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

import pytest
import torch
from pytest import param
from torch.utils.data import DataLoader

from transformers import AutoModelForSeq2SeqLM, AutoTokenizer, MBartTokenizer
from transformers.testing_utils import require_multigpu

from .distillation import distill_main, evaluate_checkpoint
from .finetune import main
from .pack_dataset import pack_data_dir
from .run_eval import generate_summaries_or_translations, run_generate
from .utils import MBartDataset, Seq2SeqDataset, label_smoothed_nll_loss, lmap, load_json


logging.basicConfig(level=logging.DEBUG)

logger = logging.getLogger()
CUDA_AVAILABLE = torch.cuda.is_available()
CHEAP_ARGS = {
    "label_smoothing": 0.2,
    "early_stopping_patience": 2,
    "logger_name": "default",
    "length_penalty": 0.5,
    "cache_dir": "",
    "task": "summarization",
    "num_workers": 2,
    "alpha_hid": 0,
    "freeze_embeds": True,
    "enc_only": False,
    "tgt_suffix": "",
    "resume_from_checkpoint": None,
    "sortish_sampler": True,
    "student_decoder_layers": 1,
    "val_check_interval": 1.0,
    "output_dir": "",
    "fp16": CUDA_AVAILABLE,
    "no_teacher": False,
    "fp16_opt_level": "O1",
    "gpus": 1 if CUDA_AVAILABLE else 0,
    "n_tpu_cores": 0,
    "max_grad_norm": 1.0,
    "do_train": True,
    "do_predict": True,
    "accumulate_grad_batches": 1,
    "server_ip": "",
    "server_port": "",
    "seed": 42,
    "model_name_or_path": "sshleifer/bart-tiny-random",
    "config_name": "",
    "tokenizer_name": "facebook/bart-large",
    "do_lower_case": False,
    "learning_rate": 0.3,
    "weight_decay": 0.0,
    "adam_epsilon": 1e-08,
    "warmup_steps": 0,
    "max_epochs": 1,
    "train_batch_size": 2,
    "eval_batch_size": 2,
    "max_source_length": 12,
    "max_target_length": 12,
    "val_max_target_length": 12,
    "test_max_target_length": 12,
    "fast_dev_run": False,
    "no_cache": False,
    "n_train": -1,
    "n_val": -1,
    "n_test": -1,
    "student_encoder_layers": 1,
    "alpha_loss_encoder": 0.0,
    "freeze_encoder": False,
    "auto_scale_batch_size": False,
}


def _dump_articles(path: Path, articles: list):
    content = "\n".join(articles)
    Path(path).open("w").writelines(content)


ARTICLES = [" Sam ate lunch today.", "Sams lunch ingredients."]
SUMMARIES = ["A very interesting story about what I ate for lunch.", "Avocado, celery, turkey, coffee"]
T5_TINY = "patrickvonplaten/t5-tiny-random"
BART_TINY = "sshleifer/bart-tiny-random"
MBART_TINY = "sshleifer/tiny-mbart"
MARIAN_TINY = "sshleifer/tiny-marian-en-de"
stream_handler = logging.StreamHandler(sys.stdout)
logger.addHandler(stream_handler)
logging.disable(logging.CRITICAL)  # remove noisy download output from tracebacks


def make_test_data_dir(**kwargs):
    tmp_dir = Path(tempfile.mkdtemp(**kwargs))
    for split in ["train", "val", "test"]:
        _dump_articles((tmp_dir / f"{split}.source"), ARTICLES)
        _dump_articles((tmp_dir / f"{split}.target"), SUMMARIES)
    return tmp_dir


class TestSummarizationDistiller(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        logging.disable(logging.CRITICAL)  # remove noisy download output from tracebacks
        return cls

    @require_multigpu
    def test_multigpu(self):
        updates = dict(no_teacher=True, freeze_encoder=True, gpus=2, sortish_sampler=False,)
        self._test_distiller_cli(updates)

    def test_distill_no_teacher(self):
        updates = dict(student_encoder_layers=2, student_decoder_layers=1, no_teacher=True)
        self._test_distiller_cli(updates)

    def test_distill_checkpointing_with_teacher(self):
        updates = dict(
            student_encoder_layers=2,
            student_decoder_layers=1,
            max_epochs=4,
            val_check_interval=0.25,
            alpha_hid=2.0,
            model_name_or_path="IGNORE_THIS_IT_DOESNT_GET_USED",
        )
        model = self._test_distiller_cli(updates, check_contents=False)

        ckpts = list(Path(model.output_dir).glob("*.ckpt"))
        self.assertEqual(1, len(ckpts))
        transformer_ckpts = list(Path(model.output_dir).glob("**/*.bin"))
        self.assertEqual(len(transformer_ckpts), 2)
        examples = lmap(str.strip, model.hparams.data_dir.joinpath("test.source").open().readlines())
        out_path = tempfile.mktemp()
        generate_summaries_or_translations(examples, out_path, str(model.output_dir / "best_tfmr"))
        self.assertTrue(Path(out_path).exists())

