Gamelib/src/main/java/uulm/teamname/marvelous/gamelibrary/gamelogic/GameLogic.java

package uulm.teamname.marvelous.gamelibrary.gamelogic;

import uulm.teamname.marvelous.gamelibrary.IntVector2;
import uulm.teamname.marvelous.gamelibrary.Tuple;
import uulm.teamname.marvelous.gamelibrary.entities.Entity;
import uulm.teamname.marvelous.gamelibrary.entities.Character;
import uulm.teamname.marvelous.gamelibrary.entities.EntityID;
import uulm.teamname.marvelous.gamelibrary.entities.StoneType;
import uulm.teamname.marvelous.gamelibrary.entities.StatType;
import uulm.teamname.marvelous.gamelibrary.events.*;
import uulm.teamname.marvelous.gamelibrary.events.Event;
import uulm.teamname.marvelous.gamelibrary.requests.CharacterRequest;
import uulm.teamname.marvelous.gamelibrary.requests.Request;
import uulm.teamname.marvelous.gamelibrary.requests.RequestType;

import java.awt.*;
import java.awt.geom.Line2D;
import java.util.ArrayList;

/** Contains game logic handling. */
class GameLogic {
    /**
     * Produces resulting {@link Event}s from a given {@link Request}.
     * @param state The game state to execute on
     * @param request The request to execute
     * @return The list of resulting events
     */
    public static ArrayList<Event> executeRequest(GameState state, Request request) {
        ArrayList<Event> result = new ArrayList<>();

        switch(request.type) {
            case MeleeAttackRequest, RangedAttackRequest -> {
                CharacterRequest data = (CharacterRequest)request;
                result.add(new EventBuilder(request.type == RequestType.MeleeAttackRequest ? EventType.MeleeAttackEvent : EventType.RangedAttackEvent)
                        .withOriginEntity(data.originEntity)
                        .withTargetEntity(data.targetEntity)
                        .withOriginField(data.originField)
                        .withTargetField(data.targetField)
                        .withAmount(data.value)
                        .buildCharacterEvent());
                result.add(new EventBuilder(EventType.ConsumedAPEvent)
                        .withTargetEntity(data.originEntity)
                        .withTargetField(data.originField)
                        .withAmount(1)
                        .buildEntityEvent());
                result.add(new EventBuilder(EventType.TakenDamageEvent)
                        .withTargetEntity(data.targetEntity)
                        .withTargetField(data.targetField)
                        .withAmount(data.value)
                        .buildEntityEvent());
            }
            case MoveRequest -> {
                CharacterRequest data = (CharacterRequest)request;
                result.add(new EventBuilder(EventType.MoveEvent)
                        .withOriginEntity(data.originEntity)
                        .withOriginField(data.originField)
                        .withTargetField(data.targetField)
                        .buildCharacterEvent());
                result.add(new EventBuilder(EventType.ConsumedMPEvent)
                        .withTargetEntity(data.originEntity)
                        .withTargetField(data.targetField) //when this event gets handled, the character already moved to the target field
                        .withAmount(1)
                        .buildEntityEvent());
                for(Entity entity: state.entities.findByPosition(data.targetField)) {
                    if(entity instanceof Character) {
                        result.add(new EventBuilder(EventType.MoveEvent)
                                .withOriginEntity(entity.id)
                                .withOriginField(data.targetField)
                                .withTargetField(data.originField)
                                .buildCharacterEvent());
                        break; //we should only have one character per field anyways
                    }
                }
            }
            case ExchangeInfinityStoneRequest, UseInfinityStoneRequest -> {
                CharacterRequest data = (CharacterRequest)request;
                result.add(new EventBuilder(request.type == RequestType.ExchangeInfinityStoneRequest ? EventType.ExchangeInfinityStoneEvent : EventType.UseInfinityStoneEvent)
                        .withOriginEntity(data.originEntity)
                        .withOriginField(data.originField)
                        .withTargetEntity(data.targetEntity)
                        .withTargetField(data.targetField)
                        .withStoneType(data.stoneType)
                        .buildCharacterEvent());
                result.add(new EventBuilder(EventType.ConsumedAPEvent)
                        .withTargetEntity(data.originEntity)
                        .withTargetField(data.originField)
                        .withAmount(1)
                        .buildEntityEvent());
                //TODO: add infinity stone usage effect in GameLogic.executeRequest
            }
            case DisconnectRequest -> {
                result.add(new EventBuilder(EventType.DisconnectEvent)
                        .buildGameEvent());
            }
        }

