from __future__ import annotations

import hashlib
import json
from pathlib import Path
import shutil

from PIL import Image, ImageChops

from generator.engraving.fonts import Fonts
from generator.engraving.layout import layout_score
from generator.engraving.raster import rasterize_page
from generator.engraving.types import EngravingError, Style

ENGINE_NAME = 'Vamp Python'
ENGINE_VERSION = '1.0.0'
PAGE_WIDTH = 976
PAGE_HEIGHT = 484

def check_page(path: Path) -> None:
  with Image.open(path) as image:
    image.load()
    if image.format != 'PNG' or image.size != (PAGE_WIDTH, PAGE_HEIGHT):
      raise EngravingError(f'{path.name}: expected a {PAGE_WIDTH}x{PAGE_HEIGHT} PNG page')
    white = Image.new('RGBA', image.size, 'white')
    white.alpha_composite(image.convert('RGBA'))
    ink = ImageChops.difference(white.convert('RGB'), Image.new('RGB', image.size, 'white')).convert('L').point(lambda x: 255 if x > 32 else 0)
    bounds = ink.getbbox()
    if not bounds:
      raise EngravingError(f'{path.name}: engraver produced a blank page')
    if bounds[0] < 4 or bounds[1] < 4 or bounds[2] > PAGE_WIDTH - 4 or bounds[3] > PAGE_HEIGHT - 4:
      raise EngravingError(f'{path.name}: notation reaches the page edge; refusing potentially clipped output')

def engrave_tree(root: Path, fonts: Path) -> None:
  paths = sorted(root.rglob('*.json'))
  if not paths:
    return
  family = Fonts(fonts)
  style = Style()
  for path in paths:
    document = json.loads(path.read_text(encoding='utf-8'))
    try:
      layout = layout_score(document, style, family)
      destination = path.with_suffix('.pages')
      if destination.exists():
        shutil.rmtree(destination)
      destination.mkdir()
      entries = []
      for page in layout.pages:
        name = f'{page.number:04}.png'
        target = destination / name
        rasterize_page(page, family).save(target, format='PNG')
        check_page(target)
        entries.append({'path': destination.name + '/' + name, 'sha256': hashlib.sha256(target.read_bytes()).hexdigest()})
      music = {k: v for k, v in document.items() if k != 'schema_version'}
      bundle = {'schema_version': 3, 'music': music, 'presentation': {'engine': ENGINE_NAME, 'engine_version': ENGINE_VERSION, 'style_sha256': layout.fingerprint, 'width': PAGE_WIDTH, 'height': PAGE_HEIGHT, 'pages': entries}}
      path.write_text(json.dumps(bundle, indent=2, ensure_ascii=False) + '\n', encoding='utf-8')
    except ValueError as error:
      raise EngravingError(f'{path.relative_to(root)}: {error}') from error