from __future__ import annotations

import dataclasses
import typing

import generator.score

@dataclasses.dataclass(frozen=True)
class ArrangementSection:
  label: str
  source_measure_index: int
  measure_count: int
  section_index: int
  role: typing.Literal["accompaniment", "melody", "vocal", "rest", "slash"]

def phrase_aware_edge_measure_count(body_measure_count: int) -> int:
  if body_measure_count >= 8:
    return 8
  if body_measure_count >= 4:
    return 4
  return body_measure_count

def section_role(part_type: str, section_index: int) -> typing.Literal["accompaniment", "melody", "vocal", "rest", "slash"]:
  if part_type == "acoustic":
    return "slash" if section_index == 3 else "accompaniment"
  if part_type == "electric":
    if section_index == 4:
      return "slash"
    if section_index == 2:
      return "melody"
    if section_index in {1, 5, 6}:
      return "accompaniment"
    return "rest"
  return "vocal" if section_index in {1, 5, 6} else "rest"

def full_arrangement_sections(measures: list[dict], part_type: str) -> list[ArrangementSection]:
  if not measures:
    return []
  body_start = generator.score.body_start_measure_index(measures)
  if body_start >= len(measures):
    return []
  body_measure_count = len(measures) - body_start
  edge_measure_count = phrase_aware_edge_measure_count(body_measure_count)
  edge_source_measure = body_start + body_measure_count - edge_measure_count
  specs = (
    ("Rhythm Lead-in", edge_source_measure, edge_measure_count, 0),
    ("Vocal Melody", body_start, body_measure_count, 1),
    ("Guitar Melody", body_start, body_measure_count, 2),
    ("Acoustic Solo", body_start, body_measure_count, 3),
    ("Electric Solo", body_start, body_measure_count, 4),
    ("Vocal Melody", body_start, body_measure_count, 5),
    ("Ending", edge_source_measure, edge_measure_count, 6),
  )
  return [
    ArrangementSection(label=label, source_measure_index=start, measure_count=count, section_index=index, role=section_role(part_type, index))
    for label, start, count, index in specs
    if count > 0
  ]