"""Frozen DTW sentence point spans, independent of ordinary token intervals."""
from token_alignment import BOUNDARY, TEXT_TOKEN_LIMIT

POLICY = "dtw-token-sentences-v1;centisecond-points;first-last-point-span;exact-text;no-labels"


def aligned_segments(document, offset_ms, duration_ms):
    from run import segments
    originals = segments(document, offset_ms, duration_ms)
    raw_rows = [row for row in document["transcription"] if row["text"].strip()]
    result = []
    previous = 0
    for index, (row, original) in enumerate(zip(raw_rows, originals)):
        tokens = row.get("tokens")
        if not isinstance(tokens, list) or not 0 < len(tokens) <= 4096:
            raise ValueError("Missing or oversized DTW tokens")
        accepted = []
        for token in tokens:
            token_id, text = token.get("id"), token.get("text")
            if type(token_id) is not int or token_id < 0 or not isinstance(text, str):
                raise ValueError("Invalid DTW token identity")
            if token_id >= TEXT_TOKEN_LIMIT:
                if not text.startswith("[_") or not text.endswith("]"):
                    raise ValueError("Unrecognized special token")
                continue
            point = token.get("t_dtw")
            if type(point) is not int or not 0 <= point * 10 <= duration_ms or point * 10 < previous:
                raise ValueError("Missing, invalid or nonmonotonic DTW point")
            previous = point * 10
            accepted.append((text, previous))
        if "".join(token[0] for token in accepted) != row["text"]:
            raise ValueError("DTW text differs from original recognized segment")
        phrase = []
        for token_index, token in enumerate(accepted):
            phrase.append(token)
            if BOUNDARY.search(token[0]) or token_index == len(accepted) - 1:
                text = "".join(part[0] for part in phrase)
                if text.strip():
                    result.append({"start_ms": offset_ms + phrase[0][1],
                                   "end_ms": offset_ms + phrase[-1][1], "text": text,
                                   "original_segment_index": index,
                                   "original_start_ms": original["start_ms"],
                                   "original_end_ms": original["end_ms"]})
                phrase = []
    if len(result) > 10000:
        raise ValueError("Oversized DTW passages")
    return result