package data.scripts.ai;

import com.fs.starfarer.api.Global;
import com.fs.starfarer.api.combat.CombatEntityAPI;
import com.fs.starfarer.api.combat.DamageType;
import com.fs.starfarer.api.combat.GuidedMissileAI;
import com.fs.starfarer.api.combat.MissileAIPlugin;
import com.fs.starfarer.api.combat.MissileAPI;
import com.fs.starfarer.api.combat.ShipAPI;
import com.fs.starfarer.api.combat.ShipCommand;
import com.fs.starfarer.api.util.IntervalUtil;

import java.util.Collections;
import java.util.List;
import java.util.ListIterator;
import org.lwjgl.util.vector.Vector2f;

import org.lazywizard.lazylib.CollectionUtils;
import org.lazywizard.lazylib.MathUtils;
import org.lazywizard.lazylib.VectorUtils;
import org.lazywizard.lazylib.combat.AIUtils;
import org.lazywizard.lazylib.combat.CombatUtils;

public class exigency_MMMAI2 implements MissileAIPlugin, GuidedMissileAI {

    private final static float SHIT_ACCURACY_RANGE = 300f;
    private final static float SHIT_ACCURACY_AMOUNT = 75f;
    // Time until self destructing
    private final static float FUSE_TIME = 10.5f;
    // Our missile object
    private final MissileAPI missile;
    // Our current target (can be null)
    private CombatEntityAPI target;
    private float offtarget;
    private float baseofftarget;
    private float lifetimer;
    private final float offsetAngle;
    private IntervalUtil timer = new IntervalUtil(0.1f, 0.2f);

    public static ShipAPI findBestTarget(MissileAPI missile) {
        ShipAPI source = missile.getSource();
        if (source != null && source.getShipTarget() != null && !source.getShipTarget().isHulk()) {
            return source.getShipTarget();
        }

        ShipAPI closest = null;
        float distance, closestDistance = Float.MAX_VALUE;

        for (ShipAPI tmp : AIUtils.getEnemiesOnMap(missile)) {
            distance = MathUtils.getDistance(tmp, missile.getLocation());
            if (distance < closestDistance) {
                closest = tmp;
                closestDistance = distance;
            }
        }

        return closest;
    }

    public exigency_MMMAI2(MissileAPI missile, ShipAPI launchingShip) {
        this.missile = missile;
        this.offtarget = 20f * (0.6f + 0.4f * (float) Math.random());       // Max initial off target (scatters missiles at launch)
        this.baseofftarget = 20f * (0.6f + 0.4f * (float) Math.random());   // Min off target (makes missiles stay scattered)
        if ((float) Math.random() > 0.5f) {
            this.offtarget *= -1f;
            this.baseofftarget *= -1f;
        }
        this.lifetimer = FUSE_TIME;
        this.offsetAngle = (float) Math.random() * 360f;

        // Support for 'fire at target by clicking on them' behavior
        List<ShipAPI> directTargets = CombatUtils.getShipsWithinRange(launchingShip.getMouseTarget(), 100f);
        if (!directTargets.isEmpty()) {
            Collections.sort(directTargets, new CollectionUtils.SortEntitiesByDistance(launchingShip.getMouseTarget()));
            ListIterator<ShipAPI> iter = directTargets.listIterator();
            while (iter.hasNext()) {
                ShipAPI tmp = iter.next();
                if (!tmp.isHulk() && tmp.getOwner() != launchingShip.getOwner()) {
                    setTarget(tmp);
                    break;
                }
            }
        }

        // Otherwise, use default MMMAI2 targeting AI
        if (target == null) {
            setTarget(findBestTarget(missile));
        }
    }

    @Override
    public void advance(float amount) {
        if (Global.getCombatEngine().isPaused()) {
            return;
        }

        lifetimer -= amount;
        if (lifetimer <= 0f) {
            Global.getCombatEngine().applyDamage(missile, missile.getLocation(), missile.getHitpoints(), DamageType.OTHER, 0, true, true, missile);
            return;
        }

        timer.advance(amount);

        // Apparently commands still work while fizzling
        if (missile.isFading() || missile.isFizzling()) {
            return;
        }

        // If our current target is lost, assign a new one
        if (target == null || (target instanceof ShipAPI && ((ShipAPI) target).isHulk()) || (missile.getOwner() == target.getOwner()) || !Global.getCombatEngine().isEntityInPlay(target)) {
            setTarget(findBestTarget(missile));
            missile.giveCommand(ShipCommand.ACCELERATE);
            return;
        }

        // Head towards the target, with tail chase guidance
        float distance = MathUtils.getDistance(missile.getLocation(), target.getLocation());
        float offset = 0f;
        if (distance <= SHIT_ACCURACY_RANGE) {
            offset = SHIT_ACCURACY_AMOUNT * (1f - distance / SHIT_ACCURACY_RANGE);
        }
        Vector2f guidedTarget = MathUtils.getPointOnCircumference(target.getLocation(), offset, offsetAngle);
        float angularDistance = MathUtils.getShortestRotation(missile.getFacing(), VectorUtils.getAngle(missile.getLocation(), guidedTarget));

        if (timer.intervalElapsed()) {
            offtarget = (offtarget > 0 ? offtarget - 1 : offtarget + 1); // Reduce off target counter
        }

        float offtargetby = (0f + (offtarget + (baseofftarget * target.getCollisionRadius() / 100f)));

        // Make it slightly more accurate as missile gets closer to target
        if (distance <= target.getCollisionRadius() * 2f) {
            offtargetby *= (distance - target.getCollisionRadius() * 1.5f) / target.getCollisionRadius() + 0.5f;
        }

        if (Math.abs(angularDistance) >= 70f || distance <= target.getCollisionRadius() * 1.5f) {
            missile.setAngularVelocity(angularDistance * 1.5f);
            offtargetby *= 0f;
        }

        float AbsAngD = Math.abs(angularDistance - offtargetby);

        // Point towards target
        if (AbsAngD > 0.5) {
            // Makes missile fly off target
            missile.giveCommand(angularDistance > offtargetby ? ShipCommand.TURN_LEFT : ShipCommand.TURN_RIGHT);
        }

        // Course correction
        if (AbsAngD < 5) {
            float MFlightAng = VectorUtils.getAngle(new Vector2f(0, 0), missile.getVelocity());
            float MFlightCC = MathUtils.getShortestRotation(missile.getFacing(), MFlightAng);
            if (Math.abs(MFlightCC) > 20) {
                missile.giveCommand(MFlightCC < 0 ? ShipCommand.STRAFE_LEFT : ShipCommand.STRAFE_RIGHT);
            }
        }

        // Accelerate if the target is within angle tolerances
        if (Math.abs(angularDistance) <= 90f) {
            missile.giveCommand(ShipCommand.ACCELERATE);
        }

        // Stop turning once missile is on target
        if (AbsAngD < 0.4) {
            missile.setAngularVelocity(0);
        }
    }

    @Override
    public CombatEntityAPI getTarget() {
        return target;
    }

    @Override
    public final void setTarget(CombatEntityAPI target) {
        this.target = target;
    }
}