"""Mode A: the click surface.

The estimator is covered elsewhere. What is checked here is the shell contract --
which exit code a verdict produces, what each output flag emits, and which flag
combinations are refused before any config.json is fetched.
"""

from __future__ import annotations

import inspect
import json
from collections.abc import Callable, Iterator
from typing import Any

import pytest
from click.testing import CliRunner, Result
from fitcheck import cli
from fitcheck.cli import main

_MODEL = "meta-llama/Llama-3.1-8B"

_ENV = {"COLUMNS": "200", "TERM": "dumb", "NO_COLOR": "1"}

_FITTING = (
    "--qlora",
    "--lora-r", "64",
    "--lora-targets", "q,k,v,o",
    "--batch-size", "1",
    "--seq-len", "2048",
    "--flash-attn",
    "--gpu", "4090",
)


@pytest.fixture
def runner() -> CliRunner:
    if "mix_stderr" in inspect.signature(CliRunner).parameters:
        return CliRunner(env=_ENV, mix_stderr=False)
    return CliRunner(env=_ENV)


@pytest.fixture
def llama_on_hub(
    fake_config_download: Callable[[dict[str, Any]], None],
    llama_31_8b_config: dict[str, Any],
) -> None:
    fake_config_download(llama_31_8b_config)


@pytest.fixture
def no_repl(monkeypatch: pytest.MonkeyPatch) -> Iterator[list[dict[str, Any]]]:
    """Swap the REPL for a recorder: Mode B has its own test file."""
    calls: list[dict[str, Any]] = []

    def _fake_run_repl(console: object, training: object = None, gpu: object = None) -> int:
        calls.append({"training": training, "gpu": gpu})
        return 0

    monkeypatch.setattr(cli, "run_repl", _fake_run_repl)
    yield calls


def _flat(result: Result) -> str:
    return " ".join((result.stdout + result.stderr).split())




def test_a_fitting_config_exits_zero(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING])

    assert result.exit_code == 0
    assert "FITS" in _flat(result)


def test_a_config_that_does_not_fit_exits_one(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--batch-size", "4"])

    assert result.exit_code == 1
    assert "DOES NOT FIT" in _flat(result)


def test_an_unknown_gpu_exits_two(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(main, [_MODEL, "--gpu", "rtx-9090"])

    assert result.exit_code == 2
    assert "Unknown GPU 'rtx-9090'" in _flat(result)


def test_an_unreadable_config_exits_two(
    runner: CliRunner, fake_config_download: Callable[..., None]
) -> None:
    fake_config_download({"hidden_size": 4096})

    result = runner.invoke(main, ["some/model"])

    assert result.exit_code == 2




def test_list_gpus_prints_the_database_and_exits_zero(runner: CliRunner) -> None:
    result = runner.invoke(main, ["--list-gpus"])

    assert result.exit_code == 0
    output = _flat(result)
    assert "fitcheck GPU database" in output
    assert "4090" in output
    assert "Usable (MiB)" in output


def test_json_output_carries_every_component_and_the_verdict(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--json"])

    assert result.exit_code == 0
    payload = json.loads(result.stdout)
    assert set(payload["memory_mib"]) == {
        "weights", "lora", "optimizer", "gradients", "activations", "overhead", "total",
    }
    assert payload["verdict"]["fits"] is True
    assert payload["model"]["num_params"] == 8_030_261_248
    assert payload["gpu"]["usable_mib"] == 23_500
    assert payload["training"]["quantization"] == "nf4"
    assert payload["trainable_params"] == 54_525_952
    assert payload["activations_per_layer_mib"] > 0
    assert (
        payload["verdict"]["estimated_max_batch_size"]
        == payload["verdict"]["max_batch_size"]
    )
    assert payload["verdict"]["recommended_batch_size"] == 1
    assert payload["verdict"]["recommendation_basis"] == "point_estimate_margin"


def test_json_output_still_exits_one_when_it_does_not_fit(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--batch-size", "4", "--json"])

    assert result.exit_code == 1
    assert json.loads(result.stdout)["verdict"]["fits"] is False


def test_verbose_adds_the_per_layer_detail_panel(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--verbose"])

    output = _flat(result)
    assert "hidden_size" in output
    assert "A_layer, all saved tensors for one layer" in output
    assert "A_act charged" in output


