//
// Copyright 2020-Present (c) Raja Lehtihet & Wael El Oraiby
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. 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.
//
// 3. Neither the name of the copyright holder nor the names of its 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 LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER 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, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
#![no_std]
#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
#[allow(improper_ctypes)]

use core::alloc::*;
use core::*;
use core::sync::atomic::*;

mod os;
use os::*;

pub mod hash;
pub mod vec;
pub mod hashmap;
pub mod string;

pub use vec::*;
pub use hashmap::*;
pub use string::*;

pub unsafe fn realloc_fallback(
    alloc: &System,
    ptr: *mut u8,
    old_layout: Layout,
    new_size: usize,
) -> *mut u8 {
    // Docs for GlobalAlloc::realloc require this to be valid:
    let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());

    let new_ptr = GlobalAlloc::alloc(alloc, new_layout);
    if !new_ptr.is_null() {
        let size = cmp::min(old_layout.size(), new_size);
        ptr::copy_nonoverlapping(ptr, new_ptr, size);
        GlobalAlloc::dealloc(alloc, ptr, old_layout);
    }
    new_ptr
}

pub const sysalloc : System = System;

pub unsafe fn alloc<T>() -> *mut T {
     sysalloc.alloc(Layout::new::<T>()) as *mut rs_ctypes::c_void as *mut T
}

pub unsafe fn free<T>(t: *mut T) {
    sysalloc.dealloc(t as *mut u8, Layout::new::<T>());
}

// TODO: change this to const generics when they become stable and return a slice
pub unsafe fn alloc_array<T>(res_count: usize) -> *mut T {
    let l = Layout::array::<T>(res_count);
    match l {
        Ok(layout) => sysalloc.alloc(layout) as *mut T,
        _ => panic!("unable to create layout")
    }
}

pub unsafe fn alloc_array_zeroed<T>(res_count: usize) -> *mut T {
    let l = Layout::array::<T>(res_count);
    match l {
        Ok(layout) => sysalloc.alloc_zeroed(layout) as *mut T,
        _ => panic!("unable to create layout")
    }
}

// TODO: change this to slice once const generics stable
pub unsafe fn free_array<T>(ptr: *mut T, count: usize, res_count: usize) {
    if count > res_count {
        panic!("count exceeded reserved count")
    }

    let arr      = core::slice::from_raw_parts_mut(ptr, count); // this will keep a pointer (will not free it)
    for i in 0..count {
        ::core::ptr::drop_in_place(&arr[i] as *const T as *mut T);
    }
    let l = Layout::array::<T>(count);
    match l {
        Ok(layout) => sysalloc.dealloc(ptr as *mut u8, layout),
        _ => panic!("unable to create layout")
    }
}

// TODO: change this to slice once const generics stable
pub unsafe fn free_array_ptr<T>(ptr: *mut T, count: usize) {
    let l = Layout::array::<T>(count);
    match l {
        Ok(layout) => sysalloc.dealloc(ptr as *mut u8, layout),
        _ => panic!("unable to create layout")
    }
}


////////////////////////////////////////////////////////////////////////////////
/// TODO: remove these when the alloc handler stabilize in alloc
////////////////////////////////////////////////////////////////////////////////
#[repr(C)]
pub struct Unique<T: ?Sized> {
    ptr         : *mut T,
    _marker     : ::core::marker::PhantomData<T>,
}

impl<T: ?Sized> Unique<T> {
    pub fn new(ptr: *mut T) -> Self { Self { ptr : ptr, _marker: ::core::marker::PhantomData } }
    pub fn get_mut_ptr(&mut self) -> *mut T { self.ptr }
    pub fn get_ptr(&self) -> *const T { self.ptr }
}

#[repr(C)]
pub struct Box<T: ?Sized>{
    uptr: Unique<T>
}

impl<T: ?Sized> Drop for Box<T> {
    fn drop(&mut self) {
        unsafe {
            ::core::ptr::drop_in_place(self.uptr.get_mut_ptr());
            let addr = self.uptr.get_mut_ptr() as *mut u8;  // TODO: this is a hack to pass thin to fat type conversion error
            free(addr);
        }
    }
}

impl<T: Sized> Box<T> {
    #[inline(always)]
    pub fn new(x: T) -> Self {
        unsafe {
            let addr = alloc::<T>();
            ptr::write(addr, x);
            Self { uptr: Unique::new(addr) }
        }
    }

    pub fn unbox(self) -> T {
        unsafe {
            let ptr = self.uptr.ptr;
            let v = Self::into_raw(self).read();
            free(ptr);
            v
        }
    }

    pub fn get_unique(&mut self) -> &mut Unique<T> {
        &mut self.uptr
    }
}


impl<T: ?Sized> Box<T> {
    pub fn as_ref(&self) -> &T { unsafe { &(*self.uptr.get_ptr()) } }
    pub fn as_mut(&mut self) -> &T { unsafe { &mut (*self.uptr.get_mut_ptr()) } }
    pub fn into_raw(this: Self) -> *mut T {
        let m = ::core::mem::ManuallyDrop::new(this);
        m.uptr.ptr
    }

    pub fn from_raw(raw: *mut T) -> Self {
        Self { uptr: Unique::new(raw) }
    }
}


