use crate::client::error::MessageError;
use crate::client::Client;
use crate::data_value::DataValue;
use crate::messages::telemetry_definition::TelemetryDefinitionRequest;
use crate::messages::telemetry_entry::TelemetryEntry;
use api_core::data_type::{DataType, ToDataType};
use chrono::{DateTime, Utc};
use std::marker::PhantomData;
use std::sync::Arc;
use tokio::sync::{oneshot, RwLock};
use tokio_util::sync::CancellationToken;
use uuid::Uuid;

pub struct TelemetryRegistry {
    client: Arc<Client>,
}

impl TelemetryRegistry {
    pub fn new(client: Arc<Client>) -> Self {
        Self { client }
    }

    #[inline]
    pub async fn register_generic(
        &self,
        name: impl Into<String>,
        data_type: DataType,
    ) -> GenericTelemetryHandle {
        // inner for compilation performance
        async fn inner(
            client: Arc<Client>,
            name: String,
            data_type: DataType,
        ) -> GenericTelemetryHandle {
            let cancellation_token = CancellationToken::new();
            let cancel_token = cancellation_token.clone();
            let stored_client = client.clone();

            let response_uuid = Arc::new(RwLock::new(Uuid::nil()));

            let response_uuid_inner = response_uuid.clone();
            let (tx, rx) = oneshot::channel();

            tokio::spawn(async move {
                let mut write_lock = Some(response_uuid_inner.write().await);
                let _ = tx.send(());
                while !cancel_token.is_cancelled() {
                    if let Ok(response) = client
                        .send_request(TelemetryDefinitionRequest {
                            name: name.clone(),
                            data_type,
                        })
                        .await
                    {
                        let mut lock = match write_lock {
                            None => response_uuid_inner.write().await,
                            Some(lock) => lock,
                        };
                        // Update the value in the lock
                        *lock = response.uuid;
                        // Set this value so the loop works
                        write_lock = None;
                    }

                    client.wait_disconnected().await;
                }
            });

            // Wait until the write lock is acquired
            let _ = rx.await;
            // Wait until the write lock is released for the first time
            drop(response_uuid.read().await);

            GenericTelemetryHandle {
                cancellation_token,
                uuid: response_uuid,
                client: stored_client,
                data_type,
            }
        }
        inner(self.client.clone(), name.into(), data_type).await
    }

    #[inline]
    pub async fn register<T: ToDataType>(&self, name: impl Into<String>) -> TelemetryHandle<T> {
        self.register_generic(name, T::DATA_TYPE).await.coerce()
    }
}

impl Drop for GenericTelemetryHandle {
    fn drop(&mut self) {
        self.cancellation_token.cancel();
    }
}

pub struct GenericTelemetryHandle {
    cancellation_token: CancellationToken,
    uuid: Arc<RwLock<Uuid>>,
    client: Arc<Client>,
    data_type: DataType,
}

impl GenericTelemetryHandle {
    pub async fn publish(
        &self,
        value: DataValue,
        timestamp: DateTime<Utc>,
    ) -> Result<(), MessageError> {
        if value.to_data_type() != self.data_type {
            return Err(MessageError::IncorrectDataType {
                expected: self.data_type,
                actual: value.to_data_type(),
            });
        }
        let Ok(lock) = self.uuid.try_read() else {
            return Ok(());
        };
        let uuid = *lock;
        drop(lock);

        self.client
            .send_message_if_connected(TelemetryEntry {
                uuid,
                value,
                timestamp,
            })
            .await
            .or_else(|e| match e {
                MessageError::TokioLockError(_) => Ok(()),
                e => Err(e),
            })?;

        Ok(())
    }

    #[inline]
    pub async fn publish_now(&self, value: DataValue) -> Result<(), MessageError> {
        self.publish(value, Utc::now()).await
    }

    fn coerce<T: Into<DataValue>>(self) -> TelemetryHandle<T> {
        TelemetryHandle::<T> {
            generic_handle: self,
            _phantom: PhantomData,
        }
    }
}

pub struct TelemetryHandle<T> {
    generic_handle: GenericTelemetryHandle,
    _phantom: PhantomData<T>,
}

impl<T> TelemetryHandle<T> {
    pub fn to_generic(self) -> GenericTelemetryHandle {
        self.generic_handle
    }
    pub fn as_generic(&self) -> &GenericTelemetryHandle {
        &self.generic_handle
    }
}

impl<T: Into<DataValue>> TelemetryHandle<T> {
    #[inline]
    pub async fn publish(&self, value: T, timestamp: DateTime<Utc>) -> Result<(), MessageError> {
        self.as_generic().publish(value.into(), timestamp).await
    }

    #[inline]
    pub async fn publish_now(&self, value: T) -> Result<(), MessageError> {
        self.publish(value, Utc::now()).await
    }
}

