# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

from transformers import AutoTokenizer

from vllm.sampling_params import SamplingParams
from vllm.v1.engine import EngineCoreRequest
from vllm.v1.engine.detokenizer import IncrementalDetokenizer

# ruff: noqa: E501


def test_fast_inc_detok_invalid_utf8_err_case():
    """
    Test edge case where tokenizer can produce non-monotonic,
    invalid UTF-8 output, which breaks the internal state of
    tokenizers' DecodeStream.
    See https://github.com/vllm-project/vllm/issues/17448.

    Thanks to reproducer from @fpaupier:
    https://gist.github.com/fpaupier/0ed1375bd7633c5be6c894b1c7ac1be3.
    """
    tokenizer = AutoTokenizer.from_pretrained("google/gemma-3-1b-it")

    # Create a test request
    prompt_token_ids = [107, 4606, 236787, 107]
    params = SamplingParams(skip_special_tokens=True)
    request = EngineCoreRequest(
        "test",
        prompt_token_ids,
        None,
        None,
        None,
        params,
        None,
        None,
        0.0,
        None,
        cache_salt=None,
        data_parallel_rank=None,
    )

    detokenizer = IncrementalDetokenizer.from_new_request(tokenizer, request)

    assert detokenizer.__class__.__name__ == "FastIncrementalDetokenizer", \
        "Should use FastIncrementalDetokenizer by default"

    # Process tokens incrementally
    test_tokens = [
        236840, 107, 138, 236782, 107, 140, 236775, 6265, 1083, 623, 121908,
        147418, 827, 107, 140, 236775, 6265, 236779, 2084, 1083, 623, 203292,
        827, 107, 140, 236775, 6265, 236779, 7777, 1083, 623, 121908, 147418,
        569, 537, 236789, 65880, 569, 537, 236789, 62580, 853, 115693, 210118,
        35178, 16055, 1270, 759, 215817, 4758, 1925, 1117, 827, 107, 140,
        236775, 5654, 1083, 623, 110733, 46291, 827, 107, 140, 236775, 5654,
        236779, 2084, 1083, 623, 136955, 56731, 827, 107, 140, 236775, 5654,
        236779, 7777, 1083, 623, 194776, 2947, 496, 109811, 1608, 890, 215817,
        4758, 1925, 1117, 2789, 432, 398, 602, 31118, 569, 124866, 134772, 509,
        19478, 1640, 33779, 236743, 236770, 236819, 236825, 236771, 432, 398,
        432, 237167, 827, 107, 140, 236775, 77984, 1083, 623, 2709, 236745,
        2555, 513, 236789, 602, 31118, 569
    ]

    output = ""
    for i, token_id in enumerate(test_tokens):
        detokenizer.update([token_id], False)

        finished = i == len(test_tokens) - 1
        output += detokenizer.get_next_output_text(finished, delta=True)


# fmt: off
    assert output == r'''[
  {
    "source": "Résultats",
    "source_type": "CONCEPT",
    "source_description": "Résultats de l'analyse de l'impact des opérations israéliennes sur la frontière libanaise",
    "target": "Israël",
    "target_type": "ORGANIZATION",
    "target_description": "Pays qui a obtenu à sa frontière libanaise « un niveau de calme inédit depuis les années 1960 »",
    "relationship": "Obtention d'un niveau de'''