package seng302.gameServer;

import javafx.scene.paint.Color;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import seng302.gameServer.messages.*;
import seng302.model.*;
import seng302.model.mark.CompoundMark;
import seng302.model.mark.Mark;
import seng302.model.mark.MarkOrder;
import seng302.utilities.GeoUtility;
import seng302.utilities.XMLParser;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.util.*;

/**
 * A Static class to hold information about the current state of the game (model)
 * Also contains logic for updating itself on regular time intervals on its own thread
 * Created by wmu16 on 10/07/17.
 */
public class GameState implements Runnable {
    @FunctionalInterface
    interface NewMessageListener {

        void notify(Message message);
    }

    private Logger logger = LoggerFactory.getLogger(GameState.class);

    private static final Integer STATE_UPDATES_PER_SECOND = 60;
    public static Double ROUNDING_DISTANCE = 50d; // TODO: 14/08/17 wmu16 - Look into this value further
    public static final Double MARK_COLLISION_DISTANCE = 15d;
    public static final Double YACHT_COLLISION_DISTANCE = 25.0;
    public static final Double BOUNCE_DISTANCE_MARK = 20.0;
    public static final Double BOUNCE_DISTANCE_YACHT = 30.0;
    public static final Double COLLISION_VELOCITY_PENALTY = 0.3;

    private static Long previousUpdateTime;
    public static Double windDirection;
    private static Double windSpeed;

    private static Boolean customizationFlag; // dirty flag to tell if a player has customized their boat.

    private static String hostIpAddress;
    private static List<Player> players;
    private static Map<Integer, ServerYacht> yachts;
    private static Boolean isRaceStarted;
    private static GameStages currentStage;
    private static MarkOrder markOrder;
    private static long startTime;
    private static Set<Mark> marks;
    private static List<Limit> courseLimit;
    private static Integer maxPlayers = 8;


    private static List<NewMessageListener> markListeners;

    private static Map<Player, String> playerStringMap = new HashMap<>();
    /*
        Ideally I would like to make this class an object instantiated by the server and given to
        it's created threads if necessary. Outside of that I think the dependencies on it
        (atm only Yacht & GameClient) can be removed from most other classes. The observable list of
        players could be pulled directly from the server by the GameClient since it instantiates it
        and it is reasonable for it to pull data. The current setup of publicly available statics is
        pretty meh IMO because anything can change it making it unreliable and like people did with
        the old ServerParser class everything that needs shared just gets thrown in the static
        collections and things become a real mess.
     */

    public GameState(String hostIpAddress) {
        windDirection = 180d;
        windSpeed = 10000d;
        this.hostIpAddress = hostIpAddress;
        yachts = new HashMap<>();
        players = new ArrayList<>();
        GameState.hostIpAddress = hostIpAddress;
        customizationFlag = false;

        currentStage = GameStages.LOBBYING;
        isRaceStarted = false;
        //set this when game stage changes to prerace
        previousUpdateTime = System.currentTimeMillis();
        markOrder = new MarkOrder(); //This could be instantiated at some point with a select map?
        markListeners = new ArrayList<>();

        resetStartTime();

        new Thread(this, "GameState").start();   //Run the auto updates on the game state

        marks = new MarkOrder().getAllMarks();
        setCourseLimit("/server_config/race.xml");
    }

    private void setCourseLimit(String url) {
        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        documentBuilderFactory.setNamespaceAware(true);
        DocumentBuilder documentBuilder;
        Document document = null;
        try {
            documentBuilder = documentBuilderFactory.newDocumentBuilder();
            document = documentBuilder.parse(new InputSource(getClass().getResourceAsStream(url)));
        } catch (Exception e) {
            // sorry, we have to catch general one, otherwise we have to catch five different exceptions.
            logger.trace("Failed to load course limit for boundary collision detection.", e);
        }
        courseLimit = XMLParser.parseRace(document).getCourseLimit();
    }

