/*
 *   This file is a part of the SteamWar software.
 *
 *   Copyright (C) 2025 SteamWar.de-Serverteam
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Affero General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *   GNU Affero General Public License for more details.
 *
 *   You should have received a copy of the GNU Affero General Public License
 *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package de.steamwar.lobby.particle.elements.touch;

import de.steamwar.lobby.particle.BodyMotion;
import de.steamwar.lobby.particle.ParticleElement;
import de.steamwar.lobby.particle.ParticleTickData;
import de.steamwar.lobby.particle.elements.DelegatingParticleElement;
import org.bukkit.Location;
import org.bukkit.entity.Player;
import org.bukkit.util.Vector;

import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;

// A line of particles between nearby players who show the same link. It starts in one player's particle and blends
// into the other's towards them. Each pair is drawn by only one of them.
public class TeamLink extends DelegatingParticleElement {

    public static final double RANGE = 8;
    private static final double CHEST = 1.2;
    // Spreads the blend evenly along the line, so it does not flicker from tick to tick
    private static final double GOLDEN_RATIO = 0.6180339887;

    private record Showing(long tick, ParticleElement particle) {
    }

    // Per link, who showed it in which tick with which particle
    private static final Map<String, Map<Player, Showing>> SHOWING = new HashMap<>();

    private final String link;
    private final double spacing;

    public TeamLink(String link, ParticleElement particleElement, double spacing) {
        super(particleElement);
        this.link = link;
        this.spacing = spacing;
    }

    @Override
    public void tick(ParticleTickData particleTickData) {
        Player player = particleTickData.getPlayer();
        long now = BodyMotion.currentTick();
        Map<Player, Showing> showing = SHOWING.computeIfAbsent(link, key -> new WeakHashMap<>());
        showing.put(player, new Showing(now, particleElement));

        Location from = player.getLocation().add(0, CHEST, 0);
        for (Map.Entry<Player, Showing> other : showing.entrySet()) {
            Player partner = other.getKey();
            // Still showing it, and drawn by the player with the smaller id only
            if (partner == player || other.getValue().tick() < now - 1 || player.getUniqueId().compareTo(partner.getUniqueId()) > 0) continue;
            Location to = partner.getLocation().add(0, CHEST, 0);
            if (to.getWorld() != from.getWorld() || to.distanceSquared(from) > RANGE * RANGE) continue;

            Vector step = to.toVector().subtract(from.toVector());
            int points = (int) Math.ceil(step.length() / spacing);
            step.multiply(1.0 / points);
            for (int i = 1; i < points; i++) {
                double towardsPartner = (double) i / points;
                ParticleElement particle = (i * GOLDEN_RATIO) % 1 < towardsPartner ? other.getValue().particle() : particleElement;
                particle.tick(particleTickData.withLocation(from.clone().add(step.clone().multiply(i))));
            }
        }
    }
}