from __future__ import annotations

import fractions
import pathlib

import generator.accompaniment
import generator.guitar
import generator.model
import generator.pitch
import generator.rhythm
import generator.score

PART_TYPES = ('acoustic', 'electric', 'vocal')

def source_paths(directory: pathlib.Path, *, practice: bool = False) -> list[pathlib.Path]:
  if not directory.is_dir():
    raise ValueError(f'{"practice" if practice else "performance"} source directory not found: {directory}')
  paths = sorted(directory.rglob('*.xml'))
  identities = {}
  for path in paths:
    if practice:
      if path.parent != directory or len(path.stem) != 4 or not path.stem.isascii() or not path.stem.isdecimal():
        raise ValueError(f'{path}: practice sources require a four-digit filename directly under data/practice')
    elif path.parent != directory:
      raise ValueError(f'{path}: performance sources belong directly under data/songs')
    identity = path.stem if practice else generator.score.slugify(path.stem)
    if identity in identities:
      raise ValueError(f'{identities[identity]} and {path}: conflicting output path {identity}-acoustic.json')
    identities[identity] = path
  return paths

def prepare_document(document: dict, *, practice: bool = False) -> dict:
  validate_source(document, practice=practice)
  return generator.pitch.concert_document(document, octave_transposing=True)

def generated_voice(measure: dict, role: str, previous: dict | None) -> list[dict]:
  length = generator.model.fraction(measure['duration'])
  if role == 'rest':
    return [generator.model.make_event('rest', fractions.Fraction(), length, 'rest', written={'type': 'whole', 'dots': 0}) | {'measure_rest': True}]
  if role != 'slash':
    raise ValueError(f'{role} requires a preplanned rhythm')
  events = []
  states = [(fractions.Fraction(), measure['meter'])]
  states.extend((generator.model.fraction(a['onset']), a['meter']) for a in measure.get('attributes', []) if 'meter' in a)
  for index, (onset, meter) in enumerate(states):
    end = states[index + 1][0] if index + 1 < len(states) else length
    beats = generator.model.beat_lengths(meter)
    beat_index = 0
    while onset < end:
      duration = min(beats[beat_index % len(beats)] if beats else end - onset, end - onset)
      event = generator.model.make_event(f'slash-{len(events)}', onset, duration, 'note')
      event['notehead'] = 'slash'
      events.append(event)
      onset += duration
      beat_index += 1
  return events

def validate_source(document: dict, *, practice: bool = False) -> None:
  voices = set()
  for measure in generator.score.source_staff(document)['measures']:
    for state in [measure, *measure.get('attributes', [])]:
      if state.get('clef', {}).get('sign') in ('TAB', 'percussion'):
        raise ValueError(f'{measure["id"]}: parts require a pitched, non-TAB source')
      if 'staff_details' in state:
        generator.guitar.validate_tuning(state, measure['id'])
    for voice in measure['voices']:
      voices.add(voice['id'])
      for note in voice['notes']:
        if practice and len(note['pitches']) > 1:
          raise ValueError(f'{measure["id"]}: practice requires a monophonic melody, not chord stacks')
        if any('tablature' in p or 'unpitched' in p for p in note['pitches']):
          raise ValueError(f'{measure["id"]}: authored TAB and percussion are unsupported')
  if practice and len(voices) > 1:
    raise ValueError('practice requires one monophonic voice')

def build_measure(source: dict, identifier: str, role: str, part: str, previous: dict | None, label: str = '', rhythm: generator.rhythm.Bar | None = None) -> dict:
  voices = generator.score.copy_source_voices(source, strip_lyrics=role == 'melody') if role in ('vocal', 'melody') else None
  notes = [n for v in voices for n in v['notes']] if voices else generator.accompaniment.realize(source, rhythm, previous) if rhythm is not None else generated_voice(source, role, previous)
  if role in ('melody', 'vocal'):
    for note in notes:
      note['pitches'] = [generator.pitch.shift_pitch(p, 7, 12) for p in note['pitches']]
  result = generator.score.make_measure(identifier, source, [] if voices else notes, section_label=label)
  if voices:
    result['voices'] = voices
  result['transpose'] = {'diatonic': 0, 'chromatic': 0, 'octave_change': -1, 'explicit': True}
  result['clef']['octave_change'] = 0
  for change in result.get('attributes', []):
    change.pop('transpose', None)
    if 'clef' in change:
      change['clef']['octave_change'] = 0
  if part != 'vocal':
    result['clef'] = {'sign': 'G', 'line': 2, 'octave_change': 0}
    result['staff_details'] = {'lines': 5, 'tunings': [], 'capo': 0}
    for change in result.get('attributes', []):
      change.pop('clef', None)
      change.pop('staff_details', None)
  return result