"""Versioned production vocabulary. This module never reads audition inputs."""
from __future__ import annotations
import contextlib
import contextvars
import dataclasses
import functools
import hashlib
import json
from pathlib import Path
from fractions import Fraction as F

ROOT = Path(__file__).resolve().parents[1] / 'data' / 'composition'
ACTIVE = contextvars.ContextVar('composition_vocabulary', default=None)

def load(root=ROOT):
  # Content, not just the directory, keys memoization. Long-lived individual
  # role builds must observe edited production data without restarting Python.
  names = ('roles', 'grammar', 'harmony', 'lead_ins', 'rhythms', 'melodic_vocabulary')
  return _load(tuple((name, (Path(root)/(name+'.json')).read_text()) for name in names))

@functools.lru_cache(maxsize=16)
def _load(contents):
  result = {}
  for name, text in contents:
    value = json.loads(text)
    if value.get('version') != 1 or not value.get('provenance') or not value.get('license'):
      raise ValueError(f'{name}: unsupported or unprovenanced production vocabulary')
    entries = value.get('cells', value.get('patterns', value.get('colors', value.get('transformations', []))))
    if len({v['id'] for v in entries}) != len(entries):
      raise ValueError(f'{name}: duplicate vocabulary ID')
    result[name] = value
  cells=result['rhythms']['cells']+result['melodic_vocabulary']['cells']
  if len({c['id'] for c in cells})!=len(cells):
    raise ValueError('Duplicate rhythmic identity across production vocabularies')
  for c in cells:
    if c['purpose'] not in ('entrance','continue','connect','answer','arrival'):
      raise ValueError(c['id']+': unknown rhythmic purpose')
  paths=result['melodic_vocabulary']['chord_paths']
  if len({p['id'] for p in paths})!=len(paths):raise ValueError('Duplicate chord-path operator')
  for p in paths:
    if p['direction'] not in ('up','down','toward') or p['members'] not in ('basic','defining'):
      raise ValueError(p['id']+': invalid chord traversal')
    if not p['member_steps'] or any(type(s)!=int or not 1<=abs(s)<=3 for s in p['member_steps']):
      raise ValueError(p['id']+': invalid chord-member step')
    if not p['prefix_attacks'] or any(n not in (2,3,4) for n in p['prefix_attacks']) or not 1<=p['max_interval']<=12:
      raise ValueError(p['id']+': unsupported bounded chord prefix')
  return result

@functools.lru_cache(maxsize=1)
def _default():
  return {'data': load(), 'role': '', 'settings': {}}

def current():
  return ACTIVE.get() or _default()

def data(name):
  return current()['data'][name]

def role(name=None):
  active = current()
  name = name or active['role']
  return {**active['data']['roles']['roles'].get(name, {}), **active['settings']}

@contextlib.contextmanager
def using(resources, name, settings=None):
  token = ACTIVE.set({'data': resources, 'role': name, 'settings': settings or {}})
  try:
    yield
  finally:
    ACTIVE.reset(token)

def fingerprint(value):
  return hashlib.sha256(json.dumps(value, sort_keys=True, separators=(',', ':')).encode()).hexdigest()

@dataclasses.dataclass(frozen=True)
class RhythmCell:
  id: str
  pattern: tuple
  duration: F
  purpose: str
  difficulty: str | None = None
  subdivision: str = 'binary'
  entry: str = 'attack'
  exit: str = 'continue'


def rhythm_cells(tempo, purpose=None):
  limits = data('roles')['difficulty']
  for cell in (*data('rhythms')['cells'],*data('melodic_vocabulary')['cells']):
    if purpose is not None and cell['purpose'] != purpose:
      continue
    difficulty = cell.get('difficulty')
    if difficulty and tempo > limits[difficulty + '_max_bpm']:
      continue
    cursor, notes = F(), []
    for value in cell['values']:
      rest = value.startswith('r:')
      duration = F(value[2:] if rest else value)
      if duration <= 0:
        raise ValueError(cell['id'] + ': nonpositive rhythm duration')
      if not rest:
        notes.append((cursor, cursor + duration))
      cursor += duration
    if difficulty and len(notes) > limits['burst_attacks']:
      continue
    from generator.solo import groups
    realized=groups.describe(tuple(notes),source=cell['id'])
    family=cell.get('subdivision','binary')
    if family=='triplet' and not any(g.family=='triplet' for g in realized):raise ValueError(cell['id']+': missing complete tuplet group')
    yield RhythmCell(cell['id'],tuple(notes),cursor,cell['purpose'],difficulty,family,cell.get('entry','attack'),cell.get('exit','continue'))