end:
        if (e)
            udev_enumerate_unref(e);
        if (udev)
            udev_unref(udev);
    }
    return priv->device_path_default;
}

/* Reconstruct a device path without our prefix */
static const gchar *
get_device_path(GstVaapiDisplay *display)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);
    const gchar *device_path = priv->device_path;

    if (!device_path)
        return NULL;

    g_return_val_if_fail(is_device_path(device_path), NULL);

    device_path += NAME_PREFIX_LENGTH;
    if (*device_path == '\0')
        return NULL;
    return device_path;
}

/* Mangle device path with our prefix */
static gboolean
set_device_path(GstVaapiDisplay *display, const gchar *device_path)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);

    g_free(priv->device_path);
    priv->device_path = NULL;

    if (!device_path) {
        device_path = get_default_device_path(display);
        if (!device_path)
            return FALSE;
    }
    priv->device_path = g_strdup_printf("%s%s", NAME_PREFIX, device_path);
    return priv->device_path != NULL;
}

/* Set device path from file descriptor */
static gboolean
set_device_path_from_fd(GstVaapiDisplay *display, gint drm_device)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);
    const gchar *busid, *path, *str;
    gsize busid_length, path_length;
    struct udev *udev = NULL;
    struct udev_device *device;
    struct udev_enumerate *e = NULL;
    struct udev_list_entry *l;
    gboolean success = FALSE;

    g_free(priv->device_path);
    priv->device_path = NULL;

    if (drm_device < 0)
        goto end;

    busid = drmGetBusid(drm_device);
    if (!busid)
        goto end;
    if (strncmp(busid, "pci:", 4) != 0)
        goto end;
    busid += 4;
    busid_length = strlen(busid);

    udev = udev_new();
    if (!udev)
        goto end;

    e = udev_enumerate_new(udev);
    if (!e)
        goto end;

    udev_enumerate_add_match_subsystem(e, "drm");
    udev_enumerate_scan_devices(e);
    udev_list_entry_foreach(l, udev_enumerate_get_list_entry(e)) {
        path = udev_list_entry_get_name(l);
        str  = strstr(path, busid);
        if (!str || str <= path || str[-1] != '/')
            continue;

        path_length = strlen(path);
        if (str + busid_length >= path + path_length)
            continue;
        if (strncmp(&str[busid_length], "/drm/card", 9) != 0)
            continue;

        device = udev_device_new_from_syspath(udev, path);
        if (!device)
            continue;

        path = udev_device_get_devnode(device);
        priv->device_path = g_strdup_printf("%s%s", NAME_PREFIX, path);
        udev_device_unref(device);
        break;
    }
    success = TRUE;

end:
    if (e)
        udev_enumerate_unref(e);
    if (udev)
        udev_unref(udev);
    return success;
}

static gboolean
gst_vaapi_display_drm_bind_display(GstVaapiDisplay *display,
    gpointer native_display)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);

    priv->drm_device = GPOINTER_TO_INT(native_display);
    priv->use_foreign_display = TRUE;

    if (!set_device_path_from_fd(display, priv->drm_device))
        return FALSE;
    return TRUE;
}

static gboolean
gst_vaapi_display_drm_open_display(GstVaapiDisplay *display, const gchar *name)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);
    GstVaapiDisplayCache *cache;
    const GstVaapiDisplayInfo *info;

    cache = gst_vaapi_display_get_cache();
    g_return_val_if_fail(cache != NULL, FALSE);

    if (!set_device_path(display, name))
        return FALSE;

    info = gst_vaapi_display_cache_lookup_by_name(cache, priv->device_path,
        compare_device_path, NULL);
    if (info) {
        priv->drm_device = GPOINTER_TO_INT(info->native_display);
        priv->use_foreign_display = TRUE;
    }
    else {
        priv->drm_device = open(get_device_path(display), O_RDWR|O_CLOEXEC);
        if (priv->drm_device < 0)
            return FALSE;
        priv->use_foreign_display = FALSE;
    }
    return TRUE;
}

static void
gst_vaapi_display_drm_close_display(GstVaapiDisplay *display)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);

    if (priv->drm_device >= 0) {
        if (!priv->use_foreign_display)
            close(priv->drm_device);
        priv->drm_device = -1;
    }

    if (priv->device_path) {
        g_free(priv->device_path);
        priv->device_path = NULL;
    }

    if (priv->device_path_default) {
        g_free(priv->device_path_default);
        priv->device_path_default = NULL;
    }
}

static gboolean
gst_vaapi_display_drm_get_display_info(GstVaapiDisplay *display,
    GstVaapiDisplayInfo *info)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);
    GstVaapiDisplayCache *cache;
    const GstVaapiDisplayInfo *cached_info;

    /* Return any cached info even if child has its own VA display */
    cache = gst_vaapi_display_get_cache();
    if (!cache)
        return FALSE;
    cached_info = gst_vaapi_display_cache_lookup_by_native_display(
        cache, GINT_TO_POINTER(priv->drm_device));
    if (cached_info) {
        *info = *cached_info;
        return TRUE;
    }

