"""Local article validation and portable packages. Never changes downloaded files."""
import hashlib
import json
from pathlib import Path
import re
import unicodedata
from urllib.parse import unquote

from modules.package import make_package

MAX_PACKAGE_BYTES = 48 * 1024 * 1024
FOOTER = re.compile(r'(?:^|\n)来源：([^\n]+)，如有侵权，请联系删除。\s*$')


def validate_images(body, directory):
    """Conservative inline-image preflight; the importer remains the final parser."""
    if re.search(r'!\[[^\]]*\]\s*\[', body):
        raise ValueError('不支持引用式图片，请改成内联图片路径')
    for start in re.finditer(r'!\[[^\]]*\]\(', body):
        pos, depth, quote, angle = start.end(), 1, '', False
        begin = pos
        while pos < len(body):
            ch = body[pos]
            if ch == '\\':
                pos += 2
                continue
            if quote:
                if ch == quote:
                    quote = ''
            elif not angle and depth == 1 and body[pos - 1].isspace() and ch in ('"', "'"):
                quote = ch
            elif ch == '<':
                angle = True
            elif ch == '>':
                angle = False
            elif not angle and ch == '(':
                depth += 1
            elif not angle and ch == ')':
                depth -= 1
                if not depth:
                    break
            pos += 1
        if depth:
            raise ValueError('图片引用括号不完整')
        target = body[begin:pos].strip()
        target = target[1:target.index('>')] if target.startswith('<') and '>' in target else re.sub(r'\s+["\'][\s\S]*["\']\s*$', '', target)
        target = unquote(re.sub(r'\\([()\\ ])', r'\1', target))
        if re.match(r'^(?:[a-zA-Z][\w+.-]*:|/|\\)', target):
            raise ValueError('图片必须使用目录内相对路径：' + target)
        image = (directory / target).resolve()
        if not image.is_relative_to(directory) or not image.is_file():
            raise ValueError('缺图或图片路径超出目录：' + target)
        if image.suffix.lower() not in ('.jpg', '.jpeg', '.png', '.gif'):
            raise ValueError('不支持的配图格式：' + target)
        if not 0 < image.stat().st_size < 20 * 1024 * 1024:
            raise ValueError('配图为空或达到 20 MiB：' + target)


def short_title(title, budget=75):
    """Keep a UTF-8 prefix within budget, adding three ASCII dots if shortened."""
    if len(title.encode('utf-8')) <= budget or (title.endswith('...') and len(title.encode('utf-8')) <= budget + 3):
        return title
    out = ''
    used = 0
    for ch in title:
        size = len(ch.encode('utf-8'))
        if used + size > budget:
            break
        out += ch
        used += size
    return out + '...'


def inspect_article(directory):
    directory = Path(directory).resolve(strict=True)
    candidates = sorted(directory.glob('*.md'))
    if len(candidates) != 1:
        raise ValueError('每个文章目录必须恰好包含一个 Markdown 文件')
    md = candidates[0]
    if not md.resolve().is_relative_to(directory):
        raise ValueError('Markdown 不得链接到目录外')
    raw = md.read_text(encoding='utf-8-sig')
    heading = re.match(r'^\s*#\s+([^\n]+)\n?', raw)
    title = (heading[1] if heading else md.stem).strip()
    body = raw[heading.end():].strip() if heading else raw.strip()
    footer = FOOTER.search(body)
    if not footer:
        raise ValueError('文末缺少标准来源尾注，请补充来源后再扫描')
    source = footer[1].strip()
    body = body[:footer.start()].strip()
    if not title or not body:
        raise ValueError('标题或正文为空')
    validate_images(body, directory)
    for file in directory.rglob('*'):
        if file.suffix.lower() in ('.webp', '.avif', '.svg'):
            raise ValueError('发现暂不支持的图片格式：' + file.name + '；请另存为 JPG/PNG/GIF 并更新引用')
    pack = make_package(directory)
    if sum(len(i['base64']) for i in pack['images']) > MAX_PACKAGE_BYTES:
        raise ValueError('文章包超过 48 MiB，请减少单篇图片体积')
    pack['title'] = short_title(title)
    # Preserve body and exact final footer for the formatter; the original file stays intact.
    pack['markdown'] = '# ' + pack['title'] + '\n\n' + body + '\n\n来源：' + source + '，如有侵权，请联系删除。\n'
    content = unicodedata.normalize('NFC', body)
    # Hash file contents, not directory/title; renamed copies share their article identity.
    image_hashes = []
    for item in pack['images']:
        import base64
        digest = hashlib.sha256(base64.b64decode(item['base64'])).hexdigest()
        content = content.replace(item['path'], 'image:' + digest)
        image_hashes.append(digest)
    identity = hashlib.sha256((content + '\n' + '\n'.join(sorted(set(image_hashes)))).encode()).hexdigest()
    metadata = {}
    marker = directory / '.article.json'
    if marker.is_file():
        metadata = json.loads(marker.read_text())
    return dict(article_key=identity, markdown_sha256=hashlib.sha256(md.read_bytes()).hexdigest(),
                directory=str(directory), original_title=title, title=pack['title'], source=source,
                image_count=len(pack['images']), package=pack,
                source_keys=metadata.get('fingerprints', []))