import math

from rapidfuzz import fuzz
import re
import regex
from statistics import mean

CHUNK_MIN_CHARS = 25

def chunk_text(text, chunk_len=500):
    chunks = [text[i:i+chunk_len] for i in range(0, len(text), chunk_len)]
    chunks = [c for c in chunks if c.strip() and len(c) > CHUNK_MIN_CHARS]
    return chunks


def overlap_score(hypothesis_chunks, reference_chunks):
    if len(reference_chunks) > 0:
        length_modifier = len(hypothesis_chunks) / len(reference_chunks)
    else:
        length_modifier = 0
    search_distance = max(len(reference_chunks) // 5, 10)
    chunk_scores = []
    for i, hyp_chunk in enumerate(hypothesis_chunks):
        max_score = 0
        total_len = 0
        i_offset = int(i * length_modifier)
        chunk_range = range(max(0, i_offset-search_distance), min(len(reference_chunks), i_offset+search_distance))
        for j in chunk_range:
            ref_chunk = reference_chunks[j]
            score = fuzz.ratio(hyp_chunk, ref_chunk, score_cutoff=30) / 100
            if score > max_score:
                max_score = score
                total_len = len(ref_chunk)
        chunk_scores.append(max_score)
    return chunk_scores


def score_text(hypothesis, reference):
    # Returns a 0-1 alignment score
    hypothesis_chunks = chunk_text(hypothesis)
    reference_chunks = chunk_text(reference)
    chunk_scores = overlap_score(hypothesis_chunks, reference_chunks)
    if len(chunk_scores) > 0:
        mean_score = mean(chunk_scores)
        return mean_score
    else:
        return 0
    #return mean(chunk_scores)