    /* Otherwise, create VA display if there is none already */
    info->native_display = GINT_TO_POINTER(priv->drm_device);
    info->display_name   = priv->device_path;
    if (!info->va_display) {
        info->va_display = vaGetDisplayDRM(priv->drm_device);
        if (!info->va_display)
            return FALSE;
        info->display_type = GST_VAAPI_DISPLAY_TYPE_DRM;
    }
    return TRUE;
}

static void
gst_vaapi_display_drm_init(GstVaapiDisplay *display)
{
    GstVaapiDisplayDRMPrivate * const priv =
        GST_VAAPI_DISPLAY_DRM_PRIVATE(display);

    priv->drm_device = -1;
}

static void
gst_vaapi_display_drm_class_init(GstVaapiDisplayDRMClass *klass)
{
    GstVaapiMiniObjectClass * const object_class =
        GST_VAAPI_MINI_OBJECT_CLASS(klass);
    GstVaapiDisplayClass * const dpy_class = GST_VAAPI_DISPLAY_CLASS(klass);

    gst_vaapi_display_class_init(&klass->parent_class);

    object_class->size          = sizeof(GstVaapiDisplayDRM);
    dpy_class->init             = gst_vaapi_display_drm_init;
    dpy_class->bind_display     = gst_vaapi_display_drm_bind_display;
    dpy_class->open_display     = gst_vaapi_display_drm_open_display;
    dpy_class->close_display    = gst_vaapi_display_drm_close_display;
    dpy_class->get_display      = gst_vaapi_display_drm_get_display_info;
}

static inline const GstVaapiDisplayClass *
gst_vaapi_display_drm_class(void)
{
    static GstVaapiDisplayDRMClass g_class;
    static gsize g_class_init = FALSE;

    if (g_once_init_enter(&g_class_init)) {
        gst_vaapi_display_drm_class_init(&g_class);
        g_once_init_leave(&g_class_init, TRUE);
    }
    return GST_VAAPI_DISPLAY_CLASS(&g_class);
}

/**
 * gst_vaapi_display_drm_new:
 * @device_path: the DRM device path
 *
 * Opens an DRM file descriptor using @device_path and returns a newly
 * allocated #GstVaapiDisplay object. The DRM display will be cloed
 * when the reference count of the object reaches zero.
 *
 * If @device_path is NULL, the DRM device path will be automatically
 * determined as the first positive match in the list of available DRM
 * devices.
 *
 * Return value: a newly allocated #GstVaapiDisplay object
 */
GstVaapiDisplay *
gst_vaapi_display_drm_new(const gchar *device_path)
{
    return gst_vaapi_display_new(gst_vaapi_display_drm_class(),
        GST_VAAPI_DISPLAY_INIT_FROM_DISPLAY_NAME, (gpointer)device_path);
}

/**
 * gst_vaapi_display_drm_new_with_device:
 * @device: an open DRM device (file descriptor)
 *
 * Creates a #GstVaapiDisplay based on the open DRM @device. The
 * caller still owns the device file descriptor and must call close()
 * when all #GstVaapiDisplay references are released. Doing so too
 * early can yield undefined behaviour.
 *
 * Return value: a newly allocated #GstVaapiDisplay object
 */
GstVaapiDisplay *
gst_vaapi_display_drm_new_with_device(gint device)
{
    g_return_val_if_fail(device >= 0, NULL);

    return gst_vaapi_display_new(gst_vaapi_display_drm_class(),
        GST_VAAPI_DISPLAY_INIT_FROM_NATIVE_DISPLAY, GINT_TO_POINTER(device));
}

/**
 * gst_vaapi_display_drm_get_device:
 * @display: a #GstVaapiDisplayDRM
 *
 * Returns the underlying DRM device file descriptor that was created
 * by gst_vaapi_display_drm_new() or that was bound from
 * gst_vaapi_display_drm_new_with_device().
 *
 * Return value: the DRM file descriptor attached to @display
 */
gint
gst_vaapi_display_drm_get_device(GstVaapiDisplayDRM *display)
{
    g_return_val_if_fail(GST_VAAPI_IS_DISPLAY_DRM(display), -1);

    return GST_VAAPI_DISPLAY_DRM_DEVICE(display);
}

/**
 * gst_vaapi_display_drm_get_device_path:
 * @display: a #GstVaapiDisplayDRM
 *
 * Returns the underlying DRM device path name was created by
 * gst_vaapi_display_drm_new() or that was bound from
 * gst_vaapi_display_drm_new_with_device().
 *
 * Note: the #GstVaapiDisplayDRM object owns the resulting string, so
 * it shall not be deallocated.
 *
 * Return value: the DRM device path name attached to @display
 */
const gchar *
gst_vaapi_display_drm_get_device_path(GstVaapiDisplayDRM *display)
{
    g_return_val_if_fail(GST_VAAPI_IS_DISPLAY_DRM(display), NULL);

    return get_device_path(GST_VAAPI_DISPLAY_CAST(display));
}