/*
 * Copyright (c) 2017-2019 sel-project
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
/**
 * Copyright: Copyright (c) 2017-2019 sel-project
 * License: MIT
 * Authors: Kripth
 * Source: $(HTTP github.com/sel-project/selery/source/selery/effect.d, selery/effect.d)
 */
module selery.effect;

import selery.about : tick_t;
import selery.entity.human : Human;
import selery.entity.living : Living;
import selery.event.world.damage;
import selery.event.world.entity : EntityHealEvent;
import selery.player.player : isPlayerInstance;

static import sul.effects;
public import sul.effects : Effects;

class Effect {
	
	public enum tick_t UNLIMITED = int.max / 20;
	
	public static Effect fromId(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker=null) {
		switch(effect.java.id) {
			case Effects.speed.java.id: return new SpeedChange(effect, victim, level, duration, attacker);
			case Effects.slowness.java.id: return new SpeedChange(effect, victim, level, duration, attacker);
			case Effects.instantHealth.java.id: return new InstantHealth(effect, victim, level, attacker);
			case Effects.instantDamage.java.id: return new InstantDamage(effect, victim, level, attacker);
			case Effects.regeneration.java.id: return new Regeneration(effect, victim, level, duration, attacker);
			case Effects.invisibility.java.id: return new Invisibility(effect, victim, level, duration, attacker);
			case Effects.hunger.java.id: return new Hunger(effect, victim, level, duration, attacker);
			case Effects.poison.java.id: return new Poison(effect, victim, level, duration, attacker);
			case Effects.wither.java.id: return new Wither(effect, victim, level, duration, attacker);
				//TODO health boost
				//TODO absorption
			case Effects.saturation.java.id: return new Saturation(effect, victim, level, duration, attacker);
			case Effects.levitation.java.id: return new Levitation(effect, victim, level, duration, attacker);
			default: return new Effect(effect, victim, level, duration, attacker);
		}
	}
	
	public static Effect fromId(sul.effects.Effect effect, Living victim, ubyte level, Living attacker=null) {
		return fromId(effect, victim, level, 30, attacker);
	}
	
	//TODO from string
	
	//TODO from java
	
	//TODO from pocket
	
	public const sul.effects.Effect effect;
	
	private Living n_victim;
	private Living n_attacker;
	
	public immutable ubyte level;
	public immutable uint levelFromOne;
	
	public immutable tick_t duration;
	protected tick_t ticks = 0;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		this.effect = effect;
		this.n_victim = victim;
		this.n_attacker = attacker;
		this.level = level;
		this.levelFromOne = 1 + level;
		this.duration = duration * 20;
	}
	
	public final pure nothrow @property @safe @nogc ubyte id() {
		return this.effect.java;
	}
	
	public final pure nothrow @property @safe @nogc Living victim() {
		return this.n_victim;
	}
	
	public final pure nothrow @property @safe @nogc Living attacker() {
		return this.n_attacker;
	}
	
	public pure nothrow @property @safe @nogc bool instant() {
		return false;
	}
	
	// called after the effect is added
	public void onStart() {}
	
	// called after the effect id removed
	public void onStop() {}
	
	public void tick() {
		this.ticks++;
	}
	
	public final pure nothrow @property @safe @nogc bool finished() {
		return this.ticks >= this.duration;
	}
	
	public bool opEquals(sul.effects.Effect e) {
		return this.id == e.java.id;
	}
	
	alias effect this;
	
}

class SpeedChange : Effect {
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
	}
	
	public override void onStart() {
		this.victim.recalculateSpeed();
	}
	
	public override void onStop() {
		this.victim.recalculateSpeed();
	}
	
}

abstract class InstantEffect : Effect {
	
	public this(sul.effects.Effect, Living victim, ubyte level, Living attacker) {
		super(effect, victim, level, 0, attacker);
	}
	
	public final override pure nothrow @property @safe @nogc bool instant() {
		return true;
	}
	
	public override void onStart() {
		this.apply();
	}
	
	protected abstract void apply();
	
