/*************************************************************************/
/*  path_2d.cpp                                                          */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                      https://godotengine.org                          */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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/* a copy of this software and associated documentation files (the       */
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#include "path_2d.h"

#include "core/config/engine.h"
#include "core/math/geometry_2d.h"
#include "scene/scene_string_names.h"

#ifdef TOOLS_ENABLED
#include "editor/editor_scale.h"
#endif

#ifdef TOOLS_ENABLED
Rect2 Path2D::_edit_get_rect() const {
	if (!curve.is_valid() || curve->get_point_count() == 0) {
		return Rect2(0, 0, 0, 0);
	}

	Rect2 aabb = Rect2(curve->get_point_position(0), Vector2(0, 0));

	for (int i = 0; i < curve->get_point_count(); i++) {
		for (int j = 0; j <= 8; j++) {
			real_t frac = j / 8.0;
			Vector2 p = curve->interpolate(i, frac);
			aabb.expand_to(p);
		}
	}

	return aabb;
}

bool Path2D::_edit_use_rect() const {
	return curve.is_valid() && curve->get_point_count() != 0;
}

bool Path2D::_edit_is_selected_on_click(const Point2 &p_point, double p_tolerance) const {
	if (curve.is_null()) {
		return false;
	}

	for (int i = 0; i < curve->get_point_count(); i++) {
		Vector2 s[2];
		s[0] = curve->get_point_position(i);

		for (int j = 1; j <= 8; j++) {
			real_t frac = j / 8.0;
			s[1] = curve->interpolate(i, frac);

			Vector2 p = Geometry2D::get_closest_point_to_segment(p_point, s);
			if (p.distance_to(p_point) <= p_tolerance) {
				return true;
			}

			s[0] = s[1];
		}
	}

	return false;
}
#endif

void Path2D::_notification(int p_what) {
	if (p_what == NOTIFICATION_DRAW && curve.is_valid()) {
		//draw the curve!!

		if (!Engine::get_singleton()->is_editor_hint() && !get_tree()->is_debugging_navigation_hint()) {
			return;
		}

#ifdef TOOLS_ENABLED
		const float line_width = 2 * EDSCALE;
#else
		const float line_width = 2;
#endif
		const Color color = Color(0.5, 0.6, 1.0, 0.7);

		for (int i = 0; i < curve->get_point_count(); i++) {
			Vector2 prev_p = curve->get_point_position(i);

			for (int j = 1; j <= 8; j++) {
				real_t frac = j / 8.0;
				Vector2 p = curve->interpolate(i, frac);
				draw_line(prev_p, p, color, line_width);
				prev_p = p;
			}
		}
	}
}

void Path2D::_curve_changed() {
	if (!is_inside_tree()) {
		return;
	}

	if (!Engine::get_singleton()->is_editor_hint() && !get_tree()->is_debugging_navigation_hint()) {
		return;
	}

	update();
}

void Path2D::set_curve(const Ref<Curve2D> &p_curve) {
	if (curve.is_valid()) {
		curve->disconnect("changed", callable_mp(this, &Path2D::_curve_changed));
	}

	curve = p_curve;

	if (curve.is_valid()) {
		curve->connect("changed", callable_mp(this, &Path2D::_curve_changed));
	}

	_curve_changed();
}

Ref<Curve2D> Path2D::get_curve() const {
	return curve;
}

void Path2D::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_curve", "curve"), &Path2D::set_curve);
	ClassDB::bind_method(D_METHOD("get_curve"), &Path2D::get_curve);

	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve2D", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_EDITOR_INSTANTIATE_OBJECT), "set_curve", "get_curve");
}

/////////////////////////////////////////////////////////////////////////////////

void PathFollow2D::_update_transform() {
	if (!path) {
		return;
	}

	Ref<Curve2D> c = path->get_curve();
	if (!c.is_valid()) {
		return;
	}

	float path_length = c->get_baked_length();
	if (path_length == 0) {
		return;
	}
	Vector2 pos = c->interpolate_baked(offset, cubic);

	if (rotates) {
		float ahead = offset + lookahead;

		if (loop && ahead >= path_length) {
			// If our lookahead will loop, we need to check if the path is closed.
			int point_count = c->get_point_count();
			if (point_count > 0) {
				Vector2 start_point = c->get_point_position(0);
				Vector2 end_point = c->get_point_position(point_count - 1);
				if (start_point == end_point) {
					// Since the path is closed we want to 'smooth off'
					// the corner at the start/end.
					// So we wrap the lookahead back round.
					ahead = Math::fmod(ahead, path_length);
				}
			}
		}

		Vector2 ahead_pos = c->interpolate_baked(ahead, cubic);

		Vector2 tangent_to_curve;
		if (ahead_pos == pos) {
			// This will happen at the end of non-looping or non-closed paths.
			// We'll try a look behind instead, in order to get a meaningful angle.
			tangent_to_curve =
					(pos - c->interpolate_baked(offset - lookahead, cubic)).normalized();
		} else {
			tangent_to_curve = (ahead_pos - pos).normalized();
		}

		Vector2 normal_of_curve = -tangent_to_curve.orthogonal();

		pos += tangent_to_curve * h_offset;
		pos += normal_of_curve * v_offset;

		set_rotation(tangent_to_curve.angle());

	} else {
		pos.x += h_offset;
		pos.y += v_offset;
	}

	set_position(pos);
}

void PathFollow2D::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			path = Object::cast_to<Path2D>(get_parent());
			if (path) {
				_update_transform();
			}

