#include <stdlib.h>

#include "engine/logger.h"

#include "scene.h"

Scene* currentScene = NULL;



Transform identity() {
	return (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = 0.0f,
	                     .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = 0.0f,
	                     .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = 0.0f,
	                     .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f };
}

void multiply(Transform* transform, Transform by) {
	GLfloat* a = (GLfloat*) &by;
	GLfloat* b = (GLfloat*) transform;

	for (size_t row = 0; row < 4; ++row) {
		for (size_t col = 0; col < 4; ++col) {
			b[(row * 4) + col] =
				a[(row * 4) + 0] * b[(0 * 4) + col]
				+ a[(row * 4) + 1] * b[(1 * 4) + col]
				+ a[(row * 4) + 2] * b[(2 * 4) + col]
				+ a[(row * 4) + 3] * b[(3 * 4) + col];
		}
	}
}

void translate(Transform* transform, Vector3D vec) {
	multiply(transform, (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = vec.x,
                                      .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = vec.y,
                                      .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = vec.z,
                                      .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f });
}

Vector3D translationOf(Transform transform) {
	return (Vector3D) { transform.a4, transform.b4, transform.c4 };
}

Scene* newScene() {
	Scene* scene = malloc(sizeof(Scene));
	*scene = (Scene) { .parent = NULL,
	                   .numChildren = 0u,
	                   .children = NULL,
	                   .transform = identity(),
	                   .solid = NULL };
	return scene;
}

void insertChildScene(Scene* scene, Scene* newChild) {
	if (!scene || !newChild) {
		return;
	}
	if (newChild->parent) {
		logError(
			"Cannot insert scene 0x%p as child of 0x%p, because it is already child of 0x%p",
			newChild,
			scene,
			newChild->parent);
		return;
	}

	scene->children = realloc(scene->children, ++(scene->numChildren) * sizeof(Scene*));
	scene->children[scene->numChildren - 1] = newChild;

	newChild->parent = scene;
}

void reparentScene(Scene* scene, Scene* newParent) {
	if (!scene) {
		return;
	}

	if (scene->parent) {
		Scene* parent = scene->parent;
		size_t indexInParent = parent->numChildren;
		for (size_t i = 0; i < parent->numChildren; ++i) {
			if (parent->children[i] == scene) {
				indexInParent = i;
				break;
			}
		}
		// This includes the hopefully impossible case where parent->numChildren == 0
		if (indexInParent == parent->numChildren) {
			logError("Scene %p not found in children of parent %p", scene, parent);
		}
		else {
			for (size_t i = indexInParent; i < parent->numChildren - 1; ++i) {
				parent->children[i] = parent->children[i + 1];
			}
			parent->children = realloc(parent->children, --(parent->numChildren) * sizeof(Scene*));
		}
	}

	scene->parent = NULL;

	insertChildScene(newParent, scene);
}