#include "shadowMapper.h"
#include "gfx/gl/shaders/vs-shadowDynamicPoint.h"
#include "gfx/gl/shaders/vs-shadowFixedPoint.h"
#include "gfx/models/texture.h"
#include "location.hpp"
#include "maths.h"
#include "sceneProvider.h"
#include "sceneShader.h"
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtx/transform.hpp>
#include <glm/matrix.hpp>

ShadowMapper::ShadowMapper(const glm::ivec2 & s) : size {s}
{
	glBindTexture(GL_TEXTURE_2D, depthMap);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, size.x, size.y, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
	static constexpr glm::vec3 border {std::numeric_limits<float>::infinity()};
	glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, glm::value_ptr(border));

	glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
	glDrawBuffer(GL_NONE);
	glReadBuffer(GL_NONE);
	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
		throw std::runtime_error("Framebuffer not complete!");
	}
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

glm::mat4x4
ShadowMapper::update(const SceneProvider & scene, const glm::vec3 & dir) const
{
	const glm::vec3 centre {0.F, 0.F, 0.F};
	const glm::vec3 range = glm::normalize(dir) * 1800.F;
	const auto lightProjection = glm::ortho(-1200.F, 1200.F, -1200.F, 1200.F, 0.F, 3600.F);
	const auto lightView = glm::lookAt(centre - range, centre, north);
	const auto lightViewProjection = lightProjection * lightView;
	fixedPoint.setViewProjection(lightViewProjection);
	dynamicPoint.setViewProjection(lightViewProjection);

	glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
	glViewport(0, 0, size.x, size.y);
	glClear(GL_DEPTH_BUFFER_BIT);
	glEnable(GL_DEPTH_TEST);
	glCullFace(GL_FRONT);
	scene.shadows(*this);
	glCullFace(GL_BACK);

	return lightViewProjection;
}

ShadowMapper::FixedPoint::FixedPoint() : Program {shadowFixedPoint_vs}, viewProjectionLoc {*this, "viewProjection"} { }
void
ShadowMapper::FixedPoint::setViewProjection(const glm::mat4 & viewProjection) const
{
	use();
	glUniformMatrix4fv(viewProjectionLoc, 1, GL_FALSE, glm::value_ptr(viewProjection));
}
void
ShadowMapper::FixedPoint::use() const
{
	glUseProgram(*this);
}

ShadowMapper::DynamicPoint::DynamicPoint() :
	Program {shadowDynamicPoint_vs}, viewProjectionLoc {*this, "viewProjection"}, modelLoc {*this, "model"}
{
}
void
ShadowMapper::DynamicPoint::setViewProjection(const glm::mat4 & viewProjection) const
{
	glUseProgram(*this);
	glUniformMatrix4fv(viewProjectionLoc, 1, GL_FALSE, glm::value_ptr(viewProjection));
}
void
ShadowMapper::DynamicPoint::use(const Location & location) const
{
	glUseProgram(*this);
	const auto model = glm::translate(location.pos) * rotate_ypr(location.rot);
	glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
}