#include "gpu.h"

#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <string.h>

#ifndef M_PI
#define M_PI 3.14159265358979324
#endif

#define W 800
#define H 600

static const vertex_t vertices[] = {
	{ { -1, -1 }, { 1, 0, 0 } },
	{ { 1, -1 }, { 0, 1, 0 } },
	{ { 1, 1 }, { 0, 0, 1 } },
	{ { -1, 1 }, { 1, 1, 1 } },
};

static const uint16_t indices[] = { 0, 1, 2, 2, 3, 0 };

// clang-format off
#define ID \
	{ \
		1, 0, 0, 0, \
		0, 1, 0, 0, \
		0, 0, 1, 0, \
		0, 0, 0, 1, \
	}

#define SCALE(sf) \
	{ \
		sf, 0,  0,  0, \
		0,  sf, 0,  0, \
		0,  0,  sf, 0, \
		0,  0,  0,  1, \
	}

#define TRANSLATE(x, y, z) \
	{ \
		1, 0, 0, 0, \
		0, 1, 0, 0, \
		0, 0, 1, 0, \
		x, y, z, 1, \
	}

#define ROT_X(a) \
	{ \
		1, 0,       0,        0, \
		0, cosf(a), sinf(a),  0, \
		0, -sinf(a), cosf(a), 0, \
		0, 0,       0,        1, \
	}

#define ROT_Y(a) \
	{ \
		cosf(a), 0, -sinf(a), 0, \
		0,       1, 0,        0, \
		sinf(a), 0, cosf(a),  0, \
		0,       0, 0,        1, \
	}

#define ROT_Z(a) \
	{ \
		cosf(a),  sinf(a), 0, 0, \
		-sinf(a), cosf(a), 0, 0, \
		0,        0,       1, 0, \
		0,        0,       0, 1, \
	}
// clang-format on

static void
key_callback(GLFWwindow *window, int key, int scancode, int action, int mods)
{
	(void)window;
	(void)scancode;
	(void)mods;

	switch (key) {
	case GLFW_KEY_Q:
		if (action == GLFW_PRESS)
			glfwSetWindowShouldClose(window, GL_TRUE);
		break;
	}
}

static void mul(mat4_t out, const mat4_t left, const mat4_t right)
{
	for (unsigned y = 0; y < 4; ++y) {
		for (unsigned x = 0; x < 4; ++x) {
			out[y + 4 * x] = 0;
			for (unsigned i = 0; i < 4; ++i)
				out[y + 4 * x] += left[y + 4 * i] * right[i + 4 * x];
		}
	}
}

static void persp(mat4_t out, float aspect, float fov, float ncp, float fcp)
{
	const float r = 2 * ncp * tanf(fov / 2);
	const float t = r * aspect;

	// clang-format off
	const mat4_t m = {
		ncp / t, 0,        0,                        0,
		0,       -ncp / r, 0,                        0,
		0,       0,        fcp / (fcp - ncp),        1,
		0,       0,        -fcp * ncp / (fcp - ncp), 0,
	};
	// clang-format on

	memcpy(out, m, sizeof(mat4_t));
}

int main()
{
	// Set up window
	glfwInit();
	glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
	glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
	GLFWwindow *window = glfwCreateWindow(W, H, "Foo", nullptr, nullptr);
	assert(window);

	// Register input callbacks
	glfwSetKeyCallback(window, key_callback);

	// Initialise GPU
	const gpu_config_t gpu_config = {
		.application_name = "Foo",
		.window = window,
		.vertex_data = vertices,
		.vertex_data_size = sizeof(vertices),
		.index_data = indices,
		.index_data_size = sizeof(indices),
	};
	gpu_ctx_t gpu;
	gpu_init(&gpu, &gpu_config);

	mvp_t mvp = {
		.model = ID,
		.view = TRANSLATE(0, 0, 4.0),
	};
	persp(mvp.proj, (float)W / H, M_PI / 6, 0.1, 10.0);

	const mat4_t rot = ROT_Y(M_PI / 128);
	while (!glfwWindowShouldClose(window)) {
		glfwPollEvents();

		mat4_t tmp;
		memcpy(tmp, mvp.model, sizeof(mat4_t));
		mul(mvp.model, rot, tmp);

		gpu_render(&gpu, &mvp);
	}

	// Clean up
	gpu_cleanup(&gpu);
	glfwDestroyWindow(window);
	glfwTerminate();

	return 0;
}