def test_explain_names_the_largest_component(runner: CliRunner, llama_on_hub: None) -> None:
    """At bs=1 the NF4 base outweighs everything else."""
    result = runner.invoke(main, [_MODEL, *_FITTING, "--explain"])

    output = _flat(result)
    assert "Largest component: base model weights" in output
    assert "quantization scales" in output


def test_explain_blames_the_logits_once_the_batch_grows(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--batch-size", "4", "--explain"])

    output = _flat(result)
    assert "Largest component: activations" in output
    assert "A_logits" in output


def test_no_color_still_renders_the_report(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(main, [_MODEL, *_FITTING, "--no-color"])

    assert result.exit_code == 0
    assert "TOTAL (predicted peak)" in _flat(result)


def test_version_flag_prints_the_package_name(runner: CliRunner) -> None:
    result = runner.invoke(main, ["--version"])

    assert result.exit_code == 0
    assert "fitcheck" in result.output


def test_package_version_falls_back_when_the_dist_is_missing(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    def _missing(name: str) -> str:
        raise cli.PackageNotFoundError(name)

    monkeypatch.setattr(cli, "version", _missing)

    assert cli._package_version() == "unknown"




def test_infer_prices_weights_plus_kv_cache(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(
        main, ["infer", _MODEL, "--quant", "nf4", "--seq-len", "2048", "--gpu", "4090"]
    )

    assert result.exit_code == 0
    output = _flat(result)
    assert "fitcheck infer" in output
    assert "KV cache" in output
    assert "TOTAL (resident)" in output


def test_infer_json_reports_the_cache_unit_costs(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main, ["infer", _MODEL, "--quant", "nf4", "--concurrent", "4", "--json"]
    )

    assert result.exit_code == 0
    payload = json.loads(result.stdout)
    assert payload["serving"]["num_concurrent"] == 4
    assert payload["kv_cache_mib_per_request"] > 0
    assert payload["kv_cache_mib_per_token"] > 0
    assert payload["verdict"]["max_concurrent"] >= 1


def test_infer_exits_one_when_the_cache_does_not_fit(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main, ["infer", _MODEL, "--seq-len", "16384", "--concurrent", "64", "--gpu", "t4"]
    )

    assert result.exit_code == 1


def test_infer_refuses_double_quant_outside_nf4(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, ["infer", _MODEL, "--quant", "int8", "--double-quant"])

    assert result.exit_code == 2
    assert "--double-quant" in _flat(result)




def test_advise_sweeps_and_exits_zero_when_something_fits(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main,
        [
            "advise", _MODEL, "--seq-lens", "1024", "--batch-sizes", "1",
            "--lora-ranks", "8", "--qlora", "--flash-attn", "--gpu", "a100-80",
        ],
    )

    assert result.exit_code == 0
    output = _flat(result)
    assert "fitcheck advise" in output
    assert "THE WALL" in output
    assert "PRICE OF EACH AXIS" in output


def test_advise_exits_one_when_nothing_fits(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(
        main,
        [
            "advise", _MODEL, "--seq-lens", "8192", "--batch-sizes", "8",
            "--lora-ranks", "64", "--gpu", "t4",
        ],
    )

    assert result.exit_code == 1
    assert "nothing here fits" in _flat(result)


def test_advise_json_carries_the_sweep_and_the_ceilings(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main,
        [
            "advise", _MODEL, "--seq-lens", "1024", "--batch-sizes", "1,2",
            "--lora-ranks", "8", "--qlora", "--flash-attn", "--gpu", "a100-80", "--json",
        ],
    )

    assert result.exit_code == 0
    payload = json.loads(result.stdout)
    assert payload["sweep"] == {
        "batch_sizes": [1, 2], "seq_lens": [1024], "lora_ranks": [8]
    }
    assert payload["grid_size"] == 2
    assert payload["ceilings"]
    assert payload["prices"]
    assert payload["recommended"]["command"].startswith("fitcheck")


def test_advise_rejects_a_seq_len_past_the_declared_maximum(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main, ["advise", _MODEL, "--seq-lens", "1024,8192", "--max-seq-len", "4096"]
    )

    assert result.exit_code == 2
    assert "exceed --max-seq-len 4,096" in _flat(result)


def test_advise_rejects_a_non_numeric_sweep_value(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, ["advise", _MODEL, "--seq-lens", "1024,lots"])

