import difflib
import re
from typing import List, Tuple


def preprocess(text: str) -> List[str]:
    return re.sub(r"[^\w\s]", "", text.lower()).split()


def tokenize_raw_text(text: str) -> List[str]:
    return re.findall(r"\b\w+(?:'\w+)?\b|[^\w\s]", text)


def extract_segment_with_punct(raw_words: List[str], start_index: int, word_count: int) -> Tuple[
    List[Tuple[str, bool]], int]:
    segment = []
    word_seen = 0
    i = start_index

    while word_seen < word_count and i < len(raw_words):
        word = raw_words[i]
        if re.match(r"\w+", word):  # це слово
            punct = ""
            i += 1
            while i < len(raw_words) and not re.match(r"\w+", raw_words[i]):
                punct += raw_words[i]
                i += 1
            segment.append((word + punct, True))
            word_seen += 1
        else:
            segment.append((word, False))
            i += 1

    return segment, i


def style_word(word: str, correct: bool) -> str:
    color = "#e6ffe6" if correct else "#ffe6e6"
    text_color = "#006600" if correct else "#990000"
    content = word if correct else "..."
    return (
        f"<span style='background-color:{color}; color:{text_color}; padding:4px 10px; "
        f"margin:4px; border-radius:999px; font-weight:500; display:inline-block;'>{content}</span>"
    )


def highlight_fuzzy_diff(user_text: str, original_text: str) -> Tuple[str, int]:
    original_words_raw = tokenize_raw_text(original_text)
    original_words_clean = preprocess(original_text)
    user_words_clean = preprocess(user_text)

    matcher = difflib.SequenceMatcher(None, user_words_clean, original_words_clean)
    highlighted = []
    correct_count = 0
    total_count = 0
    original_pointer = 0

    for op, i1, i2, j1, j2 in matcher.get_opcodes():
        word_count = j2 - j1
        segment_raw, original_pointer = extract_segment_with_punct(original_words_raw, original_pointer, word_count)

        for token, is_word in segment_raw:
            if is_word:
                total_count += 1
                is_correct = op == "equal"
                if is_correct:
                    correct_count += 1
                highlighted.append(style_word(token, is_correct))
            else:
                highlighted.append(token)

    score_percent = round((correct_count / total_count) * 100) if total_count > 0 else 0
    return " ".join(highlighted), score_percent