        return result;
    }

    /**
     * Checks a {@link Request} for validity for a {@link GameState}.
     * @param state The game state to check on
     * @param request The request to validate
     * @return Whether or not the request is valid
     */
    public static boolean checkRequest(GameState state, Request request) {
        try {
            switch(request.type) {
                case MeleeAttackRequest, RangedAttackRequest -> {
                    CharacterRequest data = (CharacterRequest)request;

                    Character origin = getCharacter(state, data.originField, data.originEntity);
                    Character target = getCharacter(state, data.targetField, data.targetEntity);

                    requireAlive(origin);
                    requireAlive(target);
                    requireAP(origin, 1);

                    if(request.type == RequestType.MeleeAttackRequest) {
                        if(origin.meleeDamage != data.value) {
                            throw new InvalidRequestException();
                        }
                        if(data.originField.distanceManhattan(data.targetField) > 1) {
                            throw new InvalidRequestException();
                        }
                    }else if(request.type == RequestType.RangedAttackRequest) {
                        if(origin.rangedDamage != data.value) {
                            throw new InvalidRequestException();
                        }
                        if(data.originField.distanceManhattan(data.targetField) > origin.attackRange) {
                            throw new InvalidRequestException();
                        }
                        if(data.originField.distanceManhattan(data.targetField) <= 1) {
                            throw new InvalidRequestException();
                        }
                        requireLineOfSight(state, data.originField, data.targetField);
                    }

                    return true;
                }
                case MoveRequest -> {
                    CharacterRequest data = (CharacterRequest)request;

                    Character origin = getCharacter(state, data.originField, data.originEntity);

                    requireAlive(origin);
                    requireMP(origin, 1);
                    verifyCoordinates(state, data.targetField);

                    if(state.entities.blocksMovement(data.targetField)) {
                        throw new InvalidRequestException();
                    }

                    return true;
                }
                case ExchangeInfinityStoneRequest -> {
                    CharacterRequest data = (CharacterRequest)request;

                    Character origin = getCharacter(state, data.originField, data.originEntity);
                    Character target = getCharacter(state, data.targetField, data.targetEntity);

                    requireAlive(origin);
                    requireAlive(target);
                    requireAP(origin, 1);
                    requireInfinityStone(origin, data.stoneType);

                    return true;
                }
                case UseInfinityStoneRequest -> {
                    CharacterRequest data = (CharacterRequest)request;

                    Character origin = getCharacter(state, data.originField, data.originEntity);
                    Character target = getCharacter(state, data.targetField, data.targetEntity);

                    requireAlive(origin);
                    requireAP(origin, 1);
                    requireInfinityStone(origin, data.stoneType);

                    //TODO: properly verify UseInfinityStoneRequest in GameLogic.checkRequest
                    if(!target.isActive()) {
                        throw new InvalidRequestException();
                    }

                    return true;

