/*
 * 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 <stdio.h>
#include <stdlib.h>

#include "common.h"

static struct gbm gbm;

const struct gbm * init_gbm(int drm_fd, int w, int h)
{
	gbm.dev = gbm_create_device(drm_fd);

	gbm.surface = gbm_surface_create(gbm.dev, w, h,
			GBM_FORMAT_XRGB8888,
			GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
	if (!gbm.surface) {
		printf("failed to create gbm surface\n");
		return NULL;
	}

	gbm.width = w;
	gbm.height = h;

	return &gbm;
}


int init_egl(struct egl *egl, const struct gbm *gbm)
{
	EGLint major, minor, n;

	static const EGLint context_attribs[] = {
		EGL_CONTEXT_CLIENT_VERSION, 2,
		EGL_NONE
	};

	static const EGLint config_attribs[] = {
		EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
		EGL_RED_SIZE, 1,
		EGL_GREEN_SIZE, 1,
		EGL_BLUE_SIZE, 1,
		EGL_ALPHA_SIZE, 0,
		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
		EGL_NONE
	};

#define get_proc(name) do { \
		egl->name = (void *)eglGetProcAddress(#name); \
	} while (0)

	get_proc(eglGetPlatformDisplayEXT);

	if (egl->eglGetPlatformDisplayEXT) {
		egl->display = egl->eglGetPlatformDisplayEXT(EGL_PLATFORM_GBM_KHR,
				gbm->dev, NULL);
	} else {
		egl->display = eglGetDisplay((void *)gbm->dev);
	}

	if (!eglInitialize(egl->display, &major, &minor)) {
		printf("failed to initialize\n");
		return -1;
	}

	printf("Using display %p with EGL version %d.%d\n",
			egl->display, major, minor);

	printf("EGL Version \"%s\"\n", eglQueryString(egl->display, EGL_VERSION));
	printf("EGL Vendor \"%s\"\n", eglQueryString(egl->display, EGL_VENDOR));
	printf("EGL Extensions \"%s\"\n", eglQueryString(egl->display, EGL_EXTENSIONS));

	if (!eglBindAPI(EGL_OPENGL_ES_API)) {
		printf("failed to bind api EGL_OPENGL_ES_API\n");
		return -1;
	}

	if (!eglChooseConfig(egl->display, config_attribs, &egl->config, 1, &n) || n != 1) {
		printf("failed to choose config: %d\n", n);
		return -1;
	}

	egl->context = eglCreateContext(egl->display, egl->config,
			EGL_NO_CONTEXT, context_attribs);
	if (egl->context == NULL) {
		printf("failed to create context\n");
		return -1;
	}

	egl->surface = eglCreateWindowSurface(egl->display, egl->config,
			(EGLNativeWindowType)gbm->surface, NULL);
	if (egl->surface == EGL_NO_SURFACE) {
		printf("failed to create egl surface\n");
		return -1;
	}

	/* connect the context to the surface */
	eglMakeCurrent(egl->display, egl->surface, egl->surface, egl->context);

	printf("GL Extensions: \"%s\"\n", glGetString(GL_EXTENSIONS));

	return 0;
}

int create_program(const char *vs_src, const char *fs_src)
{
	GLuint vertex_shader, fragment_shader, program;
	GLint ret;

	vertex_shader = glCreateShader(GL_VERTEX_SHADER);

	glShaderSource(vertex_shader, 1, &vs_src, NULL);
	glCompileShader(vertex_shader);

	glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &ret);
	if (!ret) {
		char *log;

		printf("vertex shader compilation failed!:\n");
		glGetShaderiv(vertex_shader, GL_INFO_LOG_LENGTH, &ret);
		if (ret > 1) {
			log = malloc(ret);
			glGetShaderInfoLog(vertex_shader, ret, NULL, log);
			printf("%s", log);
		}

		return -1;
	}

	fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);

	glShaderSource(fragment_shader, 1, &fs_src, NULL);
	glCompileShader(fragment_shader);

	glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &ret);
	if (!ret) {
		char *log;

		printf("fragment shader compilation failed!:\n");
		glGetShaderiv(fragment_shader, GL_INFO_LOG_LENGTH, &ret);

		if (ret > 1) {
			log = malloc(ret);
			glGetShaderInfoLog(fragment_shader, ret, NULL, log);
			printf("%s", log);
		}

		return -1;
	}

	program = glCreateProgram();

	glAttachShader(program, vertex_shader);
	glAttachShader(program, fragment_shader);

	return program;
}

int link_program(unsigned program)
{
	GLint ret;

	glLinkProgram(program);

	glGetProgramiv(program, GL_LINK_STATUS, &ret);
	if (!ret) {
		char *log;

		printf("program linking failed!:\n");
		glGetProgramiv(program, GL_INFO_LOG_LENGTH, &ret);

		if (ret > 1) {
			log = malloc(ret);
			glGetProgramInfoLog(program, ret, NULL, log);
			printf("%s", log);
		}

		return -1;
	}

	return 0;
}