import sys
import types
from unittest import main
from unittest.mock import patch

import torch

if "sgl_kernel" not in sys.modules:
    sys.modules["sgl_kernel"] = types.ModuleType("sgl_kernel")
if "sgl_kernel.kvcacheio" not in sys.modules:
    kvcacheio_stub = types.ModuleType("sgl_kernel.kvcacheio")
    for name in (
        "transfer_kv_all_layer",
        "transfer_kv_all_layer_direct_lf_pf",
        "transfer_kv_all_layer_lf_pf",
        "transfer_kv_all_layer_lf_ph",
        "transfer_kv_all_layer_mla",
        "transfer_kv_all_layer_mla_lf_pf",
        "transfer_kv_direct",
        "transfer_kv_per_layer",
        "transfer_kv_per_layer_direct_pf_lf",
        "transfer_kv_per_layer_mla",
        "transfer_kv_per_layer_mla_pf_lf",
        "transfer_kv_per_layer_pf_lf",
        "transfer_kv_per_layer_ph_lf",
    ):
        setattr(kvcacheio_stub, name, lambda *args, **kwargs: None)
    sys.modules["sgl_kernel.kvcacheio"] = kvcacheio_stub

from sglang.srt.managers.cache_controller import HiCacheController
from sglang.srt.mem_cache.cp_shared_kv_layout import CpSharedKVLayout
from sglang.test.ci.ci_register import register_cpu_ci
from sglang.test.test_utils import CustomTestCase

register_cpu_ci(est_time=2, suite="stage-a-test-cpu")


class FakeHostPool:
    def __init__(self, alloc_result):
        self.alloc_result = alloc_result
        self.alloc_calls = []
        self.backups = []
        self.loads = []
        self.frees = []
        self.page_size = 4
        self.layout = "page_first_direct"

    def alloc(self, need_size):
        self.alloc_calls.append(need_size)
        if self.alloc_result is None:
            return None
        return self.alloc_result[:need_size].clone()

    def backup_from_device_all_layer(
        self, device_pool, host_indices, device_indices, io_backend
    ):
        self.backups.append((host_indices.clone(), device_indices.clone()))

    def load_to_device_per_layer(
        self, device_pool, host_indices, device_indices, layer_id, io_backend
    ):
        self.loads.append((host_indices.clone(), device_indices.clone(), layer_id))

    def free(self, indices):
        self.frees.append(indices.clone())
        return len(indices)


class FakeDevicePool:
    device = "cpu"
    layer_num = 1

    def register_layer_transfer_counter(self, counter):
        self.counter = counter


class FakeAllocator:
    def __init__(self, alloc_result=None):
        self.alloc_result = alloc_result
        self.alloc_calls = []
        self.cp_size = 4
        self.cp_rank = 1

    def get_kvcache(self):
        return FakeDevicePool()

    def alloc(self, need_size):
        self.alloc_calls.append(need_size)
        if self.alloc_result is None:
            return None
        return self.alloc_result[:need_size].clone()


class DummyEvent:
    def record(self):
        pass

    def wait(self, stream):
        pass

    def query(self):
        return True

    def synchronize(self):
        pass


class DummyStream:
    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc, tb):
        return False


class DummyDeviceModule:
    Event = DummyEvent
    Stream = DummyStream

    @staticmethod
    def stream(stream):
        return stream


class DummyLayerDoneCounter:
    def __init__(self):
        self.events = [
            type(
                "ProducerEvent",
                (),
                {
                    "start_event": DummyEvent(),
                    "finish_event": DummyEvent(),
                    "complete": lambda self, layer_id: None,
                },
            )()
        ]

    def update_producer(self):
        return 0


class TestHiCacheControllerCPWrite(CustomTestCase):
    def setUp(self):
        self.device_module_patcher = patch(
            "sglang.srt.managers.cache_controller.device_module",
            DummyDeviceModule,
        )
        self.nsa_pool_patcher = patch(
            "sglang.srt.managers.cache_controller.NSATokenToKVPool",
            FakeDevicePool,
        )
        self.device_module_patcher.start()
        self.nsa_pool_patcher.start()
        self.addCleanup(self.device_module_patcher.stop)
        self.addCleanup(self.nsa_pool_patcher.stop)

    def make_controller(self, host_pool, allocator=None, cp_rank=1):
        allocator = allocator or FakeAllocator()
        controller = HiCacheController(
            token_to_kv_pool_allocator=allocator,
            mem_pool_host=host_pool,
            page_size=4,
            tp_group=None,
            load_cache_event=__import__("threading").Event(),
            io_backend="direct",
            cp_shared_kv_layout=CpSharedKVLayout(
                page_size=4, cp_size=4, cp_rank=cp_rank
            ),
        )
        controller.layer_done_counter = DummyLayerDoneCounter()
        return controller

    def test_cp_write_filters_to_owned_physical_locs(self):
        host_pool = FakeHostPool(torch.tensor([100, 101, 102, 103], dtype=torch.int64))
        controller = self.make_controller(host_pool, cp_rank=1)
        logical_locs = torch.arange(4, 20, dtype=torch.int64)

        result = controller.write(logical_locs, node_id=7)

        self.assertEqual(result.metadata.logical_len, 16)
        self.assertEqual(result.metadata.owned_positions.tolist(), [4, 5, 6, 7])
        self.assertEqual(result.metadata.host_indices.tolist(), [100, 101, 102, 103])
        self.assertEqual(host_pool.alloc_calls, [4])
        self.assertEqual(host_pool.backups[0][1].tolist(), [4, 5, 6, 7])

    def test_cp_write_zero_owned_returns_metadata_and_noop_ack(self):
        host_pool = FakeHostPool(torch.tensor([], dtype=torch.int64))
        controller = self.make_controller(host_pool, cp_rank=3)
        logical_locs = torch.arange(4, 8, dtype=torch.int64)

        result = controller.write(logical_locs, node_id=8)

        self.assertEqual(result.metadata.logical_len, 4)
        self.assertEqual(result.metadata.host_indices.tolist(), [])
        self.assertEqual(host_pool.alloc_calls, [])
        self.assertEqual(len(controller.ack_write_queue), 1)

    def test_cp_write_allocation_failure_reports_required_host_slots(self):
        host_pool = FakeHostPool(None)
        controller = self.make_controller(host_pool, cp_rank=1)
        logical_locs = torch.arange(4, 20, dtype=torch.int64)

        result = controller.write(logical_locs, node_id=9)

        self.assertEqual(result.required_host_slots, 4)


if __name__ == "__main__":
    main()