from __future__ import annotations

import bisect
import copy
import dataclasses
import fractions

import generator.accompaniment
import generator.guitar
import generator.model

@dataclasses.dataclass(frozen=True)
class MeasureOrigin:
  onset: fractions.Fraction
  role: str
  measure: dict
  start: fractions.Fraction = fractions.Fraction()
  end: fractions.Fraction | None = None

@dataclasses.dataclass(frozen=True)
class VoicingLink:
  target: dict
  references: tuple[dict, ...]

def link_voicings(source: list[dict], origins: list[MeasureOrigin]) -> list[VoicingLink]:
  """Link accompaniment to melody attacks in the same authored harmony span."""
  boundaries, previous, start = [], None, fractions.Fraction()
  for measure in source:
    for harmony in measure['harmonies']:
      if not generator.accompaniment.same_chord(previous, harmony):
        boundaries.append(start + generator.model.fraction(harmony['onset']))
      previous = harmony
    start += generator.model.fraction(measure['duration'])
  melody, targets = {}, []
  for origin in origins:
    for voice in origin.measure['voices']:
      for note in voice['notes']:
        local = generator.model.fraction(note['onset'])
        if '_harmony' not in note or local < origin.start or (origin.end is not None and local >= origin.end):
          continue
        onset = origin.onset + local
        span = bisect.bisect_right(boundaries, onset)
        if origin.role == 'melody' and note.get('_harmonize'):
          melody.setdefault(span, []).append((onset, note['_harmony'], note))
        elif origin.role == 'accompaniment':
          targets.append((span, onset, note))
  links = []
  for span, onset, note in targets:
    matches = [(time, reference) for time, harmony, reference in melody.get(span, []) if generator.accompaniment.same_chord(harmony, note['_harmony'])]
    # Before the first melody chord, use the first grip in this harmony span.
    matches.sort(key=lambda item: (item[0] > onset, abs(item[0] - onset), item[1]['id']))
    if matches:
      links.append(VoicingLink(note, tuple(reference for _, reference in matches)))
  return links

def reuse_voicings(links: list[VoicingLink]) -> None:
  """Copy placed melody grips without changing either part's rhythm or ties."""
  for link in links:
    for reference in link.references:
      strings = tuple(sorted((p['tablature']['string'] for p in reference['pitches']), reverse=True))
      if strings not in generator.guitar.ELECTRIC_STRINGS:
        continue
      note = link.target
      note['pitches'] = [copy.deepcopy({**{k: p[k] for k in ('letter', 'alter', 'octave', 'tablature')}, 'id': f'{note["id"]}_s{p["tablature"]["string"]}', 'duration': note['duration'], 'written': note['written']}) for p in reference['pitches']]
      break