# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Unit tests for NixlConnectorScheduler with HMA and Mamba N-1 prefill."""

from unittest.mock import patch

import pytest

from vllm import LLM, SamplingParams
from vllm.config import KVTransferConfig
from vllm.v1.core.single_type_kv_cache_manager import (
    FullAttentionManager,
    SlidingWindowManager,
)

from .utils import (
    create_request,
    create_vllm_config,
    make_kv_cache_config,
    make_nixl_scheduler,
)


@pytest.mark.cpu_test
@pytest.mark.parametrize(
    "swa_enabled,expected_sw_sizes",
    [
        # SWA enabled: FullAttentionSpec (0) + SlidingWindowSpec (2048/16=128)
        (True, [0, 128 + 1]),
        # SWA disabled: only FullAttentionSpec (0)
        (False, [0]),
    ],
)
@patch("vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.current_platform")
def test_sw_sizes(mock_platform, swa_enabled, expected_sw_sizes):
    """Test sw_sizes is correctly computed based on SWA enabled/disabled."""
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorScheduler,
    )

    mock_platform.device_type = "cpu"

    block_size = 16
    vllm_config = create_vllm_config(block_size=block_size)
    # SW 2048 tokens=>128 blocks
    kv_cache_config = make_kv_cache_config(
        block_size=block_size, swa_enabled=swa_enabled, sw_size=2048
    )

    scheduler = NixlConnectorScheduler(
        vllm_config=vllm_config,
        engine_id="test-engine",
        kv_cache_config=kv_cache_config,
    )
    # in number of blocks
    assert scheduler.blocks_per_sw == expected_sw_sizes, (
        f"Expected sw_sizes={expected_sw_sizes}, got {scheduler.blocks_per_sw}"
    )


@pytest.mark.cpu_test
def test_logical_to_kernel_block_ids_with_hma():
    """Test _logical_to_kernel_block_ids expands blocks when HMA is enabled.

    When HMA is enabled, the logical block size may differ from the kernel
    block size. Each logical block maps to multiple kernel blocks.
    """
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorWorker,
    )

    # Create a mock worker with just the required attributes
    # (use __new__ to skip __init__)
    worker = object.__new__(NixlConnectorWorker)

    # Simulate HMA scenario: logical block size = 32, kernel block size = 16
    # So each logical block maps to 2 kernel blocks eg [0]->[0,1]
    worker._physical_blocks_per_logical_kv_block = 2
    # FA + SW groups (neither is MambaSpec, so both get expanded)
    worker.kv_cache_config = make_kv_cache_config(block_size=16, swa_enabled=True)

    # Test conversion: FA + SW group
    logical_block_ids = [[0, 1, 2], [3, 4]]
    kernel_block_ids = worker._logical_to_kernel_block_ids(logical_block_ids)

    expected_kernel_block_ids = [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9]]
    assert kernel_block_ids == expected_kernel_block_ids, (
        f"Expected {expected_kernel_block_ids}, got {kernel_block_ids}"
    )


@pytest.mark.parametrize("model_name, sw_size", [("google/gemma-3-1b-it", 512)])
def test_fewer_blocks_with_hma(monkeypatch, model_name, sw_size):
    """Test that a prefill instance returns fewer "remote blocks" for the SWA groups
    when sequence exceeds the sliding window.
    """
    kv_transfer_config = KVTransferConfig(
        kv_connector="NixlConnector",
        kv_role="kv_both",
    )
    block_size = 16
    llm_kwargs = {
        "model": model_name,
        "enforce_eager": True,
        "gpu_memory_utilization": 0.5,
        "kv_transfer_config": kv_transfer_config,
        "max_model_len": 2048,
        # NOTE: Make sure HMA is enabled
        "disable_hybrid_kv_cache_manager": False,
        "max_num_batched_tokens": 1024,
        "enable_prefix_caching": False,
        "block_size": block_size,
    }

    monkeypatch.setenv("VLLM_ENABLE_V1_MULTIPROCESSING", "0")