    assert result.exit_code == 2
    assert "'lots' is not a whole number" in _flat(result)


def test_advise_rejects_a_non_positive_sweep_value(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(main, ["advise", _MODEL, "--seq-lens", "0"])

    assert result.exit_code == 2
    assert "not a positive value" in _flat(result)


def test_advise_rejects_an_empty_sweep_axis(runner: CliRunner, llama_on_hub: None) -> None:
    result = runner.invoke(main, ["advise", _MODEL, "--seq-lens", " , "])

    assert result.exit_code == 2
    assert "at least one value is required" in _flat(result)




def test_lora_targets_accepts_a_preset_and_a_bare_module_list() -> None:
    assert cli._parse_lora_targets("MINIMAL") == ["q_proj", "v_proj"]
    assert cli._parse_lora_targets("q, v_proj ,") == ["q_proj", "v_proj"]


def test_lora_targets_rejects_an_unknown_module(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--lora-targets", "z"])

    assert result.exit_code == 2
    assert "unknown LoRA target 'z'" in _flat(result)


def test_lora_targets_rejects_a_duplicate(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--lora-targets", "q,q_proj"])

    assert result.exit_code == 2
    assert "duplicate LoRA target 'q_proj'" in _flat(result)


def test_lora_targets_rejects_an_empty_list(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--lora-targets", " , "])

    assert result.exit_code == 2
    assert "at least one target module is required" in _flat(result)


def test_no_lora_with_a_quantized_base_is_refused(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--no-lora", "--quant", "nf4"])

    assert result.exit_code == 2
    assert "is not modelled by fitcheck" in _flat(result)


def test_no_lora_conflicts_with_an_explicit_adapter_flag(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--no-lora", "--lora-r", "32"])

    assert result.exit_code == 2
    assert "--no-lora conflicts with --lora-r" in _flat(result)


def test_double_quant_under_quant_none_is_refused(runner: CliRunner) -> None:
    result = runner.invoke(main, [_MODEL, "--double-quant"])

    assert result.exit_code == 2
    assert "nothing to quantize under --quant none" in _flat(result)


def test_optimizer_dtype_only_applies_to_adamw(runner: CliRunner) -> None:
    result = runner.invoke(
        main, [_MODEL, "--optimizer", "sgd", "--optimizer-dtype", "bf16"]
    )

    assert result.exit_code == 2
    assert "applies only to --optimizer adamw" in _flat(result)


def test_an_explicit_flag_beats_the_qlora_shorthand(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main, [_MODEL, *_FITTING, "--quant", "none", "--precision", "fp16", "--json"]
    )

    payload = json.loads(result.stdout)
    assert payload["training"]["quantization"] == "none"
    assert payload["training"]["precision"] == "fp16"
    assert payload["training"]["grad_checkpoint"] is True


def test_a_vram_override_prices_a_card_outside_the_database(
    runner: CliRunner, llama_on_hub: None
) -> None:
    result = runner.invoke(
        main, [_MODEL, *_FITTING[:-2], "--gpu", "mycard", "--vram-mib", "40000", "--json"]
    )

    payload = json.loads(result.stdout)
    assert payload["gpu"]["name"] == "mycard"
    assert payload["gpu"]["vram_mib"] == 40_000




def test_no_model_id_enters_the_repl_and_exits_zero(
    runner: CliRunner, no_repl: list[dict[str, Any]]
) -> None:
    result = runner.invoke(main, ["--batch-size", "4", "--gpu", "t4"])

    assert result.exit_code == 0
    assert no_repl[0]["training"].batch_size == 4
    assert no_repl[0]["gpu"].name == "Tesla T4"


def test_the_repl_is_seeded_with_no_gpu_when_none_was_named(
    runner: CliRunner, no_repl: list[dict[str, Any]]
) -> None:
    result = runner.invoke(main, [])

    assert result.exit_code == 0
    assert no_repl[0]["gpu"] is None


@pytest.mark.parametrize("flag", ["--json", "--verbose", "--explain"])
def test_a_formatting_flag_without_a_model_is_refused(
    runner: CliRunner, no_repl: list[dict[str, Any]], flag: str
) -> None:
    result = runner.invoke(main, [flag])

    assert result.exit_code == 2
    assert "there is nothing to format" in _flat(result)
    assert not no_repl