import os

from flask import Blueprint, abort, send_file, send_from_directory

from backend.config import FRONTEND_DIST

spa_bp = Blueprint("spa", __name__)


def _frontend_index_path():
    return os.path.join(FRONTEND_DIST, "index.html")


def _has_frontend_build():
    return os.path.isfile(_frontend_index_path())


def serve_spa():
    if not _has_frontend_build():
        return (
            "前端未构建，请在 frontend 目录执行: npm install && npm run build",
            503,
            {"Content-Type": "text/plain; charset=utf-8"},
        )
    return send_file(_frontend_index_path())


@spa_bp.route("/")
def index():
    return serve_spa()


@spa_bp.route("/debug")
def debug_view():
    return serve_spa()


@spa_bp.route("/assets/<path:filename>")
def frontend_assets(filename):
    assets_dir = os.path.join(FRONTEND_DIST, "assets")
    if not os.path.isdir(assets_dir):
        abort(404)
    return send_from_directory(assets_dir, filename)


@spa_bp.route("/<path:path>")
def spa_fallback(path):
    if path.startswith("api/") or path == "qrcode.png":
        abort(404)
    if not _has_frontend_build():
        abort(404)
    dist_file = os.path.join(FRONTEND_DIST, path)
    if os.path.isfile(dist_file):
        return send_from_directory(FRONTEND_DIST, path)
    return send_file(_frontend_index_path())