    def run_hma_test(llm: LLM):
        remote_prefill_opts = {
            "do_remote_decode": True,
            "do_remote_prefill": False,
            "remote_engine_id": None,
            "remote_block_ids": None,
            "remote_host": None,
            "remote_port": None,
        }
        # Simulate sidecar request
        sampling_params = SamplingParams(
            temperature=0.0,
            max_tokens=1,
            extra_args={"kv_transfer_params": remote_prefill_opts},
        )
        scheduler = llm.llm_engine.engine_core.engine_core.scheduler
        kv_managers = scheduler.kv_cache_manager.coordinator.single_type_managers
        # HMA enabled with FA + SWA groups
        assert len(kv_managers) > 2
        for kv_manager in kv_managers:
            assert isinstance(kv_manager, (SlidingWindowManager, FullAttentionManager))
        req_to_blocks = kv_managers[0].req_to_blocks
        assert len(req_to_blocks) == 0

        # Process some request with length exceeding the sliding window
        outputs = llm.generate(["hi" * 1401], sampling_params)
        kv_params = outputs[0].kv_transfer_params

        # +1 to account for overlapping window across blocks.
        expected_num_remote_blocks = sw_size // block_size + 1
        remote_block_ids = kv_params["remote_block_ids"]
        assert (
            len(remote_block_ids[0])
            == expected_num_remote_blocks
            < len(remote_block_ids[-1])
        )
        for group_block_ids in remote_block_ids[:-1]:
            assert len(group_block_ids) == expected_num_remote_blocks

    def run_test_and_cleanup():
        llm = LLM(**llm_kwargs)
        try:
            run_hma_test(llm)
        finally:
            llm.llm_engine.engine_core.shutdown()

    run_test_and_cleanup()


@pytest.mark.cpu_test
def test_nixl_metadata_hma_block_ids_structure():
    """
    Test that NixlConnectorMetadata correctly stores block IDs for multiple
    KV cache groups when HMA is enabled.
    """
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorMetadata,
    )

    metadata = NixlConnectorMetadata()

    # Add request with block IDs for 2 groups (FA + SW)
    fa_blocks = [0, 1, 2, 3, 4, 5, 6, 7]  # 8 blocks for FA
    sw_blocks = [8, 9, 10, 11]  # 4 blocks for SW (clipped)

    metadata.add_new_req_to_recv(
        request_id="test-req-hma",
        local_block_ids=(fa_blocks, sw_blocks),
        kv_transfer_params={
            "remote_block_ids": ([10, 11, 12, 13, 14, 15, 16, 17], [18, 19, 20, 21]),
            "remote_engine_id": "remote-engine",
            "remote_request_id": "prefill-test-req-hma",
            "remote_host": "localhost",
            "remote_port": 1234,
            "tp_size": 1,
        },
    )

    assert "test-req-hma" in metadata.reqs_to_recv
    req_meta = metadata.reqs_to_recv["test-req-hma"]

    # Verify local block IDs structure
    assert len(req_meta.local_block_ids) == 2
    assert list(req_meta.local_block_ids[0]) == fa_blocks
    assert list(req_meta.local_block_ids[1]) == sw_blocks

    # Verify remote block IDs structure
    assert req_meta.remote is not None
    assert len(req_meta.remote.block_ids) == 2
    assert list(req_meta.remote.block_ids[0]) == [10, 11, 12, 13, 14, 15, 16, 17]
    assert list(req_meta.remote.block_ids[1]) == [18, 19, 20, 21]


@pytest.mark.cpu_test
def test_get_block_descs_ids_hybrid_ssm():
    """Test _get_block_descs_ids uses per-group strides for hybrid FA+SSM
    when ratio=1 (no kernel block size mismatch)."""
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorWorker,
    )

    worker = object.__new__(NixlConnectorWorker)

    num_blocks = 100
    engine_id = "test-engine"
    worker.num_regions = 2
    worker.dst_num_blocks = {engine_id: num_blocks}
    worker._has_mamba = True
    worker._is_mamba_group = [False, True]
    worker._physical_blocks_per_logical_kv_block = 1
    # num_descs = num_regions * num_blocks (no blocks_first doubling)
    worker.num_descs = 2 * num_blocks

    fa_blocks = [3, 5]
    ssm_blocks = [1, 2]
    result = worker._get_block_descs_ids(engine_id, (fa_blocks, ssm_blocks))

