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use prelude::v1::*;
use base::*;
use shim::*;
use units::*;
use isr::*;

unsafe impl<T: Sized + Copy> Send for Queue<T> {}
unsafe impl<T: Sized + Copy> Sync for Queue<T> {}

/// A queue with a finite size. The items are owned by the queue and are
/// copied.
#[derive(Debug)]
pub struct Queue<T: Sized + Copy> {
    queue: FreeRtosQueueHandle,
    item_type: PhantomData<T>,
}

impl<T: Sized + Copy> Queue<T> {
    pub fn new(max_size: usize) -> Result<Queue<T>, FreeRtosError> {

        let item_size = mem::size_of::<T>();

        let handle = unsafe { freertos_rs_queue_create(max_size as u32, item_size as u32) };

        if handle == 0 as *const _ {
            return Err(FreeRtosError::OutOfMemory);
        }

        Ok(Queue {
            queue: handle,
            item_type: PhantomData,
        })
    }

    /// Send an item to the end of the queue. Wait for the queue to have empty space for it.
    pub fn send<D: DurationTicks>(&self, item: T, max_wait: D) -> Result<(), FreeRtosError> {
        unsafe {
            if freertos_rs_queue_send(self.queue,
                                      &item as *const _ as FreeRtosVoidPtr,
                                      max_wait.to_ticks()) != 0 {
                Err(FreeRtosError::QueueSendTimeout)
            } else {
                Ok(())
            }
        }
    }

    /// Send an item to the end of the queue, from an interrupt.
    pub fn send_from_isr(&self,
                         context: &mut InterruptContext,
                         item: T)
                         -> Result<(), FreeRtosError> {
        unsafe {
            if freertos_rs_queue_send_isr(self.queue,
                                          &item as *const _ as FreeRtosVoidPtr,
                                          context.get_task_field_mut()) != 0 {
                Err(FreeRtosError::QueueFull)
            } else {
                Ok(())
            }
        }
    }

    /// Wait for an item to be available on the queue.
    pub fn receive<D: DurationTicks>(&self, max_wait: D) -> Result<T, FreeRtosError> {
        unsafe {
            let mut buff = mem::zeroed::<T>();
            let r = freertos_rs_queue_receive(self.queue,
                                              &mut buff as *mut _ as FreeRtosMutVoidPtr,
                                              max_wait.to_ticks());
            if r == 0 {
                return Ok(buff);
            } else {
                return Err(FreeRtosError::QueueReceiveTimeout);
            }
        }
    }
}

impl<T: Sized + Copy> Drop for Queue<T> {
    fn drop(&mut self) {
        unsafe {
            freertos_rs_queue_delete(self.queue);
        }
    }
}