    public static String getHostIpAddress() {
        return hostIpAddress;
    }

    public static Set<Mark> getMarks() {
        return Collections.unmodifiableSet(marks);
    }

    public static List<Player> getPlayers() {
        return players;
    }

    public static void addPlayer(Player player) {
        players.add(player);
        String playerText = player.getYacht().getSourceId() + " " + player.getYacht().getBoatName()
            + " " + player.getYacht().getCountry();
        playerStringMap.put(player, playerText);
    }

    public static void removePlayer(Player player) {
        players.remove(player);
        playerStringMap.remove(player);
    }

    public static void addYacht(Integer sourceId, ServerYacht yacht) {
        yachts.put(sourceId, yacht);
    }

    public static void removeYacht(Integer yachtId) {
        yachts.remove(yachtId);
    }

    public static Boolean getIsRaceStarted() {
        return isRaceStarted;
    }

    public static GameStages getCurrentStage() {
        return currentStage;
    }

    public static void setCurrentStage(GameStages currentStage) {
        GameState.currentStage = currentStage;
    }

    public static MarkOrder getMarkOrder() {
        return markOrder;
    }

    public static long getStartTime() {
        return startTime;
    }

    public static void resetStartTime(){
        startTime = System.currentTimeMillis() + MainServerThread.TIME_TILL_START;
    }

    public static Double getWindDirection() {
        return windDirection;
    }

    public static void setWindDirection(Double newWindDirection) {
        windDirection = newWindDirection;
    }

    public static void setWindSpeed(Double newWindSpeed) {
        windSpeed = newWindSpeed;
    }

    public static Double getWindSpeedMMS() {
        return windSpeed;
    }

    public static Double getWindSpeedKnots() {
        return GeoUtility.mmsToKnots(windSpeed); // TODO: 26/07/17 cir27 - remove magic numbers
    }

    public static Map<Integer, ServerYacht> getYachts() {
        return yachts;
    }


    /**
     * Generates a new ID based off the size of current players + 1
     *
     * @return a playerID to be allocated to a new connetion
     */
    public static Integer getUniquePlayerID() {
        // TODO: 22/07/17 wmu16 - This may not be robust enough and may have to be improved on.
        return yachts.size() + 1;
    }


    /**
     * A thread to have the game state update itself at certain intervals
     */
    @Override
    public void run() {

        while (currentStage != GameStages.FINISHED) {
            try {
                Thread.sleep(1000 / STATE_UPDATES_PER_SECOND);
            } catch (InterruptedException e) {
                System.out.println("[GameState] interrupted exception");
            }
            if (currentStage == GameStages.PRE_RACE || currentStage == GameStages.RACING) {
                update();
            }

            if (currentStage == GameStages.RACING) {
                update();
            }
        }
    }

    public static void updateBoat(Integer sourceId, BoatAction actionType) {
        ServerYacht playerYacht = yachts.get(sourceId);
        switch (actionType) {
            case VMG:
                playerYacht.turnToVMG();
                break;
            case SAILS_IN:
                playerYacht.toggleSailIn();
                break;
            case SAILS_OUT:
                playerYacht.toggleSailIn();
                break;
            case TACK_GYBE:
                playerYacht.tackGybe(windDirection);
                break;
            case UPWIND:
                playerYacht.turnUpwind();
                break;
            case DOWNWIND:
                playerYacht.turnDownwind();
                break;
        }
    }

    /**
     * Called periodically in this GameState thread to update the GameState values
     */
    public void update() {
        Boolean raceFinished = true;

        Double timeInterval = (System.currentTimeMillis() - previousUpdateTime) / 1000000.0;
        previousUpdateTime = System.currentTimeMillis();
        if (System.currentTimeMillis() > startTime) {
            GameState.setCurrentStage(GameStages.RACING);
        }
        for (ServerYacht yacht : yachts.values()) {
            updateVelocity(yacht);
            yacht.runAutoPilot();
            yacht.updateLocation(timeInterval);
            if (yacht.getBoatStatus() != BoatStatus.FINISHED) {
                checkCollision(yacht);
                checkForLegProgression(yacht);
                raceFinished = false;
            }
        }

        if (raceFinished) {
            currentStage = GameStages.FINISHED;
        }
    }

