"""Written chord, source-key motion, and bounded expressive treatments.

There is no preselected scale map. Optional colors never rewrite a chord;
permission follows the actual sounded interval and validated resolution.
"""
from __future__ import annotations
import dataclasses
import functools
import fractions
import generator.harmony
import generator.model
import generator.solo.types
import generator.solo.profiles
import generator.solo.expressions
import generator.solo.recognition

@dataclasses.dataclass(frozen=True)
class Roles:
  basic: frozenset
  specified: frozenset
  degrees: tuple

@functools.lru_cache(maxsize=512)
def degree_roles(kind, root, degrees):
  basic, specified, labels = set(), set(), {}
  for degree, alter in degrees:
    pc = int(root + generator.harmony.degree_semitones(degree, alter)) % 12
    structural = degree in (1, 3, 5, 6, 7) or degree in (2, 4) and kind in ('suspended-second', 'suspended-fourth')
    (basic if structural else specified).add(pc)
    labels.setdefault(pc, []).append(degree)
  return Roles(frozenset(basic), frozenset(specified - basic), tuple((p, tuple(v)) for p, v in sorted(labels.items())))

def roles(chord):
  if not chord or chord['kind'] == 'none':
    return Roles(frozenset(), frozenset(), ())
  root = chord['root']
  pc = generator.model.NATURAL[root['letter']] + generator.model.alteration(root['alter'])
  return degree_roles(chord['kind'], pc, tuple(sorted(generator.harmony.degrees(chord).items())))

@dataclasses.dataclass(frozen=True)
class Span:
  start: fractions.Fraction
  end: fractions.Fraction
  roles: Roles
  chord: str
  key: dict
  pitches: frozenset

@dataclasses.dataclass(frozen=True)
class Result:
  valid: bool
  exposure: float
  pending: tuple = ()
  error: str = ''
  contracts: tuple = ()

