import datasets
import numpy as np
import sacrebleu
from rouge_score import rouge_scorer, scoring


try:
    import sacrebleu
    from rouge_score import rouge_scorer, scoring
except ModuleNotFoundError as e:
    raise type(e)(
        "`sacrebleu` and `rouge_score` are required for evaluating the model on NorEval."
    ) from e


ROUGE_SCORER = None


def preprocess_function(examples):
    def _format_answers(answers):
        formatted_answers = []
        for answer in answers:
            answer = answer.strip()
            if len(answer):
                # Add a period after all answers.
                if answer[-1] != ".":
                    formatted_answers.append(answer + ".")
                else:
                    formatted_answers.append(answer)
        return formatted_answers

    incorrect_answers = _format_answers(examples["incorrect_answers"])
    correct_answers = _format_answers(examples["correct_answers"])
    return {
        "question": examples["question"].strip(),
        "correct_answers": correct_answers,
        "incorrect_answers": incorrect_answers,
    }


def process_docs(dataset: datasets.Dataset) -> datasets.Dataset:
    return dataset.map(preprocess_function)


def process_results(doc, results):
    completion = results[0]
    true_refs, false_refs = doc["correct_answers"], doc["incorrect_answers"]
    all_refs = true_refs + false_refs

    # BLEU
    bleu_scores = [bleu([[ref]], [completion]) for ref in all_refs]
    bleu_correct = np.nanmax(bleu_scores[: len(true_refs)])
    bleu_incorrect = np.nanmax(bleu_scores[len(true_refs) :])
    bleu_max = bleu_correct
    bleu_diff = bleu_correct - bleu_incorrect
    bleu_acc = int(bleu_correct > bleu_incorrect)

    # ROUGE-N
    rouge_scores = [rouge([ref], [completion]) for ref in all_refs]
    # ROUGE-1
    rouge1_scores = [score["rouge1"] for score in rouge_scores]
    rouge1_correct = np.nanmax(rouge1_scores[: len(true_refs)])
    rouge1_incorrect = np.nanmax(rouge1_scores[len(true_refs) :])
    rouge1_max = rouge1_correct
    rouge1_diff = rouge1_correct - rouge1_incorrect
    rouge1_acc = int(rouge1_correct > rouge1_incorrect)
    # ROUGE-2
    rouge2_scores = [score["rouge2"] for score in rouge_scores]
    rouge2_correct = np.nanmax(rouge2_scores[: len(true_refs)])
    rouge2_incorrect = np.nanmax(rouge2_scores[len(true_refs) :])
    rouge2_max = rouge2_correct
    rouge2_diff = rouge2_correct - rouge2_incorrect
    rouge2_acc = int(rouge2_correct > rouge2_incorrect)
    # ROUGE-L
    rougeL_scores = [score["rougeLsum"] for score in rouge_scores]
    rougeL_correct = np.nanmax(rougeL_scores[: len(true_refs)])
    rougeL_incorrect = np.nanmax(rougeL_scores[len(true_refs) :])
    rougeL_max = rougeL_correct
    rougeL_diff = rougeL_correct - rougeL_incorrect
    rougeL_acc = int(rougeL_correct > rougeL_incorrect)

    return {
        "bleu_max": bleu_max,
        "bleu_acc": bleu_acc,
        "bleu_diff": bleu_diff,
        "rouge1_max": rouge1_max,
        "rouge1_acc": rouge1_acc,
        "rouge1_diff": rouge1_diff,
        "rouge2_max": rouge2_max,
        "rouge2_acc": rouge2_acc,
        "rouge2_diff": rouge2_diff,
        "rougeL_max": rougeL_max,
        "rougeL_acc": rougeL_acc,
        "rougeL_diff": rougeL_diff,
    }


def bleu(refs, preds):
    """
    Returns `t5` style BLEU scores. See the related implementation:
    https://github.com/google-research/text-to-text-transfer-transformer/blob/3d10afd51ba97ac29eb66ae701eca274488202f7/t5/evaluation/metrics.py#L41

    :param refs:
        A `list` of `list` of reference `str`s.
    :param preds:
        A `list` of predicted `str`s.
    """
    score = sacrebleu.corpus_bleu(
        preds,
        refs,
        smooth_method="exp",
        smooth_value=0.0,
        force=False,
        lowercase=False,
        tokenize="intl",
        use_effective_order=False,
    ).score
    return score


def rouge(refs, preds):
    """
    Returns `t5` style ROUGE scores. See the related implementation:
    https://github.com/google-research/text-to-text-transfer-transformer/blob/3d10afd51ba97ac29eb66ae701eca274488202f7/t5/evaluation/metrics.py#L68

    :param refs:
        A `list` of reference `strs`.
    :param preds:
        A `list` of predicted `strs`.
    """
    rouge_types = ["rouge1", "rouge2", "rougeLsum"]
    scorer = rouge_scorer.RougeScorer(rouge_types)
    # Add newlines between sentences to correctly compute `rougeLsum`.

    global ROUGE_SCORER
    if ROUGE_SCORER is None:
        # init RougeScorer once (https://github.com/EleutherAI/lm-evaluation-harness/issues/1692)--rouge_types are constant
        ROUGE_SCORER = rouge_scorer.RougeScorer(rouge_types)
    scorer = ROUGE_SCORER

    def _prepare_summary(summary):
        summary = summary.replace(" . ", ".\n")
        return summary

    # Accumulate confidence intervals.
    aggregator = scoring.BootstrapAggregator()
    for ref, pred in zip(refs, preds):
        ref = _prepare_summary(ref)
        pred = _prepare_summary(pred)
        aggregator.add_scores(scorer.score(ref, pred))
    result = aggregator.aggregate()
    return {type: result[type].mid.fmeasure * 100 for type in rouge_types}
