"""Tests for giant/sample.py's v0.3.0 stage-model sampling — the AR loop
(`sample_secondaries_ar`) and non-"physical" `particle_type.target` coverage
for the one-shot samplers."""

import pytest
import torch

from giant.constants import COND_DIM, CONT_SLOT_DIM, K_MAX, PARTICLE_PHYS_DIM, X_DIM
from giant.model.network import (
    Stage1Model,
    Stage2Autoregressive,
    Stage2OneShot,
    stage2_trunk_sec_dim,
)
from giant.sample import (
    sample_flow,
    sample_secondaries,
    sample_secondaries_ar,
    sample_secondaries_wgan,
    sample_wgan,
)

_PHYS_CFG = {"type": "physical", "emb_dim": 8, "n_layers": 1}


def _particle_material_cfg(conditioning: str, emb_dim: int) -> tuple[dict, dict]:
    cfg = {"type": conditioning, "emb_dim": emb_dim, "n_layers": 1}
    return dict(cfg), dict(cfg)


def _cond(B: int, pdg: int = 3, mat: int = 2) -> tuple[torch.Tensor, torch.Tensor]:
    cond_cont = torch.randn(B, COND_DIM)
    cond_cat = torch.stack(
        [torch.randint(0, pdg, (B,)), torch.randint(0, mat, (B,))], dim=1
    )
    return cond_cont, cond_cat


def _conditioning_for(target: str) -> str:
    # target="embedding" regresses against the conditioning's own embedding
    # table — only meaningful when the
    # conditioning axis is itself "embedding".
    return "embedding" if target == "embedding" else "physical"


def _stage2_oneshot(
    target: str, generator: str, emb_dim: int = 6, pdg: int = 3, mat: int = 2
) -> Stage2OneShot:
    particle_cfg, material_cfg = _particle_material_cfg(
        _conditioning_for(target), emb_dim
    )
    particle_type_cfg = {"target": target}
    # build_models (giant/model/network.py) computes sec_dim this same way
    # before constructing Stage2OneShot — its own default (SEC_DIM, the
    # "physical" width) is only correct for target="physical".
    sec_dim = stage2_trunk_sec_dim(particle_type_cfg, generator, K_MAX, emb_dim)
    return Stage2OneShot(
        pdg_vocab=pdg,
        mat_vocab=mat,
        particle_cfg=particle_cfg,
        material_cfg=material_cfg,
        hidden_dim=32,
        n_res_blocks=2,
        generator=generator,
        time_dim=16,
        noise_dim=8,
        sec_dim=sec_dim,
        particle_type_cfg=particle_type_cfg,
    ).eval()


def _stage2_ar(
    target: str,
    generator: str,
    emb_dim: int = 6,
    pdg: int = 3,
    mat: int = 2,
    k_max: int = 5,
    history: str = "markov",
) -> Stage2Autoregressive:
    particle_cfg, material_cfg = _particle_material_cfg(
        _conditioning_for(target), emb_dim
    )
    return Stage2Autoregressive(
        pdg_vocab=pdg,
        mat_vocab=mat,
        particle_cfg=particle_cfg,
        material_cfg=material_cfg,
        hidden_dim=32,
        n_res_blocks=2,
        generator=generator,
        time_dim=16,
        noise_dim=8,
        k_max=k_max,
        particle_type_cfg={"target": target},
        history=history,
        attn_n_heads=2,
        attn_n_layers=1,
    ).eval()


def _expected_type_dim(target: str, emb_dim: int) -> int:
    return PARTICLE_PHYS_DIM if target == "physical" else emb_dim


# ── Stage-1 n_sec ownership ──────────────────────────────────────────────────


def test_sample_flow_returns_none_n_sec_when_stage1_owns_no_head():
    model = Stage1Model(
        pdg_vocab=3,
        mat_vocab=2,
        particle_cfg=_PHYS_CFG,
        material_cfg=_PHYS_CFG,
        hidden_dim=16,
        n_res_blocks=1,
    )
    cond_cont, cond_cat = _cond(4)
    sample, n_sec = sample_flow(model, cond_cont, cond_cat, steps=2)
    assert sample.shape == (4, X_DIM)
    assert n_sec is None


def test_sample_wgan_returns_none_n_sec_when_stage1_owns_no_head():
    model = Stage1Model(
        pdg_vocab=3,
        mat_vocab=2,
        particle_cfg=_PHYS_CFG,
        material_cfg=_PHYS_CFG,
        hidden_dim=16,
        n_res_blocks=1,
        generator="wgan",
        noise_dim=8,
    )
    cond_cont, cond_cat = _cond(4)
    sample, n_sec = sample_wgan(model, cond_cont, cond_cat)
    assert sample.shape == (4, X_DIM)
    assert n_sec is None


def test_sample_flow_returns_n_sec_for_legacy_stage1():
    model = Stage1Model(
        pdg_vocab=3,
        mat_vocab=2,
        particle_cfg=_PHYS_CFG,
        material_cfg=_PHYS_CFG,
        hidden_dim=16,
        n_res_blocks=1,
        n_sec_head_k_max=K_MAX,
    )
    cond_cont, cond_cat = _cond(5)
    _, n_sec = sample_flow(model, cond_cont, cond_cat, steps=2)
    assert n_sec is not None and n_sec.shape == (5,)


