import * as THREE from "three";
import { AREngine } from "./ar-engine.js";
import { Ghost } from "./ghost.js";
import { scanQR } from "./qr.js";

/* ============ DOM ============ */
const $ = (id) => document.getElementById(id);
const titleScreen = $("title-screen");
const huntScreen = $("hunt-screen");
const capabilityEl = $("capability");
const startBtn = $("start-btn");
const howBtn = $("how-btn");
const howto = $("howto");
const howtoClose = $("howto-close");
const scanPrompt = $("scan-prompt");
const hud = $("hud");
const scoreEl = $("score");
const nearbyEl = $("nearby");
const exitBtn = $("exit-btn");
const reticle = $("reticle");
const captureProgressEl = $("capture-progress");
const lockLabel = $("lock-label");
const dirHint = $("dir-hint");
const trapBtn = $("trap-btn");
const captureFlash = $("capture-flash");
const toast = $("toast");
const canvas = $("gl-canvas");
const video = $("camera-feed");

/* ============ STATE ============ */
let engine = null;
let detectedMode = "none";
let ghosts = [];
let score = 0;
let scanned = false;
let scanStart = 0;
let trapping = false;
let lockedGhost = null;
let spawnTimer = 0;
let roster = [];        // ghost specs fetched after a QR scan (empty = procedural ghosts)
let activeSetTitle = null;
const CAPTURE_RATE = 0.55;      // progress per second while locked
const DECAY_RATE = 0.9;         // progress lost per second when not locked
const AIM_CONE = 0.92;          // dot-product threshold for "on target"
const MAX_GHOSTS = 5;
const RING_CIRC = 2 * Math.PI * 54;

const _camDir = new THREE.Vector3();
const _toGhost = new THREE.Vector3();
const _ghostPos = new THREE.Vector3();
const _camPos = new THREE.Vector3();
const _right = new THREE.Vector3();

/* ============ CAPABILITY CHECK ============ */
(async function init() {
  detectedMode = await AREngine.detect();
  if (detectedMode === "xr") {
    capabilityEl.textContent = "✓ Full AR ready — world tracking supported";
    capabilityEl.className = "capability full";
    startBtn.disabled = false;
  } else if (detectedMode === "fallback") {
    capabilityEl.textContent = "✓ Camera AR mode — gyro look-around (no WebXR on this device)";
    capabilityEl.className = "capability fallback";
    startBtn.disabled = false;
  } else {
    capabilityEl.textContent = "⚠ No camera/AR available. Try a phone with a rear camera.";
    capabilityEl.className = "capability none";
    startBtn.disabled = true;
  }
})();

/* ============ UI WIRING ============ */
howBtn.addEventListener("click", () => howto.classList.add("open"));
howtoClose.addEventListener("click", () => howto.classList.remove("open"));
startBtn.addEventListener("click", scanAndStart);
const freeBtn = $("free-btn");
if (freeBtn) freeBtn.addEventListener("click", () => { roster = []; activeSetTitle = null; startHunt(); });
exitBtn.addEventListener("click", endHunt);

// Trap button — pointer + touch
const holdOn = (e) => { e.preventDefault(); trapping = true; trapBtn.classList.add("holding"); };
const holdOff = (e) => { e.preventDefault(); trapping = false; trapBtn.classList.remove("holding"); };
trapBtn.addEventListener("pointerdown", holdOn);
trapBtn.addEventListener("pointerup", holdOff);
trapBtn.addEventListener("pointercancel", holdOff);
trapBtn.addEventListener("pointerleave", holdOff);

/* ============ START / END ============ */
async function scanAndStart() {
  const code = await scanQR();
  if (!code) return; // user cancelled
  try {
    const res = await fetch("/api/scan/" + encodeURIComponent(code));
    if (!res.ok) {
      const err = await res.json().catch(() => ({}));
      showTitleNote(err.error || "Unknown set code", true);
      return;
    }
    const data = await res.json();
    roster = data.ghosts || [];
    activeSetTitle = data.set?.title || null;
    if (!roster.length) {
      showTitleNote("That set has no active ghosts yet", true);
      return;
    }
    startHunt();
  } catch (e) {
    console.error(e);
    showTitleNote("Couldn't reach the server", true);
  }
}

function showTitleNote(msg, isError) {
  capabilityEl.textContent = (isError ? "⚠ " : "") + msg;
  capabilityEl.className = "capability " + (isError ? "none" : "fallback");
}

async function startHunt() {
  titleScreen.classList.remove("active");
  huntScreen.classList.add("active");

  engine = new AREngine(canvas, video);
  engine.onFrame = frameUpdate;
  engine.onEnd(() => resetToTitle());

  try {
    await engine.start(detectedMode);
  } catch (e) {
    console.error(e);
    showToast("AR FAILED");
    setTimeout(endHunt, 1500);
    return;
  }

  // Start scan phase
  scanned = false;
  scanStart = performance.now();
  scanPrompt.classList.remove("hidden");
  hud.classList.add("hidden");
  score = 0;
  scoreEl.textContent = "0";
}

function endHunt() {
  ghosts.forEach((g) => g.dispose());
  ghosts = [];
  if (engine) engine.stop();
  resetToTitle();
}

function resetToTitle() {
  huntScreen.classList.remove("active");
  titleScreen.classList.add("active");
  hud.classList.add("hidden");
}

