"use strict";

(function (global) {
  const policy = global.TarinaiItemUpdatePolicy;

  function itemUpdateInterval(item) {
    const interval = policy.itemUpdateInterval(item);
    return Number.isFinite(interval) ? interval : Infinity;
  }

  function candidateItems(worldRef) {
    return policy.candidateItems(worldRef);
  }

  function ensureBuckets(worldRef) {
    return policy.ensureBuckets(worldRef);
  }

  function heapPush(heap, entry) {
    heap.push(entry);
    let i = heap.length - 1;
    while (i > 0) {
      const p = (i - 1) >> 1;
      if (heap[p].time <= entry.time) break;
      heap[i] = heap[p];
      i = p;
    }
    heap[i] = entry;
  }

  function heapPop(heap) {
    if (!heap.length) return null;
    const root = heap[0];
    const last = heap.pop();
    if (heap.length && last) {
      let i = 0;
      while (true) {
        let c = i * 2 + 1;
        if (c >= heap.length) break;
        if (c + 1 < heap.length && heap[c + 1].time < heap[c].time) c++;
        if (heap[c].time >= last.time) break;
        heap[i] = heap[c];
        i = c;
      }
      heap[i] = last;
    }
    return root;
  }

  function schedulerSignature(worldRef) {
    return [
      (worldRef.items || []).length,
      worldRef.itemBucketRebuildsTotal || 0,
      worldRef.itemBucketsDirty ? 1 : 0,
    ].join(":");
  }


  function scheduleItem(state, item, now, interval = itemUpdateInterval(item)) {
    if (!item || item.dead || !Number.isFinite(interval)) return false;
    if (interval <= 0) {
      state.realtime.push(item);
      item._schedulerRealtime = true;
      return true;
    }
    const token = (item._schedulerToken || 0) + 1;
    item._schedulerToken = token;
    item._schedulerRealtime = false;
    if (!Number.isFinite(item._schedulerLastAt)) item._schedulerLastAt = now;
    heapPush(state.heap, { time: now + interval, item, token });
    return true;
  }

  function rebuild(worldRef, reason = "manual") {
    ensureBuckets(worldRef);
    const now = worldRef.time || 0;
    const state = {
      heap: [],
      realtime: [],
      signature: schedulerSignature(worldRef),
      rebuilds: ((worldRef._itemUpdateScheduler?.rebuilds || 0) + 1),
      reason,
    };
    for (const item of candidateItems(worldRef)) {
      item._schedulerLastAt = Number.isFinite(item._schedulerLastAt) ? item._schedulerLastAt : now;
      scheduleItem(state, item, now, itemUpdateInterval(item));
    }
    worldRef._itemUpdateScheduler = state;
    worldRef._itemUpdateRealtime = state.realtime;
    return state;
  }

  function ensure(worldRef) {
    const sig = schedulerSignature(worldRef);
    if (!worldRef._itemUpdateScheduler || worldRef._itemUpdateScheduler.signature !== sig) return rebuild(worldRef, "signature");
    return worldRef._itemUpdateScheduler;
  }

  function runRealtime(worldRef, state, dt) {
    let ran = 0;
    const now = worldRef.time || 0;
    const nextRealtime = [];
    for (const item of state.realtime || []) {
      if (!item || item.dead) continue;
      const interval = itemUpdateInterval(item);
      if (!Number.isFinite(interval)) {
        item._schedulerRealtime = false;
        continue;
      }
      if (interval <= 0) {
        global.TarinaiItemRuntime.updateOne(item, dt, worldRef);
        item._schedulerLastAt = now;
        ran += 1;
        if (Number.isFinite(itemUpdateInterval(item)) && itemUpdateInterval(item) <= 0) nextRealtime.push(item);
        else scheduleItem(state, item, now, itemUpdateInterval(item));
      } else {
        scheduleItem(state, item, now, interval);
      }
    }
    state.realtime = nextRealtime;
    worldRef._itemUpdateRealtime = state.realtime;
    return ran;
  }