}

class InstantHealth : InstantEffect {
	
	public this(sul.effects.Effect, Living victim, ubyte level, Living attacker) {
		super(effect, victim, level, attacker);
	}
	
	protected override void apply() {
		//TODO heal entity (or damage undeads)
	}
	
}

class InstantDamage : InstantEffect {
	
	public this(sul.effects.Effect, Living victim, ubyte level, Living attacker) {
		super(effect, victim, level, attacker);
	}
	
	protected override void apply() {
		//TODO damage entity (or heal undeads)
	}
	
}

abstract class RepetitionEffect(tick_t[] repetitions) : Effect {
	
	protected immutable tick_t repeat;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
		static if(repetitions.length > 1) {
			this.repeat = level < repetitions.length ? repetitions[level] : repetitions[$-1];
		} else {
			this.repeat = repetitions[0];
		}
	}
	
	public override void tick() {
		super.tick();
		if(this.ticks % this.repeat == 0) {
			this.onRepeat();
		}
	}
	
	public abstract void onRepeat();
	
}

class Regeneration : RepetitionEffect!([50, 25, 12, 6, 3, 1]) {
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
	}
	
	public override void onRepeat() {
		this.victim.heal(new EntityHealEvent(this.victim, 1));
	}
	
}

class Invisibility : Effect {
	
	private bool invisible, show_nametag;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
	}
	
	public override void onStart() {
		this.invisible = this.victim.invisible;
		this.show_nametag = this.victim.showNametag;
		this.victim.invisible = true;
		this.victim.showNametag = false;
	}
	
	public override void onStop() {
		this.victim.invisible = this.invisible;
		this.victim.showNametag = this.show_nametag;
	}
	
}

class Hunger : Effect {
	
	private Human human;
	private immutable float exhaustion;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
		this.human = cast(Human)victim; //TODO assert this
		this.exhaustion = .005f * levelFromOne;
	}
	
	public override void tick() {
		super.tick();
		this.human.exhaust(this.exhaustion);
	}
	
}

class Poison : RepetitionEffect!([25, 12, 6, 3, 1]) {
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
	}
	
	public override void onRepeat() {
		if(this.victim.health > 1) {
			this.victim.attack(new EntityDamageByPoisonEvent(this.victim)); //TODO thrown by player
		}
	}
	
}

class Wither : RepetitionEffect!([40, 20, 10, 5, 2, 1]) {
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
	}
	
	public override void onRepeat() {
		this.victim.attack(new EntityDamageByWitherEffectEvent(this.victim)); //TODO thrown by player
	}
	
}

class Saturation : Effect {
	
	private Human human;
	private immutable uint food;
	private immutable float saturation;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
		this.human = cast(Human)victim; //TODO assert this
		this.food = this.levelFromOne;
		this.saturation = this.levelFromOne * 2;
	}
	
	public override void tick() {
		super.tick();
		if(this.human.hunger < 20) this.human.hunger = this.human.hunger + this.food;
		this.human.saturate(this.saturation);
	}
	
}

class Levitation : Effect {
	
	private void delegate() apply;
	private immutable double distance;
	
	public this(sul.effects.Effect effect, Living victim, ubyte level, tick_t duration, Living attacker) {
		super(effect, victim, level, duration, attacker);
		this.distance = .9 * this.levelFromOne / 20;
		if(!isPlayerInstance(victim)) {
			this.apply = &this.move;
		} else {
			this.apply = &this.doNothing;
		}
	}
	
	public override void tick() {
		super.tick();
		this.apply();
	}
	
	private void move() {
		//TODO check flying and underwater
		//TODO do not move into a block
		this.victim.move(this.victim.position + [0, this.distance, 0]);
	}
	
	private void doNothing() {}
	
}