/*
 * Copyright (c) 2017 Rob Clark <rclark@redhat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "common.h"
#include "drm.h"

static void
drm_fb_destroy_callback(struct gbm_bo *bo, void *data)
{
	int drm_fd = gbm_device_get_fd(gbm_bo_get_device(bo));
	struct drm_fb *fb = data;
	struct gbm_device *gbm = gbm_bo_get_device(bo);

	if (fb->fb_id)
		drmModeRmFB(drm_fd, fb->fb_id);

	free(fb);
}

struct drm_fb * drm_fb_get_from_bo(struct gbm_bo *bo)
{
	int drm_fd = gbm_device_get_fd(gbm_bo_get_device(bo));
	struct drm_fb *fb = gbm_bo_get_user_data(bo);
	uint32_t width, height, stride, handle;
	int ret;

	if (fb)
		return fb;

	fb = calloc(1, sizeof *fb);
	fb->bo = bo;

	width = gbm_bo_get_width(bo);
	height = gbm_bo_get_height(bo);
	stride = gbm_bo_get_stride(bo);
	handle = gbm_bo_get_handle(bo).u32;

	ret = drmModeAddFB(drm_fd, width, height, 24, 32, stride, handle, &fb->fb_id);
	if (ret) {
		printf("failed to create fb: %s\n", strerror(errno));
		free(fb);
		return NULL;
	}

	gbm_bo_set_user_data(bo, fb, drm_fb_destroy_callback);

	return fb;
}

static uint32_t find_crtc_for_encoder(const drmModeRes *resources,
		const drmModeEncoder *encoder) {
	int i;

	for (i = 0; i < resources->count_crtcs; i++) {
		/* possible_crtcs is a bitmask as described here:
		 * https://dvdhrm.wordpress.com/2012/09/13/linux-drm-mode-setting-api
		 */
		const uint32_t crtc_mask = 1 << i;
		const uint32_t crtc_id = resources->crtcs[i];
		if (encoder->possible_crtcs & crtc_mask) {
			return crtc_id;
		}
	}

	/* no match found */
	return -1;
}

static uint32_t find_crtc_for_connector(const struct drm *drm, const drmModeRes *resources,
		const drmModeConnector *connector) {
	int i;

	for (i = 0; i < connector->count_encoders; i++) {
		const uint32_t encoder_id = connector->encoders[i];
		drmModeEncoder *encoder = drmModeGetEncoder(drm->fd, encoder_id);

		if (encoder) {
			const uint32_t crtc_id = find_crtc_for_encoder(resources, encoder);

			drmModeFreeEncoder(encoder);
			if (crtc_id != 0) {
				return crtc_id;
			}
		}
	}

	/* no match found */
	return -1;
}

int init_drm(struct drm *drm, const char *device)
{
	drmModeRes *resources;
	drmModeConnector *connector = NULL;
	drmModeEncoder *encoder = NULL;
	int i, area;

	drm->fd = open(device, O_RDWR);

	if (drm->fd < 0) {
		printf("could not open drm device\n");
		return -1;
	}

	resources = drmModeGetResources(drm->fd);
	if (!resources) {
		printf("drmModeGetResources failed: %s\n", strerror(errno));
		return -1;
	}

	/* find a connected connector: */
	for (i = 0; i < resources->count_connectors; i++) {
		connector = drmModeGetConnector(drm->fd, resources->connectors[i]);
		if (connector->connection == DRM_MODE_CONNECTED) {
			/* it's connected, let's use this! */
			break;
		}
		drmModeFreeConnector(connector);
		connector = NULL;
	}

	if (!connector) {
		/* we could be fancy and listen for hotplug events and wait for
		 * a connector..
		 */
		printf("no connected connector!\n");
		return -1;
	}

	/* find prefered mode or the highest resolution mode: */
	for (i = 0, area = 0; i < connector->count_modes; i++) {
		drmModeModeInfo *current_mode = &connector->modes[i];

		if (current_mode->type & DRM_MODE_TYPE_PREFERRED) {
			drm->mode = current_mode;
		}

		int current_area = current_mode->hdisplay * current_mode->vdisplay;
		if (current_area > area) {
			drm->mode = current_mode;
			area = current_area;
		}
	}

	if (!drm->mode) {
		printf("could not find mode!\n");
		return -1;
	}

	/* find encoder: */
	for (i = 0; i < resources->count_encoders; i++) {
		encoder = drmModeGetEncoder(drm->fd, resources->encoders[i]);
		if (encoder->encoder_id == connector->encoder_id)
			break;
		drmModeFreeEncoder(encoder);
		encoder = NULL;
	}

	if (encoder) {
		drm->crtc_id = encoder->crtc_id;
	} else {
		uint32_t crtc_id = find_crtc_for_connector(drm, resources, connector);
		if (crtc_id == 0) {
			printf("no crtc found!\n");
			return -1;
		}

		drm->crtc_id = crtc_id;
	}

	for (i = 0; i < resources->count_crtcs; i++) {
		if (resources->crtcs[i] == drm->crtc_id) {
			drm->crtc_index = i;
			break;
		}
	}

	drmModeFreeResources(resources);

	drm->connector_id = connector->connector_id;

	return 0;
}