from __future__ import annotations

import logging

from flask import Flask, abort, jsonify, request

from .config import Config, DATA_DIR, ensure_dirs
from .extensions import db, login_manager
from .models import AppSetting, User
from .prediction import FEATURES, load_model
from .security import csrf_token, validate_csrf_token
from .time_utils import current_year_for_timezone, format_datetime_for_timezone


def create_app(config_object: type[Config] = Config, *, load_model_on_start: bool = True) -> Flask:
    ensure_dirs()
    configure_logging()

    app = Flask(__name__, template_folder="../templates", static_folder="../static")
    app.config.from_object(config_object)

    if app.config.get("SECRET_KEY_GENERATED"):
        logging.warning("未设置 SECRET_KEY，已生成临时密钥；服务重启后登录会话将失效。")

    db.init_app(app)
    login_manager.init_app(app)
    login_manager.login_view = "main.login"
    login_manager.login_message = "请先登录后再访问该页面。"

    register_app_hooks(app)

    from .routes import bp

    app.register_blueprint(bp)

    with app.app_context():
        db.create_all()
        init_admin_user(app)

    if load_model_on_start:
        try:
            app.config["RSF_MODEL"] = load_model(app.config["MODEL_PATH"])
            logging.info("模型加载成功")
        except Exception as exc:
            app.config["RSF_MODEL"] = None
            logging.exception("模型加载失败: %s", exc)

    return app


def configure_logging() -> None:
    logging.basicConfig(
        filename=str(DATA_DIR / "app.log"),
        level=logging.INFO,
        format="%(asctime)s - %(levelname)s - %(message)s",
    )


def init_admin_user(app: Flask) -> None:
    admin_username = app.config["ADMIN_USERNAME"]
    admin_password = app.config["ADMIN_PASSWORD"]
    if admin_password:
        admin = User.query.filter_by(username=admin_username).first()
        if admin is None:
            admin = User(username=admin_username, is_admin=True)
            admin.set_password(admin_password)
            db.session.add(admin)
        else:
            admin.is_admin = True
            if not admin.check_password(admin_password):
                admin.set_password(admin_password)
        db.session.commit()
    elif not User.query.filter_by(is_admin=True).first():
        logging.warning("未设置 ADMIN_PASSWORD，跳过自动创建管理员账号。")

    default_admin = User.query.filter_by(username="admin", is_admin=True).first()
    if default_admin and default_admin.check_password("admin123"):
        logging.warning("检测到默认管理员密码 admin123，请立即通过 ADMIN_PASSWORD 更新。")


def register_app_hooks(app: Flask) -> None:
    @login_manager.user_loader
    def load_user(user_id: str):
        try:
            return db.session.get(User, int(user_id))
        except (TypeError, ValueError):
            return None

    @app.context_processor
    def inject_helpers():
        def now_year() -> int:
            return current_year_for_timezone(app.config["APP_TIMEZONE"])

        def format_datetime(value) -> str:
            return format_datetime_for_timezone(value, app.config["APP_TIMEZONE"])

        return {
            "feature_list": FEATURES,
            "now_year": now_year,
            "format_datetime": format_datetime,
            "csrf_token": csrf_token,
            "allow_registration": AppSetting.get_bool(
                "allow_registration",
                app.config["ALLOW_REGISTRATION"],
            ),
        }

    @app.errorhandler(413)
    def handle_file_too_large(_exc):
        max_mb = app.config["MAX_CONTENT_LENGTH"] // (1024 * 1024)
        if request.path == "/predict":
            return jsonify({"error": f"文件过大，请上传 {max_mb}MB 以内的文件。"}), 413
        return f"文件过大，请上传 {max_mb}MB 以内的文件。", 413

    @app.before_request
    def protect_csrf():
        if request.method not in {"POST", "PUT", "PATCH", "DELETE"}:
            return None
        if validate_csrf_token():
            return None
        if request.path == "/predict" or request.headers.get("X-Requested-With") == "XMLHttpRequest":
            return jsonify({"error": "CSRF 校验失败，请刷新页面后重试。"}), 400
        abort(400)