#[repr(C)]
struct ArcCell<T: ?Sized> {
    count: AtomicIsize,
    data: T,
}

impl<T: ?Sized> ArcCell<T> {
    pub fn count(&self) -> isize {
        self.count.load(Ordering::Relaxed)
    }

    pub fn inc(&mut self) {
        self.count.fetch_add(1, Ordering::SeqCst);
    }

    pub fn dec(&mut self) -> isize { self.count.fetch_sub(1, Ordering::SeqCst) }
}

pub struct Arc<T: ?Sized>(*mut ArcCell<T>);

impl<T: ?Sized> Arc<T> {
    pub fn as_ptr(this: &Arc<T>) -> *const T {
        unsafe { &(*this.0).data as *const T }
    }
}

impl<T: Sized> Arc<T> {
    pub fn new(x: T) -> Self {
        unsafe {
            let addr = alloc::<ArcCell<T>>();
            ptr::write(addr, ArcCell { data: x, count: AtomicIsize::new(1) });
            Self(addr)
        }
    }
}

impl<T: ?Sized> Drop for Arc<T> {
    fn drop(&mut self) {
        unsafe {
            let s = &mut (*self.0);
            if s.dec() == 1 {
                ::core::ptr::drop_in_place(self.0);
                let addr = self.0 as *mut u8;  // TODO: this is a hack to pass thin to fat type conversion error
                free(addr);
            }
        }
    }
}

impl<T: ?Sized> Clone for Arc<T> {
    fn clone(&self) -> Self {
        unsafe {
            let s = &mut (*self.0);
            s.inc();
            Self(self.0)
        }
    }
}


impl<T: ?Sized> core::ops::Deref for Arc<T> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        unsafe { &(*self.0).data }
    }
}

impl<T: ?Sized> AsRef<T> for Arc<T> {
    fn as_ref(&self) -> &T {
        unsafe { &(*self.0).data }
    }
}

unsafe impl<T: ?Sized> Send for Arc<T> {}
unsafe impl<T: ?Sized> Sync for Arc<T> {}

#[cfg(test)]
mod tests {
    use super::*;
    extern crate std;

    #[test]
    fn testDrop() {
        let _b0 = Box::new(1234);
        let _b1 = Box::new(1234345);
        let mut v = std::vec::Vec::new();
        for i in 0..100 {
            v.push(i);
        }
        let _bv = Box::new(v);
    }

    #[test]
    fn testDropVecVec() {
        let _b0 = Box::new(1234);
        let _b1 = Box::new(1234345);
        let mut v = std::vec::Vec::new();
        for _ in 0..100 {
            let mut vj = std::vec::Vec::new();
            for j in 0..100 {
                vj.push(j);
            }
            v.push(vj);
        }
        let _bv = Box::new(v);
    }

    #[test]
    fn testBoxUnbox() {
        let b = Box::new(1234);
        let _v = b.unbox();
    }

    #[test]
    fn testBoxUnboxVecVec() {
        let _b0 = Box::new(1234);
        let _b1 = Box::new(1234345);
        let mut v = std::vec::Vec::new();
        for _ in 0..100 {
            let mut vj = std::vec::Vec::new();
            for j in 0..100 {
                vj.push(j);
            }
            v.push(vj);
        }
        let v2 = Box::new(v);
        let _v3 = v2.unbox();
    }

    #[test]
    fn testBoxFromToRaw() {
        let b = Box::new(1234);
        let r = Box::into_raw(b);
        let _b = Box::from_raw(r);
    }


    trait TestTrait : Drop {
        fn blabla(&self);
    }

    struct TestStruct {
        a: std::vec::Vec<usize>
    }

    impl TestTrait for TestStruct {
        fn blabla(&self) {}
    }

    impl Drop for TestStruct {
        fn drop(&mut self) {
        }
    }

    struct TestStruct2 {
        t: Box<dyn TestTrait>
    }

    #[test]
    fn testTrait() {
        let mut v = std::vec::Vec::new();
        v.push(123);
        v.push(456);
        let a = Box::new(TestStruct { a: v });
        let _ = Box::from_raw(Box::into_raw(a) as *mut dyn TestTrait);
    }

    #[test]
    fn testArc() {
        let mut v = std::vec::Vec::new();
        v.push(123);
        v.push(456);
        let _ = Arc::new(TestStruct { a: v });
    }

    #[test]
    fn testArcRef() {
        let mut v = std::vec::Vec::new();
        v.push(123);
        v.push(456);
        let a = Arc::new(TestStruct { a: v });
        let d = a.as_ref();
        assert_eq!(d.a[0], 123);
        assert_eq!(d.a[1], 456);
        let f = &*a;
        assert_eq!(f.a[0], 123);
        assert_eq!(f.a[1], 456);
    }
}