package uulm.teamname.marvelous.gamelibrary.gamelogic;

import uulm.teamname.marvelous.gamelibrary.IntVector2;
import uulm.teamname.marvelous.gamelibrary.Tuple;
import uulm.teamname.marvelous.gamelibrary.entities.*;
import uulm.teamname.marvelous.gamelibrary.entities.Character;
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;
import java.util.Collections;
import java.util.concurrent.atomic.AtomicInteger;

/** 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());

                if(request.type == RequestType.UseInfinityStoneRequest) {
                    switch(((CharacterRequest) request).stoneType) {
                        case SpaceStone -> {
                            result.add(new EventBuilder(EventType.MoveEvent)
                                    .withOriginEntity(data.originEntity)
                                    .withOriginField(data.originField)
                                    .withTargetField(data.targetField)
                                    .buildCharacterEvent());
                        }
                        case MindStone -> {
                            EntityType target = data.originEntity.type == EntityType.P1 ? EntityType.P2 : EntityType.P1;
                            Line2D line = new Line2D.Float(data.originField.getX(), data.originField.getY(), data.targetField.getX(), data.targetField.getY());
                            for(int i = data.originField.getX(); i <= data.targetField.getX(); i++) {
                                for(int j = data.originField.getY(); j <= data.targetField.getY(); j++) {
                                    var cell = new Rectangle.Float(i - 0.5f, j - 0.5f, 1, 1);
                                    if(line.intersects(cell)) {
                                        for(Entity entity: state.entities.findByPosition(data.targetField)) {
                                            if(entity.id.isSameType(target)) {
                                                result.add(new EventBuilder(EventType.TakenDamageEvent)
                                                        .withTargetEntity(entity.id)
                                                        .withTargetField(new IntVector2(i, j))
                                                        .withAmount(data.value)
                                                        .buildEntityEvent());
                                            }
                                        }
                                    }
                                }
                            }
                        }
                        case RealityStone -> {
                            if(data.originEntity == data.targetEntity) { // => place stone
                                //TODO: use config values
                                result.add(new EventBuilder(EventType.SpawnEntityEvent)
                                        .withTargetField(data.targetField)
                                        .withEntity(new Rock(new EntityID(EntityType.Rocks, state.entities.findFreeRockSlot()), data.targetField, 100))
                                        .buildEntityEvent());
                            }else { // => destroy stone
                                result.add(new EventBuilder(EventType.DestroyedEntityEvent)
                                        .withTargetField(data.targetField)
                                        .withTargetEntity(data.targetEntity)
                                        .buildEntityEvent());
                            }
                        }
                        case PowerStone -> {
                            Character origin = (Character)state.entities.findEntity(data.originEntity);
                            int dmg = (int)Math.round(origin.hp.getValue() * 0.1);
                            if(origin.hp.getValue() != 1 && dmg > 0) {
                                result.add(new EventBuilder(EventType.TakenDamageEvent)
                                        .withTargetEntity(data.originEntity)
                                        .withTargetField(data.originField)
                                        .withAmount(dmg)
                                        .buildEntityEvent());
                            }
                            result.add(new EventBuilder(EventType.TakenDamageEvent)
                                    .withTargetEntity(data.targetEntity)
                                    .withTargetField(data.targetField)
                                    .withAmount(data.value)
                                    .buildEntityEvent());
                        }
                        case TimeStone -> {
                            Character origin = (Character)state.entities.findEntity(data.originEntity);
                            int ap = origin.ap.max - origin.ap.getValue();
                            if(ap < 0) {
                                result.add(new EventBuilder(EventType.ConsumedAPEvent)
                                        .withTargetEntity(data.originEntity)
                                        .withTargetField(data.originField)
                                        .withAmount(ap)
                                        .buildEntityEvent());
                            }
                            int mp = origin.mp.max - origin.mp.getValue();
                            if(mp < 0) {
                                result.add(new EventBuilder(EventType.ConsumedMPEvent)
                                        .withTargetEntity(data.originEntity)
                                        .withTargetField(data.originField)
                                        .withAmount(mp)
                                        .buildEntityEvent());
                            }
                        }
                        case SoulStone -> {
                            Character target = (Character)state.entities.findEntity(data.targetEntity);
                            result.add(new EventBuilder(EventType.HealedEvent)
                                    .withTargetEntity(data.targetEntity)
                                    .withTargetField(data.targetField)
                                    .withAmount(target.hp.max)
                                    .buildEntityEvent());
                        }
                    }
                }
            }
            case EndRoundRequest -> {
                result.addAll(handleTurnEnd(state)); //why is it called end round request when it ends a turn...
            }
            case Req -> {
                result.add(buildGameStateEvent(state));
            }
        }

