from __future__ import annotations

import hashlib
import importlib.metadata
import json
from pathlib import Path
import shutil
import platform
import tempfile

from PIL import features

def renderer_identity(fonts, style) -> dict:
  root = Path(__file__).resolve().parents[1]
  versions = {name: importlib.metadata.version(name) for name in ('Pillow', 'fonttools', 'aggdraw')}
  versions.update({name: features.version(name) for name in features.get_supported()})
  sources = [*root.joinpath('engraving').glob('*.py'), root / 'model.py', root / 'harmony.py', root / 'requirements.txt']
  return {'fonts_style': fonts.fingerprint(style), 'python': {'implementation': platform.python_implementation(), 'version': platform.python_version()}, 'dependencies': versions,
    'sources': {path.relative_to(root).as_posix(): hashlib.sha256(path.read_bytes()).hexdigest() for path in sorted(sources)}}

def renderer_fingerprint(fonts, style) -> str:
  return hashlib.sha256(json.dumps(renderer_identity(fonts, style), sort_keys=True).encode()).hexdigest()

def renderer_namespace(cache: Path, renderer: str) -> Path:
  namespace = cache / renderer
  if namespace.parent.is_symlink() or namespace.is_symlink():
    raise ValueError('engraving cache namespaces must not be symlinks')
  return namespace

def score_fingerprint(document: dict, renderer: str) -> str:
  music = {key: value for key, value in document.items() if key != 'playback'}
  return hashlib.sha256(json.dumps([renderer, music], sort_keys=True, ensure_ascii=False).encode()).hexdigest()

def restore_pages(entry: Path, destination: Path) -> list[dict] | None:
  from generator.engraving import check_page
  try:
    if entry.is_symlink():
      return None
    manifest = entry / 'pages.json'
    if manifest.is_symlink():
      return None
    pages = json.loads(manifest.read_text(encoding='utf-8'))
    if not isinstance(pages, list) or not 0 < len(pages) <= 10000:
      return None
    destination.mkdir(parents=True, exist_ok=True)
    for index, page in enumerate(pages, 1):
      if not isinstance(page, dict) or set(page) != {'path', 'sha256'} or page['path'] != f'{index:04}.png':
        return None
      path = entry / page['path']
      if path.is_symlink():
        return None
      target = destination / page['path']
      shutil.copyfile(path, target)
      if hashlib.sha256(target.read_bytes()).hexdigest() != page['sha256']:
        return None
      check_page(target)
    return pages
  except (OSError, ValueError, TypeError):
    return None

def store_pages(entry: Path, destination: Path, pages: list[dict]) -> None:
  entry.parent.mkdir(parents=True, exist_ok=True)
  if entry.is_symlink() or entry.is_file():
    entry.unlink(missing_ok=True)
  entry.mkdir(exist_ok=True)
  with tempfile.TemporaryDirectory(prefix='.engraving-', dir=entry.parent) as temporary:
    staged = Path(temporary)
    for page in pages:
      shutil.copyfile(destination / page['path'], staged / page['path'])
    (staged / 'pages.json').write_text(json.dumps(pages), encoding='utf-8')
    # Identical keys have identical pages; publish complete files, then the manifest.
    for name in [page['path'] for page in pages] + ['pages.json']:
      target = entry / name
      if target.is_dir() and not target.is_symlink():
        shutil.rmtree(target, ignore_errors=True)
      (staged / name).replace(target)