use crate::message::MessageBytes;
use crate::res::IFResult;
use alloc::string::String;

/// Some data that can be provided to the interface to send the message to a target.
///
/// For IP this might be `IP:port`.
/// Radio interface, for example, may not have the functionality of targeting, but that's fine
pub(crate) type TargetingData = String;

/// In an std environment we require that the interface can be send safely between threads
#[cfg(not(feature = "std"))]
pub trait InterfaceRequirements {}

#[cfg(feature = "std")]
pub trait InterfaceRequirements: Send + Sync {}

/// An interface that can be used to
pub trait Interface: InterfaceRequirements {
    /// Run one main loop iteration.
    /// On platforms that support concurrency, these functions will be run simultaneously for all interfaces.
    /// Most likely, this function will accept messages and save them somewhere internally to give out later in `Interface.receive()`.
    ///
    /// For systems that don't support concurrency, there can be only one interface in this function waits for a message (to avoid blocking).
    /// That's why it's necessary to check if it is the case for this interface, and it's done using function `Interface::has_blocking_main()`
    fn main_loop_iteration(&mut self) -> IFResult<()>;
    /// Check if `main_loop_iteration` stops execution and waits for a message
    fn has_blocking_main(&self) -> bool {
        false // hopefully...
    }
    /// Get some way of identification for this interface
    fn id(&self) -> &str;
    /// Send a message. If no `interface_data` is provided, we should consider it to be a broadcast.
    /// If, on the other hand, `interface_data` is not `None`, it should be used to send the message to the target.
    fn send(
        &mut self,
        message: &[u8], /*MessageBytes*/
        interface_data: Option<TargetingData>,
    ) -> IFResult<()>;
    /// Receive a message through this interface. Returns a result with an option of (message bytes, target).
    /// `None` means there is no message available at the time.
    /// The implementations of this function shouldn't wait for new messages, but
    fn receive(&mut self) -> IFResult<Option<(MessageBytes, TargetingData /*interface data*/)>>;
}

#[cfg(test)]
pub mod test_interface {
    use crate::interface::{Interface, InterfaceRequirements, TargetingData};
    use crate::message::MessageBytes;
    use crate::res::IFResult;
    use alloc::string::String;
    use alloc::vec::Vec;
    use alloc::vec;
    use alloc::string::ToString;
    use alloc::sync::Arc;
    use spin::Mutex;

    #[derive(Default)]
    pub struct SimpleTestInterface {
        messages: Vec<(Vec<u8>, TargetingData)>,
    }

    impl InterfaceRequirements for SimpleTestInterface {}

    impl Interface for SimpleTestInterface {
        fn main_loop_iteration(&mut self) -> IFResult<()> {
            Ok(())
        }

        fn id(&self) -> &str {
            "test_interface"
        }

        fn send(&mut self, message: &[u8], interface_data: Option<TargetingData>) -> IFResult<()> {
            self.messages
                .push((Vec::from(message), interface_data.unwrap_or_default()));
            Ok(())
        }

        fn receive(&mut self) -> IFResult<Option<(MessageBytes, TargetingData)>> {
            Ok(self.messages.pop())
        }
    }

    pub type Storage = Vec<(Vec<u8>, TargetingData)>;

    #[derive(Default)]
    pub struct TestInterface {
        this_peer_id: String,
        storage: Arc<Mutex<Storage>>,
        messages: Vec<(Vec<u8>, TargetingData)>,
    }

    impl Interface for TestInterface {
        fn main_loop_iteration(&mut self) -> IFResult<()> {
            let mut storage_locked = self.storage.lock();
            while let Some(i) = storage_locked
                .iter()
                .position(|msg| msg.1 == self.this_peer_id || msg.1.is_empty())
            {
                self.messages.push(storage_locked.remove(i));
            }
            Ok(())
        }

        fn id(&self) -> &str {
            "test_interface"
        }

        fn send(&mut self, message: &[u8], target: Option<TargetingData>) -> IFResult<()> {
            self
                .storage
                .lock()
                .push((Vec::from(message), target.unwrap_or_default()));
            Ok(())
        }

        fn receive(&mut self) -> IFResult<Option<(MessageBytes, TargetingData)>> {
            Ok(self.messages.pop())
        }
    }

    impl InterfaceRequirements for TestInterface {}

    pub fn create_test_interfaces(n: usize) -> Vec<TestInterface> {
        let storage_mutex = Arc::new(Mutex::new(vec![]));
        (0..n).map(|i| TestInterface {
            this_peer_id: i.to_string(),
            storage: storage_mutex.clone(),
            messages: vec![],
        }).collect()
    }

    #[test]
    fn test_test_interface() {
        let mut interfaces = create_test_interfaces(2);
        interfaces[0].send(b"123", Some("1".to_string())).unwrap();
        interfaces[1].main_loop_iteration().unwrap();
        assert_eq!(interfaces[1].receive().unwrap().unwrap().0.as_slice(), b"123");
    }
}