package ch.asynk.tankontank.engine;

import java.util.List;
import java.util.ArrayDeque;
import java.util.LinkedList;
import java.util.Vector;

public class SearchBoard
{
    public class Node
    {
        public int col;
        public int row;
        public int search;
        public int remaining;
        public Node parent;
        public boolean roadMarch;

        public Node(int col, int row)
        {
            this.col = col;
            this.row = row;
        }
    }

    private int cols;
    private int rows;
    private Board board;
    private Node nodes[];
    private int searchCount;
    private LinkedList<Node> queue;
    private ArrayDeque<Node> stack;
    private ArrayDeque<Node> roadMarch;
    private List<Node> result;
    private Node adjacents[];
    private Board.Orientation directions[];

    public SearchBoard(Board board, int cols, int rows)
    {
        this.cols = cols;
        this.rows = rows;
        this.board = board;
        this.nodes = new Node[cols * rows];
        for (int j = 0; j < rows; j++) {
            int dx = ((j + 1) / 2);
            for (int i = 0; i < cols; i++)
                nodes[i + (j * cols)] = new Node((i + dx), j);
        }
        this.searchCount = 0;
        this.queue = new LinkedList<Node>();
        this.stack = new ArrayDeque<Node>(20);
        this.roadMarch = new ArrayDeque<Node>(5);
        this.result = new Vector<Node>(10);
        this.adjacents = new Node[6];
        this.directions = new Board.Orientation[6];
        directions[0] = Board.Orientation.NORTH;
        directions[1] = Board.Orientation.NORTH_EAST;
        directions[2] = Board.Orientation.SOUTH_EAST;
        directions[3] = Board.Orientation.SOUTH;
        directions[4] = Board.Orientation.SOUTH_WEST;
        directions[5] = Board.Orientation.NORTH_WEST;
    }

    private Node getNode(int col, int row)
    {
        int colOffset = ((row + 1) / 2);
        if ((col < colOffset) || (row < 0) || (row >= rows) || ((col - colOffset) >= cols))
            return null;

        return nodes[((col - colOffset)) + (row * cols)];
    }

    public void adjacentMoves(Node src)
    {
        // move to enter dst by directions[i]
        adjacents[0] = getNode((src.col - 1), src.row);
        adjacents[1] = getNode(src.col, (src.row + 1));
        adjacents[2] = getNode((src.col + 1), (src.row + 1));
        adjacents[3] = getNode((src.col + 1), src.row);
        adjacents[4] = getNode(src.col, (src.row - 1));
        adjacents[5] = getNode((src.col - 1), (src.row - 1));
    }

    public List<Node> reachableFrom(Pawn pawn, int col, int row)
    {
        searchCount += 1;
        result.clear();

        Node start = getNode(col, row);
        start.parent = null;
        start.search = searchCount;
        start.remaining = pawn.getMovementPoints();
        start.roadMarch = true;

        if (start.remaining <= 0)
            return result;

        int roadMarchBonus = pawn.getRoadMarchBonus();
        boolean first = true;

        stack.push(start);

        while (stack.size() != 0) {
            Node src = stack.pop();

            if (src.remaining <= 0) {
                if (src.roadMarch) {
                    src.remaining = roadMarchBonus;
                    roadMarch.push(src);
                }
                continue;
            }

            adjacentMoves(src);

            for(int i = 0; i < 6; i++) {
                Node dst = adjacents[i];
                if (dst != null) {

                    Tile t = board.getTile(dst.col, dst.row);
                    boolean road = t.road(directions[i]);
                    int cost = t.costFrom(pawn, directions[i], road);
                    boolean mayMoveOne = first && t.atLeastOneMove(pawn);
                    int r = src.remaining - cost;
                    boolean roadMarch = road && src.roadMarch;

                    if (dst.search == searchCount) {
                        if ((r >= 0) && ((r > dst.remaining) || (roadMarch && ((r + roadMarchBonus) >= dst.remaining)))) {
                            dst.remaining = r;
                            dst.parent = src;
                            dst.roadMarch = roadMarch;
                        }
                    } else {
                        dst.search = searchCount;
                        if ((r >= 0) || mayMoveOne) {
                            dst.parent = src;
                            dst.remaining = r;
                            dst.roadMarch = roadMarch;
                            stack.push(dst);
                            result.add(dst);
                        } else {
                            dst.parent = null;
                            dst.remaining = Integer.MAX_VALUE;
                        }
                    }
                }
            }
            first = false;
        }

        while(roadMarch.size() != 0) {
            Node src = roadMarch.pop();

            adjacentMoves(src);

            for(int i = 0; i < 6; i++) {
                Node dst = adjacents[i];
                if (dst != null) {

