/// @name Snake Auto (Campaign) v5
using System;
using System.Linq;
using System.Collections.Generic;

const long HEAD_ID = 769407982;
const int TARGET_KIND = 3666;
const int SNAKE_KIND = 5478;

const int GAME_MIN_X = 37;
const int GAME_MAX_X = 59;
const int GAME_MIN_Y = 29;
const int GAME_MAX_Y = 51;

// Confirmed controls
const int CTRL_UP = 769407385;
const int CTRL_RIGHT = 769406820;
const int CTRL_DOWN = 769407085;
const int CTRL_LEFT = 769407116;

static readonly string[] DIRS = { "UP", "DOWN", "LEFT", "RIGHT" };

DateTime lastCmdTime = DateTime.MinValue;
DateTime lastInfo = DateTime.MinValue;
string lastSentDir = "";
int curDir = -1; // 0=UP 1=DOWN 2=LEFT 3=RIGHT
(int x, int y) prevHead = (-1, -1);

HashSet<(int x, int y)> fillVisited = new HashSet<(int, int)>();
Queue<(int x, int y)> fillQueue = new Queue<(int, int)>();
HashSet<(int x, int y)> pathVisited = new HashSet<(int, int)>();
Queue<((int x, int y) pos, int dist)> pathQueue = new Queue<((int, int), int)>();

bool InBoard(int x, int y)
    => x >= GAME_MIN_X && x <= GAME_MAX_X && y >= GAME_MIN_Y && y <= GAME_MAX_Y;

void Next(int x, int y, int d, out int nx, out int ny)
{
    nx = x + (d == 3 ? 1 : d == 2 ? -1 : 0);
    ny = y + (d == 1 ? 1 : d == 0 ? -1 : 0);
}

int Opp(int d) => d ^ 1;

int DirFromDelta(int dx, int dy)
{
    if (Math.Abs(dx) >= Math.Abs(dy))
        return dx < 0 ? 2 : 3;
    return dy < 0 ? 0 : 1;
}

int IdForDir(int d)
    => d == 0 ? CTRL_UP : d == 1 ? CTRL_DOWN : d == 2 ? CTRL_LEFT : CTRL_RIGHT;

bool TryGetButtonPos(int id, out int x, out int y)
{
    var b = GetFloorItem(id);
    if (b == null)
    {
        x = 0;
        y = 0;
        return false;
    }
    x = b.Location.X;
    y = b.Location.Y;
    return true;
}

void Cmd(int d)
{
    string nd = DIRS[d];
    if (nd == lastSentDir && (DateTime.Now - lastCmdTime).TotalMilliseconds < 110)
        return;

    int id = IdForDir(d);

    if (TryGetButtonPos(id, out int bx, out int by))
        Move(bx, by);

    Send(Out["ClickFurni"], id, 0);

    lastCmdTime = DateTime.Now;
    lastSentDir = nd;
}

bool Bad(int x, int y, HashSet<(int x, int y)> body)
{
    if (!InBoard(x, y)) return true;
    return body.Contains((x, y));
}

int Fill(int sx, int sy, HashSet<(int x, int y)> body, int cap)
{
    if (Bad(sx, sy, body)) return 0;

    fillVisited.Clear();
    fillQueue.Clear();

    fillVisited.Add((sx, sy));
    fillQueue.Enqueue((sx, sy));

    int c = 0;
    while (fillQueue.Count > 0 && c < cap)
    {
        var p = fillQueue.Dequeue();
        c++;
        for (int d = 0; d < 4; d++)
        {
            Next(p.x, p.y, d, out int nx, out int ny);
            if (!Bad(nx, ny, body) && fillVisited.Add((nx, ny)))
                fillQueue.Enqueue((nx, ny));
        }
    }
    return c;
}

int Dist(int sx, int sy, int tx, int ty, HashSet<(int x, int y)> body, int cap)
{
    if (sx == tx && sy == ty) return 0;

    pathVisited.Clear();
    pathQueue.Clear();

    pathVisited.Add((sx, sy));
    pathQueue.Enqueue(((sx, sy), 0));

    while (pathQueue.Count > 0)
    {
        var cur = pathQueue.Dequeue();
        if (cur.dist >= cap) return 999;

