package uulm.teamname.marvelous.gamelibrary.gamelogic;

import uulm.teamname.marvelous.gamelibrary.IntVector2;
import uulm.teamname.marvelous.gamelibrary.events.Event;
import uulm.teamname.marvelous.gamelibrary.requests.Request;

import java.util.Observer;

/** Represents a game instance. */
public class GameInstance {
    /** The private {@link GameState} of the instance */
    private final GameState _state;

    /** The public view for the underlying {@link GameState} of the instance */
    public final GameStateView state;

    /** The {@link GameStateManager} managing the {@link GameState} of the instance */
    private final GameStateManager manager;

    /** The {@link EventEmitter} for {@link Event}s resulting from {@link Request}s */
    private final EventEmitter emitter = new EventEmitter();

    /** Constructs a new {@link GameInstance}. */
    public GameInstance(IntVector2 mapSize) {
        _state = new GameState(mapSize);
        this.state = new GameStateView(_state);
        manager = new GameStateManager(_state);
    }

    /**
     * Checks a checksum with the current one.
     * @param input The checksum to compare to
     * @return Whether or not the checksum matches
     */
    public boolean checkChecksum(long input) {
        return ChecksumCalculator.checkChecksum(_state, input);
    }

    /**
     * Calculates the current checksum of the game state.
     * @return The calculated checksum
     */
    public long calculateChecksum() {
        return ChecksumCalculator.calculateChecksum(_state);
    }

    /**
     * Checks an array of {@link Request}s for validity and automatically applies them if valid.
     * @param requests The requests to check
     * @return Whether or not the given set of requests was valid
     */
    public boolean checkRequestsAndApply(Request... requests) {
        if(manager.processRequests(requests, true)) {
            emit(manager.apply());
            return true;
        }
        return false;
    }

    /**
     * Checks an array of {@link Request}s for validity without applying it.
     * @param requests The requests to check
     * @return Whether or not the given set of requests is valid
     */
    public boolean checkRequestsSilent(Request... requests) {
        return manager.processRequests(requests, false);
    }

    /**
     * Applies an array of {@link Event}s to the game state.
     * @param events The events to apply.
     */
    public void applyEvents(Event... events) {
        manager.applyEvents(events);
    }

    /**
     * Adds an {@link Observer} for events.
     * @param observer The observer to add
     */
    public void addObserver(Observer observer) {
        emitter.addObserver(observer);
    }

    /**
     * Instructs the emitter to emit an array of {@link Event}s.
     * @param events The events to emit
     */
    private void emit(Event... events) {
        emitter.update(events);
    }
}