    /**
     * Check if the yacht has crossed the course limit
     *
     * @param yacht the yacht to be tested
     * @return a boolean value of if there is a boundary collision
     */
    private static Boolean checkBoundaryCollision(ServerYacht yacht) {
        for (int i = 0; i < courseLimit.size() - 1; i++) {
            if (GeoUtility.checkCrossedLine(courseLimit.get(i), courseLimit.get(i + 1),
                yacht.getLastLocation(), yacht.getLocation()) != 0) {
                return true;
            }
        }
        if (GeoUtility.checkCrossedLine(courseLimit.get(courseLimit.size() - 1), courseLimit.get(0),
            yacht.getLastLocation(), yacht.getLocation()) != 0) {
            return true;
        }
        return false;
    }

    public static void checkCollision(ServerYacht serverYacht) {
        ServerYacht collidedYacht = checkYachtCollision(serverYacht);
        if (collidedYacht != null) {
            GeoPoint originalLocation = serverYacht.getLocation();
            serverYacht.setLocation(
                calculateBounceBack(serverYacht, originalLocation, BOUNCE_DISTANCE_YACHT)
            );
            serverYacht.setCurrentVelocity(
                serverYacht.getCurrentVelocity() * COLLISION_VELOCITY_PENALTY
            );
            collidedYacht.setLocation(
                calculateBounceBack(collidedYacht, originalLocation, BOUNCE_DISTANCE_YACHT)
            );
            collidedYacht.setCurrentVelocity(
                collidedYacht.getCurrentVelocity() * COLLISION_VELOCITY_PENALTY
            );
            notifyMessageListeners(
                new YachtEventCodeMessage(serverYacht.getSourceId())
            );
        } else {
            Mark collidedMark = checkMarkCollision(serverYacht);
            if (collidedMark != null) {
                serverYacht.setLocation(
                    calculateBounceBack(serverYacht, collidedMark, BOUNCE_DISTANCE_MARK)
                );
                serverYacht.setCurrentVelocity(
                    serverYacht.getCurrentVelocity() * COLLISION_VELOCITY_PENALTY
                );
                notifyMessageListeners(
                    new YachtEventCodeMessage(serverYacht.getSourceId())
                );
            }
            else{
                if (checkBoundaryCollision(serverYacht)) {
                    serverYacht.setLocation(
                            calculateBounceBack(serverYacht, serverYacht.getLocation(),
                                    BOUNCE_DISTANCE_YACHT)
                    );
                    serverYacht.setCurrentVelocity(
                            serverYacht.getCurrentVelocity() * COLLISION_VELOCITY_PENALTY
                    );
                    notifyMessageListeners(
                            new YachtEventCodeMessage(serverYacht.getSourceId())
                    );
                }
            }
        }
    }


    private void updateVelocity(ServerYacht yacht) {
        Double velocity = yacht.getCurrentVelocity();
        Double trueWindAngle = Math.abs(windDirection - yacht.getHeading());
        Double boatSpeedInKnots = PolarTable.getBoatSpeed(getWindSpeedKnots(), trueWindAngle);
        Double maxBoatSpeed = GeoUtility.knotsToMMS(boatSpeedInKnots);
        // TODO: 15/08/17 remove magic numbers from these equations.
        if (yacht.getSailIn()) {
            if (velocity < maxBoatSpeed - 500) {
                yacht.changeVelocity(maxBoatSpeed / 100);
            } else if (velocity > maxBoatSpeed + 500) {
                yacht.changeVelocity(-velocity / 200);
            } else {
                yacht.setCurrentVelocity(maxBoatSpeed);
            }
        } else {
            if (velocity > 3000) {
                yacht.changeVelocity(-velocity / 200);
            } else if (velocity > 100) {
                yacht.changeVelocity(-velocity / 50);
            } else if (velocity <= 100) {
                yacht.setCurrentVelocity(0d);
            }
        }
    }