#[cfg(test)]
mod tests {
    use crate::client::error::MessageError;
    use crate::client::telemetry::TelemetryRegistry;
    use crate::client::tests::create_test_client;
    use crate::client::Callback;
    use crate::messages::payload::RequestMessagePayload;
    use crate::messages::telemetry_definition::{
        TelemetryDefinitionRequest, TelemetryDefinitionResponse,
    };
    use crate::messages::telemetry_entry::TelemetryEntry;
    use crate::messages::ResponseMessage;
    use api_core::data_type::DataType;
    use api_core::data_value::DataValue;
    use futures_util::FutureExt;
    use std::sync::Arc;
    use std::time::Duration;
    use tokio::task::yield_now;
    use tokio::time::timeout;
    use tokio::try_join;
    use uuid::Uuid;

    #[tokio::test]
    async fn generic() {
        // if _c drops then we are disconnected
        let (mut rx, _c, client) = create_test_client();

        let tlm = TelemetryRegistry::new(Arc::new(client));
        let tlm_handle = tlm.register_generic("generic", DataType::Float32);

        let tlm_uuid = Uuid::new_v4();

        let expected_rx = async {
            let msg = rx.recv().await.unwrap();
            let Callback::Once(responder) = msg.callback else {
                panic!("Expected Once Callback");
            };
            assert!(msg.msg.response.is_none());
            let RequestMessagePayload::TelemetryDefinitionRequest(TelemetryDefinitionRequest {
                name,
                data_type,
            }) = msg.msg.payload
            else {
                panic!("Expected Telemetry Definition Request")
            };
            assert_eq!(name, "generic".to_string());
            assert_eq!(data_type, DataType::Float32);
            responder
                .send(ResponseMessage {
                    uuid: Uuid::new_v4(),
                    response: Some(msg.msg.uuid),
                    payload: TelemetryDefinitionResponse { uuid: tlm_uuid }.into(),
                })
                .unwrap();
        };

        let (tlm_handle, _) = try_join!(
            timeout(Duration::from_secs(1), tlm_handle),
            timeout(Duration::from_secs(1), expected_rx),
        )
        .unwrap();

        assert_eq!(*tlm_handle.uuid.try_read().unwrap(), tlm_uuid);

        // This should NOT block if there is space in the queue
        tlm_handle
            .publish_now(0.0f32.into())
            .now_or_never()
            .unwrap()
            .unwrap();

        let tlm_msg = timeout(Duration::from_secs(1), rx.recv())
            .await
            .unwrap()
            .unwrap();
        assert!(matches!(tlm_msg.callback, Callback::None));
        match tlm_msg.msg.payload {
            RequestMessagePayload::TelemetryEntry(TelemetryEntry { uuid, value, .. }) => {
                assert_eq!(uuid, tlm_uuid);
                assert_eq!(value, DataValue::Float32(0.0f32));
            }
            _ => panic!("Expected Telemetry Entry"),
        }
    }

    #[tokio::test]
    async fn mismatched_type() {
        let (mut rx, _, client) = create_test_client();

        let tlm = TelemetryRegistry::new(Arc::new(client));
        let tlm_handle = tlm.register_generic("generic", DataType::Float32);

        let tlm_uuid = Uuid::new_v4();

        let expected_rx = async {
            let msg = rx.recv().await.unwrap();
            let Callback::Once(responder) = msg.callback else {
                panic!("Expected Once Callback");
            };
            assert!(msg.msg.response.is_none());
            let RequestMessagePayload::TelemetryDefinitionRequest(TelemetryDefinitionRequest {
                name,
                data_type,
            }) = msg.msg.payload
            else {
                panic!("Expected Telemetry Definition Request")
            };
            assert_eq!(name, "generic".to_string());
            assert_eq!(data_type, DataType::Float32);
            responder
                .send(ResponseMessage {
                    uuid: Uuid::new_v4(),
                    response: Some(msg.msg.uuid),
                    payload: TelemetryDefinitionResponse { uuid: tlm_uuid }.into(),
                })
                .unwrap();
        };

        let (tlm_handle, _) = try_join!(
            timeout(Duration::from_secs(1), tlm_handle),
            timeout(Duration::from_secs(1), expected_rx),
        )
        .unwrap();

        assert_eq!(*tlm_handle.uuid.try_read().unwrap(), tlm_uuid);

        match timeout(
            Duration::from_secs(1),
            tlm_handle.publish_now(0.0f64.into()),
        )
        .await
        .unwrap()
        {
            Err(MessageError::IncorrectDataType { expected, actual }) => {
                assert_eq!(expected, DataType::Float32);
                assert_eq!(actual, DataType::Float64);
            }
            _ => panic!("Error Expected"),
        }
    }

