import math


MODEL_RATE = 88200
LOOKAHEAD_SECONDS = .030


def register_group(written):
    return 0 if written <= 73 else 1 if written <= 75 else 2 if written == 76 else 3


def prepare_controls(events, prepare_gap=False, prepare_pressure=False, lookahead=LOOKAHEAD_SECONDS):
    if not .018 + 1 / MODEL_RATE < lookahead < .060:
        raise ValueError('Preparation must precede the unchanged tongue anticipation window')
    result, preparations = [], []
    for index, event in enumerate(events):
        pressure = event['pressurePa']
        if event.get('pressureEndPa', pressure) != pressure:
            raise ValueError('This controller preserves constant per-note controls, not an unsupported pressure ramp')
        current = dict(event, originalNoteIndex=index, preparationOnly=False)
        if index + 1 == len(events) or register_group(event['writtenMidi']) == register_group(events[index + 1]['writtenMidi']):
            result.append(current)
            continue
        following = events[index + 1]
        start = round(event['time'] * MODEL_RATE)
        end = round((event['time'] + event['duration']) * MODEL_RATE)
        next_start = round(following['time'] * MODEL_RATE)
        prepared = round((following['time'] - lookahead) * MODEL_RATE)
        if not start + math.ceil(.008 * MODEL_RATE) < prepared < end or prepared >= next_start - math.ceil(.018 * MODEL_RATE):
            result.append(current)
            continue
        prepared_time = prepared / MODEL_RATE
        current['duration'] = prepared_time - event['time']
        tail = dict(event, originalNoteIndex=index, preparationOnly=True, time=prepared_time,
                    duration=(end - prepared) / MODEL_RATE, tongued=False)
        tail['pressurePa'] = following['pressurePa'] if prepare_pressure else pressure
        tail['pressureEndPa'] = tail['pressurePa']
        tail['gapM'] = following['gapM'] if prepare_gap else event['gapM']
        result.extend((current, tail))
        preparations.append({'originalNoteIndex': index, 'nextOriginalNoteIndex': index + 1,
                             'heldWrittenMidi': event['writtenMidi'], 'followingWrittenMidi': following['writtenMidi'],
                             'preparationStartModelSample': prepared, 'originalGateEndModelSample': end,
                             'followingMusicalOnsetModelSample': next_start, 'lookaheadSeconds': lookahead,
                             'pressurePrepared': prepare_pressure, 'gapPrepared': prepare_gap,
                             'preparedPressurePa': tail['pressurePa'], 'preparedGapM': tail['gapM'],
                             'noNewTonguedAttackOrFingeringChange': True})
    return result, preparations