        return result;
    }

    /**
     * Builds a {@link EventType#GamestateEvent} for the given {@link GameState}.
     * @param state The game state to use
     * @return The resulting event
     */
    public static Event buildGameStateEvent(GameState state) {
        return new EventBuilder(EventType.GamestateEvent)
                .withEntities(state.entities.export())
                .withTurnOrder((EntityID[])state.turnOrder.toArray())
                .withMapSize(state.mapSize)
                .withActiveCharacter(state.activeCharacter)
                .withStoneCooldowns(state.stoneCooldown.export())
                .withWinCondition(state.won)
                .buildGameStateEvent();
    }

    /**
     * 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.distanceChebyshev(data.targetField) > 1) {
                            throw new InvalidRequestException();
                        }
                    }else if(request.type == RequestType.RangedAttackRequest) {
                        if(origin.rangedDamage != data.value) {
                            throw new InvalidRequestException();
                        }
                        if(data.originField.distanceChebyshev(data.targetField) > origin.attackRange) {
                            throw new InvalidRequestException();
                        }
                        if(data.originField.distanceChebyshev(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(data.originField.distanceChebyshev(data.targetField) != 1) {
                        throw new InvalidRequestException();
                    }

                    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);

                    if(data.originField.distanceChebyshev(data.targetField) != 1) {
                        throw new InvalidRequestException();
                    }

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

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

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

                    switch(((CharacterRequest) request).stoneType) {
                        case SpaceStone -> {
                            verifyCoordinates(state, data.targetField);

                            if(state.entities.blocksMovement(data.targetField)) {
                                throw new InvalidRequestException();
                            }
                        }
                        case MindStone -> {
                            if(data.originField == data.targetField) {
                                throw new InvalidRequestException();
                            }
                            //TODO: mind stone damage check (config) ???????
                        }
                        case RealityStone -> {
                            if(data.originEntity == data.targetEntity) { // => place stone
                                if(state.entities.findByPosition(data.targetField).size() != 0) {
                                    throw new InvalidRequestException();
                                }
                            }else { // => destroy stone
                                boolean hasRock = false;
                                for(Entity entity: state.entities.findByPosition(data.targetField)) {
                                    if(entity.id.isSameType(EntityType.Rocks)) {
                                        hasRock = true;
                                        break;
                                    }
                                }
                                if(!hasRock) {
                                    throw new InvalidRequestException();
                                }
                            }
                        }
                        case PowerStone -> {
                            Character target = getCharacter(state, data.targetField, data.targetEntity);

                            requireAlive(target);

                            if(origin.rangedDamage * 2 != data.value) {
                                throw new InvalidRequestException();
                            }
                        }
                        case TimeStone -> {
                            // "👍  i approve" - the server
                        }
                        case SoulStone -> {
                            Character target = getCharacter(state, data.targetField, data.targetEntity);

                            if(target.hp.getValue() != 0) {
                                throw new InvalidRequestException();
                            }
                        }
                    }

                    return true;
                }
                case Req -> {
                    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) {
        switch(event.type) {
            case DestroyedEntityEvent -> {
                state.entities.removeEntity(((EntityEvent)event).targetEntity);
            }
            case TakenDamageEvent -> {
                ((Character)state.entities.findEntity(((CharacterEvent)event).targetEntity)).hp.decreaseValue(((CharacterEvent)event).amount);
            }
            case ConsumedAPEvent -> {
                ((Character)state.entities.findEntity(((CharacterEvent)event).targetEntity)).ap.decreaseValue(((CharacterEvent)event).amount);
            }
            case ConsumedMPEvent -> {
                ((Character)state.entities.findEntity(((CharacterEvent)event).targetEntity)).mp.decreaseValue(((CharacterEvent)event).amount);
            }
            case SpawnEntityEvent -> {
                state.entities.addEntity(((EntityEvent)event).entity);
            }
            case HealedEvent -> {
                ((Character)state.entities.findEntity(((CharacterEvent)event).targetEntity)).hp.increaseValue(((CharacterEvent)event).amount);
            }
            case MoveEvent -> {
                (state.entities.findEntity(((CharacterEvent)event).originEntity)).setPosition(((CharacterEvent)event).targetField);
            }
            case ExchangeInfinityStoneEvent -> {
                ((Character)state.entities.findEntity(((CharacterEvent)event).originEntity)).inventory.removeStone(((CharacterEvent)event).stoneType);
                ((Character)state.entities.findEntity(((CharacterEvent)event).targetEntity)).inventory.addStone(((CharacterEvent)event).stoneType);
            }
        }
    }