		} break;
		case NOTIFICATION_EXIT_TREE: {
			path = nullptr;
		} break;
	}
}

void PathFollow2D::set_cubic_interpolation(bool p_enable) {
	cubic = p_enable;
}

bool PathFollow2D::get_cubic_interpolation() const {
	return cubic;
}

void PathFollow2D::_validate_property(PropertyInfo &property) const {
	if (property.name == "offset") {
		float max = 10000.0;
		if (path && path->get_curve().is_valid()) {
			max = path->get_curve()->get_baked_length();
		}

		property.hint_string = "0," + rtos(max) + ",0.01,or_lesser,or_greater";
	}
}

String PathFollow2D::get_configuration_warning() const {
	if (!is_visible_in_tree() || !is_inside_tree()) {
		return String();
	}

	String warning = Node2D::get_configuration_warning();

	if (!Object::cast_to<Path2D>(get_parent())) {
		if (!warning.is_empty()) {
			warning += "\n\n";
		}
		warning += TTR("PathFollow2D only works when set as a child of a Path2D node.");
	}

	return warning;
}

void PathFollow2D::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_offset", "offset"), &PathFollow2D::set_offset);
	ClassDB::bind_method(D_METHOD("get_offset"), &PathFollow2D::get_offset);

	ClassDB::bind_method(D_METHOD("set_h_offset", "h_offset"), &PathFollow2D::set_h_offset);
	ClassDB::bind_method(D_METHOD("get_h_offset"), &PathFollow2D::get_h_offset);

	ClassDB::bind_method(D_METHOD("set_v_offset", "v_offset"), &PathFollow2D::set_v_offset);
	ClassDB::bind_method(D_METHOD("get_v_offset"), &PathFollow2D::get_v_offset);

	ClassDB::bind_method(D_METHOD("set_unit_offset", "unit_offset"), &PathFollow2D::set_unit_offset);
	ClassDB::bind_method(D_METHOD("get_unit_offset"), &PathFollow2D::get_unit_offset);

	ClassDB::bind_method(D_METHOD("set_rotates", "enable"), &PathFollow2D::set_rotates);
	ClassDB::bind_method(D_METHOD("is_rotating"), &PathFollow2D::is_rotating);

	ClassDB::bind_method(D_METHOD("set_cubic_interpolation", "enable"), &PathFollow2D::set_cubic_interpolation);
	ClassDB::bind_method(D_METHOD("get_cubic_interpolation"), &PathFollow2D::get_cubic_interpolation);

	ClassDB::bind_method(D_METHOD("set_loop", "loop"), &PathFollow2D::set_loop);
	ClassDB::bind_method(D_METHOD("has_loop"), &PathFollow2D::has_loop);

	ClassDB::bind_method(D_METHOD("set_lookahead", "lookahead"), &PathFollow2D::set_lookahead);
	ClassDB::bind_method(D_METHOD("get_lookahead"), &PathFollow2D::get_lookahead);

	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "offset", PROPERTY_HINT_RANGE, "0,10000,0.01,or_lesser,or_greater"), "set_offset", "get_offset");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "unit_offset", PROPERTY_HINT_RANGE, "0,1,0.0001,or_lesser,or_greater", PROPERTY_USAGE_EDITOR), "set_unit_offset", "get_unit_offset");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "h_offset"), "set_h_offset", "get_h_offset");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "v_offset"), "set_v_offset", "get_v_offset");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "rotates"), "set_rotates", "is_rotating");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "cubic_interp"), "set_cubic_interpolation", "get_cubic_interpolation");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "loop"), "set_loop", "has_loop");
	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "lookahead", PROPERTY_HINT_RANGE, "0.001,1024.0,0.001"), "set_lookahead", "get_lookahead");
}

void PathFollow2D::set_offset(float p_offset) {
	offset = p_offset;
	if (path) {
		if (path->get_curve().is_valid()) {
			float path_length = path->get_curve()->get_baked_length();

			if (loop) {
				offset = Math::fposmod(offset, path_length);
				if (!Math::is_zero_approx(p_offset) && Math::is_zero_approx(offset)) {
					offset = path_length;
				}
			} else {
				offset = CLAMP(offset, 0, path_length);
			}
		}

		_update_transform();
	}
	_change_notify("offset");
	_change_notify("unit_offset");
}

void PathFollow2D::set_h_offset(float p_h_offset) {
	h_offset = p_h_offset;
	if (path) {
		_update_transform();
	}
}

float PathFollow2D::get_h_offset() const {
	return h_offset;
}

void PathFollow2D::set_v_offset(float p_v_offset) {
	v_offset = p_v_offset;
	if (path) {
		_update_transform();
	}
}

float PathFollow2D::get_v_offset() const {
	return v_offset;
}

float PathFollow2D::get_offset() const {
	return offset;
}

void PathFollow2D::set_unit_offset(float p_unit_offset) {
	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
		set_offset(p_unit_offset * path->get_curve()->get_baked_length());
	}
}

float PathFollow2D::get_unit_offset() const {
	if (path && path->get_curve().is_valid() && path->get_curve()->get_baked_length()) {
		return get_offset() / path->get_curve()->get_baked_length();
	} else {
		return 0;
	}
}

void PathFollow2D::set_lookahead(float p_lookahead) {
	lookahead = p_lookahead;
}

float PathFollow2D::get_lookahead() const {
	return lookahead;
}

void PathFollow2D::set_rotates(bool p_rotates) {
	rotates = p_rotates;
	_update_transform();
}

bool PathFollow2D::is_rotating() const {
	return rotates;
}

void PathFollow2D::set_loop(bool p_loop) {
	loop = p_loop;
}

bool PathFollow2D::has_loop() const {
	return loop;
}