package ch.zhaw.pm2.racetrack;

import ch.zhaw.pm2.racetrack.given.ConfigSpecification;
import ch.zhaw.pm2.racetrack.given.TrackSpecification;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

/**
 * This class represents the racetrack board.
 *
 * <p>The racetrack board consists of a rectangular grid of 'width' columns and 'height' rows.
 * The zero point of he grid is at the top left. The x-axis points to the right and the y-axis points downwards.</p>
 * <p>Positions on the track grid are specified using {@link PositionVector} objects. These are vectors containing an
 * x/y coordinate pair, pointing from the zero-point (top-left) to the addressed space in the grid.</p>
 *
 * <p>Each position in the grid represents a space which can hold an enum object of type {@link Config.SpaceType}.<br>
 * Possible Space types are:
 * <ul>
 *  <li>WALL : road boundary or off track space</li>
 *  <li>TRACK: road or open track space</li>
 *  <li>FINISH_LEFT, FINISH_RIGHT, FINISH_UP, FINISH_DOWN :  finish line spaces which have to be crossed
 *      in the indicated direction to winn the race.</li>
 * </ul>
 * <p>Beside the board the track contains the list of cars, with their current state (position, velocity, crashed,...)</p>
 *
 * <p>At initialization the track grid data is read from the given track file. The track data must be a
 * rectangular block of text. Empty lines at the start are ignored. Processing stops at the first empty line
 * following a non-empty line, or at the end of the file.</p>
 * <p>Characters in the line represent SpaceTypes. The mapping of the Characters is as follows:</p>
 * <ul>
 *   <li>WALL : '#'</li>
 *   <li>TRACK: ' '</li>
 *   <li>FINISH_LEFT : '&lt;'</li>
 *   <li>FINISH_RIGHT: '&gt;'</li>
 *   <li>FINISH_UP   : '^;'</li>
 *   <li>FINISH_DOWN: 'v'</li>
 *   <li>Any other character indicates the starting position of a car.<br>
 *       The character acts as the id for the car and must be unique.<br>
 *       There are 1 to {@link Config#MAX_CARS} allowed. </li>
 * </ul>
 *
 * <p>All lines must have the same length, used to initialize the grid width).
 * Beginning empty lines are skipped.
 * The the tracks ends with the first empty line or the file end.<br>
 * An {@link InvalidTrackFormatException} is thrown, if
 * <ul>
 *   <li>not all track lines have the same length</li>
 *   <li>the file contains no track lines (grid height is 0)</li>
 *   <li>the file contains more than {@link Config#MAX_CARS} cars</li>
 * </ul>
 *
 * <p>The Track can return a String representing the current state of the race (including car positons)</p>
 */
public class Track implements TrackSpecification {

    public static final char CRASH_INDICATOR = 'X';
    private List<String> track;
    private List<Car> cars;
    private final List<PositionVector> finishLine;

    /**
     * Initialize a Track from the given track file.
     *
     * @param trackFile Reference to a file containing the track data
     * @throws FileNotFoundException       if the given track file could not be found
     * @throws InvalidTrackFormatException if the track file contains invalid data (no tracklines, ...)
     */
    public Track(File trackFile) throws FileNotFoundException, InvalidTrackFormatException, PositionVectorNotValid {
        track = new ArrayList<>();
        cars = new ArrayList<>();
        finishLine = new ArrayList<>();
        readFile(trackFile);
        findFinish();
        addCars();
    }

    /**
     * This method reads the File and saves it to the track ArrayList Line by Line
     *
     * @param trackFile the File where the track has been documented
     * @throws FileNotFoundException if the FilePath is invalid.
     */
    private void readFile(File trackFile) throws FileNotFoundException {
        Scanner scanner = new Scanner(trackFile);
        while (scanner.hasNextLine()) {
            track.add(scanner.nextLine());
        }
    }


    private void addCars() throws InvalidTrackFormatException {
        ConfigSpecification.SpaceType[] spaceTypes = ConfigSpecification.SpaceType.values();
        List<Character> allSpaceTypesAsChar = new ArrayList<>();
        List<Character> usedSymbolForCar = new ArrayList<>();