    # FA group: stride=num_blocks=100, offset=0
    #   region0: [3, 5],  region1: [103, 105]
    # SSM group: stride=logical_blocks=100 (=num_blocks/ratio=100/1),
    #   offset=num_descs=200
    #   region0: [201, 202],  region1: [301, 302]
    expected = [3, 5, 103, 105, 201, 202, 301, 302]
    assert list(result) == expected, f"Expected {expected}, got {list(result)}"


@pytest.mark.cpu_test
def test_get_block_descs_ids_kernel_block_mismatch():
    """Test _get_block_descs_ids uses different strides for FA (kernel blocks)
    vs SSM (logical blocks) when ratio > 1."""
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorWorker,
    )

    worker = object.__new__(NixlConnectorWorker)

    ratio = 4
    logical_blocks = 100
    num_blocks = logical_blocks * ratio  # 400 kernel blocks
    engine_id = "test-engine"
    worker.num_regions = 2
    worker.dst_num_blocks = {engine_id: num_blocks}
    worker._has_mamba = True
    worker._is_mamba_group = [False, True]
    worker._physical_blocks_per_logical_kv_block = ratio
    worker.num_descs = 2 * num_blocks  # 800

    fa_blocks = [3, 7]  # kernel-level block IDs
    ssm_blocks = [1, 2]  # logical block IDs
    result = worker._get_block_descs_ids(engine_id, (fa_blocks, ssm_blocks))

    # FA group: stride=num_blocks=400, offset=0
    #   region0: [3, 7],  region1: [403, 407]
    # SSM group: stride=logical_blocks=400//4=100, offset=num_descs=800
    #   region0: [801, 802],  region1: [901, 902]
    expected = [3, 7, 403, 407, 801, 802, 901, 902]
    assert list(result) == expected, f"Expected {expected}, got {list(result)}"


@pytest.mark.cpu_test
def test_nixl_metadata_hybrid_ssm_block_ids():
    """Test NixlConnectorMetadata correctly stores block IDs for FA + SSM
    groups with different block counts (kernel mismatch active)."""
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorMetadata,
    )

    metadata = NixlConnectorMetadata()

    # FA: 8 kernel blocks (2 logical * ratio=4), SSM: 2 logical blocks
    fa_blocks = [0, 1, 2, 3, 4, 5, 6, 7]
    ssm_blocks = [0, 1]

    metadata.add_new_req_to_recv(
        request_id="test-req-hybrid",
        local_block_ids=(fa_blocks, ssm_blocks),
        kv_transfer_params={
            "remote_block_ids": ([10, 11, 12, 13, 14, 15, 16, 17], [20, 21]),
            "remote_engine_id": "remote-engine",
            "remote_request_id": "prefill-test-req-hybrid",
            "remote_host": "localhost",
            "remote_port": 1234,
            "tp_size": 1,
        },
    )

    assert "test-req-hybrid" in metadata.reqs_to_recv
    req_meta = metadata.reqs_to_recv["test-req-hybrid"]

    # Verify local block IDs: different lengths per group
    assert len(req_meta.local_block_ids) == 2
    assert list(req_meta.local_block_ids[0]) == fa_blocks
    assert list(req_meta.local_block_ids[1]) == ssm_blocks
    assert len(req_meta.local_block_ids[0]) != len(req_meta.local_block_ids[1])

    # Verify remote block IDs: same asymmetry preserved
    assert req_meta.remote is not None
    assert len(req_meta.remote.block_ids) == 2
    assert list(req_meta.remote.block_ids[0]) == [10, 11, 12, 13, 14, 15, 16, 17]
    assert list(req_meta.remote.block_ids[1]) == [20, 21]
    assert len(req_meta.remote.block_ids[0]) != len(req_meta.remote.block_ids[1])


