#include "Camera3D.h"

#include <glm/gtc/matrix_transform.hpp>

namespace charcoal
{
	Camera3D::Camera3D(
		float fov_y,
		float aspect_ratio,
		float znear,
		float zfar,
		const vec3& position,
		const vec3& forward,
		const vec3& up,
		const vec3& right
	)
	{
		update_frustum(fov_y, aspect_ratio, znear, zfar);
		update_position(position);
		update_orientation(forward, up, right);
	}

	void Camera3D::update_frustum(float fov_y, float aspect_ratio, float znear, float zfar)
	{
		m_projection_matrix = glm::perspective(fov_y, aspect_ratio, znear, zfar);
	}

	void Camera3D::update_position(const vec3& position)
	{
		m_position = position;
	}

	void Camera3D::update_orientation(const vec3& forward, const vec3& up, const vec3& right)
	{
		vec3 real_forward;
		vec3 real_up;
		vec3 real_right;

		if (right == vec3(0.0f))
			real_right = glm::normalize(glm::cross(forward, up));
		else
			real_right = right;

		real_forward = glm::normalize(forward);
		real_up = glm::cross(real_right, real_forward);

		m_forward = vec4(real_forward, 0.0f);
		m_up = vec4(real_up, 0.0f);
		m_right = vec4(real_right, 0.0f);
	}

	void Camera3D::direct_update_orientation(const vec3& forward, const vec3& up, const vec3& right)
	{
		m_forward = vec4(forward, 0.0f);
		m_up = vec4(up, 0.0f);
		m_right = vec4(right, 0.0f);
	}

	void Camera3D::translate(const vec3& translation)
	{
		m_position += translation;
	}

	void Camera3D::rotate(const vec3& axis, float angle)
	{
		mat4 rotation = glm::rotate(mat4(1.0f), angle, axis);
		m_forward = rotation * m_forward;
		m_up = rotation * m_up;
		m_right = rotation * m_right;
	}

	void Camera3D::prerender()
	{
		// This works but it mirrors the scene left and right?
		m_view_matrix = mat4(
			vec4(m_right.x, m_up.x, -m_forward.x, 0.0f),
			vec4(m_right.y, m_up.y, -m_forward.y, 0.0f),
			vec4(m_right.z, m_up.z, -m_forward.z, 0.0f),
			vec4(-glm::dot(vec3(m_right), m_position), -glm::dot(vec3(m_up), m_position), glm::dot(vec3(m_forward), m_position), 1.0f)
		);

	}
}