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/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0.
 */

// This code was copied and then modified from Tokio's Axum.

/* Copyright (c) 2021 Tower Contributors
 *
 * Permission is hereby granted, free of charge, to any
 * person obtaining a copy of this software and associated
 * documentation files (the "Software"), to deal in the
 * Software without restriction, including without
 * limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software
 * is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice
 * shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
 * ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
 * SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
 * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

//! Extension extraction to share state across handlers.

use super::rejection::{ExtensionRejection, ExtensionsAlreadyExtracted, MissingExtension};
use async_trait::async_trait;
use axum::extract::{FromRequest, RequestParts};
use std::ops::Deref;

/// Extractor that gets a value from [request extensions].
///
/// This is commonly used to share state across handlers.
///
/// If the extension is missing it will reject the request with a `500 Internal
/// Server Error` response.
///
/// [request extensions]: https://docs.rs/http/latest/http/struct.Extensions.html
#[derive(Debug, Clone, Copy)]
pub struct Extension<T>(pub T);

#[async_trait]
impl<T, B> FromRequest<B> for Extension<T>
where
    T: Clone + Send + Sync + 'static,
    B: Send,
{
    type Rejection = ExtensionRejection;

    async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
        let value = req
            .extensions()
            .ok_or(ExtensionsAlreadyExtracted)?
            .get::<T>()
            .ok_or_else(|| {
                MissingExtension::from_err(format!(
                    "Extension of type `{}` was not found. Perhaps you forgot to add it?",
                    std::any::type_name::<T>()
                ))
            })
            .map(|x| x.clone())?;

        Ok(Extension(value))
    }
}

impl<T> Deref for Extension<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}