// Redstone Link Addon
//
// Wireless redstone for the SilverLABS multiworld. Place a transmitter next to
// any redstone source and a receiver anywhere else, give both the same channel
// name, and the receiver emits full-strength power whenever the transmitter is
// powered. No wire, no line of sight, no support block, any distance.
//
// Why a block swap: Bedrock custom blocks can READ redstone power but cannot
// EMIT it -- there is no script API for that. So a live receiver is physically
// replaced by a vanilla redstone block (strength 15, omnidirectional, needs no
// support) and swapped back when the channel goes quiet. registry.js remembers
// where the receivers are, because while powered the block no longer says so.
//
// Known limits, by design:
//   * Both ends must be in loaded chunks. Out-of-range links simply do nothing.
//   * ~2 tick latency. Not for sub-tick contraptions.
//   * Binary, not graded: output is always 15.

import { world, system, ItemStack, BlockPermutation } from "@minecraft/server";
import { ModalFormData } from "@minecraft/server-ui";
import { isTransmitterPowered } from "./power.js";
import * as registry from "./registry.js";

const TX_ID = "silverlabs:redstone_link_tx";
const RX_ID = "silverlabs:redstone_link_rx";
const LIVE_ID = "minecraft:redstone_block";

const TICK_INTERVAL = 2;
const MAX_CHANNEL_LEN = 24;
const DEFAULT_CHANNEL = "default";

function roleOf(typeId) {
  if (typeId === TX_ID) return "tx";
  if (typeId === RX_ID) return "rx";
  return null;
}

function sanitiseChannel(raw) {
  if (typeof raw !== "string") return "";
  return raw.trim().toLowerCase().slice(0, MAX_CHANNEL_LEN);
}

function blockAt(node) {
  // Returns undefined when the chunk is not loaded -- callers must treat that
  // as "unknown", never as "gone", or we would delete live nodes.
  let dim;
  try { dim = world.getDimension(node.d); } catch (_) { return undefined; }
  if (!dim) return undefined;
  try { return dim.getBlock({ x: node.x, y: node.y, z: node.z }); } catch (_) { return undefined; }
}

function setBlockTo(block, typeId) {
  try {
    block.setPermutation(BlockPermutation.resolve(typeId));
    return true;
  } catch (e) {
    console.warn(`[RedstoneLink] failed to set ${typeId}: ${e}`);
    return false;
  }
}

// --- The link engine ------------------------------------------------------

function tick() {
  const nodes = registry.all();
  if (nodes.length === 0) return;

  // Receiver positions grouped by channel, so a transmitter can ignore power
  // coming from its own channel's receivers (self-latch guard).
  const rxKeysByChannel = new Map();
  for (const n of nodes) {
    if (n.r !== "rx" || !n.c) continue;
    let set = rxKeysByChannel.get(n.c);
    if (!set) { set = new Set(); rxKeysByChannel.set(n.c, set); }
    set.add(registry.nodeKey(n));
  }

  const stale = new Set();
  const live = new Set();

  // Pass 1 -- which channels are being driven?
  for (const n of nodes) {
    if (n.r !== "tx") continue;
    const b = blockAt(n);
    if (b === undefined) continue;               // chunk unloaded: unknown
    if (b.typeId !== TX_ID) { stale.add(registry.nodeKey(n)); continue; }
    if (!n.c || live.has(n.c)) continue;         // unset, or already known live
    if (isTransmitterPowered(b, rxKeysByChannel.get(n.c))) live.add(n.c);
  }

  // Pass 2 -- make every receiver match its channel.
  for (const n of nodes) {
    if (n.r !== "rx") continue;
    const b = blockAt(n);
    if (b === undefined) continue;
    const isOn = b.typeId === LIVE_ID;
    const isOff = b.typeId === RX_ID;
    if (!isOn && !isOff) { stale.add(registry.nodeKey(n)); continue; }
    const want = Boolean(n.c) && live.has(n.c);
    if (want && !isOn) setBlockTo(b, LIVE_ID);
    else if (!want && !isOff) setBlockTo(b, RX_ID);
  }