class Harmony:
  def __init__(self, spans, profile=None):
    self.profile = profile or generator.solo.profiles.UNRESTRICTED
    self.source_spans = spans
    self.spans = []
    self.color_eligibility = {}
    for s in spans:
      r = roles(s.chord)
      key = frozenset((generator.model.NATURAL[l] + int(generator.model.fraction(a))) % 12 for l, a in zip(generator.model.LETTERS, s.key['alterations']))
      self.spans.append(Span(s.start, s.end, r, generator.harmony.symbol(s.chord) if s.chord else 'N.C.', s.key, key | r.basic | r.specified))
    self.spans = tuple(self.spans)
  @functools.lru_cache(maxsize=2048)
  def at(self, time): return next((s for s in self.spans if s.start <= time < s.end), None)
  def segments(self, n): return tuple((s, max(n.start, s.start), min(n.end, s.end)) for s in self.spans if s.start < n.end and s.end > n.start)
  @functools.lru_cache(maxsize=8192)
  def members(self, start, end):
    spans = [s for s in self.spans if s.start < end and s.end > start]
    return frozenset.intersection(*(s.roles.basic | s.roles.specified for s in spans)) if spans else frozenset()
  @functools.lru_cache(maxsize=8192)
  def permitted(self, start, end):
    spans = [s for s in self.spans if s.start < end and s.end > start]
    return frozenset.intersection(*(s.pitches if s.chord != 'N.C.' else frozenset() for s in spans)) if spans else frozenset()
  def function(self, number, span):
    pc = number % 12
    return 'basic' if pc in span.roles.basic else 'specified_extension' if pc in span.roles.specified else 'diatonic_motion' if pc in span.pitches else 'chromatic'
  def step(self, a, b, time): return 0 < abs(a - b) <= 2
  def connected_motion(self, notes, index):
    if not 0 < index < len(notes) - 1:
      return ''
    a, n, b = notes[index - 1:index + 2]
    if a.end != n.start or n.end != b.start:
      return ''
    left = n.pitch.number() - a.pitch.number()
    right = b.pitch.number() - n.pitch.number()
    return 'neighbor' if 0 < abs(left) <= 2 and left == -right else 'passing' if 0 < abs(left) <= 2 and 0 < abs(right) <= 2 and left * right > 0 else ''
  @functools.lru_cache(maxsize=8192)
  def _ordinary(self, start, end, number):
    covered = start
    for s in self.spans:
      a, b = max(start, s.start), min(end, s.end)
      if a >= b:
        continue
      if a != covered or s.chord == 'N.C.':
        return False
      covered = b
      pc = number % 12
      if pc not in s.roles.basic | s.roles.specified and (pc not in s.pitches or end - start >= 2):
        return False
    return covered == end and end > start
  def ordinary(self, n): return self._ordinary(n.start, n.end, n.pitch.number())
  @staticmethod
  def identified(n):
    return n if n.event_id else dataclasses.replace(n, event_id=f'event:{n.start}:{n.end}:{n.pitch.label()}')
  def evaluate(self, notes, *, until=None, complete=False, expressions=(), infer=True):
    notes = tuple(self.identified(n) for n in generator.solo.types.sounding_notes(notes))
    expressions = tuple(dataclasses.replace(c, events=tuple(self.identified(n) for n in c.events),
      target=self.identified(c.target), preparation=self.identified(c.preparation) if c.preparation else None) for c in expressions)
    frontier = until if until is not None else max((n.end for n in notes), default=fractions.Fraction())
    permissions, pending, error = generator.solo.expressions.validate_frontier(notes, expressions, self, frontier, complete or until is None)
    if error:
      return Result(False, 0, error=error)
    if infer and not pending and (complete or until is None) and any(not self.ordinary(n) and n.event_id not in permissions for n in notes):
      expressions, error = generator.solo.recognition.recognize(notes, self, expressions)
      if error:
        return Result(False, 0, error=error)
      permissions, pending, error = generator.solo.expressions.validate_frontier(notes, expressions, self, frontier, True)
      if error:
        return Result(False, 0, error=error)
    exposed = sounded = fractions.Fraction()
    for n in notes:
      covered = n.start
      duration = n.end - n.start
      sounded += duration
      for s, a, b in self.segments(n):
        if a != covered or s.chord == 'N.C.':
          return Result(False, 0, error=f'{n.event_id}: missing written/carried harmony')
        covered = b
        permission = permissions.get(n.event_id)
        if permission and permission.kind == 'anticipation' and a >= permission.boundary:
          permission = None
        pc = n.pitch.number() % 12
        if pc in s.roles.basic | s.roles.specified or permission:
          continue
        if pc not in s.pitches:
          return Result(False, 0, error=f'{n.event_id}: unsupported chromatic event')
        if duration >= 2:
          return Result(False, 0, error=f'{n.event_id}: sustained nonchord tone needs an explicit treatment')
        exposed += (b - a) / 4
      if covered != n.end:
        return Result(False, 0, error=f'{n.event_id}: incomplete harmonic coverage')
    return Result(True, float(exposed / max(fractions.Fraction(1, 1000), sounded)), pending, contracts=tuple(expressions))
  def describe(self, notes, expressions=()):
    notes = tuple(self.identified(n) for n in generator.solo.types.sounding_notes(notes))
    checked = self.evaluate(notes, expressions=expressions, complete=True)
    if not checked.valid:
      raise ValueError(checked.error)
    permissions = {n.event_id: c for c in checked.contracts for n in c.events}
    return [{'start': str(a), 'end': str(b), 'attack': str(n.start), 'sounding_duration': str(n.end - n.start),
      'pitch': n.pitch.label(), 'chord': s.chord, 'function': self.function(n.pitch.number(), s),
      'expression': permissions[n.event_id].kind if n.event_id in permissions else '',
      'expression_rule': permissions[n.event_id].rule if n.event_id in permissions else '',
      'protected': n.role == 'quote'} for n in notes for s, a, b in self.segments(n)]