        evaluate_checkpoint(ckpts[0], dest_dir=Path(tempfile.mkdtemp()))

    def test_loss_fn(self):
        model = AutoModelForSeq2SeqLM.from_pretrained(BART_TINY)
        input_ids, mask = model.dummy_inputs["input_ids"], model.dummy_inputs["attention_mask"]
        target_ids = torch.tensor([[0, 4, 8, 2], [0, 8, 2, 1]], dtype=torch.long, device=model.device)
        decoder_input_ids = target_ids[:, :-1].contiguous()  # Why this line?
        lm_labels = target_ids[:, 1:].clone()  # why clone?
        model_computed_loss = model(
            input_ids, attention_mask=mask, decoder_input_ids=decoder_input_ids, labels=lm_labels, use_cache=False
        ).loss

        logits = model(input_ids, attention_mask=mask, decoder_input_ids=decoder_input_ids, use_cache=False).logits

        lprobs = torch.nn.functional.log_softmax(logits, dim=-1)
        smoothed_loss, nll_loss = label_smoothed_nll_loss(
            lprobs, lm_labels, 0.1, ignore_index=model.config.pad_token_id
        )
        with self.assertRaises(AssertionError):
            # TODO: understand why this breaks
            self.assertEqual(nll_loss, model_computed_loss)

    @unittest.skip("T5 distillation is broken at the moment")
    def test_distill_t5(self):
        updates = dict(
            student_encoder_layers=1,
            student_decoder_layers=1,
            alpha_hid=2.0,
            teacher=T5_TINY,
            model_name_or_path=T5_TINY,
            tokenizer_name=T5_TINY,
        )
        self._test_distiller_cli(updates)

    def _test_distiller_cli(self, updates, check_contents=True):
        default_updates = dict(
            label_smoothing_eps=0.0,
            early_stopping_patience=-1,
            train_batch_size=1,
            eval_batch_size=2,
            max_epochs=2,
            alpha_mlm=0.2,
            alpha_ce=0.8,
            do_predict=True,
            model_name_or_path="sshleifer/tinier_bart",
            teacher=CHEAP_ARGS["model_name_or_path"],
            val_check_interval=0.5,
            alpha_encoder_loss=0.4,
        )
        default_updates.update(updates)
        args_d: dict = CHEAP_ARGS.copy()
        tmp_dir = make_test_data_dir()
        output_dir = tempfile.mkdtemp(prefix="output_")

        args_d.update(data_dir=tmp_dir, output_dir=output_dir, **default_updates)
        model = distill_main(argparse.Namespace(**args_d))
        if not check_contents:
            return model
        contents = os.listdir(output_dir)
        ckpt_name = "val_avg_rouge2=0.0000-step_count=2.ckpt"  # "val_avg_rouge2=0.0000-epoch=1.ckpt"  # "epoch=1-val_avg_rouge2=0.0000.ckpt"
        contents = {os.path.basename(p) for p in contents}
        self.assertIn(ckpt_name, contents)

        self.assertIn("test_generations.txt", contents)
        self.assertIn("test_results.txt", contents)

        metrics = load_json(model.metrics_save_path)
        last_step_stats = metrics["val"][-1]
        self.assertGreaterEqual(last_step_stats["val_avg_gen_time"], 0.01)
        self.assertGreaterEqual(1.0, last_step_stats["val_avg_gen_time"])
        self.assertIsInstance(last_step_stats[f"val_avg_{model.val_metric}"], float)
        desired_n_evals = int(args_d["max_epochs"] * (1 / args_d["val_check_interval"]) + 1)
        self.assertEqual(len(metrics["val"]), desired_n_evals)
        self.assertEqual(len(metrics["test"]), 1)
        return model


@pytest.mark.parametrize(["model"], [pytest.param(T5_TINY), pytest.param(BART_TINY), pytest.param(MBART_TINY)])
def test_run_eval_bart(model):
    input_file_name = Path(tempfile.mkdtemp()) / "utest_input.source"
    output_file_name = input_file_name.parent / "utest_output.txt"
    assert not output_file_name.exists()
    articles = [" New York (CNN)When Liana Barrientos was 23 years old, she got married in Westchester County."]
    _dump_articles(input_file_name, articles)
    testargs = ["run_eval.py", model, str(input_file_name), str(output_file_name)]  # TODO: test score_path
    with patch.object(sys, "argv", testargs):
        run_generate()
        assert Path(output_file_name).exists()
        os.remove(Path(output_file_name))


