#静态文件管理：优雅地加载 CSS、JavaScript 和本地图片

# app/__init__.py
from flask import Flask, send_from_directory
import os

def create_app():
    app = Flask(__name__)
    # 假设media目录在项目根目录
    MEDIA_FOLDER = os.path.join(os.path.dirname(app.root_path), "media")

    # 自定义路由 /media/<path:filename> 映射到 MEDIA_FOLDER
    @app.route("/media/<path:filename>")
    def media(filename):
        return send_from_directory(MEDIA_FOLDER, filename)

    return app

# app/__init__.py
from flask import Flask
from werkzeug.middleware.shared_data import SharedDataMiddleware
import os

def create_app():
    app = Flask(__name__)
    MEDIA_FOLDER = os.path.join(os.path.dirname(app.root_path), "media")

    # 直接在WSGI层加静态服务，性能比原生高一点点
    app.wsgi_app = SharedDataMiddleware(
        app.wsgi_app,
        {"/media": MEDIA_FOLDER}
    )

    return app

# app/utils.py
from flask import current_app, url_for
import hashlib
import os

def static_hash(filename):
    """生成带内容哈希的静态文件 URL"""
    filepath = os.path.join(
        current_app.root_path, "static", filename
    )
    if os.path.exists(filepath):
        with open(filepath, "rb") as f:
            # 取前8位足够防止重复
            version_hash = hashlib.md5(f.read()).hexdigest()[:8]
        return f"{url_for('static', filename=filename)}?v={version_hash}"
    # 文件不存在就返回普通URL
    return url_for('static', filename=filename)

# app/__init__.py
from app.utils import static_hash

def create_app():
    app = Flask(__name__)
    # 注册全局模板函数
    app.add_template_global(static_hash, 'static_hash')
    return app

# app/__init__.py
import os

def create_app():
    app = Flask(__name__)

    # 配置项：上传相关
    app.config["SECRET_KEY"] = "your-secret-key-here"  # 必须要！flash消息要用
    app.config["MAX_CONTENT_LENGTH"] = 16 * 1024 * 1024  # 最大16MB
    app.config["ALLOWED_EXTENSIONS"] = {"png", "jpg", "jpeg", "gif", "webp"}  # 仅允许图片
    # 公开上传路径（static下才能直接访问）
    app.config["UPLOAD_FOLDER"] = os.path.join(
        app.root_path, "static", "uploads"
    )

    return app

# 辅助函数：检查文件扩展名
def allowed_file(filename):
    return "." in filename and \
           filename.rsplit(".", 1)[1].lower() in current_app.config["ALLOWED_EXTENSIONS"]

# app/routes/upload.py
from flask import Blueprint, request, redirect, url_for, flash, current_app
from werkzeug.utils import secure_filename
from flask_login import current_user, login_required
import os
import uuid

upload_bp = Blueprint("upload", __name__)

@upload_bp.route("/upload/avatar", methods=["POST"])
@login_required  # 需要登录才能传
def upload_avatar():
    # 1. 基础检查
    if "file" not in request.files:
        flash("请先选择文件！", "danger")
        return redirect(url_for("profile.index"))
    file = request.files["file"]
    if file.filename == "":
        flash("文件名不能为空！", "danger")
        return redirect(url_for("profile.index"))

    # 2. 检查扩展名
    if not allowed_file(file.filename):
        flash("仅支持 PNG/JPG/JPEG/GIF/WEBP 格式！", "danger")
        return redirect(url_for("profile.index"))

    # 3. 生成安全+唯一的文件名
    secure_name = secure_filename(file.filename)
    ext = secure_name.rsplit(".", 1)[1].lower()
    unique_name = f"{uuid.uuid4().hex}.{ext}"
    # 拼接最终保存路径
    avatar_path = os.path.join(
        current_app.config["UPLOAD_FOLDER"], "avatars", unique_name
    )
    # 确保目录存在
    os.makedirs(os.path.dirname(avatar_path), exist_ok=True)

    # 4. 保存文件
    file.save(avatar_path)

    # 5. 更新用户数据库（假设你有User模型）
    # 注意存相对static的路径，方便模板直接用url_for或/static访问
    current_user.avatar_url = f"/static/uploads/avatars/{unique_name}"
    db.session.commit()  # 需要导入db哦

    flash("头像上传成功！", "success")
    return redirect(url_for("profile.index"))