"""CPU contract for an in-domain captured-Music3 token-prediction experiment.

This is deliberately not a native Music3 tokenizer and it makes no claim for
arbitrary external music.  Its only eligible teachers are paired captured
Music3 waveforms, tokens, priming rows, and re-emitted waveforms.
"""
from __future__ import annotations

import pytest
import torch

from music3lab.codec import native_token_adapter as adapter


SAMPLES = 44_032
FRAMES = 25
SPLIT_SEEDS = {
    "train": tuple(range(1000, 1064)),
    "validation": tuple(range(2000, 2016)),
    "heldout": tuple(range(3000, 3016)),
}


def _sidecar(split: str) -> adapter.TokenTeacherSidecar:
    seeds = SPLIT_SEEDS[split]
    count = len(seeds)
    audio = torch.zeros(count, 2, SAMPLES)
    audio[:, 0, 0] = torch.tensor(seeds, dtype=audio.dtype)
    semantic = torch.arange(count * FRAMES, dtype=torch.int64).reshape(count, FRAMES) % 16_384
    residual = torch.arange(count * FRAMES * 7, dtype=torch.int64).reshape(count, FRAMES, 7) % 1_024
    priming = torch.arange(count * 8, dtype=torch.int64).reshape(count, 8) % 1_024
    return adapter.TokenTeacherSidecar(
        split=split,
        seeds=seeds,
        audio=audio,
        semantic=semantic,
        residual=residual,
        priming=priming,
        reemitted_audio=audio.clone(),
        source_domain="captured_music3",
    )


def test_teacher_sidecars_have_exact_64_16_16_seed_pairing_and_reemission() -> None:
    sidecars = tuple(_sidecar(name) for name in ("train", "validation", "heldout"))
    report = adapter.validate_token_teacher_sidecars(sidecars)
    assert report.split_counts == {"train": 64, "validation": 16, "heldout": 16}
    assert report.seed_sets == SPLIT_SEEDS
    assert report.source_domain == "captured_music3_only"

    missing = _sidecar("train")
    missing.reemitted_audio = None
    with pytest.raises(ValueError, match="reemitted_audio"):
        adapter.validate_token_teacher_sidecars((missing,))

    mismatched = _sidecar("train")
    mismatched.reemitted_audio[0, 0, 0] += 1
    with pytest.raises(ValueError, match="re-emitted audio"):
        adapter.validate_token_teacher_sidecars((mismatched,))


def test_waveform_adapter_emits_all_codebook_logits_and_per_code_cross_entropy() -> None:
    batch = _sidecar("validation")
    model = adapter.CapturedMusic3TokenAdapter(adapter.TokenAdapterConfig(hidden_channels=8))
    semantic_logits, residual_logits = model(batch.audio[:2])
    assert semantic_logits.shape == (2, FRAMES, 16_384)
    assert residual_logits.shape == (2, FRAMES, 7, 1_024)

    loss = adapter.token_cross_entropy(
        semantic_logits,
        residual_logits,
        batch.semantic[:2],
        batch.residual[:2],
    )
    assert set(loss) == {"semantic", "residual", "total"}
    assert loss["total"].isfinite() and loss["total"] > 0
    loss["total"].backward()
    assert any(parameter.grad is not None for parameter in model.parameters())


def test_modes_teacher_forcing_and_predicted_tokens_are_range_valid_and_renderable() -> None:
    batch = _sidecar("validation")
    modes = adapter.per_position_mode_tokens(batch.semantic, batch.residual)
    assert modes.shape == (FRAMES, 8)
    adapter.validate_predicted_tokens(modes.unsqueeze(0))

    backend = _TinyCapturedFuser()
    captured_fused = backend.expected(batch.semantic[:1], batch.residual[:1], batch.priming[:1])
    replayed = adapter.teacher_force_captured_rows(
        backend, batch.semantic[:1], batch.residual[:1], batch.priming[:1]
    )
    assert torch.equal(replayed, captured_fused)
    assert backend.sampling_rng is None

    logits = torch.full((1, FRAMES, 16_384), -20.0)
    logits[..., 7] = 20.0
    residual_logits = torch.full((1, FRAMES, 7, 1_024), -20.0)
    residual_logits[..., 9] = 20.0
    predicted = adapter.predict_tokens(logits, residual_logits)
    adapter.validate_predicted_tokens(predicted)
    rendered = adapter.render_predicted_tokens(_TinyRenderer(), predicted)
    assert rendered.shape == (1, 2, SAMPLES)

    capability = adapter.describe_capability()
    assert capability["native_tokenizer"] is False
    assert capability["arbitrary_external_music"] is False
    assert capability["domain"] == "captured_music3_only"


class _TinyCapturedFuser:
    sampling_rng = "not-called"

    @staticmethod
    def expected(semantic: torch.Tensor, residual: torch.Tensor, priming: torch.Tensor) -> torch.Tensor:
        rows = torch.cat((semantic.unsqueeze(-1), residual), dim=-1).to(torch.float32)
        return rows.mean(dim=-1, keepdim=True).expand(-1, -1, 32_768).contiguous()

    def teacher_force(self, semantic: torch.Tensor, residual: torch.Tensor, priming: torch.Tensor, *, sampling_rng=None) -> torch.Tensor:
        self.sampling_rng = sampling_rng
        return self.expected(semantic, residual, priming)


class _TinyRenderer:
    def render(self, tokens: torch.Tensor) -> torch.Tensor:
        assert tokens.shape[1:] == (FRAMES, 8)
        return torch.zeros(tokens.shape[0], 2, SAMPLES)

def test_frozen_native_token_config_and_cli_are_cpu_safe() -> None:
    import os
    import subprocess
    import sys
    from pathlib import Path

    loaded = adapter.load_native_token_config(
        Path(__file__).parents[1] / "configs/native-token-adapter-v1.yaml"
    )
    assert loaded.config.teacher.split_seeds() == SPLIT_SEEDS
    assert loaded.config.native_tokenizer is False
    result = subprocess.run(
        [
            sys.executable,
            "-B",
            str(Path(__file__).parents[1] / "scripts/run_native_token_adapter.py"),
            "--help",
        ],
        check=True,
        capture_output=True,
        text=True,
        env={
            "PATH": os.environ["PATH"],
            "PYTHONPATH": str(Path(__file__).parents[1] / "src"),
            "CUDA_VISIBLE_DEVICES": "-1",
            "PYTHONDONTWRITEBYTECODE": "1",
        },
    )
    assert "not a native tokenizer" in " ".join(result.stdout.split())