"""
Sync/async seam tests.

Tests the boundary between synchronous and asynchronous components:
  - Zinc SHM (synchronous POSIX SHM) with async-like polling
  - Control plane command processing in event loop
  - Engine hot-path with timeout budget
"""
import threading
import time
import pytest
from malkhut.ipc.zinc_plane import MalkhutZincPlane, SharedRegionWriter, SharedRegionReader
from malkhut.ipc.control_plane import MalkhutControlPlane, ControlPlaneFrame
from malkhut.engine import FulfilmentEngine
from malkhut.state import (
    AccountState, FulfilmentPolicyParams, MarketWorldState, Mode,
    OrderBookState, PriceLevel, VenueRules,
)


def _params():
    return FulfilmentPolicyParams(
        version="seam", ucb_c=1.414, max_sims=32, max_depth=2,
        rollout_depth=1, root_temperature=0.5, min_root_entropy=0.25,
        quote_offsets_ticks=(0, 1), quote_size_fractions=(0.25,),
        passive_ttl_ms=200, aggressive_ttl_ms=50,
        maker_edge_min_bps=0.5, cross_spread_edge_min_bps=5.0,
        adverse_toxicity_cancel_threshold=0.5, queue_churn_cancel_threshold=0.5,
        mae_tail_cut_bps=50.0, mfe_giveback_cut_fraction=0.5,
        max_time_in_loss_s=300.0, failed_recovery_cut_count=3,
        recovery_velocity_min_bps_per_s=0.0,
        max_symbol_notional_fraction=0.20, max_single_order_notional_fraction=0.05,
        reduce_when_global_up_fraction=0.30, session_profit_lock_fraction=0.02,
        w_expected_pnl=1.0, w_fill_probability=0.5, w_adverse_selection=2.0,
        w_queue_priority=0.5, w_inventory_risk=1.5, w_tail_loss=5.0,
        w_fee_quality=0.5, w_time_decay=0.3, w_policy_entropy=0.5,
        robust_tail_weight=2.0, toxic_counterparty_weight=3.0,
        low_liquidity_weight=2.0, latency_stress_weight=1.0,
    )


def _state():
    return MarketWorldState(
        ts_ns=1_000_000_000, mode=Mode.PAPER,
        venue=VenueRules(
            exchange="bingx", symbol="BTCUSDT", tick_size=0.1, lot_size=0.001,
            min_qty=0.001, min_notional=5.0, maker_fee_bps=-0.2, taker_fee_bps=0.5,
            post_only_supported=True, reduce_only_supported=True,
            max_orders_per_second=100, max_cancels_per_minute=120,
        ),
        book=OrderBookState(
            ts_ns=1_000_000_000, symbol="BTCUSDT",
            bids=(PriceLevel(50000.0, 1.0),), asks=(PriceLevel(50001.0, 1.0),),
        ),
        account=AccountState(
            ts_ns=1_000_000_000, equity=10000.0, wallet_balance=10000.0,
            available_balance=10000.0, margin_used=0.0, total_notional=0.0,
        ),
    )


class TestZincSyncSeam:
    def test_write_is_synchronous(self):
        """Write completes before returning."""
        plane = MalkhutZincPlane(prefix="sync_write")
        t0 = time.perf_counter_ns()
        plane.publish_book({"ts": time.time_ns()})
        elapsed_ms = (time.perf_counter_ns() - t0) / 1_000_000
        assert elapsed_ms < 100  # should be very fast
        plane.close_all()

    def test_read_timeout_returns_within_budget(self):
        """Read with timeout returns within the timeout window."""
        plane = MalkhutZincPlane(prefix="sync_read_timeout")
        plane.publish_book({"test": True})
        t0 = time.perf_counter_ns()
        data, seq = plane.read_book(timeout_ms=50)
        elapsed_ms = (time.perf_counter_ns() - t0) / 1_000_000
        assert elapsed_ms < 200  # should complete within timeout
        plane.close_all()

    def test_write_read_roundtrip_latency(self):
        """Write-to-read latency is measurable and bounded."""
        plane = MalkhutZincPlane(prefix="latency_test")
        plane.publish_book({"ts": time.time_ns()})
        t0 = time.perf_counter_ns()
        data, seq = plane.read_book(timeout_ms=50)
        latency_us = (time.perf_counter_ns() - t0) / 1_000
        assert latency_us < 10_000  # < 10ms
        plane.close_all()


class TestControlPlaneSyncSeam:
    def test_command_processing_latency(self):
        """Control plane command write-to-read is fast."""
        cp = MalkhutControlPlane()
        frame = ControlPlaneFrame(
            command="STATUS_REQUEST", ts_ns=time.time_ns(), source="test",
        )
        t0 = time.perf_counter_ns()
        cp.publish_command(frame)
        cmd = cp.read_command(timeout_ms=50)
        elapsed_us = (time.perf_counter_ns() - t0) / 1_000
        assert cmd is not None
        assert elapsed_us < 10_000  # < 10ms
        cp.close()


class TestEngineSeam:
    def test_engine_hot_path_latency(self):
        """Engine on_state completes within budget."""
        from malkhut.venue.bingx.adapter import BingXVenueAdapter
        engine = FulfilmentEngine(
            params_provider=_params,
            venue=BingXVenueAdapter(),
        )
        t0 = time.perf_counter_ns()
        engine.on_state(_state())
        elapsed_ms = (time.perf_counter_ns() - t0) / 1_000_000
        assert elapsed_ms < 200  # hot path budget

    def test_engine_stop_start_via_control_plane(self):
        """Engine can be stopped and started via control plane."""
        from malkhut.ipc.control_plane import MalkhutControlPlane, ControlPlaneFrame
        cp = MalkhutControlPlane()
        engine = FulfilmentEngine(
            params_provider=_params,
            control_plane=cp,
        )

        # Initially active
        assert engine._active

        # Stop via control plane
        cp.publish_command(ControlPlaneFrame(
            command="STOP", ts_ns=time.time_ns(), source="test",
        ))
        engine.on_state(_state())
        assert not engine._active

        # Start via control plane
        cp.publish_command(ControlPlaneFrame(
            command="START", ts_ns=time.time_ns(), source="test",
        ))
        engine.on_state(_state())
        assert engine._active

        cp.close()


class TestCrossThreadSync:
    def test_writer_in_thread_reader_in_main(self):
        """Writer in background thread, reader in main thread."""
        plane = MalkhutZincPlane(prefix="cross_thread")
        written = threading.Event()

        def bg_writer():
            for i in range(5):
                plane.publish_book({"thread_seq": i})
                time.sleep(0.01)
            written.set()

        t = threading.Thread(target=bg_writer)
        t.start()

        results = []
        for _ in range(10):
            try:
                data, seq = plane.read_book(timeout_ms=20)
                results.append(data)
            except Exception:
                pass
            time.sleep(0.005)

        t.join(timeout=5)
        plane.close_all()
        assert len(results) > 0