    #[tokio::test]
    async fn typed() {
        // if _c drops then we are disconnected
        let (mut rx, _c, client) = create_test_client();

        let tlm = TelemetryRegistry::new(Arc::new(client));
        let tlm_handle = tlm.register::<bool>("typed");

        let tlm_uuid = Uuid::new_v4();

        let expected_rx = async {
            let msg = rx.recv().await.unwrap();
            let Callback::Once(responder) = msg.callback else {
                panic!("Expected Once Callback");
            };
            assert!(msg.msg.response.is_none());
            let RequestMessagePayload::TelemetryDefinitionRequest(TelemetryDefinitionRequest {
                name,
                data_type,
            }) = msg.msg.payload
            else {
                panic!("Expected Telemetry Definition Request")
            };
            assert_eq!(name, "typed".to_string());
            assert_eq!(data_type, DataType::Boolean);
            responder
                .send(ResponseMessage {
                    uuid: Uuid::new_v4(),
                    response: Some(msg.msg.uuid),
                    payload: TelemetryDefinitionResponse { uuid: tlm_uuid }.into(),
                })
                .unwrap();
        };

        let (tlm_handle, _) = try_join!(
            timeout(Duration::from_secs(1), tlm_handle),
            timeout(Duration::from_secs(1), expected_rx),
        )
        .unwrap();

        assert_eq!(*tlm_handle.as_generic().uuid.try_read().unwrap(), tlm_uuid);

        // This should NOT block if there is space in the queue
        tlm_handle
            .publish_now(true)
            .now_or_never()
            .unwrap()
            .unwrap();
        // This should block as there should not be space in the queue
        assert!(tlm_handle.publish_now(false).now_or_never().is_none());

        let tlm_msg = timeout(Duration::from_secs(1), rx.recv())
            .await
            .unwrap()
            .unwrap();
        assert!(matches!(tlm_msg.callback, Callback::None));
        match tlm_msg.msg.payload {
            RequestMessagePayload::TelemetryEntry(TelemetryEntry { uuid, value, .. }) => {
                assert_eq!(uuid, tlm_uuid);
                assert_eq!(value, DataValue::Boolean(true));
            }
            _ => panic!("Expected Telemetry Entry"),
        }

        let _make_generic_again = tlm_handle.to_generic();
    }

    #[tokio::test]
    async fn reconnect() {
        // if _c drops then we are disconnected
        let (mut rx, connected, client) = create_test_client();

        let tlm = TelemetryRegistry::new(Arc::new(client));
        let tlm_handle = tlm.register_generic("generic", DataType::Float32);

        let tlm_uuid = Uuid::new_v4();

        let expected_rx = async {
            let msg = rx.recv().await.unwrap();
            let Callback::Once(responder) = msg.callback else {
                panic!("Expected Once Callback");
            };
            assert!(msg.msg.response.is_none());
            let RequestMessagePayload::TelemetryDefinitionRequest(TelemetryDefinitionRequest {
                name,
                data_type,
            }) = msg.msg.payload
            else {
                panic!("Expected Telemetry Definition Request")
            };
            assert_eq!(name, "generic".to_string());
            assert_eq!(data_type, DataType::Float32);
            responder
                .send(ResponseMessage {
                    uuid: Uuid::new_v4(),
                    response: Some(msg.msg.uuid),
                    payload: TelemetryDefinitionResponse { uuid: tlm_uuid }.into(),
                })
                .unwrap();
        };

        let (tlm_handle, _) = try_join!(
            timeout(Duration::from_secs(1), tlm_handle),
            timeout(Duration::from_secs(1), expected_rx),
        )
        .unwrap();

        assert_eq!(*tlm_handle.uuid.try_read().unwrap(), tlm_uuid);

        // Notify Disconnect
        connected.send_replace(false);
        // Notify Reconnect
        connected.send_replace(true);

        {
            let new_tlm_uuid = Uuid::new_v4();

            let msg = rx.recv().await.unwrap();
            let Callback::Once(responder) = msg.callback else {
                panic!("Expected Once Callback");
            };
            assert!(msg.msg.response.is_none());
            let RequestMessagePayload::TelemetryDefinitionRequest(TelemetryDefinitionRequest {
                name,
                data_type,
            }) = msg.msg.payload
            else {
                panic!("Expected Telemetry Definition Request")
            };
            assert_eq!(name, "generic".to_string());
            assert_eq!(data_type, DataType::Float32);
            responder
                .send(ResponseMessage {
                    uuid: Uuid::new_v4(),
                    response: Some(msg.msg.uuid),
                    payload: TelemetryDefinitionResponse { uuid: new_tlm_uuid }.into(),
                })
                .unwrap();

            // Yield to the executor so that the UUIDs can be updated
            yield_now().await;

            assert_eq!(*tlm_handle.uuid.try_read().unwrap(), new_tlm_uuid);
        }
    }
}