# ── Mamba N-1 prefill tests ──────────────────────────────────────────────


@pytest.mark.cpu_test
@pytest.mark.parametrize(
    "has_mamba,is_hma_required,expected_count",
    [
        (True, True, 9),
        (False, False, 10),
        (False, True, 10),
    ],
    ids=["mamba", "fa_only", "swa_only"],
)
def test_mamba_n1_d_side(has_mamba, is_hma_required, expected_count):
    """D-side: Mamba gets N-1 matched tokens, non-Mamba gets N."""
    sched = make_nixl_scheduler(has_mamba=has_mamba, is_hma_required=is_hma_required)
    req = create_request(num_tokens=10, do_remote_prefill=True)

    count, is_async = sched.get_num_new_matched_tokens(req, num_computed_tokens=0)
    assert count == expected_count
    assert is_async is True


@pytest.mark.cpu_test
def test_mamba_n1_p_side_truncation():
    """P-side: Mamba truncates prompt to N-1, sets max_tokens=1.

    Also verifies idempotency (calling again is a no-op) which is
    needed for preemption safety via the _p_side_truncated guard,
    and that non-Mamba models skip truncation entirely.
    """
    sched = make_nixl_scheduler(has_mamba=True, is_hma_required=True)
    req = create_request(num_tokens=10, do_remote_decode=True)
    req.max_tokens = 128
    original_len = len(req.prompt_token_ids)

    count, is_async = sched.get_num_new_matched_tokens(req, num_computed_tokens=0)

    assert count == 0
    assert is_async is False
    assert len(req.prompt_token_ids) == original_len - 1
    assert req.num_prompt_tokens == original_len - 1
    assert req.max_tokens == 1
    assert req.kv_transfer_params["_p_side_truncated"] is True

    # Idempotency: second call must not truncate further
    sched.get_num_new_matched_tokens(req, num_computed_tokens=0)
    assert len(req.prompt_token_ids) == original_len - 1

    # Non-Mamba: truncation is skipped
    fa_sched = make_nixl_scheduler(has_mamba=False, is_hma_required=False)
    fa_req = create_request(num_tokens=10, do_remote_decode=True)
    fa_original = len(fa_req.prompt_token_ids)

    fa_sched.get_num_new_matched_tokens(fa_req, num_computed_tokens=0)
    assert len(fa_req.prompt_token_ids) == fa_original


@pytest.mark.cpu_test
@pytest.mark.parametrize(
    "swa_enabled,mamba_enabled,expected_has_mamba,expected_is_hma",
    [
        (True, True, True, True),
        (True, False, False, True),
        (False, False, False, False),
    ],
    ids=["fa_swa_mamba", "fa_swa_only", "fa_only"],
)
@patch("vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.current_platform")
def test_has_mamba_init(
    mock_platform,
    swa_enabled,
    mamba_enabled,
    expected_has_mamba,
    expected_is_hma,
):
    """Test _has_mamba / _is_hma_required derived from kv_cache_groups."""
    from vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector import (
        NixlConnectorScheduler,
    )

    mock_platform.device_type = "cpu"

    block_size = 16
    vllm_config = create_vllm_config(block_size=block_size)
    # VllmConfig.__post_init__ auto-disables HMA when kv_transfer_config
    # is set; override so we can test the scheduler's own derivation.
    vllm_config.scheduler_config.disable_hybrid_kv_cache_manager = False
    kv_cache_config = make_kv_cache_config(
        block_size=block_size,
        swa_enabled=swa_enabled,
        mamba_enabled=mamba_enabled,
    )

    scheduler = NixlConnectorScheduler(
        vllm_config=vllm_config,
        engine_id="test-engine",
        kv_cache_config=kv_cache_config,
    )
    assert scheduler._has_mamba is expected_has_mamba
    assert scheduler._is_hma_required is expected_is_hma
