"""Attachment validation, storage and retention without request parsing."""

import os
import secrets
import re
import time
from datetime import datetime
from urllib.parse import unquote

from .config import get_setting



def cleanup_uploads():
    """Keep attachments referenced by chat history; expire unused uploads after 7 days."""
    try:
        udir = get_setting('UPLOAD_DIR')
        if not os.path.isdir(udir):
            return
        from .db import connect
        connection = connect()
        try:
            referenced = set()
            rows = connection.execute("SELECT content FROM messages WHERE content LIKE '%/uploads/%' "
                                      "UNION ALL SELECT content FROM human_messages WHERE content LIKE '%/uploads/%'")
            for (content,) in rows:
                referenced.update(unquote(name) for name in re.findall(r'/uploads/([A-Za-z0-9_.%-]+)', content or ''))
        finally:
            connection.close()
        cutoff = time.time() - 7 * 86400
        for f in os.listdir(udir):
            if f in referenced:
                continue
            fp = os.path.join(udir, f)
            if os.path.isfile(fp) and os.path.getmtime(fp) < cutoff:
                os.remove(fp)
    except Exception as e:
        print(f'[清理上传文件失败] {e}')


def upload_file(files):
    """上传附件：保存到 uploads 目录，返回文件名与访问地址"""
    if 'file' not in files:
        return ({'ok': False, 'error': '没有文件'}, 400)
    f = files['file']
    if not f or not f.filename:
        return ({'ok': False, 'error': '文件名为空'}, 400)
    ext = os.path.splitext(f.filename)[1].lower()
    if ext not in get_setting('ALLOWED_EXT'):
        return ({'ok': False, 'error': f'不支持的格式 {ext}，仅支持图片/PDF/TXT/CSV'}, 400)
    f.seek(0, os.SEEK_END)
    size = f.tell()
    f.seek(0)
    if size > get_setting('MAX_UPLOAD_MB') * 1024 * 1024:
        return ({'ok': False, 'error': f"文件超过 {get_setting('MAX_UPLOAD_MB')}MB"}, 400)
    os.makedirs(get_setting('UPLOAD_DIR'), exist_ok=True)
    safe_name = secrets.token_hex(16) + ext
    f.save(os.path.join(get_setting('UPLOAD_DIR'), safe_name))
    from .db import connect, now_str
    from .visitor_service import visitor_id
    owner = visitor_id()
    if owner:
        connection = connect()
        try:
            with connection:
                connection.execute('INSERT INTO visitor_uploads(filename,visitor_id,ctime) VALUES(?,?,?)',
                                   (safe_name, owner, now_str()))
        finally:
            connection.close()
    is_image = ext in ('.png', '.jpg', '.jpeg', '.gif', '.webp')
    return {'ok': True, 'name': f.filename, 'url': f'/uploads/{safe_name}', 'is_image': is_image}