    /**
     * Calculates the distance to the next mark (closest of the two if a gate mark). For purposes of
     * mark rounding
     *
     * @return A distance in metres. Returns -1 if there is no next mark
     * @throws IndexOutOfBoundsException If the next mark is null (ie the last mark in the race)
     * Check first using {@link seng302.model.mark.MarkOrder#isLastMark(Integer)}
     */
    private Double calcDistanceToCurrentMark(ServerYacht yacht) throws IndexOutOfBoundsException {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        GeoPoint location = yacht.getLocation();

        if (currentMark.isGate()) {
            Mark sub1 = currentMark.getSubMark(1);
            Mark sub2 = currentMark.getSubMark(2);
            Double distance1 = GeoUtility.getDistance(location, sub1);
            Double distance2 = GeoUtility.getDistance(location, sub2);
            if (distance1 < distance2) {
                yacht.setClosestCurrentMark(sub1);
                return distance1;
            } else {
                yacht.setClosestCurrentMark(sub2);
                return distance2;
            }
        } else {
            yacht.setClosestCurrentMark(currentMark.getSubMark(1));
            return GeoUtility.getDistance(location, currentMark.getSubMark(1));
        }
    }


    /**        lobbyController.setPlayerListSource(clientLobbyList);
     * 4 Different cases of progression in the race 1 - Passing the start line 2 - Passing any
     * in-race Gate 3 - Passing any in-race Mark 4 - Passing the finish line
     *
     * @param yacht the current yacht to check for progression
     */
    private void checkForLegProgression(ServerYacht yacht) {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);

        Boolean hasProgressed;
        if (currentMarkSeqID == 0) {
            hasProgressed = checkStartLineCrossing(yacht);
        } else if (markOrder.isLastMark(currentMarkSeqID)) {
            hasProgressed = checkFinishLineCrossing(yacht);
        } else if (currentMark.isGate()) {
            hasProgressed = checkGateRounding(yacht);
        } else {
            hasProgressed = checkMarkRounding(yacht);
        }

        if (hasProgressed) {
            yacht.incrementLegNumber();
            sendMarkRoundingMessage(yacht);
            logMarkRounding(yacht);
            yacht.setHasPassedLine(false);
            yacht.setHasEnteredRoundingZone(false);
            yacht.setHasPassedThroughGate(false);
            if (!markOrder.isLastMark(currentMarkSeqID)) {
                yacht.incrementMarkSeqID();
            }
        }
    }


    /**
     * If we pass the start line gate in the correct direction, progress
     *
     * @param yacht The current yacht to check for
     */
    private Boolean checkStartLineCrossing(ServerYacht yacht) {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        GeoPoint lastLocation = yacht.getLastLocation();
        GeoPoint location = yacht.getLocation();

        Mark mark1 = currentMark.getSubMark(1);
        Mark mark2 = currentMark.getSubMark(2);
        CompoundMark nextMark = markOrder.getNextMark(currentMarkSeqID);

        Integer crossedLine = GeoUtility.checkCrossedLine(mark1, mark2, lastLocation, location);
        if (crossedLine > 0) {
            Boolean isClockwiseCross = GeoUtility.isClockwise(mark1, mark2, nextMark.getMidPoint());
            if (crossedLine == 2 && isClockwiseCross || crossedLine == 1 && !isClockwiseCross) {
                yacht.setClosestCurrentMark(mark1);
                yacht.setBoatStatus(BoatStatus.RACING);
                return true;
            }
        }

        return false;
    }


    /**
     * This algorithm checks for mark rounding. And increments the currentMarSeqID number attribute
     * of the yacht if so. A visual representation of this algorithm can be seen on the Wiki under
     * 'mark passing algorithm'
     *
     * @param yacht The current yacht to check for
     */
    private Boolean checkMarkRounding(ServerYacht yacht) {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        GeoPoint lastLocation = yacht.getLastLocation();
        GeoPoint location = yacht.getLocation();
        GeoPoint nextPoint = markOrder.getNextMark(currentMarkSeqID).getMidPoint();
        GeoPoint prevPoint = markOrder.getPreviousMark(currentMarkSeqID).getMidPoint();
        GeoPoint midPoint = GeoUtility.getDirtyMidPoint(nextPoint, prevPoint);

        if (calcDistanceToCurrentMark(yacht) < ROUNDING_DISTANCE) {
            yacht.setHasEnteredRoundingZone(true);
        }

