#include "terrain_modifier.h"
#include "core/config/engine.h"
#include "core/variant/variant.h"
#include "macros.h"
#include <algorithm>

void TerrainModifier::_bind_methods() {
	BIND_HPROPERTY(Variant::INT, blend_mode, PROPERTY_HINT_ENUM, BlendMode_hint());
	BIND_PROPERTY(Variant::FLOAT, blend_distance);
	ADD_SIGNAL(MethodInfo(sig_changed));
}

void TerrainModifier::_notification(int what) {
	switch (what) {
		default:
			return;
		case NOTIFICATION_ENTER_TREE:
			if (Engine::get_singleton()->is_editor_hint()) {
				set_notify_transform(true);
			}
			this->thread_safe_global_position = get_global_position();
		case NOTIFICATION_TRANSFORM_CHANGED:
			if (Engine::get_singleton()->is_editor_hint()) {
				emit_signal(sig_changed);
			}
			this->thread_safe_global_position = get_global_position();
			return;
	}
}

float TerrainModifier::blend(float under, float over) {
	float const difference{ under - over };
	float const distance{ Math::abs(difference) };
	// .25 because we need half of each half of the blend range to be used
	float const center_distance{
		this->blend_distance == 0.f
				? 0.f
				: this->blend_distance * 0.25f - distance / this->blend_distance
	};
	if (center_distance < 0.f) {
		if (this->blend_mode == Override) {
			return over;
		} else if (this->blend_mode == Add) {
			return under > over ? under : over;
		} else {
			return under > over ? over : under;
		}
	}
	float const smooth_center_distance{ center_distance * center_distance };
	if (this->blend_mode == Override) {
		return over + smooth_center_distance;
	} else {
		return (this->blend_mode == Add
						? (under > over ? under : over) + smooth_center_distance
						: (under > over ? over : under) - smooth_center_distance);
	}
}

void TerrainModifier::changed() {
	this->dirty = true;
	emit_signal(sig_changed);
}

void TerrainModifier::changed_deferred() {
	callable_mp(this, &self_type::changed).call_deferred();
}

float TerrainModifier::evaluate_at(Vector2 world_coordinate, float before) {
	Vector3 const global_position{ get_thread_safe_global_position() };
	world_coordinate -= { global_position.x, global_position.z };
	return blend(before, 0.0);
}

Vector3 TerrainModifier::get_thread_safe_global_position() const {
	return this->thread_safe_global_position;
}

void TerrainModifier::set_blend_distance(float value) {
	this->blend_distance = value;
	emit_signal(sig_changed);
}

float TerrainModifier::get_blend_distance() const {
	return this->blend_distance;
}

void TerrainModifier::set_blend_mode(BlendMode mode) {
	this->blend_mode = mode;
	emit_signal(sig_changed);
}

TerrainModifier::BlendMode TerrainModifier::get_blend_mode() const {
	return this->blend_mode;
}

String const TerrainModifier::sig_changed{ "changed" };

void SharedMutex::lock_shared() {
	this->lock.lock();
	this->shared_count++;
	this->lock.unlock();
}

void SharedMutex::unlock_shared() {
	this->lock.lock();
	this->shared_count--;
	this->lock.unlock();
}

void SharedMutex::lock_exclusive() {
	while (true) {
		this->lock.lock();
		if (this->shared_count == 0) {
			return;
		}
		this->lock.unlock();
	}
}

void SharedMutex::unlock_exclusive() {
	this->lock.unlock();
}

void TerrainModifierDistance::_bind_methods() {
	BIND_HPROPERTY(Variant::OBJECT, distance_weight_curve, PROPERTY_HINT_RESOURCE_TYPE, "Curve");
	BIND_HPROPERTY(Variant::OBJECT, distance_height_curve, PROPERTY_HINT_RESOURCE_TYPE, "Curve");
}

void TerrainModifierDistance::curves_changed() {
	this->lock.lock_shared();
	if (this->distance_height_curve.is_valid()) {
		this->distance_height_curve->bake();
	}
	if (this->distance_weight_curve.is_valid()) {
		this->distance_weight_curve->bake();
	}
	this->lock.unlock_shared();
	changed();
}

float TerrainModifierDistance::distance_at(Vector2 const &world_coordinate) {
	Vector3 const global_position{ get_thread_safe_global_position() };
	return world_coordinate.distance_to({ global_position.x, global_position.z });
}

float TerrainModifierDistance::evaluate_at(Vector2 world_coordinate, float before) {
	this->lock.lock_shared();
	if (this->distance_weight_curve.is_null() || this->distance_height_curve.is_null()) {
		this->lock.unlock_shared();
		return before;
	}
	float const distance{ distance_at(world_coordinate) };
	if (distance >= this->distance_weight_curve->get_max_domain()) {
		this->lock.unlock_shared();
		return before;
	}
	float const weight_offset{
		std::clamp(distance, this->distance_weight_curve->get_min_domain(), this->distance_weight_curve->get_max_domain())
	};
	float const height_offset{
		std::clamp(distance, this->distance_height_curve->get_min_domain(), this->distance_height_curve->get_max_domain())
	};
	this->lock.unlock_shared();

	this->lock.lock_exclusive();
	float const weight{ this->distance_weight_curve->sample_baked(weight_offset) };
	float const height{ this->distance_height_curve->sample_baked(height_offset) };
	this->lock.unlock_exclusive();

	this->lock.lock_shared();
	float out{ weight <= 0.f ? before : Math::lerp(before, blend(before, height + get_thread_safe_global_position().y), weight) };
	this->lock.unlock_shared();

	return out;
}

PackedStringArray TerrainModifierDistance::get_configuration_warnings() const {
	PackedStringArray warnings{ super_type::get_configuration_warnings() };
	if (this->distance_weight_curve.is_null()) {
		warnings.push_back("distance_weight_curve is invalid, add a valid distance_weight_curve");
	}
	if (this->distance_height_curve.is_null()) {
		warnings.push_back("distance_height_curve is invalid, add a valid distance_height_curve");
	}
	return warnings;
}

void TerrainModifierDistance::set_distance_weight_curve(Ref<Curve> curve) {
	this->lock.lock_exclusive();
	if (Engine::get_singleton()->is_editor_hint()) {
		if (this->distance_weight_curve.is_valid()) {
			this->distance_weight_curve->disconnect_changed(callable_mp(this, &self_type::curves_changed));
		}
		if (curve.is_valid()) {
			curve->connect_changed(callable_mp(this, &self_type::curves_changed));
		}
	}
	this->distance_weight_curve = curve;
	this->lock.unlock_exclusive();
	curves_changed();
	update_configuration_warnings();
}

Ref<Curve> TerrainModifierDistance::get_distance_weight_curve() const {
	return this->distance_weight_curve;
}

void TerrainModifierDistance::set_distance_height_curve(Ref<Curve> curve) {
	this->lock.lock_exclusive();
	if (Engine::get_singleton()->is_editor_hint()) {
		if (this->distance_height_curve.is_valid()) {
			this->distance_height_curve->disconnect_changed(callable_mp(this, &self_type::curves_changed));
		}
		if (curve.is_valid()) {
			curve->connect_changed(callable_mp(this, &self_type::curves_changed));
		}
	}
	this->distance_height_curve = curve;
	this->lock.unlock_exclusive();
	curves_changed();
	update_configuration_warnings();
}

Ref<Curve> TerrainModifierDistance::get_distance_height_curve() const {
	return this->distance_height_curve;
}