    /**
     * Starts end of round handling if necessary.
     * @param state The game state to work on
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> checkTurnEnd(GameState state) {
        if(
            ((Character) state.entities.findEntity(state.activeCharacter)).ap.getValue() <= 0 &&
            ((Character) state.entities.findEntity(state.activeCharacter)).mp.getValue() <= 0
        ) {
            return handleTurnEnd(state);
        }

        return new ArrayList<>();
    }

    /**
     * Handles everything that happens at the end of a turn, including new rounds.
     * @param state The game state to work on
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> handleTurnEnd(GameState state) {
        ArrayList<Event> result = new ArrayList<>();

        ArrayList<EntityID> alive = new ArrayList<>();

        for (EntityID id: state.turnOrder) {
            Character character = ((Character)state.entities.findEntity(id));

            if(character.hp.getValue() > 0){
                alive.add(id);
            }

            if(character.inventory.getFreeSlots() == 0) { // no slots => has all infinity stones
                result.addAll(handlePlayerWin(state, character));
                return result;
            }
        }

        if(alive.isEmpty()) {
            result.addAll(handleThanosWin(state));
            return result;
        }

        int index = alive.indexOf(state.activeCharacter);
        AtomicInteger turnOrderSize = new AtomicInteger(alive.size());
        if(index == alive.size() - 1) {
            result.addAll(handleRoundStart(state, turnOrderSize));
        }else {
            state.activeCharacter = alive.get(index + 1);
        }

        result.addAll(handleTurnStart(state, turnOrderSize.get()));

        return result;
    }

    /**
     * Handles everything that happens at the beginning of new rounds.
     * @param state The game state to work on
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> handleRoundStart(GameState state, AtomicInteger turnOrderSize) {
        ArrayList<Event> result = new ArrayList<>();

        state.roundNumber++;

        Collections.shuffle(state.turnOrder);

        ArrayList<EntityID> alive = new ArrayList<>();
        for (EntityID id: state.turnOrder) {
            Character character = ((Character)state.entities.findEntity(id));
            if(character.hp.getValue() > 0){
                alive.add(id);
            }
        }

        turnOrderSize.set(alive.size());

        state.activeCharacter = alive.get(0);

        result.add(new EventBuilder(EventType.RoundSetupEvent)
                .withRoundCount(state.roundNumber)
                .withCharacterOrder(alive.toArray(new EntityID[0]))
                .buildGameEvent());

        return result;
    }

    /**
     * Handles everything that happens at the beginning of a turn.
     * @param state The game state to work on
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> handleTurnStart(GameState state, int turnOrderSize) {
        ArrayList<Event> result = new ArrayList<>();

        state.turnNumber++;

        Character activeCharacter = (Character)state.entities.findEntity(state.activeCharacter);

        if(activeCharacter.ap.getValue() != activeCharacter.ap.max) {
            result.add(new EventBuilder(EventType.ConsumedAPEvent)
                    .withTargetEntity(state.activeCharacter)
                    .withTargetField(activeCharacter.getPosition())
                    .withAmount(activeCharacter.ap.getValue() - activeCharacter.ap.max)
                    .buildGameEvent());
        }
        if(activeCharacter.mp.getValue() != activeCharacter.mp.max) {
            result.add(new EventBuilder(EventType.ConsumedMPEvent)
                    .withTargetEntity(state.activeCharacter)
                    .withTargetField(activeCharacter.getPosition())
                    .withAmount(activeCharacter.mp.getValue() - activeCharacter.mp.max)
                    .buildGameEvent());
        }
        result.add(new EventBuilder(EventType.TurnEvent)
                .withTurnCount(turnOrderSize)
                .withNextCharacter(state.activeCharacter)
                .buildGameEvent());

        return result;
    }

    /**
     * Handles the victory of a player through one character.
     * @param state The game state to work on
     * @param winner The winning character
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> handlePlayerWin(GameState state, Character winner) {
        ArrayList<Event> result = new ArrayList<>();

        state.won = true;

        result.add(new EventBuilder(EventType.WinEvent)
                .withPlayerWon(winner.id.id)
                .buildGameEvent());

        return result;
    }

    /**
     * Handles the victory of thanos after all characters are knocked out.
     * @param state The game state to work on
     * @return The list of resulting {@link Event}s
     */
    public static ArrayList<Event> handleThanosWin(GameState state) {
        ArrayList<Event> result = new ArrayList<>();

        state.won = true;

        //TODO: add thanos victory event

        return result;
    }

    /**
     * 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;
    }
}