"""E2E-style smoke coverage for the GRPO training notebook."""

from __future__ import annotations

import json
from pathlib import Path

from sql_env.training import rollout as rollout_module
from sql_env.training.config import GRPOConfig
from sql_env.training.notebook_pipeline import (
    build_trainer,
    run_training_with_metrics,
    sample_random_baseline,
)
from sql_env.training.data_loading import filter_questions_by_difficulty
from sql_env.training.rewards import (
    reward_correctness,
    reward_operational,
    reward_progress,
)
from sql_env.training.rollout import rollout_func


NOTEBOOK_PATH = Path("notebooks/train_grpo.ipynb")


def _read_notebook() -> dict:
    return json.loads(NOTEBOOK_PATH.read_text(encoding="utf-8"))


def _code_sources(notebook: dict) -> list[str]:
    cells = notebook.get("cells", [])
    return [
        "".join(cell.get("source", []))
        for cell in cells
        if cell.get("cell_type") == "code"
    ]


def test_training_notebook_smoke_structure() -> None:
    """Notebook includes the core GRPO training flow cells."""

    assert NOTEBOOK_PATH.exists(), "notebooks/train_grpo.ipynb must exist"

    notebook = _read_notebook()
    sources = "\n".join(_code_sources(notebook))

    assert "GRPOConfig(" in sources
    assert "load_model_and_tokenizer(config.model_name)" in sources
    assert "grpo_trainer_cls=GRPOTrainer" in sources
    assert "run_training_with_metrics" in sources
    assert "matplotlib.pyplot as plt" in sources

    before_index = sources.find("before_rollouts = sample_random_baseline")
    train_index = sources.find("run_training_with_metrics(trainer)")
    assert before_index != -1
    assert train_index != -1
    assert before_index < train_index


def test_question_filtering_by_difficulty() -> None:
    """Difficulty filtering keeps only questions in the allowed set."""

    questions = [
        {"question_text": "q1", "difficulty": "easy"},
        {"question_text": "q2", "difficulty": "medium"},
        {"question_text": "q3", "difficulty": "hard"},
    ]

    filtered = filter_questions_by_difficulty(questions, ["easy"])
    assert [item["question_text"] for item in filtered] == ["q1"]


class _FakeTokenizer:
    def apply_chat_template(
        self,
        messages: list[dict[str, str]],
        tokenize: bool = False,
        add_generation_prompt: bool = True,
    ) -> str:
        del messages
        del tokenize
        del add_generation_prompt
        return "prompt"


class _FakeModel:
    def __init__(self) -> None:
        self._count = 0

    def generate(self, prompt: str, max_new_tokens: int) -> str:
        del prompt
        del max_new_tokens
        self._count += 1
        if self._count == 1:
            return "QUERY: SELECT 1"
        return "ANSWER: 42"


class _FakeEnvironment:
    def __init__(self, step_budget: int) -> None:
        self.step_budget = step_budget
        self.step_count = 0
        self.state = type("State", (), {"episode_id": "ep-e2e"})()

    def reset(self, *, seed: int | None = None):
        del seed
        self.step_count = 0
        return self._observation(done=False, result="")

    def step(self, action):
        self.step_count += 1
        if getattr(action, "action_type", "") == "ANSWER":
            return self._observation(
                done=True, result="Answer submitted: correct.", reward=1.0
            )
        return self._observation(done=False, result="ok", reward=0.1)

    def _observation(self, done: bool, result: str, reward: float | None = 0.0):
        from sql_env.models import SQLObservation

        return SQLObservation(
            question="How many rows?",
            schema_info="Available tables:\n- t",
            result=result,
            error="",
            step_count=self.step_count,
            budget_remaining=max(0, self.step_budget - self.step_count),
            action_history=[],
            done=done,
            reward=reward,
        )


def test_training_pipeline_smoke(monkeypatch) -> None:
    """Happy-path rollout + reward computation produces trainable signals."""

    config = GRPOConfig(
        questions_path="data/questions/questions_train.json",
        db_dir="data/databases",
        output_dir="outputs/grpo_test",
        step_budget=2,
    )
    tokenizer = _FakeTokenizer()
    model = _FakeModel()
    fake_env = _FakeEnvironment(step_budget=2)

    monkeypatch.setattr(rollout_module, "_build_environment", lambda *_: fake_env)

    rollouts = rollout_func(["Count rows"], model, tokenizer, config)
    assert len(rollouts) == 1

    metadata = [item["metadata"] for item in rollouts]
    completions = [
        [{"role": "assistant", "content": item["content"]}] for item in rollouts
    ]

    correctness = reward_correctness(completions, metadata=metadata)
    progress = reward_progress(completions, metadata=metadata)
    operational = reward_operational(completions, metadata=metadata)

    assert correctness == [1.0]
    assert len(progress) == 1
    assert 0.0 <= progress[0] <= 1.0
    assert len(operational) == 1


class _FakeTRLConfig:
    def __init__(self, **kwargs):
        self.kwargs = kwargs


class _FakeTrainer:
    def __init__(
        self,
        *,
        model,
        processing_class,
        args,
        train_dataset,
        reward_funcs,
    ) -> None:
        self.model = model
        self.processing_class = processing_class
        self.args = args
        self.train_dataset = train_dataset
        self.reward_funcs = reward_funcs
        self.state = type("State", (), {"log_history": []})()
        self.train_called = False

    def train(self) -> dict[str, str]:
        self.train_called = True
        self.state.log_history = [{"step": 1, "reward": 0.25}]
        return {"status": "ok"}


def test_notebook_pipeline_executes_training_step(monkeypatch) -> None:
    """Notebook pipeline helper builds trainer and executes train()."""

    config = GRPOConfig(
        questions_path="data/questions/questions_train.json",
        db_dir="data/databases",
        output_dir="outputs/grpo_test",
        step_budget=2,
    )
    tokenizer = _FakeTokenizer()
    model = _FakeModel()
    fake_env = _FakeEnvironment(step_budget=2)
    monkeypatch.setattr(rollout_module, "_build_environment", lambda *_: fake_env)

    trainer = build_trainer(
        model=model,
        tokenizer=tokenizer,
        prompts=[{"prompt": "Count rows"}],
        config=config,
        trl_grpo_config_cls=_FakeTRLConfig,
        grpo_trainer_cls=_FakeTrainer,
        reward_funcs=[reward_correctness, reward_progress, reward_operational],
    )

    output, steps, rewards = run_training_with_metrics(trainer)

    assert trainer.train_called is True
    assert output == {"status": "ok"}
    assert steps == [1]
    assert rewards == [0.25]


def test_random_baseline_transcripts_are_generated() -> None:
    """Random baseline helper generates readable transcripts per prompt."""

    baseline = sample_random_baseline(["q1", "q2"], step_budget=3, seed=7)
    assert len(baseline) == 2
    assert all(item["metadata"]["policy"] == "random" for item in baseline)
    assert all(item["completion"] for item in baseline)