  function runDue(worldRef, state) {
    let ran = 0;
    const now = worldRef.time || 0;
    const maxDue = Math.max(24, Math.ceil((state.heap.length || 0) * 0.08));
    let dueRuns = 0;
    while (state.heap.length && state.heap[0].time <= now + 0.0001 && dueRuns < maxDue) {
      const entry = heapPop(state.heap);
      const item = entry?.item;
      if (!item || item.dead || item._schedulerToken !== entry.token) continue;
      const interval = itemUpdateInterval(item);
      if (!Number.isFinite(interval)) continue;
      if (interval <= 0) {
        state.realtime.push(item);
        item._schedulerRealtime = true;
        continue;
      }
      const elapsed = Math.min(10, Math.max(0.001, now - (item._schedulerLastAt ?? entry.time - interval)));
      global.TarinaiItemRuntime.updateOne(item, elapsed, worldRef);
      item._schedulerLastAt = now;
      ran += 1;
      dueRuns += 1;
      scheduleItem(state, item, now, itemUpdateInterval(item));
    }
    return ran;
  }

  function physicsBudgetFor(worldRef) {
    const tier = global.TarinaiPerf.renderQualityTier();
    const itemCount = (worldRef?.items || []).length || 0;
    const activeHint = worldRef?._itemUpdateRealtime?.length || 0;
    const mobile = Boolean(global.TarinaiInputMode.snapshot().touchFirst || (global.innerWidth || 9999) <= 760);
    if (mobile && tier !== "high") return { maxPairs: 112, maxLinks: 72, postMaxPairs: 28, maxSubsteps: 2 };
    if (mobile) return { maxPairs: 150, maxLinks: 96, postMaxPairs: 40, maxSubsteps: 2 };
    if (tier === "low") return { maxPairs: 140, maxLinks: 90, postMaxPairs: 36, maxSubsteps: 2 };
    if (tier === "medium" || tier === "mid") {
      const crowded = itemCount > 64 && activeHint <= 2;
      return crowded
        ? { maxPairs: 150, maxLinks: 105, postMaxPairs: 44, maxSubsteps: 2 }
        : { maxPairs: 190, maxLinks: 130, postMaxPairs: 60, maxSubsteps: 3 };
    }
    return itemCount > 80
      ? { maxPairs: 240, maxLinks: 170, postMaxPairs: 78, maxSubsteps: 4 }
      : { maxPairs: 300, maxLinks: 210, postMaxPairs: 100, maxSubsteps: 5 };
  }

  function run(worldRef, dt) {
    const end = global.TarinaiPerf.begin("update.items");
    try {
      const state = ensure(worldRef);
      const realtimeEnd = global.TarinaiPerf.begin("update.items.realtime");
      let realtimeRan = runRealtime(worldRef, state, dt);
      let ran = realtimeRan;
      if (realtimeEnd) realtimeEnd();
      const dueEnd = global.TarinaiPerf.begin("update.items.scheduled");
      const dueRan = runDue(worldRef, state);
      ran += dueRan;
      if (dueEnd) dueEnd();
      const physicsEnd = global.TarinaiPerf.begin("update.physicsWorld");
      const physicsBudget = physicsBudgetFor(worldRef);
      const physicsWorld = global.TarinaiPhysicsWorldSystem.updateWorld(worldRef, dt, physicsBudget);
      const mechanicalWorld = physicsWorld.mechanical || null;
      const constraintWorld = physicsWorld.constraintRan || 0;
      const postConstraintPairs = physicsWorld.postConstraintPairs || 0;
      const poisonContactRemoved = worldRef.resolvePoisonBlockItemContacts?.({ maxPoison: 24, maxTargets: 80 }) || 0;
      if (physicsEnd) physicsEnd();
      state.signature = schedulerSignature(worldRef);
      worldRef._itemUpdateSchedulerStats = {
        heap: state.heap.length,
        realtime: state.realtime.length,
        rebuilds: state.rebuilds,
        lastReason: state.reason,
        lastRan: ran,
        realtimeRan,
        dueRan,
        sleeping: state.heap.length,
        activeRealtime: state.realtime.length,
        physicsBudget,
        physics: physicsWorld || mechanicalWorld,
        constraints: constraintWorld,
        postConstraintPairs,
        mechanicalStats: worldRef._mechanicalWorldStats || null,
        constraintStats: worldRef._constraintWorldStats || null,
      };
      return ran + (physicsWorld.ran || mechanicalWorld?.ran || 0) + constraintWorld + poisonContactRemoved;
    } finally {
      if (end) end();
    }
  }

  function trackedDynamicItems(worldRef) {
    return worldRef?._itemUpdateRealtime || [];
  }

  global.TarinaiItemUpdateScheduler = Object.freeze({ run, trackedDynamicItems });
})(typeof window !== "undefined" ? window : globalThis);