from __future__ import annotations

import generator.harmony
import generator.model
import generator.pitch

def chord_notes(chord: dict) -> tuple[tuple[int, str], ...]:
  return tuple((degree, generator.model.pitch_name(generator.pitch.shift_pitch({**chord['root'], 'octave': 4}, degree - 1, generator.harmony.degree_semitones(degree, alter)))) for degree, alter in generator.harmony.degrees(chord).items())

def passage(part: str, solo, choices, library) -> str:
  lines = [f'{part.capitalize()}: {solo.label}', 'Positions use the score’s measure labels and quarter-note beats; sequential measure indices are also shown.', '']
  lines.append('Scale map:')
  previous = None
  for choice in choices:
    label = choice.scale.label() if choice.scale else 'No exact match within the permitted catalog.' if choice.span.chord else 'N.C.'
    if label != previous:
      lines.append(f'  Measure {choice.span.source_measure}, beat {choice.span.beat}: {label}')
      lines.append('    ' + choice.reason)
    previous = label
  lines.extend(('', 'Chord detail:'))
  for choice in choices:
    span, scale = choice.span, choice.scale
    if span.chord is None:
      continue
    chord = span.chord
    notes = chord_notes(chord)
    required = [name for _, name in notes]
    if bass := chord.get('bass'):
      required.append(generator.model.pitch_name(bass))
    targets = [name for degree, name in notes if degree in (3, 7)] or [name for _, name in notes]
    lines.append(f'Measure {span.source_measure}, beat {span.beat}; sequential measure {span.measure}; offset {span.start} through {span.end}')
    lines.append('  Chord: ' + generator.harmony.symbol(chord) + '; required pitches: ' + ', '.join(dict.fromkeys(required)))
    if scale:
      root = generator.model.pitch_number({**chord['root'], 'octave': 4}) % 12
      degree, mode = library.chord_mode(scale, generator.model.pitch_name(chord['root'])) if root in scale.pitches else (None, None)
      lines.append('  Parent: ' + scale.label() + ' [' + ', '.join(scale.notes) + ']')
      lines.append(f'  Parent degree: {degree or "omitted root"}; chord-root mode: {mode or "not assigned"}')
      lines.append('  Chord-tone targets: ' + ', '.join(targets))
      if generator.model.pitch_name(chord['root']) == scale.root:
        lines.append('  Tonic resolution target: ' + scale.root)
    else:
      lines.append('  No exact match within the permitted catalog.')
    lines.extend(('  Reason: ' + choice.reason, ''))
  return '\n'.join(lines)