import argparse
import os
import sys
import tempfile
from pathlib import Path
from unittest.mock import patch

import pytest
import pytorch_lightning as pl
import timeout_decorator
import torch

from transformers import BartForConditionalGeneration
from transformers.testing_utils import slow

from .finetune import SummarizationModule, main
from .test_seq2seq_examples import CUDA_AVAILABLE, MBART_TINY
from .utils import load_json


MODEL_NAME = MBART_TINY
# TODO(SS): MODEL_NAME = "sshleifer/student_mbart_en_ro_1_1"


@slow
@pytest.mark.skipif(not CUDA_AVAILABLE, reason="too slow to run on CPU")
def test_model_download():
    """This warms up the cache so that we can time the next test without including download time, which varies between machines."""
    BartForConditionalGeneration.from_pretrained(MODEL_NAME)


@timeout_decorator.timeout(120)
@slow
@pytest.mark.skipif(not CUDA_AVAILABLE, reason="too slow to run on CPU")
def test_train_mbart_cc25_enro_script():
    data_dir = "examples/seq2seq/test_data/wmt_en_ro"
    env_vars_to_replace = {
        "$MAX_LEN": 200,
        "$BS": 4,
        "$GAS": 1,
        "$ENRO_DIR": data_dir,
        "facebook/mbart-large-cc25": MODEL_NAME,
        # 1 encoder and 1 decoder layer from finetuned mbart en-ro. Should be able to start >0 and improve quickly.
        # Download is 600MB in previous test.
        "val_check_interval=0.25": "val_check_interval=1.0",
    }

    # Clean up bash script
    bash_script = Path("examples/seq2seq/train_mbart_cc25_enro.sh").open().read().split("finetune.py")[1].strip()
    bash_script = bash_script.replace("\\\n", "").strip().replace("$@", "")
    for k, v in env_vars_to_replace.items():
        bash_script = bash_script.replace(k, str(v))
    output_dir = tempfile.mkdtemp(prefix="output")

    if CUDA_AVAILABLE:
        gpus = 1  # torch.cuda.device_count()
    else:
        gpus = 0
    bash_script = bash_script.replace("--fp16", "")
    testargs = (
        ["finetune.py"]
        + bash_script.split()
        + [
            f"--output_dir={output_dir}",
            f"--gpus={gpus}",
            "--learning_rate=3e-1",
            "--warmup_steps=0",
            "--val_check_interval=1.0",
            "--tokenizer_name=facebook/mbart-large-en-ro",
        ]
    )
    with patch.object(sys, "argv", testargs):
        parser = argparse.ArgumentParser()
        parser = pl.Trainer.add_argparse_args(parser)
        parser = SummarizationModule.add_model_specific_args(parser, os.getcwd())
        args = parser.parse_args()
        args.do_predict = False
        # assert args.gpus == gpus THIS BREAKS for multigpu
        model = main(args)

    # Check metrics
    metrics = load_json(model.metrics_save_path)
    first_step_stats = metrics["val"][0]
    last_step_stats = metrics["val"][-1]
    assert len(metrics["val"]) == (args.max_epochs / args.val_check_interval)  # +1 accounts for val_sanity_check

    assert last_step_stats["val_avg_gen_time"] >= 0.01

    assert first_step_stats["val_avg_bleu"] < last_step_stats["val_avg_bleu"]  # model learned nothing
    assert 1.0 >= last_step_stats["val_avg_gen_time"]  # model hanging on generate. Maybe bad config was saved.
    assert isinstance(last_step_stats[f"val_avg_{model.val_metric}"], float)

    # check lightning ckpt can be loaded and has a reasonable statedict
    contents = os.listdir(output_dir)
    ckpt_path = [x for x in contents if x.endswith(".ckpt")][0]
    full_path = os.path.join(args.output_dir, ckpt_path)
    ckpt = torch.load(full_path, map_location="cpu")
    expected_key = "model.model.decoder.layers.0.encoder_attn_layer_norm.weight"
    assert expected_key in ckpt["state_dict"]
    assert ckpt["state_dict"]["model.model.decoder.layers.0.encoder_attn_layer_norm.weight"].dtype == torch.float32

    # TODO(SS): turn on args.do_predict when PL bug fixed.
    if args.do_predict:
        contents = {os.path.basename(p) for p in contents}
        assert "test_generations.txt" in contents
        assert "test_results.txt" in contents
        # assert len(metrics["val"]) ==  desired_n_evals
        assert len(metrics["test"]) == 1