        //In case current mark is a gate, loop through all marks just in case
        for (Mark thisCurrentMark : currentMark.getMarks()) {
            if (GeoUtility.isPointInTriangle(lastLocation, location, midPoint, thisCurrentMark)) {
                yacht.setHasPassedLine(true);
            }
        }

        return yacht.hasPassedLine() && yacht.hasEnteredRoundingZone();
    }


    /**
     * Checks if a gate line has been crossed and in the correct direction
     *
     * @param yacht The current yacht to check for
     */
    private Boolean checkGateRounding(ServerYacht yacht) {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        GeoPoint lastLocation = yacht.getLastLocation();
        GeoPoint location = yacht.getLocation();

        Mark mark1 = currentMark.getSubMark(1);
        Mark mark2 = currentMark.getSubMark(2);
        CompoundMark prevMark = markOrder.getPreviousMark(currentMarkSeqID);
        CompoundMark nextMark = markOrder.getNextMark(currentMarkSeqID);

        Integer crossedLine = GeoUtility.checkCrossedLine(mark1, mark2, lastLocation, location);

        //We have crossed the line
        if (crossedLine > 0) {
            Boolean isClockwiseCross = GeoUtility.isClockwise(mark1, mark2, prevMark.getMidPoint());

            //Check we cross the line in the correct direction
            if (crossedLine == 1 && isClockwiseCross || crossedLine == 2 && !isClockwiseCross) {
                yacht.setHasPassedThroughGate(true);
            }
        }

        Boolean prevMarkSide = GeoUtility.isClockwise(mark1, mark2, prevMark.getMidPoint());
        Boolean nextMarkSide = GeoUtility.isClockwise(mark1, mark2, nextMark.getMidPoint());

        if (yacht.hasPassedThroughGate()) {
            //Check if we need to round this gate after passing through
            if (prevMarkSide == nextMarkSide) {
                return checkMarkRounding(yacht);
            } else {
                return true;
            }
        }

        return false;
    }

    /**
     * If we pass the finish gate in the correct direction
     *
     * @param yacht The current yacht to check for
     */
    private Boolean checkFinishLineCrossing(ServerYacht yacht) {
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        GeoPoint lastLocation = yacht.getLastLocation();
        GeoPoint location = yacht.getLocation();

        Mark mark1 = currentMark.getSubMark(1);
        Mark mark2 = currentMark.getSubMark(2);
        CompoundMark prevMark = markOrder.getPreviousMark(currentMarkSeqID);

        Integer crossedLine = GeoUtility.checkCrossedLine(mark1, mark2, lastLocation, location);
        if (crossedLine > 0) {
            Boolean isClockwiseCross = GeoUtility.isClockwise(mark1, mark2, prevMark.getMidPoint());
            if (crossedLine == 1 && isClockwiseCross || crossedLine == 2 && !isClockwiseCross) {
                yacht.setClosestCurrentMark(mark1);
                yacht.setBoatStatus(BoatStatus.FINISHED);
                return true;
            }
        }

        return false;
    }

    /**
     * Handles player customization.
     *
     * @param playerID The ID of the player being modified.
     * @param requestType the type of player customization the player wants
     * @param customizeData the data related to the customization (color, name, shape)
     */
    public static void customizePlayer(long playerID, CustomizeRequestType requestType,
        byte[] customizeData) {
        ServerYacht playerYacht = yachts.get((int) playerID);

