app/entities/creatures/strategies/FleeStrategy.js

import Strategy from './Strategy.js';
import Creature from '../Creature.js';
import Dungeon from '../../../dungeons/Dungeon.js';

import Moves from '../moves/Moves.js';

export default class FleeStrategy extends Strategy {
    getNextMove(dungeon, creature) {
        if(!(dungeon instanceof Dungeon)) {
            throw new Error('First parameter must be a Dungeon');
        } else if(!(creature instanceof Creature)) {
            throw new Error('Second parameter must be a Creature');
        }
        var tile = dungeon.getTile(creature);

        var enemies = creature.getVisibleEnemies(dungeon);
        if(enemies.length === 0) {
            return null;
        } else {
            var quarry = enemies.reduce(function(enemy1, enemy2) {
                var d1 = tile.getDirectDistance(dungeon.getTile(enemy1));
                var d2 = tile.getDirectDistance(dungeon.getTile(enemy2));
                if(d1 <= d2) {
                    return enemy1;
                } else {
                    return enemy2;
                }
            });

            var surroundingTiles = tile.getNeighbors8(dungeon).filter((tile) => {
                return creature.canOccupyNow(tile);
            }).filter((tile) => {
                // Fleeing creature won't stand next to enemy
                return !tile.getNeighbors8(dungeon).find((tile)=>tile.getCreature() && tile.getCreature().isEnemy(creature));
            });

            if(surroundingTiles.length === 0) {
                return null;
            } else {
                var target = surroundingTiles.reduce(function(tile1, tile2) {
                    var d1 = tile.getDirectDistance(tile1);
                    var d2 = tile.getDirectDistance(tile2);
                    return d1 > d2 ? tile1 : tile2;
                });

                var dx = target.getX() - tile.getX();
                var dy = target.getY() - tile.getY();

                return new Moves.MovementMove(tile, dx, dy);
            }
        }
    }
}