//! Tick-loop integration systems for background workers (#843 Part C).
//!
//! - `poll_worker_results`: runs in PreInput, drains completed results
//! - `push_worker_requests`: runs in PostSnapshot, queues new work
//!
//! Both are no-ops when no results/requests are pending. The worker pools
//! exist as Bevy Resources — systems access them via `Res<ChunkGenWorker>` etc.

use bevy_ecs::prelude::*;

use super::stubs::{ChunkGenWorker, NpcPrepWorker, OffscreenTickWorker};

/// PreInput: poll all worker pools for completed results.
///
/// Currently logs completions at debug level — real incorporation logic
/// (spawning chunks, activating NPCs) plugs in at Phase 5+.
///
/// **DETERMINISM GAP (D-010):** Results are incorporated at the tick they
/// happen to be ready, not at a deterministic tick. Two runs with the same
/// seed may incorporate a chunk at tick 500 vs tick 502 depending on CPU
/// load — diverging world state from that point.
///
/// This is acceptable while all handlers are no-ops (no simulation state
/// is modified). Before any handler produces real state changes, implement
/// a `WorkerResultLog` resource that records `(tick, worker_type, result)`.
/// Replay reads from the log instead of polling channels. See plan #843.
pub fn poll_worker_results(
    chunk_worker: Option<Res<ChunkGenWorker>>,
    npc_worker: Option<Res<NpcPrepWorker>>,
    offscreen_worker: Option<Res<OffscreenTickWorker>>,
) {
    if let Some(worker) = chunk_worker {
        for (result, _strategy) in worker.pool.drain() {
            tracing::debug!(
                chunk_x = result.chunk_x,
                chunk_y = result.chunk_y,
                "ChunkGen result ready"
            );
        }
    }

    if let Some(worker) = npc_worker {
        for (result, _strategy) in worker.pool.drain() {
            tracing::debug!(area = %result.area_id, "NpcPrep result ready");
        }
    }

    if let Some(worker) = offscreen_worker {
        for (result, _strategy) in worker.pool.drain() {
            tracing::debug!(
                area = %result.area_id,
                ticks = result.ticks_advanced,
                "OffscreenTick result ready"
            );
        }
    }
}

/// PostSnapshot: push new work requests based on player state.
///
/// Placeholder — real logic (predict player movement direction, queue
/// chunks ahead, snapshot departing NPCs) plugs in at Phase 5+.
pub fn push_worker_requests() {
    // No-op until chunk streaming and NPC tier transitions are implemented.
    // The worker pools are ready to receive requests via:
    //   chunk_worker.submit(req, DeliveryStrategy::GracefulDegrade);
    //   npc_worker.pool.submit(WorkRequest { ... });
}