/**************************************************************************/
/*  lightmap_gi_gizmo_plugin.cpp                                          */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "lightmap_gi_gizmo_plugin.h"

#include "editor/editor_node.h"
#include "editor/editor_settings.h"
#include "editor/editor_string_names.h"
#include "scene/3d/lightmap_gi.h"

LightmapGIGizmoPlugin::LightmapGIGizmoPlugin() {
	Color gizmo_color = EDITOR_GET("editors/3d_gizmos/gizmo_colors/lightmap_lines");

	gizmo_color.a = 0.1;
	create_material("lightmap_lines", gizmo_color);

	Ref<StandardMaterial3D> mat = memnew(StandardMaterial3D);
	mat->set_shading_mode(StandardMaterial3D::SHADING_MODE_UNSHADED);
	// Fade out probes when camera gets too close to them.
	mat->set_distance_fade(StandardMaterial3D::DISTANCE_FADE_PIXEL_DITHER);
	mat->set_distance_fade_min_distance(0.5);
	mat->set_distance_fade_max_distance(1.5);
	mat->set_flag(StandardMaterial3D::FLAG_ALBEDO_FROM_VERTEX_COLOR, true);
	mat->set_flag(StandardMaterial3D::FLAG_SRGB_VERTEX_COLOR, false);
	mat->set_flag(StandardMaterial3D::FLAG_DISABLE_FOG, true);

	add_material("lightmap_probe_material", mat);

	create_icon_material("baked_indirect_light_icon", EditorNode::get_singleton()->get_editor_theme()->get_icon(SNAME("GizmoLightmapGI"), EditorStringName(EditorIcons)));
}

bool LightmapGIGizmoPlugin::has_gizmo(Node3D *p_spatial) {
	return Object::cast_to<LightmapGI>(p_spatial) != nullptr;
}

String LightmapGIGizmoPlugin::get_gizmo_name() const {
	return "LightmapGI";
}

int LightmapGIGizmoPlugin::get_priority() const {
	return -1;
}

void LightmapGIGizmoPlugin::redraw(EditorNode3DGizmo *p_gizmo) {
	Ref<Material> icon = get_material("baked_indirect_light_icon", p_gizmo);
	LightmapGI *baker = Object::cast_to<LightmapGI>(p_gizmo->get_node_3d());
	Ref<LightmapGIData> data = baker->get_light_data();

	p_gizmo->clear();

	p_gizmo->add_unscaled_billboard(icon, 0.05);

	if (data.is_null() || !p_gizmo->is_selected()) {
		return;
	}

	Ref<Material> material_lines = get_material("lightmap_lines", p_gizmo);
	Ref<Material> material_probes = get_material("lightmap_probe_material", p_gizmo);

	Vector<Vector3> lines;
	HashSet<Vector2i> lines_found;

	Vector<Vector3> points = data->get_capture_points();
	if (points.size() == 0) {
		return;
	}
	Vector<Color> sh = data->get_capture_sh();
	if (sh.size() != points.size() * 9) {
		return;
	}

	Vector<int> tetrahedrons = data->get_capture_tetrahedra();

	for (int i = 0; i < tetrahedrons.size(); i += 4) {
		for (int j = 0; j < 4; j++) {
			for (int k = j + 1; k < 4; k++) {
				Vector2i pair;
				pair.x = tetrahedrons[i + j];
				pair.y = tetrahedrons[i + k];

				if (pair.y < pair.x) {
					SWAP(pair.x, pair.y);
				}
				if (lines_found.has(pair)) {
					continue;
				}
				lines_found.insert(pair);
				lines.push_back(points[pair.x]);
				lines.push_back(points[pair.y]);
			}
		}
	}

	p_gizmo->add_lines(lines, material_lines);

	int stack_count = 8;
	int sector_count = 16;

	float sector_step = (Math_PI * 2.0) / sector_count;
	float stack_step = Math_PI / stack_count;

	Vector<Vector3> vertices;
	Vector<Color> colors;
	Vector<int> indices;
	float radius = 0.3;

	for (int p = 0; p < points.size(); p++) {
		int vertex_base = vertices.size();
		Vector3 sh_col[9];
		for (int i = 0; i < 9; i++) {
			sh_col[i].x = sh[p * 9 + i].r;
			sh_col[i].y = sh[p * 9 + i].g;
			sh_col[i].z = sh[p * 9 + i].b;
		}

		for (int i = 0; i <= stack_count; ++i) {
			float stack_angle = Math_PI / 2 - i * stack_step; // starting from pi/2 to -pi/2
			float xy = radius * Math::cos(stack_angle); // r * cos(u)
			float z = radius * Math::sin(stack_angle); // r * sin(u)

			// add (sector_count+1) vertices per stack
			// the first and last vertices have same position and normal, but different tex coords
			for (int j = 0; j <= sector_count; ++j) {
				float sector_angle = j * sector_step; // starting from 0 to 2pi

				// vertex position (x, y, z)
				float x = xy * Math::cos(sector_angle); // r * cos(u) * cos(v)
				float y = xy * Math::sin(sector_angle); // r * cos(u) * sin(v)

				Vector3 n = Vector3(x, z, y);
				vertices.push_back(points[p] + n);
				n.normalize();

				const float c1 = 0.429043;
				const float c2 = 0.511664;
				const float c3 = 0.743125;
				const float c4 = 0.886227;
				const float c5 = 0.247708;
				Vector3 light = (c1 * sh_col[8] * (n.x * n.x - n.y * n.y) +
						c3 * sh_col[6] * n.z * n.z +
						c4 * sh_col[0] -
						c5 * sh_col[6] +
						2.0 * c1 * sh_col[4] * n.x * n.y +
						2.0 * c1 * sh_col[7] * n.x * n.z +
						2.0 * c1 * sh_col[5] * n.y * n.z +
						2.0 * c2 * sh_col[3] * n.x +
						2.0 * c2 * sh_col[1] * n.y +
						2.0 * c2 * sh_col[2] * n.z);

				colors.push_back(Color(light.x, light.y, light.z, 1));
			}
		}

		for (int i = 0; i < stack_count; ++i) {
			int k1 = i * (sector_count + 1); // beginning of current stack
			int k2 = k1 + sector_count + 1; // beginning of next stack

			for (int j = 0; j < sector_count; ++j, ++k1, ++k2) {
				// 2 triangles per sector excluding first and last stacks
				// k1 => k2 => k1+1
				if (i != 0) {
					indices.push_back(vertex_base + k1);
					indices.push_back(vertex_base + k2);
					indices.push_back(vertex_base + k1 + 1);
				}

				// k1+1 => k2 => k2+1
				if (i != (stack_count - 1)) {
					indices.push_back(vertex_base + k1 + 1);
					indices.push_back(vertex_base + k2);
					indices.push_back(vertex_base + k2 + 1);
				}
			}
		}
	}

	Array array;
	array.resize(RS::ARRAY_MAX);
	array[RS::ARRAY_VERTEX] = vertices;
	array[RS::ARRAY_INDEX] = indices;
	array[RS::ARRAY_COLOR] = colors;

	Ref<ArrayMesh> mesh;
	mesh.instantiate();
	mesh->add_surface_from_arrays(Mesh::PRIMITIVE_TRIANGLES, array, Array(), Dictionary(), 0); //no compression
	mesh->surface_set_material(0, material_probes);

	p_gizmo->add_mesh(mesh);
}
