import { SquareVectorDistance } from "simulation/ai/common-api/utils.js";

export class EntityCollection
{
	constructor(sharedAI, entities = new Map(), filters = [])
	{
		this._ai = sharedAI;
		this._entities = entities;
		this._filters = filters;
		this.dynamicProp = [];
		for (const filter of this._filters)
			if (filter.dynamicProperties.length)
				this.dynamicProp = this.dynamicProp.concat(filter.dynamicProperties);

		Object.defineProperty(this, "length", { "get": () => this._entities.size });
		this.frozen = false;
	}

	Serialize()
	{
		const filters = [];
		for (const f of this._filters)
			filters.push(uneval(f));
		return {
			"ents": this.toIdArray(),
			"frozen": this.frozen,
			"filters": filters
		};
	}

	Deserialize(data, sharedAI)
	{
		this._ai = sharedAI;
		for (const id of data.ents)
			this._entities.set(id, sharedAI._entities.get(id));

		for (const f of data.filters)
			this._filters.push(eval(f));

		if (data.frozen)
			this.freeze();
		else
			this.defreeze();
	}

	/**
	 * If an entitycollection is frozen, it will never automatically add a unit.
	 * But can remove one.
	 * this makes it easy to create entity collection that will auto-remove dead units
	 * but never add new ones.
	 */
	freeze()
	{
		this.frozen = true;
	}

	defreeze()
	{
		this.frozen = false;
	}

	toIdArray()
	{
		return Array.from(this._entities.keys());
	}

	toEntityArray()
	{
		return Array.from(this._entities.values());
	}

	values()
	{
		return this._entities.values();
	}

	toString()
	{
		return "[EntityCollection " + this.toEntityArray().join(" ") + "]";
	}

	filter(filter, thisp)
	{
		if (typeof filter === "function")
			filter = { "func": filter, "dynamicProperties": [] };

		const ret = new Map();
		for (const [id, ent] of this._entities)
			if (filter.func.call(thisp, ent, id, this))
				ret.set(id, ent);

		return new EntityCollection(this._ai, ret, this._filters.concat([filter]));
	}

	/**
	 * Returns the (at most) n entities nearest to targetPos.
	 */
	filterNearest(targetPos, n)
	{
		// Compute the distance of each entity
		const data = []; // [ [id, ent, distance], ... ]
		for (const [id, ent] of this._entities)
			if (ent.position())
				data.push([id, ent, SquareVectorDistance(targetPos, ent.position())]);

		// Sort by increasing distance
		data.sort((a, b) => a[2] - b[2]);

		if (n === undefined)
			n = data.length;
		else
			n = Math.min(n, data.length);

		// Extract the first n
		const ret = new Map();
		for (let i = 0; i < n; ++i)
			ret.set(data[i][0], data[i][1]);

		return new EntityCollection(this._ai, ret);
	}

	filter_raw(callback, thisp)
	{
		const ret = new Map();
		for (const [id, ent] of this._entities)
		{
			const val = ent._entity;
			if (callback.call(thisp, val, id, this))
				ret.set(id, ent);
		}
		return new EntityCollection(this._ai, ret);
	}

	forEach(callback)
	{
		for (const ent of this._entities.values())
			callback(ent);
		return this;
	}

	hasEntities()
	{
		return this._entities.size !== 0;
	}

	move(x, z, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "walk",
			"entities": this.toIdArray(),
			"x": x,
			"z": z,
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	moveToRange(x, z, min, max, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "walk-to-range",
			"entities": this.toIdArray(),
			"x": x,
			"z": z,
			"min": min,
			"max": max,
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	attackMove(x, z, targetClasses, allowCapture = true, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "attack-walk",
			"entities": this.toIdArray(),
			"x": x,
			"z": z,
			"targetClasses": targetClasses,
			"allowCapture": allowCapture,
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	moveIndiv(x, z, queued = false, pushFront = false)
	{
		for (const id of this._entities.keys())
			Engine.PostCommand(PlayerID, {
				"type": "walk",
				"entities": [id],
				"x": x,
				"z": z,
				"queued": queued,
				"pushFront": pushFront
			});
		return this;
	}

	garrison(target, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "garrison",
			"entities": this.toIdArray(),
			"target": target.id(),
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	occupyTurret(target, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "occupy-turret",
			"entities": this.toIdArray(),
			"target": target.id(),
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	destroy()
	{
		Engine.PostCommand(PlayerID, { "type": "delete-entities", "entities": this.toIdArray() });
		return this;
	}

	attack(unitId, queued = false, pushFront = false)
	{
		Engine.PostCommand(PlayerID, {
			"type": "attack",
			"entities": this.toIdArray(),
			"target": unitId,
			"queued": queued,
			"pushFront": pushFront
		});
		return this;
	}

	/** violent, aggressive, defensive, passive, standground */
	setStance(stance)
	{
		Engine.PostCommand(PlayerID, {
			"type": "stance",
			"entities": this.toIdArray(),
			"name": stance
		});
		return this;
	}

	/** Returns the average position of all units */
	getCentrePosition()
	{
		const sumPos = [0, 0];
		let count = 0;
		for (const ent of this._entities.values())
		{
			if (!ent.position())
				continue;
			sumPos[0] += ent.position()[0];
			sumPos[1] += ent.position()[1];
			count++;
		}

		return count ? [sumPos[0]/count, sumPos[1]/count] : undefined;
	}

	/**
	 * returns the average position from the sample first units.
	 * This might be faster for huge collections, but there's
	 * always a risk that it'll be unprecise.
	 */
	getApproximatePosition(sample)
	{
		const sumPos = [0, 0];
		let i = 0;
		for (const ent of this._entities.values())
		{
			if (!ent.position())
				continue;
			sumPos[0] += ent.position()[0];
			sumPos[1] += ent.position()[1];
			i++;
			if (i === sample)
				break;
		}

		return i ? [sumPos[0]/i, sumPos[1]/i] : undefined;
	}

	hasEntId(id)
	{
		return this._entities.has(id);
	}

	/** Removes an entity from the collection, returns true if the entity was a member, false otherwise */
	removeEnt(ent)
	{
		if (!this._entities.has(ent.id()))
			return false;
		this._entities.delete(ent.id());
		return true;
	}

	/** Adds an entity to the collection, returns true if the entity was not member, false otherwise */
	addEnt(ent)
	{
		if (this._entities.has(ent.id()))
			return false;
		this._entities.set(ent.id(), ent);
		const temp = this.toEntityArray();
		temp.sort((a, b) => a.id() - b.id());
		this._entities.clear();
		for (const e of temp)
			this._entities.set(e.id(), e);
		return true;
	}

	/**
	 * Checks the entity against the filters, and adds or removes it appropriately, returns true if the
	 * entity collection was modified.
	 * Force can add a unit despite a freezing.
	 * If an entitycollection is frozen, it will never automatically add a unit.
	 * But can remove one.
	 */
	updateEnt(ent, force)
	{
		let passesFilters = true;
		for (const filter of this._filters)
			passesFilters = passesFilters && filter.func(ent);

		if (passesFilters)
		{
			if (!force && this.frozen)
				return false;
			return this.addEnt(ent);
		}

		return this.removeEnt(ent);
	}

	registerUpdates()
	{
		this._ai.registerUpdatingEntityCollection(this);
	}

	unregister()
	{
		this._ai.removeUpdatingEntityCollection(this);
	}

	dynamicProperties()
	{
		return this.dynamicProp;
	}

	setUID(id)
	{
		this._UID = id;
	}

	getUID()
	{
		return this._UID;
	}
}