// Copyright (C) 2017-2018 Baidu, Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
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//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use thread::SgxThread;
use core::cell::RefCell;

struct SgxThreadInfo {
    thread: SgxThread,
}

thread_local! { static THREAD_INFO: RefCell<Option<SgxThreadInfo>> = RefCell::new(None) }

impl SgxThreadInfo {

    fn with<R, F>(f: F) -> Option<R> where F: FnOnce(&mut SgxThreadInfo) -> R {
        THREAD_INFO.try_with(move |c| {
            if c.borrow().is_none() {
                *c.borrow_mut() = Some(SgxThreadInfo {
                    thread: SgxThread::new(),
                })
            }
            f(c.borrow_mut().as_mut().unwrap())
        }).ok()
    }
}

pub fn current_thread() -> Option<SgxThread> {
    SgxThreadInfo::with(|info| info.thread.clone())
}

pub fn set(thread: SgxThread) {
    THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
    THREAD_INFO.with(move |c| *c.borrow_mut() = Some(SgxThreadInfo{
        thread,
    }));
}