Desert Strife AI - Version 3

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class AI
{
    public class AIMove
    {
        public ArmyView Army;
        public TileView Target;
        public float Distance;

        public AIMove(ArmyView army, TileView target, float distance)
        {
            Army = army;
            Target = target;
            Distance = distance;
        }
    }

    public static AIMove RunAI(List<ArmyView> allies, List<ArmyView> enemies, TileView[,] world)
    {
        if (enemies.Count == 0) return null;

        var moves = new List<AIMove>();
        foreach (var ally in allies)
        {
            if (ally.Disabled) continue;
            if (!ally.CanMove) continue;
            if (ally.TechnologyExcavationIndex > 0) continue;//always excavate to the end!

            //find closest enemy
            ArmyView closestEnemy = null;
            float closestEnemyDistance = float.MaxValue;
            foreach (var enemy in enemies)
            {
                //can find path to target?
                if (PathFinder.FindPath(world, ally.CurrentTile.Position, enemy.CurrentTile.Position, ally.TeamID) == null)
                    continue;

                //check if closest target
                float distance = Distance(ally, enemy);
                if (distance < closestEnemyDistance)
                {
                    closestEnemyDistance = distance;
                    closestEnemy = enemy;
                }
            }

            //find closest technology
            TileView closestTech = null;
            float closestTechDistance = float.MaxValue;
            foreach (var tile in world)
            {
                //only check legal targets
                if (tile.Type != TileView.TypeID.Technology || tile.TechnologyCount == 0 || tile.CurrentArmy != null)
                    continue;

                //can find path to target?
                if (PathFinder.FindPath(world, ally.CurrentTile.Position, tile.Position, ally.TeamID) == null)
                    continue;

                //check if closest target
                float distance = Distance(ally.CurrentTile, tile);
                if (distance < closestTechDistance)
                {
                    closestTechDistance = distance;
                    closestTech = tile;
                }
            }

            //choose target -> enemy is default target
            TileView targetTile = closestEnemy.CurrentTile;
            float targetDistance = closestEnemyDistance;

            //go for tech if it is far away enough from closest enemy
            if (closestTech != null && closestTechDistance + 2 < closestEnemyDistance)
            {
                targetTile = closestTech;
                targetDistance = closestTechDistance;
            }

            moves.Add(new AIMove(ally, targetTile, targetDistance));
        }

        //choose best move -> attacks first, tech second
        bool bestIsAttack = false;
        float bestDistance = float.MaxValue;
        AIMove bestMove = null;
        for (int i = 0; i < moves.Count; i++)
        {
            var move = moves[i];
            if (moves[i].Target.CurrentArmy != null)
            {
                //attack
                if (move.Distance < bestDistance)
                {
                    bestIsAttack = true;
                    bestDistance = move.Distance;
                    bestMove = move;
                }
            }
            else if (!bestIsAttack)
            {
                //tech
                if (move.Distance < bestDistance)
                {
                    bestMove = move;
                    bestDistance = move.Distance;
                }
            }
        }
        return bestMove;
    }

    private static float Distance(ArmyView army1, ArmyView army2)
    {
        return Distance(army1.CurrentTile, army2.CurrentTile);
    }

    private static float Distance(TileView tile1, TileView tile2)
    {
        return Vector2.Distance(tile1.Position, tile2.Position);
    }
}