        for (ConfigSpecification.SpaceType spaceType : spaceTypes) {
            allSpaceTypesAsChar.add(spaceType.getValue());
        }


        for (int j = 0; j < track.size(); j++) {
            String line = track.get(j);
            for (int i = 0; i < line.length(); i++) {
                char possibleCarChar = line.charAt(i);
                if (!allSpaceTypesAsChar.contains(possibleCarChar)) {
                    if (usedSymbolForCar.contains(possibleCarChar)) {
                        throw new InvalidTrackFormatException();
                    }
                    usedSymbolForCar.add(possibleCarChar);
                    cars.add(new Car(possibleCarChar, new PositionVector(i, j)));
                }
            }
        }

    }

    private void findFinish() throws InvalidTrackFormatException {
        for (int i = 0; i < track.size(); i++) {
            String line = track.get(i);
            for (int j = 0; j < line.length(); j++) {
                if (line.charAt(j) == ConfigSpecification.SpaceType.FINISH_LEFT.getValue() ||
                    line.charAt(j) == ConfigSpecification.SpaceType.FINISH_RIGHT.getValue() ||
                    line.charAt(j) == ConfigSpecification.SpaceType.FINISH_DOWN.getValue() ||
                    line.charAt(j) == ConfigSpecification.SpaceType.FINISH_UP.getValue()) {
                    finishLine.add(new PositionVector(j, i));
                }
            }
        }
        if (finishLine.size() == 0) {
            throw new InvalidTrackFormatException();
        }
        ConfigSpecification.SpaceType finishTyp = getSpaceType(finishLine.get(0));
        for (PositionVector positionVector : finishLine) {
            if (getSpaceType(positionVector) != finishTyp) {
                throw new InvalidTrackFormatException();
            }
        }
    }

    private PositionVector findChar(char symbol) {
        PositionVector vector = null;
        for (int i = 0; i < track.size(); i++) {
            String line = track.get(i);
            for (int j = 0; j < line.length(); j++) {
                if (line.charAt(j) == symbol) {
                    vector = new PositionVector(j, i);
                }
            }
        }
        return vector;
    }

    private void drawCharOnTrackIndicator(PositionVector positionVector, char symbol) {
        String line = track.get(positionVector.getY());
        line = line.substring(0, positionVector.getX()) + symbol + line.substring(positionVector.getX() + 1);
        track.remove(positionVector.getY());
        track.add(positionVector.getY(), line);
    }

    private void isPositionVectorOnTrack(PositionVector positionVector) throws PositionVectorNotValid {
        try{
            track.get(positionVector.getY()).charAt(positionVector.getX());
        }catch (IndexOutOfBoundsException e) {
            throw new PositionVectorNotValid();
        }
    }

    /**
     * @return all Cars
     */
    public List<Car> getCars() {
        return cars;
    }

    /**
     * @return finishLine
     */
    public List<PositionVector> getFinishLine() {
        return finishLine;
    }

    /**
     * @return the track
     */
    public List<String> getTrack() {
        return track;
    }

    /**
     * This Method will update the Car on the track
     * and will make the Car move to the next position
     *
     * @param carIndex representing the current Car
     */
    public void moveCar(int carIndex) {
        makeCarMoveInTrack(carIndex);
        //Change position of car
        getCar(carIndex).move();
    }

    /**
     * This class does change the Position of the car only in the track.
     *
     * @param carIndex of the current car
     */
    private void makeCarMoveInTrack(int carIndex) {
        PositionVector positionVector = findChar(getCarId(carIndex));
        //Removes the Car at Current Pos
        drawCharOnTrackIndicator(positionVector, ConfigSpecification.SpaceType.TRACK.getValue());
        //Adds Car at new Position
        positionVector = cars.get(carIndex).nextPosition();
        drawCharOnTrackIndicator(positionVector, cars.get(carIndex).getID());
    }