        if (requestType.equals(CustomizeRequestType.NAME)) {
            String name = new String(customizeData);
            playerYacht.setBoatName(name);
        } else if (requestType.equals(CustomizeRequestType.COLOR)) {
            int red = customizeData[0] & 0xFF;
            int green = customizeData[1] & 0xFF;
            int blue = customizeData[2] & 0xFF;
            Color yachtColor = Color.rgb(red, green, blue);
            playerYacht.setBoatColor(yachtColor);
        }
    }

    private static Mark checkMarkCollision(ServerYacht yacht) {
        Set<Mark> marksInRace = GameState.getMarks();
        for (Mark mark : marksInRace) {
            if (GeoUtility.getDistance(yacht.getLocation(), mark)
                <= MARK_COLLISION_DISTANCE) {
                return mark;
            }
        }
        return null;
    }

    /**
     * Calculate the new position of the boat after it has had a collision
     *
     * @return The boats new position
     */
    private static GeoPoint calculateBounceBack(ServerYacht yacht, GeoPoint collidedWith,
        Double bounceDistance) {
        Double heading = GeoUtility.getBearing(yacht.getLastLocation(), collidedWith);
        // Invert heading
        heading -= 180;
        Integer newHeading = Math.floorMod(heading.intValue(), 360);
        return GeoUtility
            .getGeoCoordinate(yacht.getLocation(), newHeading.doubleValue(), bounceDistance);
    }

    /**
     * Collision detection which iterates through all the yachts and check if any yacht collided
     * with this yacht. Return collided yacht or null if no collision.
     *
     * @return yacht to compare to all other yachts.
     */
    private static ServerYacht checkYachtCollision(ServerYacht yacht) {

        for (ServerYacht otherYacht : GameState.getYachts().values()) {
            if (otherYacht != yacht) {
                Double distance = GeoUtility
                    .getDistance(otherYacht.getLocation(), yacht.getLocation());
                if (distance < YACHT_COLLISION_DISTANCE) {
                    return otherYacht;
                }
            }
        }
        return null;
    }

    private void sendMarkRoundingMessage(ServerYacht yacht) {
        Integer sourceID = yacht.getSourceId();
        Integer currentMarkSeqID = yacht.getCurrentMarkSeqID();
        CompoundMark currentMark = markOrder.getCurrentMark(currentMarkSeqID);
        MarkType markType = (currentMark.isGate()) ? MarkType.GATE : MarkType.ROUNDING_MARK;
        Mark roundingMark = yacht.getClosestCurrentMark();

        // TODO: 13/8/17 figure out the rounding side, rounded mark source ID and boat status.
        Message markRoundingMessage = new MarkRoundingMessage(0, 0,
            sourceID, RoundingBoatStatus.RACING, roundingMark.getRoundingSide(), markType,
            currentMarkSeqID + 1);

        notifyMessageListeners(markRoundingMessage);
    }

    private static void notifyMessageListeners(Message message) {
        for (NewMessageListener mpl : markListeners) {
            mpl.notify(message);
        }
    }

    private void logMarkRounding(ServerYacht yacht) {
        Mark roundingMark = yacht.getClosestCurrentMark();
        logger.debug(
            String.format("Yacht srcID(%d) passed Mark srcID(%d)", yacht.getSourceId(),
                roundingMark.getSourceID()));
    }


    public static void addMarkPassListener(NewMessageListener listener) {
        markListeners.add(listener);
    }

    public static void setCustomizationFlag() {
        customizationFlag = true;
    }

    public static Boolean getCustomizationFlag() {
        return customizationFlag;
    }

    public static void resetCustomizationFlag() {
        customizationFlag = false;
    }

    public static Integer getNumberOfPlayers(){
        Integer numPlayers = 0;

        for(Player p : getPlayers()){
            if(p.getSocket().isConnected()){
                numPlayers++;
            }
        }

        return numPlayers;
    }

    public static Integer getCapacity(){
        return maxPlayers;
    }

    public static void setMaxPlayers(Integer newMax){
        maxPlayers = newMax;
    }
}