#include "post_processor.h"
#include "sys.h"
#include "shader.h"
#include "texture.h"

#include <GL/glew.h>

struct post_processor init_post_processor(i32 width, i32 height, u32 shader)
{
	struct post_processor processor = {0};
	processor.width = width;
	processor.height = height;
	glGenFramebuffers(1, &processor.msfbo);
	glGenFramebuffers(1, &processor.fbo);
	glGenRenderbuffers(1, &processor.rbo);
	glBindFramebuffer(GL_FRAMEBUFFER, processor.msfbo);
	glBindRenderbuffer(GL_RENDERBUFFER, processor.rbo);
	glRenderbufferStorageMultisample(GL_RENDERBUFFER, 4, GL_RGB, width, height);
	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, processor.rbo);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
		die("failed to create msfbo");
	glBindRenderbuffer(GL_RENDERBUFFER, 0);
	glBindFramebuffer(GL_FRAMEBUFFER, processor.fbo);
	gl_texture_t texture = (gl_texture_t)default_texture;
	generate_texture(&texture, width, height, 0);
	processor.texture = texture.id;
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, processor.texture, 0);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
		die("failed to create fbo");
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	u32 vbo;
	f32 vertices[] = {
		-1.0f, -1.0f, 0.0f, 0.0f,
		1.0f,  1.0f, 1.0f, 1.0f,
		-1.0f,  1.0f, 0.0f, 1.0f,
		-1.0f, -1.0f, 0.0f, 0.0f,
		1.0f, -1.0f, 1.0f, 0.0f,
		1.0f,  1.0f, 1.0f, 1.0f
	};
	glGenBuffers(1, &vbo);
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
	glGenVertexArrays(1, &processor.vao);
	glBindVertexArray(processor.vao);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(f32), 0);
	glBindVertexArray(0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	processor.shader = shader;
	glUseProgram(processor.shader);
	uniform_i32(processor.shader, "colorbuffer", 0);
	f32 offset = 1.0f / 300.0f;
	f32 offsets[] = {
		-offset, offset, /* top-left */
		0.0f, offset, /* top-center */
		offset, offset, /* top-right */
		-offset, 0.0f, /* center-left */
		0.0f, 0.0f, /* center */
		offset, 0.0f, /* center-right */
		-offset, -offset, /* bottom-left */
		0.0f, -offset, /* bottom-center */
		offset, -offset /* bottom-right */
	};
	glUniform2fv(glGetUniformLocation(processor.shader, "offsets"), 9, offsets);
	i32 edge_kernel[] = {
		-1, -1, -1,
		-1,  8, -1,
		-1, -1, -1
	};
	glUniform1iv(glGetUniformLocation(processor.shader, "edge_kernel"), 9, edge_kernel);
	f32 blur_kernel[] = {
		1.0f / 16.0f, 2.0f / 16.0f, 1.0f / 16.0f,
		2.0f / 16.0f, 4.0f / 16.0f, 2.0f / 16.0f,
		1.0f / 16.0f, 2.0f / 16.0f, 1.0f / 16.0f
	};
	glUniform1fv(glGetUniformLocation(processor.shader, "blur_kernel"), 9, blur_kernel);
	glUseProgram(0);
	return processor;
}

void begin_render(struct post_processor processor)
{
	glBindFramebuffer(GL_FRAMEBUFFER, processor.msfbo);
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);
}

void end_render(struct post_processor processor)
{
	glBindFramebuffer(GL_READ_FRAMEBUFFER, processor.msfbo);
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, processor.fbo);
	glBlitFramebuffer(0, 0, processor.width, processor.height, 0, 0, processor.width, processor.height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

void render_post(struct post_processor processor, f32 time)
{
	glUseProgram(processor.shader);
	uniform_f32(processor.shader, "time", time);
	uniform_i32(processor.shader, "confuse", processor.confuse);
	uniform_i32(processor.shader, "chaos", processor.chaos);
	uniform_i32(processor.shader, "shake", processor.shake);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, processor.texture);
	glBindVertexArray(processor.vao);
	glDrawArrays(GL_TRIANGLES, 0, 6);
	glBindVertexArray(0);
	glUseProgram(0);
}