#include "terrain.h"
#include "terrain/terrain_chunk.h"
#include "terrain/terrain_modifier.h"

void Terrain::_bind_methods() {}

void Terrain::ready() {
	construct_chunk_grid();
	generate_meshes();
}

void Terrain::update_modifier_list() {
	bool editor{ Engine::get_singleton()->is_editor_hint() };
	this->modifiers.clear();
	for (Variant var : get_children()) {
		if (TerrainModifier * mod{ cast_to<TerrainModifier>(var) }) {
			if (editor && !mod->is_connected(TerrainModifier::sig_changed, callable_mp(this, &self_type::on_terrain_changed))) {
				mod->connect(TerrainModifier::sig_changed, callable_mp(this, &self_type::on_terrain_changed));
			}
			this->modifiers.push_back(mod);
		}
	}
	on_terrain_changed();
}

void Terrain::child_entered(Node *node) {
	if (cast_to<TerrainModifier>(node)) {
		update_modifier_list();
	}
}

void Terrain::child_exiting(Node *node) {
	if (TerrainModifier * mod{ cast_to<TerrainModifier>(node) }) {
		this->modifiers.erase(mod);
		if (Engine::get_singleton()->is_editor_hint() && !is_queued_for_deletion()) {
			mod->disconnect(TerrainModifier::sig_changed, callable_mp(this, &self_type::on_terrain_changed));
		}

		on_terrain_changed();
	}
}

void Terrain::on_terrain_changed() {
	if (is_queued_for_deletion() || !is_inside_tree()) {
		return;
	}
	generate_meshes();
}

void Terrain::_notification(int what) {
	switch (what) {
		default:
			return;
		case NOTIFICATION_ENTER_TREE:
			if (!is_ready()) {
				connect("child_entered_tree", callable_mp(this, &self_type::child_entered));
				connect("child_exiting_tree", callable_mp(this, &self_type::child_exiting));
				connect("child_order_changed", callable_mp(this, &self_type::update_modifier_list));
			}
			return;
		case NOTIFICATION_READY:
			ready();
			return;
	}
}

void Terrain::construct_chunk_grid() {
	size_t const chunks_per_side{ this->side_length / this->chunk_size };
	Vector3 const origin{ -(float)this->side_length / 2.f, 0.f, -(float)this->side_length / 2.f };
	for (size_t y{ 0 }; y < chunks_per_side; ++y) {
		for (size_t x{ 0 }; x < chunks_per_side; ++x) {
			TerrainChunkMesh *chunk{ memnew(TerrainChunkMesh) };
			chunk->set_size(this->chunk_size);
			chunk->set_detail(this->detail);
			chunk->set_terrain(this);
			chunk->set_position(origin + Vector3{ (float)this->chunk_size * (float)x, 0.f, (float)this->chunk_size * (float)y });
			add_child(chunk);
			chunk->set_owner(this);
			this->meshes.push_back(chunk);
		}
	}
}

void Terrain::generate_meshes() {
	for (TerrainChunkMesh *mesh : this->meshes) {
		if (!mesh->is_inside_tree()) {
			return;
		}
		mesh->update_mesh();
	}
}

float Terrain::height_at(Vector2 world_coordinate) {
	float height{ 0 };
	for (TerrainModifier *mod : this->modifiers) {
		if (!mod->is_inside_tree()) {
			return height;
		}
		height = mod->evaluate_at(world_coordinate, height);
	}
	return height;
}

void Terrain::set_side_length(size_t length) {
	this->side_length = length;
	if (is_inside_tree()) {
		construct_chunk_grid();
		generate_meshes();
	}
}

size_t Terrain::get_side_length() const {
	return this->side_length;
}

void Terrain::set_chunk_size(size_t size) {
	this->chunk_size = size;
	if (is_inside_tree()) {
		construct_chunk_grid();
		generate_meshes();
	}
}

void Terrain::set_detail(size_t detail) {
	this->detail = detail;
	if (is_inside_tree()) {
		construct_chunk_grid();
		generate_meshes();
	}
}

size_t Terrain::get_detail() const {
	return this->detail;
}