/* ============ SPAWNING ============ */
function spawnGhost() {
  if (!engine) return;
  // Spawn in a ring around the camera at random bearing/elevation
  engine.camera.getWorldPosition(_camPos);
  const bearing = Math.random() * Math.PI * 2;
  const dist = 1.2 + Math.random() * 1.6;
  const elev = (Math.random() - 0.4) * 0.8;
  const pos = new THREE.Vector3(
    _camPos.x + Math.sin(bearing) * dist,
    _camPos.y + elev,
    _camPos.z + Math.cos(bearing) * dist
  );
  // If a set was scanned, spawn one of its ghosts (weighted toward common);
  // otherwise fall back to a procedural wisp.
  const spec = roster.length ? pickFromRoster() : null;
  ghosts.push(new Ghost(engine.scene, pos, spec));
}

// Rarity weighting: common is most likely, legendary rare.
function pickFromRoster() {
  const weight = (r) => (r === "legendary" ? 1 : r === "rare" ? 3 : 7);
  const total = roster.reduce((s, g) => s + weight(g.rarity), 0);
  let roll = Math.random() * total;
  for (const g of roster) {
    roll -= weight(g.rarity);
    if (roll <= 0) return g;
  }
  return roster[0];
}

/* ============ FRAME LOOP ============ */
function frameUpdate(dt, camera) {
  dt = Math.min(dt, 0.05);

  // Scan phase: wait ~3s of "mapping" then begin
  if (!scanned) {
    if (performance.now() - scanStart > 3000) {
      scanned = true;
      scanPrompt.classList.add("hidden");
      hud.classList.remove("hidden");
      // initial wave
      spawnGhost();
      spawnGhost();
    }
    return;
  }

  // Periodic spawns
  spawnTimer -= dt;
  if (spawnTimer <= 0 && ghosts.length < MAX_GHOSTS) {
    spawnGhost();
    spawnTimer = 3 + Math.random() * 3;
  }

  // Camera forward + right
  camera.getWorldDirection(_camDir);
  camera.getWorldPosition(_camPos);
  _right.crossVectors(_camDir, camera.up).normalize();

  // Update ghosts & find best aim target
  let best = null;
  let bestDot = AIM_CONE;
  let anyNearby = 0;

  for (const g of ghosts) {
    g.update(dt, camera);
    if (g.captured || g.escaped) continue;
    anyNearby++;

    g.getWorldPosition(_ghostPos);
    _toGhost.subVectors(_ghostPos, _camPos).normalize();
    const dot = _toGhost.dot(_camDir);
    if (dot > bestDot) { bestDot = dot; best = g; }
  }

  // Aiming / trapping logic
  lockedGhost = best;
  const onTarget = !!best;
  reticle.classList.toggle("locked", onTarget && trapping);

  if (onTarget) {
    lockLabel.textContent = "LOCK: " + best.displayName;
  }

  // Capture progress
  if (best) {
    if (trapping) {
      best.captureProgress += CAPTURE_RATE * dt;
      if (best.captureProgress >= 1) {
        const name = best.capture();
        score++;
        scoreEl.textContent = String(score);
        fireCapture(name);
        // remove after brief implode handled by update scaling
        setTimeout(() => {
          best.dispose();
          ghosts = ghosts.filter((x) => x !== best);
        }, 250);
      }
      best.setCaptureProgress(best.captureProgress);
    } else {
      best.captureProgress = Math.max(0, best.captureProgress - DECAY_RATE * dt);
      best.setCaptureProgress(best.captureProgress);
    }
    updateRing(best.captureProgress);
  } else {
    updateRing(0);
  }

  // Clean up escaped ghosts
  const escaped = ghosts.filter((g) => g.escaped);
  escaped.forEach((g) => { g.dispose(); });
  if (escaped.length) ghosts = ghosts.filter((g) => !g.escaped);

  // Direction hint to nearest off-screen ghost
  updateDirHint(anyNearby, best);
  nearbyEl.textContent = String(anyNearby);
}

/* ============ HUD HELPERS ============ */
function updateRing(p) {
  captureProgressEl.style.strokeDashoffset = String(RING_CIRC * (1 - p));
}

function updateDirHint(nearby, best) {
  if (best || nearby === 0) { dirHint.classList.add("hidden"); return; }
  // Find nearest ghost not on screen, point left/right
  let nearest = null, nd = Infinity;
  for (const g of ghosts) {
    if (g.captured || g.escaped) continue;
    g.getWorldPosition(_ghostPos);
    const d = _ghostPos.distanceTo(_camPos);
    if (d < nd) { nd = d; nearest = g; }
  }
  if (!nearest) { dirHint.classList.add("hidden"); return; }
  nearest.getWorldPosition(_ghostPos);
  _toGhost.subVectors(_ghostPos, _camPos).normalize();
  const side = _toGhost.dot(_right);
  dirHint.classList.remove("hidden");
  dirHint.classList.toggle("right", side > 0);
}

function fireCapture(name) {
  captureFlash.classList.remove("fire");
  void captureFlash.offsetWidth;
  captureFlash.classList.add("fire");
  showToast(name + " TRAPPED!");
  if (navigator.vibrate) navigator.vibrate([30, 40, 80]);
}

function showToast(msg) {
  toast.textContent = msg;
  toast.classList.remove("show");
  void toast.offsetWidth;
  toast.classList.add("show");
}