@pytest.mark.parametrize(
    ["model"], [pytest.param(T5_TINY), pytest.param(BART_TINY), pytest.param(MBART_TINY), pytest.param(MARIAN_TINY)],
)
def test_finetune(model):
    args_d: dict = CHEAP_ARGS.copy()
    task = "translation" if model in [MBART_TINY, MARIAN_TINY] else "summarization"
    args_d["label_smoothing"] = 0.1 if task == "translation" else 0

    tmp_dir = make_test_data_dir()
    output_dir = tempfile.mkdtemp(prefix="output_")
    args_d.update(
        data_dir=tmp_dir,
        model_name_or_path=model,
        tokenizer_name=None,
        train_batch_size=2,
        eval_batch_size=2,
        output_dir=output_dir,
        do_predict=True,
        task=task,
        src_lang="en_XX",
        tgt_lang="ro_RO",
        freeze_encoder=True,
        freeze_embeds=True,
    )
    assert "n_train" in args_d
    args = argparse.Namespace(**args_d)
    module = main(args)

    input_embeds = module.model.get_input_embeddings()
    assert not input_embeds.weight.requires_grad
    if model == T5_TINY:
        lm_head = module.model.lm_head
        assert not lm_head.weight.requires_grad
        assert (lm_head.weight == input_embeds.weight).all().item()

    else:
        bart = module.model.model
        embed_pos = bart.decoder.embed_positions
        assert not embed_pos.weight.requires_grad
        assert not bart.shared.weight.requires_grad
        # check that embeds are the same
        assert bart.decoder.embed_tokens == bart.encoder.embed_tokens
        assert bart.decoder.embed_tokens == bart.shared


def test_pack_dataset():
    tokenizer = AutoTokenizer.from_pretrained("facebook/mbart-large-cc25")

    tmp_dir = Path(make_test_data_dir())
    orig_examples = tmp_dir.joinpath("train.source").open().readlines()
    save_dir = Path(tempfile.mkdtemp(prefix="packed_"))
    pack_data_dir(tokenizer, tmp_dir, 128, save_dir)
    orig_paths = {x.name for x in tmp_dir.iterdir()}
    new_paths = {x.name for x in save_dir.iterdir()}
    packed_examples = save_dir.joinpath("train.source").open().readlines()
    # orig: [' Sam ate lunch today.\n', 'Sams lunch ingredients.']
    # desired_packed: [' Sam ate lunch today.\n Sams lunch ingredients.']
    assert len(packed_examples) < len(orig_examples)
    assert len(packed_examples) == 1
    assert len(packed_examples[0]) == sum(len(x) for x in orig_examples)
    assert orig_paths == new_paths


def test_mbart_dataset_truncation():
    tokenizer = MBartTokenizer.from_pretrained(MBART_TINY)
    tmp_dir = make_test_data_dir()
    max_len_source = max(len(tokenizer.encode(a)) for a in ARTICLES)
    max_len_target = max(len(tokenizer.encode(a)) for a in SUMMARIES)
    trunc = 4
    src_lang, tgt_lang = "ro_RO", "de_DE"  # NOT WHAT IT WAS TRAINED ON
    train_dataset = MBartDataset(
        tokenizer,
        data_dir=tmp_dir,
        type_path="train",
        max_source_length=trunc,
        max_target_length=1000,  # ignored
        src_lang=src_lang,
        tgt_lang=tgt_lang,
    )
    dataloader = DataLoader(train_dataset, batch_size=2, collate_fn=train_dataset.collate_fn)
    for batch in dataloader:
        assert isinstance(batch, dict)
        assert batch["attention_mask"].shape == batch["input_ids"].shape
        # show that articles were trimmed.
        assert batch["input_ids"].shape[1] == trunc
        # show that targets are the same len
        assert batch["decoder_input_ids"].shape[1] == trunc
        # check language codes in correct place
        assert batch["decoder_input_ids"][0, 0].item() == tokenizer.lang_code_to_id[tgt_lang]
        assert batch["decoder_input_ids"][0, -1].item() == tokenizer.eos_token_id
        assert batch["input_ids"][0, -2].item() == tokenizer.eos_token_id
        assert batch["input_ids"][0, -1].item() == tokenizer.lang_code_to_id[src_lang]

        assert max_len_target > trunc  # Truncated
        assert max_len_source > trunc
        break  # No need to test every batch


@pytest.mark.parametrize(["tok"], [pytest.param(T5_TINY), pytest.param(BART_TINY), param(MARIAN_TINY)])
def test_summarization_dataset_truncation(tok):
    tokenizer = AutoTokenizer.from_pretrained(tok)
    tmp_dir = make_test_data_dir()
    max_len_source = max(len(tokenizer.encode(a)) for a in ARTICLES)
    max_len_target = max(len(tokenizer.encode(a)) for a in SUMMARIES)
    trunc_target = 4
    train_dataset = Seq2SeqDataset(
        tokenizer, data_dir=tmp_dir, type_path="train", max_source_length=20, max_target_length=trunc_target,
    )
    dataloader = DataLoader(train_dataset, batch_size=2, collate_fn=train_dataset.collate_fn)
    for batch in dataloader:
        assert batch["attention_mask"].shape == batch["input_ids"].shape
        # show that articles were trimmed.
        assert batch["input_ids"].shape[1] == max_len_source
        assert 20 >= batch["input_ids"].shape[1]  # trimmed significantly
        # show that targets were truncated
        assert batch["decoder_input_ids"].shape[1] == trunc_target  # Truncated
        assert max_len_target > trunc_target  # Truncated
        break  # No need to test every batch