                    Tile t = board.getTile(dst.col, dst.row);
                    if (!t.road(directions[i]))
                        continue;
                    int cost = t.costFrom(pawn, directions[i], true);
                    int r = src.remaining - cost;

                    if (dst.search == searchCount) {
                        if ((r >= 0) && (r > dst.remaining)) {
                            dst.remaining = r;
                            dst.parent = src;
                            dst.roadMarch = true;
                        }
                    } else {
                        dst.search = searchCount;
                        if (r >= 0) {
                            dst.parent = src;
                            dst.remaining = r;
                            dst.roadMarch = true;
                            roadMarch.push(dst);
                            result.add(dst);
                        } else {
                            dst.parent = null;
                            dst.remaining = Integer.MAX_VALUE;
                        }
                    }
                }
            }
        }

        return result;
    }

    private void adjacentAttacks(Node src, int angle)
    {
        // move in allowed directions
        if (Board.Orientation.NORTH.isInSides(angle))
            adjacents[0] = getNode((src.col + 1), src.row);
        else
            adjacents[0] = null;

        if (Board.Orientation.NORTH_EAST.isInSides(angle))
            adjacents[1] = getNode(src.col, (src.row - 1));
        else
            adjacents[1] = null;

        if (Board.Orientation.SOUTH_EAST.isInSides(angle))
            adjacents[2] = getNode((src.col - 1), (src.row - 1));
        else
            adjacents[2] = null;

        if (Board.Orientation.SOUTH.isInSides(angle))
            adjacents[3] = getNode((src.col - 1), src.row);
        else
            adjacents[3] = null;

        if (Board.Orientation.SOUTH_WEST.isInSides(angle))
            adjacents[4] = getNode(src.col, (src.row + 1));
        else
            adjacents[4] = null;

        if (Board.Orientation.NORTH_WEST.isInSides(angle))
            adjacents[5] = getNode((src.col + 1), (src.row + 1));
        else
            adjacents[5] = null;
    }

    private boolean hasClearLineOfSight(Tile from, Tile to)
    {
        // FIXME
        return true;
    }

    public List<Node> openToAttackFrom(Pawn pawn, int col, int row)
    {
        searchCount += 1;
        result.clear();

        Tile tile = board.getTile(col, row);

        int range = pawn.getAttackRangeFrom(tile);
        int angle = pawn.getAngleOfAttack();
        int extendedAngle = pawn.getOrientation().opposite().allBut();

        Node start = getNode(col, row);
        start.search = searchCount;
        start.remaining = range;

        if (range <= 0)
            return result;

        queue.add(start);

        boolean first = true;
        while (queue.size() != 0) {
            Node src = queue.remove();

            if (src.remaining <= 0)
                continue;

            if (!first && (((range - src.remaining) % 2) == 0))
                adjacentAttacks(src, extendedAngle);
            else
                adjacentAttacks(src, angle);

            first = false;
            int rangeLeft = src.remaining - 1;

            for(int i = 0; i < 6; i++) {
                Node dst = adjacents[i];
                if (dst != null) {
                    if (dst.search == searchCount) {
                        if ((rangeLeft > dst.remaining))
                            dst.remaining = rangeLeft;
                    } else {
                        dst.search = searchCount;
                        dst.remaining = rangeLeft;
                        queue.add(dst);
                        Tile t = board.getTile(dst.col, dst.row);
                        if (t.hasTargetsFor(pawn) && hasClearLineOfSight(tile, t)) result.add(dst);
                    }
                }
            }
        }

        return result;
    }

    public List<Node> lineOfSight(int x0, int y0, int x1, int y1)
    {
        return lineOfSight(x0, y0, x1, y1, true);
    }

    public List<Node> lineOfSight(int x0, int y0, int x1, int y1, boolean check)
    {
        result.clear();

        // orthogonal axis
        int ox0 = x0 - ((y0 +1) / 2);
        int ox1 = x1 - ((y1 +1) / 2);

        int dy = y1 - y0;
        int dx = ox1 - ox0;

        int xs = 1;
        int ys = 1;
        if (dx < 0) xs = -1;
        if (dy < 0) ys = -1;
        boolean sig = !(((dx < 0) && (dy >= 0)) || ((dx >= 0) && (dy < 0)));

        dy = Math.abs(dy);
        dx = Math.abs(2 * dx);
        if ((dy % 2) == 1) {
            if ((y0 % 2) == 0) dx += xs;
            else {
                dx -= xs;
                Math.abs(dx);
            }
        }
        if (dx == 0)
            return verticalLineOfSight(x0, y0, x1, y1, check);

        int dx3 = 3 * dx;
        int dy3 = 3 * dy;

        int x = x0;
        int y = y0;
        int e = -2 * dx;

        boolean vert = (dx == 0);
        boolean flat = (dx > (3 * dy));
        boolean diag = (dx == (3 * dy));

        int step = 0;
        result.add(getNode(x, y));
        while((x != x1) || (y != y1)) {
            if (e > 0) {
                e -= (dy3 + dx3);
                y += ys;
                if (!sig)
                    x -= xs;
            } else {
                e += dy3;
                if ((e > -dx) || (!flat && (e == -dx))) {
                    e -= dx3;
                    y += ys;
                    if (sig)
                        x += xs;
                } else if ((e < -dx3) || (diag && (e == -dx3))) {
                    e += dx3;
                    y -= ys;
                    if (!sig)
                        x += xs;
                } else {
                    e += dy3;
                    x += xs;
                }
            }
            result.add(getNode(x, y));
            step += 1;
            if (step > 20) {
                return result;
            }
        }

        return result;
    }

    private List<Node> verticalLineOfSight(int x0, int y0, int x1, int y1, boolean check)
    {
        int d = ( (y1 > y0) ? 1 : -1);
        int x = x0;
        int y = y0;

        Tile t = null;
        result.add(getNode(x, y));
        while((x != x1) || (y != y1)) {
            y += d;
            t = board.getTile(x, y);
            if (!t.isOffMap()) result.add(getNode(x, y));

            x += d;
            t = board.getTile(x, y);
            if (!t.isOffMap()) result.add(getNode(x, y));

            y += d;
            t = board.getTile(x, y);
            if (!t.isOffMap()) result.add(getNode(x, y));
        }

        return result;
    }
}