# ── Stage2OneShot: non-"physical" particle_type.target ──────────────────────


@pytest.mark.parametrize("target", ["physical", "onehot", "embedding"])
def test_sample_secondaries_flow_shapes_by_target(target):
    B, emb_dim = 5, 6
    decoder = _stage2_oneshot(target, "flow", emb_dim=emb_dim)
    cond_cont, cond_cat = _cond(B)
    stage1_out = torch.randn(B, X_DIM)
    n_sec_pred = torch.randint(0, K_MAX + 1, (B,))
    sec_cont, sec_type, sec_valid = sample_secondaries(
        decoder, cond_cont, cond_cat, stage1_out, n_sec_pred, steps=2
    )
    assert sec_cont.shape == (B, K_MAX, CONT_SLOT_DIM)
    assert sec_type.shape == (B, K_MAX, _expected_type_dim(target, emb_dim))
    assert sec_valid.shape == (B, K_MAX)
    assert torch.isfinite(sec_cont).all()
    assert torch.isfinite(sec_type).all()


@pytest.mark.parametrize("target", ["physical", "onehot", "embedding"])
def test_sample_secondaries_wgan_shapes_by_target(target):
    B, emb_dim = 5, 6
    decoder = _stage2_oneshot(target, "wgan", emb_dim=emb_dim)
    cond_cont, cond_cat = _cond(B)
    stage1_out = torch.randn(B, X_DIM)
    n_sec_pred = torch.randint(0, K_MAX + 1, (B,))
    sec_cont, sec_type, sec_valid = sample_secondaries_wgan(
        decoder, cond_cont, cond_cat, stage1_out, n_sec_pred
    )
    assert sec_cont.shape == (B, K_MAX, CONT_SLOT_DIM)
    assert sec_type.shape == (B, K_MAX, _expected_type_dim(target, emb_dim))
    assert sec_valid.shape == (B, K_MAX)


# ── Stage2Autoregressive ─────────────────────────────────────────────────────


@pytest.mark.parametrize("history", ["markov", "attention"])
@pytest.mark.parametrize("generator", ["flow", "wgan"])
@pytest.mark.parametrize("target", ["physical", "onehot", "embedding"])
def test_sample_secondaries_ar_shapes(target, generator, history):
    B, k_max, emb_dim = 4, 5, 6
    decoder = _stage2_ar(
        target, generator, emb_dim=emb_dim, k_max=k_max, history=history
    )
    cond_cont, cond_cat = _cond(B)
    stage1_out = torch.randn(B, X_DIM)
    n_sec_pred = torch.randint(0, k_max + 1, (B,))
    sec_cont, sec_type, sec_valid = sample_secondaries_ar(
        decoder, cond_cont, cond_cat, stage1_out, n_sec_pred, steps=2
    )
    assert sec_cont.shape == (B, k_max, CONT_SLOT_DIM)
    assert sec_type.shape == (B, k_max, _expected_type_dim(target, emb_dim))
    assert sec_valid.shape == (B, k_max)
    assert torch.isfinite(sec_cont).all()
    assert torch.isfinite(sec_type).all()


@pytest.mark.parametrize("generator", ["flow", "wgan"])
@pytest.mark.parametrize("target", ["physical", "onehot", "embedding"])
def test_sample_secondaries_ar_valid_mask_matches_n_sec(target, generator):
    B, k_max, emb_dim = 3, 5, 6
    decoder = _stage2_ar(target, generator, emb_dim=emb_dim, k_max=k_max)
    cond_cont, cond_cat = _cond(B)
    stage1_out = torch.randn(B, X_DIM)
    n_sec_pred = torch.tensor([0, 2, k_max])
    _, _, sec_valid = sample_secondaries_ar(
        decoder, cond_cont, cond_cat, stage1_out, n_sec_pred, steps=2
    )
    for i, n in enumerate(n_sec_pred.tolist()):
        assert sec_valid[i, :n].all()
        assert not sec_valid[i, n:].any()


def test_sample_secondaries_ar_first_slot_has_no_history():
    """Slot 0 always has has_prev=False internally — nothing to assert on
    the public API directly, but a k_max=1 run should not crash on the
    "previous token" path at all (has_prev never true)."""
    B, emb_dim = 3, 6
    decoder = _stage2_ar("physical", "flow", emb_dim=emb_dim, k_max=1)
    cond_cont, cond_cat = _cond(B)
    stage1_out = torch.randn(B, X_DIM)
    n_sec_pred = torch.tensor([0, 1, 1])
    sec_cont, sec_type, sec_valid = sample_secondaries_ar(
        decoder, cond_cont, cond_cat, stage1_out, n_sec_pred, steps=2
    )
    assert sec_cont.shape == (B, 1, CONT_SLOT_DIM)
    assert sec_valid.tolist() == [[False], [True], [True]]