//! HTTP body utilities.

use crate::{BoxError, Error};
use bytes::Bytes;
use bytes::{Buf, BufMut};
use http_body::Body;

/// A boxed [`Body`] trait object.
///
/// This is used in axum as the response body type for applications. It's
/// necessary to unify multiple response bodies types into one.
pub type BoxBody = http_body::combinators::UnsyncBoxBody<Bytes, Error>;

/// Convert a [`http_body::Body`] into a [`BoxBody`].
pub fn boxed<B>(body: B) -> BoxBody
where
    B: http_body::Body<Data = Bytes> + Send + 'static,
    B::Error: Into<BoxError>,
{
    try_downcast(body).unwrap_or_else(|body| body.map_err(Error::new).boxed_unsync())
}

pub(crate) fn try_downcast<T, K>(k: K) -> Result<T, K>
where
    T: 'static,
    K: Send + 'static,
{
    let mut k = Some(k);
    if let Some(k) = <dyn std::any::Any>::downcast_mut::<Option<T>>(&mut k) {
        Ok(k.take().unwrap())
    } else {
        Err(k.unwrap())
    }
}

// copied from hyper under the following license:
// Copyright (c) 2014-2021 Sean McArthur

// 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.
pub(crate) async fn to_bytes<T>(body: T) -> Result<Bytes, T::Error>
where
    T: Body,
{
    futures_util::pin_mut!(body);

    // If there's only 1 chunk, we can just return Buf::to_bytes()
    let mut first = if let Some(buf) = body.data().await {
        buf?
    } else {
        return Ok(Bytes::new());
    };

    let second = if let Some(buf) = body.data().await {
        buf?
    } else {
        return Ok(first.copy_to_bytes(first.remaining()));
    };

    // With more than 1 buf, we gotta flatten into a Vec first.
    let cap = first.remaining() + second.remaining() + body.size_hint().lower() as usize;
    let mut vec = Vec::with_capacity(cap);
    vec.put(first);
    vec.put(second);

    while let Some(buf) = body.data().await {
        vec.put(buf?);
    }

    Ok(vec.into())
}

#[test]
fn test_try_downcast() {
    assert_eq!(try_downcast::<i32, _>(5_u32), Err(5_u32));
    assert_eq!(try_downcast::<i32, _>(5_i32), Ok(5_i32));
}