import pandas as pd
import os
import sys
from transformers import AutoTokenizer, AutoModelForSequenceClassification, TrainingArguments, Trainer
import torch
import csv

IN_FILE_NAME = "in.tsv.xz"
OUT_FILE_NAME = "out.tsv"
TRAIN_PATH = "train"
EXP_FILE_NAME = "expected.tsv"
FILE_SEP = "\t"
IN_HEADER_FILE_NAME = "in-header.tsv"
OUT_HEADER_FILE_NAME = "out-header.tsv"
PT_MODEL_NAME = "bert-base-cased"
# PT_MODEL_NAME = "roberta-base"


class CustomDataset(torch.utils.data.Dataset):
    def __init__(self, encodings, labels):
        self.encodings = encodings
        self.labels = labels

    def __getitem__(self, idx):
        item = {key: torch.tensor(val[idx])
                for key, val in self.encodings.items()}
        item['labels'] = torch.tensor(self.labels[idx])
        return item

    def __len__(self):
        return len(self.labels)


def main(dirnames):
    check_path(IN_HEADER_FILE_NAME)
    in_cols = (pd.read_csv(IN_HEADER_FILE_NAME, sep=FILE_SEP)).columns
    check_path(OUT_HEADER_FILE_NAME)
    out_cols = (pd.read_csv(OUT_HEADER_FILE_NAME, sep=FILE_SEP)).columns

    print("Reading train data...")
    train_set_features = get_tsv_data(os.path.join(
        TRAIN_PATH, IN_FILE_NAME), names=in_cols)
    train_set_labels = get_tsv_data(os.path.join(
        TRAIN_PATH, EXP_FILE_NAME), names=out_cols, compression=None)

    print("Reading input data...")
    in_sets = []
    for d in dirnames:
        print(f"\tReading dir: {d}...")
        in_sets.append(get_tsv_data(
            os.path.join(d, IN_FILE_NAME), names=in_cols))

    tokenizer = AutoTokenizer.from_pretrained(PT_MODEL_NAME)
    model = AutoModelForSequenceClassification.from_pretrained(
        PT_MODEL_NAME, num_labels=2)
    train_set_enc = tokenizer(
        [t for t in train_set_features[in_cols].agg(' '.join, axis=1)], truncation=True, padding=True)
    dataset = CustomDataset(
        train_set_enc, [int(t) for t in train_set_labels[out_cols[0]]])

    trainer = Trainer(
        model=model,
        args=TrainingArguments('./res'),
        train_dataset=dataset,
        num_train_epochs=5,
        per_device_train_batch_size=16,
        per_device_eval_batch_size=16,
    )

    trainer.train()

    for i in range(len(in_sets)):
        p = os.path.join(dirnames[i], IN_FILE_NAME)
        with open(p) as f:
            print(
                f"\tPredicting for: {p}...")
            X = [t for t in in_sets[i][in_cols].agg(' '.join, axis=1)]
            out_file_path = os.path.join(dirnames[i], OUT_FILE_NAME)
            f.write('\n'.join(trainer.predict(X)))
            print(f"Saved predictions to file: {out_file_path}")


def get_tsv_data(filename: str, names, compression="infer"):
    check_path(filename)
    return pd.read_csv(
        filename,
        sep=FILE_SEP,
        compression=compression,
        error_bad_lines=False,
        quoting=csv.QUOTE_NONE,
        header=None,
        names=names,
        dtype=str
    )


def check_path(filename: str):
    if not os.path.exists(filename):
        raise Exception(f"Path {filename} does not exist!")


if __name__ == "__main__":
    if len(sys.argv) < 2:
        raise Exception("Name of working dir not specified!")
    main(sys.argv[1:])