  if (stale.size > 0) registry.removeKeys(stale);
}

/**
 * Startup pass. Anything that got out of sync while the world was unloaded --
 * a receiver left as a redstone block after a crash, a node whose block was
 * removed by an explosion -- is corrected or forgotten here.
 */
function reconcile() {
  const nodes = registry.all();
  if (nodes.length === 0) return;
  const stale = new Set();
  let restored = 0;
  for (const n of nodes) {
    const b = blockAt(n);
    if (b === undefined) continue;
    if (n.r === "tx") {
      if (b.typeId !== TX_ID) stale.add(registry.nodeKey(n));
      continue;
    }
    if (b.typeId === LIVE_ID) {
      // No transmitter has been evaluated yet, so nothing is live: park it off.
      if (setBlockTo(b, RX_ID)) restored++;
    } else if (b.typeId !== RX_ID) {
      stale.add(registry.nodeKey(n));
    }
  }
  const dropped = registry.removeKeys(stale);
  if (restored || dropped) {
    console.warn(`[RedstoneLink] reconcile: ${restored} receiver(s) reset, ${dropped} stale node(s) dropped`);
  }
}

// --- Channel UI -----------------------------------------------------------

async function openChannelForm(player, block, node) {
  const role = roleOf(block.typeId);
  const label = role === "tx" ? "Transmitter" : "Receiver";
  const current = node?.c ?? "";

  const form = new ModalFormData()
    .title(`§6Redstone Link §7${label}`)
    .textField(
      "Channel name\n§7Any transmitter and receiver sharing a channel are linked.",
      "e.g. front-door",
      current
    );

  let res;
  try { res = await form.show(player); } catch (_) { return; }
  if (res.canceled) return;

  const channel = sanitiseChannel(res.formValues?.[0]);
  if (!channel) {
    player.sendMessage("§c[Redstone Link] §7Channel name cannot be empty.");
    return;
  }

  const saved = registry.add(block.dimension.id, block.location, role, channel);
  if (!saved) {
    player.sendMessage(`§c[Redstone Link] §7Too many links in this world (max ${registry.MAX_NODES}).`);
    return;
  }
  player.sendMessage(`§a[Redstone Link] §7${label} set to channel §f${channel}§7.`);
}

// --- Events ---------------------------------------------------------------

try {
  world.beforeEvents.playerInteractWithBlock.subscribe((event) => {
    const block = event.block;
    if (!block) return;
    const role = roleOf(block.typeId);
    if (!role) return;
    event.cancel = true;
    const playerRef = event.player;
    const dimId = block.dimension.id;
    const loc = { x: block.location.x, y: block.location.y, z: block.location.z };
    system.run(() => {
      const node = registry.find(dimId, loc);
      openChannelForm(playerRef, block, node);
    });
  });
} catch (e) {
  console.warn(`[RedstoneLink] beforeEvents.playerInteractWithBlock unavailable: ${e}`);
}

try {
  world.afterEvents.playerPlaceBlock.subscribe((event) => {
    const block = event.block;
    if (!block) return;
    const role = roleOf(block.typeId);
    if (!role) return;
    const added = registry.add(block.dimension.id, block.location, role, DEFAULT_CHANNEL);
    if (!added) {
      event.player?.sendMessage(
        `§c[Redstone Link] §7Too many links in this world (max ${registry.MAX_NODES}). This one will not work.`
      );
      return;
    }
    event.player?.sendMessage(
      `§7[Redstone Link] On channel §f${DEFAULT_CHANNEL}§7. Interact to rename it.`
    );
  });
} catch (e) {
  console.warn(`[RedstoneLink] afterEvents.playerPlaceBlock unavailable: ${e}`);
}

try {
  world.beforeEvents.playerBreakBlock.subscribe((event) => {
    const block = event.block;
    if (!block) return;
    const dimId = block.dimension.id;
    const loc = { x: block.location.x, y: block.location.y, z: block.location.z };
    const node = registry.find(dimId, loc);
    if (!node) return;

    if (block.typeId === LIVE_ID) {
      // A live receiver. Left alone, vanilla would hand out a free redstone
      // block, so intercept: drop the receiver item instead.
      event.cancel = true;
      const playerRef = event.player;
      system.run(() => {
        registry.remove(dimId, loc);
        let dim;
        try { dim = world.getDimension(dimId); } catch (_) { return; }
        try { dim.getBlock(loc)?.setPermutation(BlockPermutation.resolve("minecraft:air")); } catch (_) {}
        let creative = false;
        try { creative = playerRef?.getGameMode?.() === "creative"; } catch (_) { creative = false; }
        if (creative) return;
        try {
          dim.spawnItem(new ItemStack(RX_ID, 1), { x: loc.x + 0.5, y: loc.y + 0.5, z: loc.z + 0.5 });
        } catch (_) {}
      });
      return;
    }