    /**
     * This Method will check if the Car could crash at the specific position
     *
     * @param positionVector the position to check if the car could crash
     * @return true if car would crash. Else false.
     */
    public boolean willCrashAtPosition(int carIndex, PositionVector positionVector) throws PositionVectorNotValid {
        isPositionVectorOnTrack(positionVector);
        char charAtPosition = track.get(positionVector.getY()).charAt(positionVector.getX());
        if (getCarId(carIndex) == charAtPosition) return false;
        return (charAtPosition == ConfigSpecification.SpaceType.WALL.value);
    }

    /**
     * This Method will make the Car Crash. In Track and in the Car Object
     *
     * @param carIndex       representing current Car
     * @param positionVector where the Crash did happen
     */
    public void carDoesCrash(int carIndex, PositionVector positionVector) throws PositionVectorNotValid{
        isPositionVectorOnTrack(positionVector);
        Car car = cars.get(carIndex);
        car.crash();
        car.setPosition(positionVector);
        drawCharOnTrackIndicator(new PositionVector(positionVector.getX(), positionVector.getY()), CRASH_INDICATOR);
    }

    /**
     * Return the type of space at the given position.
     * If the location is outside the track bounds, it is considered a wall.
     *
     * @param position The coordinates of the position to examine
     * @return The type of track position at the given location
     */
    @Override
    public Config.SpaceType getSpaceType(PositionVector position) {
        //isPositionVectorOnTrack(position); Should be used but we are not allowed to change method head. We don't use function anyway
        char charAtPosition = track.get(position.getY()).charAt(position.getX());
        ConfigSpecification.SpaceType[] spaceTypes = ConfigSpecification.SpaceType.values();
        for (ConfigSpecification.SpaceType spaceType : spaceTypes) {
            if (spaceType.getValue() == charAtPosition) {
                return spaceType;
            }
        }

        return null;
    }

    /**
     * Return the number of cars.
     *
     * @return Number of cars
     */
    @Override
    public int getCarCount() {
        return cars.size();
    }

    /**
     * Get instance of specified car.
     *
     * @param carIndex The zero-based carIndex number
     * @return The car instance at the given index
     */
    @Override
    public Car getCar(int carIndex) {
        return cars.get(carIndex);
    }

    /**
     * Get the id of the specified car.
     *
     * @param carIndex The zero-based carIndex number
     * @return A char containing the id of the car
     */
    @Override
    public char getCarId(int carIndex) {
        return cars.get(carIndex).getID();
    }

    /**
     * Get the position of the specified car.
     * Returns Null if carIndex not valid
     *
     * @param carIndex The zero-based carIndex number
     * @return A PositionVector containing the car's current position
     */
    @Override
    public PositionVector getCarPos(int carIndex) {
        return findChar(cars.get(carIndex).getID());
    }

    /**
     * Get the velocity of the specified car.
     *
     * @param carIndex The zero-based carIndex number
     * @return A PositionVector containing the car's current velocity
     */
    @Override
    public PositionVector getCarVelocity(int carIndex) {
        return cars.get(carIndex).getVelocity();
    }

    /**
     * Gets character at the given position.
     * If there is a crashed car at the position, {@link #CRASH_INDICATOR} is returned.
     *
     * @param y            position Y-value
     * @param x            position X-vlaue
     * @param currentSpace char to return if no car is at position (x,y)
     * @return character representing position (x,y) on the track
     */
    @Override
    public char getCharAtPosition(int y, int x, Config.SpaceType currentSpace) {
        char charAtPos = track.get(y).charAt(x);
        PositionVector positionVector = new PositionVector(x, y);
        for (Car car : cars) {
            if (charAtPos == car.getID()) {
                return charAtPos;
            }
        }
        if (positionVector.equals(findChar(CRASH_INDICATOR))) return CRASH_INDICATOR;
        return currentSpace.getValue();
    }

    /**
     * Return a String representation of the track, including the car locations.
     *
     * @return A String representation of the track
     */
    @Override
    public String toString() {
        StringBuilder str = new StringBuilder();
        for (String line : track) str.append(line).append("\n");
        return str.toString();
    }
}