                }
                case DisconnectRequest -> {
                    //TODO: add check for DisconnectRequest in GameLogic.checkRequest

                    return true;
                }
            }
        }catch(Exception ignored) {
            return false;
        }

        return false;
    }

    /**
     * Retrieves a {@link Character} for a {@link Request}.
     * @param state The game state to use
     * @param position The requested position
     * @param entityID The requested {@link EntityID}
     * @return The found character
     * @throws InvalidRequestException if the character is invalid or not found
     */
    private static Character getCharacter(GameState state, IntVector2 position, EntityID entityID) throws InvalidRequestException {
        Entity entity = state.entities.findEntity(entityID);
        if(entity == null || entity.getPosition() != position || !(entity instanceof Character)) {
            throw new InvalidRequestException();
        }
        try {
            return (Character)entity;
        }catch(Exception ignored) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that a {@link Character} is alive.
     */
    private static void requireAlive(Character entity) throws InvalidRequestException {
        if(entity.hp.getValue() <= 0 || !entity.isActive()) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that a {@link Character} has enough {@link StatType#AP}.
     */
    private static void requireAP(Character entity, int ap) throws InvalidRequestException {
        if(entity.ap.getValue() < ap) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that a {@link Character} has enough {@link StatType#MP}.
     */
    private static void requireMP(Character entity, int mp) throws InvalidRequestException {
        if(entity.mp.getValue() < mp) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that a {@link Character} has the required {@link StoneType}.
     */
    private static void requireInfinityStone(Character entity, StoneType stone) throws InvalidRequestException {
        if(stone == null || !entity.inventory.hasStone(stone)) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that coordinates are within the playing area.
     */
    private static void verifyCoordinates(GameState state, IntVector2 position) throws InvalidRequestException {
        if(position.getX() < 0 || position.getX() >= state.mapSize.getX() || position.getY() < 0 || position.getY() >= state.mapSize.getY()) {
            throw new InvalidRequestException();
        }
    }

    /**
     * Verifies that there is a line of sight between two positions.
     */
    private static void requireLineOfSight(GameState state, IntVector2 start, IntVector2 end) throws InvalidRequestException {
        //naive code for the win!!! \o/
        //at least its early exit and probably only O(ln(n*m))
        //TODO: implement proper line rasterization algorithm in GameLogic.requireLineOfSight
        Line2D line = new Line2D.Float(start.getX(), start.getY(), end.getX(), end.getY());
        for(int i = start.getX(); i <= end.getX(); i++) {
            for(int j = start.getY(); j <= end.getY(); j++) {
                var cell = new Rectangle.Float(i - 0.5f, j - 0.5f, 1, 1);
                if(line.intersects(cell)) {
                    if(state.entities.blocksVision(new IntVector2(i, j))) {
                        throw new InvalidRequestException();
                    }
                }
            }
        }
    }

    /**
     * Applies an {@link Event} to a {@link GameState}.
     * @param state The game state to apply to
     * @param event The event to apply
     */
    public static void applyEvent(GameState state, Event event) {
        //TODO: implement GameLogic.applyEvent
    }

    /**
     * Checks a {@link GameState} for the current overtime win condition.
     * @param state The game state to check
     * @return The {@link ParticipantType} that is currently winning the game according to overtime ruling
     */
    public static ParticipantType checkWinConditions(GameState state) {
        //TODO: GameLogic.checkWinConditions is kind of ugly

        Tuple<ParticipantType, WinCondition> player1;
        Tuple<ParticipantType, WinCondition> player2;
        int value1;
        int value2;
        for(WinCondition condition: WinCondition.values()) {
            player1 = new Tuple<ParticipantType, WinCondition>(ParticipantType.Player1, condition);
            player2 = new Tuple<ParticipantType, WinCondition>(ParticipantType.Player2, condition);
            value1 = 0;
            value2 = 0;

            if(state.winConditions.containsKey(player1)) {
                value1 = state.winConditions.get(player1);
            }
            if(state.winConditions.containsKey(player2)) {
                value2 = state.winConditions.get(player2);
            }

            if(value1 > value2) {
                return ParticipantType.Player1;
            }
            if(value2 > value1) {
                return ParticipantType.Player2;
            }
        }

        return ParticipantType.None;
    }
}