package xyz.nodrop.farmingtools.client.pathfinding;

import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents;
import net.minecraft.client.MinecraftClient;
import net.minecraft.client.network.ClientPlayerEntity;
import net.minecraft.util.math.BlockPos;
import xyz.nodrop.farmingtools.client.pathfinding.PathInput;

import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.function.Consumer;

/**
 * Central controller for pathfinding.
 *
 * ┌─────────────────────────────────────────────────────┐
 * │  External script / command calls:                   │
 * │    PathfindingController.INSTANCE.goTo(x, y, z)     │
 * │    PathfindingController.INSTANCE.stop()            │
 * │    PathfindingController.INSTANCE.isRunning()       │
 * └─────────────────────────────────────────────────────┘
 *
 * The A* search runs on a background thread so the client never freezes.
 * Once the path is ready it is handed off to PathExecutor which ticks
 * on the main client thread.
 */
public class PathfindingController {

    public static final PathfindingController INSTANCE = new PathfindingController();

    private final ExecutorService threadPool = Executors.newSingleThreadExecutor(r -> {
        Thread t = new Thread(r, "farmingtools-pathfinder");
        t.setDaemon(true);
        return t;
    });

    private final PathExecutor executor = new PathExecutor();

    /** Last status message — shown on HUD. */
    private volatile String status = "Idle";

    /** Optional callback fired when path is found / fails / finishes. */
    private volatile Consumer<PathResult> onResult = null;

    private PathfindingController() {}

    // ── Registration ──────────────────────────────────────────────────────────

    public void register() {
        ClientTickEvents.END_CLIENT_TICK.register(client -> {
            executor.tick(client);

            // Auto-clear status when done
            if (!executor.isActive() && status.equals("Walking...")) {
                status = "Arrived";
            }
        });
    }

    // ── Public API (call from any thread) ─────────────────────────────────────

    /**
     * Start pathfinding to the given block position.
     * Computation happens on a background thread; walking starts automatically.
     *
     * @param onResult optional callback called with the result (may be null)
     */
    public void goTo(int x, int y, int z, boolean flying, Consumer<PathResult> onResult) {
        this.onResult = onResult;
        MinecraftClient client = MinecraftClient.getInstance();
        ClientPlayerEntity player = client.player;

        if (player == null || client.world == null) {
            status = "Not in world";
            return;
        }

        BlockPos start = player.getBlockPos();
        BlockPos goal  = new BlockPos(x, y, z);

        status = "Searching...";
        executor.stop(client);
        executor.setFlying(flying);

        threadPool.submit(() -> {
            List<BlockPos> path = AStarPathfinder.find(client.world, start, goal, flying);

            if (path.isEmpty()) {
                status = "No path found";
                if (onResult != null) onResult.accept(PathResult.failure(goal));
            } else {
                status = "Walking...";
                executor.start(path);
                if (onResult != null) onResult.accept(PathResult.success(goal, path.size()));
            }
        });
    }

    /** Convenience overload without callback. */
    public void goTo(int x, int y, int z) {
        goTo(x, y, z, false, null);
    }

    /** Convenience overload accepting BlockPos. */
    public void goTo(BlockPos goal) {
        goTo(goal.getX(), goal.getY(), goal.getZ(), false, null);
    }

    /** Stop walking immediately. */
    public void stop() {
        MinecraftClient client = MinecraftClient.getInstance();
        executor.stop(client);
        status = "Stopped";
    }

    public boolean   isRunning()       { return executor.isActive(); }
    public String    getStatus()       { return status; }
    public PathInput getCurrentInput() { return executor.getCurrentInput(); }
    public int     getProgress()    { return executor.getWaypointIndex(); }
    public int     getPathLength()  { return executor.getPathLength(); }
    public BlockPos getGoal()       { return executor.getGoal(); }
    public List<BlockPos> getCurrentPath() { return executor.getPath(); }
    public int getCurrentWaypointIndex()   { return executor.getWaypointIndex(); }
    // W PathfindingController:
    public PathExecutor getExecutor() { return executor; }

    // ── Result record ─────────────────────────────────────────────────────────

    public record PathResult(boolean success, BlockPos goal, int length) {
        static PathResult success(BlockPos g, int len) { return new PathResult(true,  g, len); }
        static PathResult failure(BlockPos g)          { return new PathResult(false, g, 0);   }
    }
}