        for (int d = 0; d < 4; d++)
        {
            Next(cur.pos.x, cur.pos.y, d, out int nx, out int ny);
            if (nx == tx && ny == ty) return cur.dist + 1;
            if (!Bad(nx, ny, body) && pathVisited.Add((nx, ny)))
                pathQueue.Enqueue(((nx, ny), cur.dist + 1));
        }
    }
    return -1;
}

int Emergency((int x, int y) head, HashSet<(int x, int y)> body)
{
    int bestDir = curDir >= 0 ? curDir : 0;
    int bestSpace = -1;

    for (int d = 0; d < 4; d++)
    {
        if (curDir >= 0 && d == Opp(curDir)) continue;

        Next(head.x, head.y, d, out int nx, out int ny);
        if (Bad(nx, ny, body)) continue;

        int space = Fill(nx, ny, body, 120);
        if (space > bestSpace)
        {
            bestSpace = space;
            bestDir = d;
        }
    }
    return bestDir;
}

int Decide((int x, int y) head, (int x, int y) target, HashSet<(int x, int y)> body)
{
    int bestDir = curDir >= 0 ? curDir : 0;
    int bestScore = int.MinValue;

    for (int d = 0; d < 4; d++)
    {
        if (curDir >= 0 && d == Opp(curDir)) continue;

        Next(head.x, head.y, d, out int nx, out int ny);
        if (Bad(nx, ny, body)) continue;

        int space = Fill(nx, ny, body, 200);
        if (space < 10) continue;

        int dist = Dist(nx, ny, target.x, target.y, body, 200);

        int score = 0;
        if (nx == target.x && ny == target.y) score += 15000;
        if (dist > 0 && dist < 999) score += (240 - dist) * 8;
        else if (dist == -1) score -= 300;

        score += Math.Min(space, 120) * 4;
        if (curDir >= 0 && d == curDir) score += 2;

        if (score > bestScore)
        {
            bestScore = score;
            bestDir = d;
        }
    }

    return bestDir;
}

Log("Snake Auto (Campaign) v5 started");
Log($"Buttons: U={CTRL_UP} R={CTRL_RIGHT} D={CTRL_DOWN} L={CTRL_LEFT}");

while (Run)
{
    Delay(18);

    var headItem = GetFloorItem(HEAD_ID);
    if (headItem == null)
    {
        if ((DateTime.Now - lastInfo).TotalMilliseconds > 1500)
        {
            Log("waiting: head not visible");
            lastInfo = DateTime.Now;
        }
        continue;
    }

    var head = (headItem.Location.X, headItem.Location.Y);
    if (!InBoard(head.Item1, head.Item2))
        continue;

    if (prevHead.x != -1)
    {
        int dx = head.Item1 - prevHead.x;
        int dy = head.Item2 - prevHead.y;
        if (dx != 0 || dy != 0)
            curDir = DirFromDelta(dx, dy);
    }
    prevHead = head;

    var body = FloorItems
        .Where(i => i != null && i.Kind == SNAKE_KIND)
        .Where(i => InBoard(i.Location.X, i.Location.Y))
        .Select(i => (i.Location.X, i.Location.Y))
        .Where(p => !(p.Item1 == head.Item1 && p.Item2 == head.Item2))
        .ToHashSet();

    var targets = FloorItems
        .Where(i => i != null && i.Kind == TARGET_KIND)
        .Where(i => InBoard(i.Location.X, i.Location.Y))
        .Select(i => (x: i.Location.X, y: i.Location.Y))
        .ToList();

    if (targets.Count == 0)
    {
        // No tile visible: stay safe, do not random reverse.
        int safe = Emergency(head, body);
        Cmd(safe);
        continue;
    }

    var target = targets
        .OrderBy(t => Math.Abs(t.x - head.Item1) + Math.Abs(t.y - head.Item2))
        .First();

    if (curDir >= 0)
    {
        Next(head.Item1, head.Item2, curDir, out int fx, out int fy);
        if (Bad(fx, fy, body))
        {
            int emergency = Emergency(head, body);
            Cmd(emergency);
            continue;
        }
    }

    int best = Decide(head, target, body);
    Cmd(best);
}