"""Immutable source events, meter boundaries and tempo. No solo construction."""
from __future__ import annotations
import dataclasses, fractions
import generator.model, generator.score, generator.solo.types

@dataclasses.dataclass(frozen=True)
class Analysis:
  boundaries: tuple
  tempo: fractions.Fraction
  melody: tuple
  body_offset: fractions.Fraction = fractions.Fraction()

def attacks(document: dict) -> tuple[generator.solo.types.Note, ...]:
  """Collapse tied tones before extracting monophonic melody fragments."""
  result, pending = [], {}
  absolute = fractions.Fraction()
  for measure in generator.score.source_staff(document)['measures']:
    for event in generator.score.measure_notes(measure):
      if event.get('grace') or event.get('cue'):
        continue
      for tone in event['pitches']:
        number = generator.model.pitch_number(tone)
        if number.denominator != 1:
          continue
        start = absolute + generator.model.fraction(event['onset'])
        end = start + generator.model.fraction(tone['duration'])
        pitch = generator.solo.types.Pitch(tone['letter'], generator.model.alteration(tone['alter']), tone['octave'])
        source = pending.pop(tone.get('tie_from'), None)
        if source is not None:
          result[source] = dataclasses.replace(result[source], end=end, sources=(*result[source].sources, event['id']))
        else:
          source = len(result)
          result.append(generator.solo.types.Note(start, end, pitch, (event['id'],)))
        if 'tie_to' in tone:
          pending[tone['id']] = source
    absolute += generator.model.fraction(measure['duration'])
  return tuple(sorted(result, key=lambda n: (n.start, -n.pitch.number(), n.sources)))

def analyze(document):
  measures = generator.score.source_staff(document)['measures']
  boundaries = [fractions.Fraction()]
  for m in measures:
    boundaries.append(boundaries[-1] + generator.model.fraction(m['duration']))
  tempo = next((generator.model.fraction(t['bpm']) * generator.model.written_length(t['written']) for m in measures for t in m.get('tempos', []) if 'bpm' in t), fractions.Fraction(120))
  return Analysis(tuple(boundaries), tempo, attacks(document), boundaries[generator.score.body_start_measure_index(measures)])