    // Unpowered node: vanilla break already returns the right item.
    system.run(() => registry.remove(dimId, loc));
  });
} catch (e) {
  console.warn(`[RedstoneLink] beforeEvents.playerBreakBlock unavailable: ${e}`);
}

// --- Console / bridge control --------------------------------------------
//
// Blocks placed by command rather than by hand -- /setblock, /fill, or the
// mc-ai-bridge MCP build tools -- never fire playerPlaceBlock, so they are not
// in the registry and stay inert. These script events give the console and the
// bridge a way to register them. sourceEntity is null when run via RCON or the
// bridge, so we never require a player here.
//
//   /scriptevent rlink:register <x> <y> <z> <channel>
//   /scriptevent rlink:unregister <x> <y> <z>
//   /scriptevent rlink:status

function announce(text) {
  try { world.getDimension("overworld").runCommand(`say ${text}`); } catch (_) {}
  console.warn(text);
}

function handleRegister(args) {
  if (args.length < 4) {
    announce("[RedstoneLink] usage: rlink:register <x> <y> <z> <channel>");
    return;
  }
  const x = Number(args[0]), y = Number(args[1]), z = Number(args[2]);
  if (!Number.isFinite(x) || !Number.isFinite(y) || !Number.isFinite(z)) {
    announce("[RedstoneLink] register: coordinates must be numbers");
    return;
  }
  const channel = sanitiseChannel(args.slice(3).join(" "));
  if (!channel) {
    announce("[RedstoneLink] register: channel name required");
    return;
  }
  const loc = { x: Math.floor(x), y: Math.floor(y), z: Math.floor(z) };
  let block;
  try { block = world.getDimension("overworld").getBlock(loc); } catch (_) { block = undefined; }
  if (!block) {
    announce(`[RedstoneLink] register: no loaded block at ${loc.x},${loc.y},${loc.z}`);
    return;
  }
  const role = roleOf(block.typeId);
  if (!role) {
    announce(`[RedstoneLink] register: ${block.typeId} is not a link block`);
    return;
  }
  const saved = registry.add("minecraft:overworld", loc, role, channel);
  if (!saved) {
    announce(`[RedstoneLink] register: registry full (max ${registry.MAX_NODES})`);
    return;
  }
  announce(`[RedstoneLink] registered ${role} at ${loc.x},${loc.y},${loc.z} on channel ${channel}`);
}

function handleUnregister(args) {
  if (args.length < 3) {
    announce("[RedstoneLink] usage: rlink:unregister <x> <y> <z>");
    return;
  }
  const loc = {
    x: Math.floor(Number(args[0])),
    y: Math.floor(Number(args[1])),
    z: Math.floor(Number(args[2])),
  };
  const gone = registry.remove("minecraft:overworld", loc);
  announce(`[RedstoneLink] unregister ${loc.x},${loc.y},${loc.z}: ${gone ? "removed" : "not found"}`);
}

function handleStatus() {
  const nodes = registry.all();
  const tx = nodes.filter((n) => n.r === "tx").length;
  const rx = nodes.filter((n) => n.r === "rx").length;
  const channels = [...new Set(nodes.map((n) => n.c).filter(Boolean))];
  announce(`[RedstoneLink] alive: ${nodes.length} node(s), ${tx} tx, ${rx} rx, channels=[${channels.join(",")}]`);
}

try {
  system.afterEvents.scriptEventReceive.subscribe((event) => {
    const id = event.id;
    if (!id || !id.startsWith("rlink:")) return;
    const args = (event.message || "").trim().split(/\s+/).filter(Boolean);
    try {
      switch (id) {
        case "rlink:register":   handleRegister(args); break;
        case "rlink:unregister": handleUnregister(args); break;
        case "rlink:status":     handleStatus(); break;
        default: announce(`[RedstoneLink] unknown command ${id}`);
      }
    } catch (e) {
      announce(`[RedstoneLink] ${id} failed: ${e}`);
    }
  });
} catch (e) {
  console.warn(`[RedstoneLink] scriptEventReceive unavailable: ${e}`);
}

// --- Boot -----------------------------------------------------------------

system.run(() => {
  try { reconcile(); } catch (e) { console.warn(`[RedstoneLink] reconcile failed: ${e}`); }
  try {
    system.runInterval(() => {
      try { tick(); } catch (e) { console.warn(`[RedstoneLink] tick failed: ${e}`); }
    }, TICK_INTERVAL);
  } catch (e) {
    console.warn(`[RedstoneLink] could not start tick loop: ${e}`);
  }
  world.sendMessage("§c[Redstone Link] §7Wireless redstone loaded.");
});