//! Common definitions for the execution of system calls

use anyhow::{anyhow, Result};
use byteorder::{NativeEndian, ReadBytesExt, WriteBytesExt};
use enum_primitive::FromPrimitive;

pub const SYSCALL_SOCKET_PATH: &str = "/syscall-a653";

enum_from_primitive! {
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum ApexSyscall {
    /// P1-5 3.2.2.1 - GET_PARTITION_STATUS
    GetPartitionStatus = 6530,
    /// P1-5 3.2.2.2 - SET_PARTITION_MODE
    SetPartitionMode = 6531,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.3.2.1 - GET_PROCESS_ID
    GetProcessId = 6542,
    /// P1-5 3.3.2.2 - GET_PROCESS_STATUS
    GetProcessStatus = 6543,
    /// P1-5 3.3.2.3 - CREATE_PROCESS
    CreateProcess = 6544,
    /// P1-5 3.3.2.4 - SET_PRIORITY
    SetPriority = 6545,
    /// P1-5 3.3.2.5 - SUSPEND_SELF
    SuspendSelf = 6546,
    /// P1-5 3.3.2.6 - SUSPEND
    Suspend = 6547,
    /// P1-5 3.3.2.7 - RESUME
    Resume = 6548,
    /// P1-5 3.3.2.8 - STOP_SELF
    StopSelf = 6549,
    /// P1-5 3.3.2.9 - STOP
    Stop = 6550,
    /// P1-5 3.3.2.10 - START
    Start = 6551,
    /// P1-5 3.3.2.11 - DELAY_START
    DelayStart = 6552,
    /// P1-5 3.3.2.12 - LOCK_PREEMPTION
    LockPreemption = 6553,
    /// P1-5 3.3.2.13 - UNLOCK_PREEMPTION
    UnlockPreemption = 6554,
    /// P1-5 3.3.2.14 - GET_MY_ID
    GetMyId = 6555,
    /// P1-5 3.3.2.15 - INITIALIZE_PROCESS_CORE_AFFINITY
    InitializeProcessCoreAffinity = 6556,
    /// P1-5 3.3.2.16 - GET_MY_PROCESSOR_CORE_ID
    GetMyProcessorCoreId = 6557,
    /// P1-5 3.3.2.17 - GET_MY_INDEX
    GetMyIndex = 6558,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.4.2.1 - TIMED_WAIT
    TimedWait = 6569,
    /// P1-5 3.4.2.2 - PERIODIC_WAIT
    PeriodicWait = 6570,
    /// P1-5 3.4.2.3 - GET_TIME
    GetTime = 6571,
    /// P1-5 3.4.2.4 - REPLENISH
    Replenish = 6572,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.6.2.1.1 - CREATE_SAMPLING_PORT
    CreateSamplingPort = 6583,
    /// P1-5 3.6.2.1.2 - WRITE_SAMPLING_MESSAGE
    WriteSamplingMessage = 6584,
    /// P1-5 3.6.2.1.3 - READ_SAMPLING_MESSAGE
    ReadSamplingMessage = 6585,
    /// P1-5 3.6.2.1.4 - GET_SAMPLING_MESSAGE_PORT_ID
    GetSamplingMessagePortId = 6586,
    /// P1-5 3.6.2.1.5 - GET_SAMPLING_PORT_STATUS
    GetSamplingPortStatus = 6587,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.6.2.1.1 - CREATE_QUEUING_PORT
    CreateQueuingPort = 6598,
    /// P1-5 3.6.2.1.2 - SEND_QUEUING_MESSAGE
    SendQueuingMessage = 6599,
    /// P1-5 3.6.2.1.3 - RECEIVE_QUEUING_MESSAGE
    ReceiveQueuingMessage = 6600,
    /// P1-5 3.6.2.1.4 - GET_QUEUING_MESSAGE_PORT_ID
    GetQueuingMessagePortId = 6601,
    /// P1-5 3.6.2.1.5 - GET_QUEUING_PORT_STATUS
    GetQueuingPortStatus = 6602,
    /// P1-5 3.6.2.1.6 - CLEAR_QUEUING_PORT
    ClearQueuingPort = 6603,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.7.2.1.1 - CREATE_BUFFER
    CreateBuffer = 6614,
    /// P1-5 3.7.2.1.2 - SEND_BUFFER
    SendBuffer = 6615,
    /// P1-5 3.7.2.1.3 - RECEIVE_BUFFER
    ReceiveBuffer = 6616,
    /// P1-5 3.7.2.1.4 - GET_BUFFER_ID
    GetBufferId = 6617,
    /// P1-5 3.7.2.1.5 - GET_BUFFER_STATUS
    GetBufferStatus = 6618,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.7.2.2.1 - CREATE_BLACKBOARD
    CreateBlackboard = 6629,
    /// P1-5 3.7.2.2.2 - DISPLAY_BLACKBOARD
    DisplayBlackboard = 6630,
    /// P1-5 3.7.2.2.3 - READ_BLACKBOARD
    ReadBlackboard = 6631,
    /// P1-5 3.7.2.2.4 - CLEAR_BLACKBOARD
    ClearBlackboard = 6632,
    /// P1-5 3.7.2.2.5 - GET_BLACKBOARD_ID
    GetBlackboardId = 6633,
    /// P1-5 3.7.2.2.6 - GET_BLACKBOARD_STATUS
    GetBlackboardStatus = 6634,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.7.2.3.1 - CREATE_SEMAPHORE
    CreateSemaphore = 6645,
    /// P1-5 3.7.2.3.2 - WAIT_SEMAPHORE
    WaitSemaphore = 6646,
    /// P1-5 3.7.2.3.3 - SIGNAL_SEMAPHORE
    SignalSemaphore = 6647,
    /// P1-5 3.7.2.3.4 - GET_SEMAPHORE_ID
    GetSemaphoreId = 6648,
    /// P1-5 3.7.2.3.5 - GET_SEMAPHORE_STATUS
    GetSemaphoreStatus = 6649,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.7.2.4.1 - CREATE_EVENT
    CreateEvent = 6660,
    /// P1-5 3.7.2.4.2 - SET_EVENT
    SetEvent = 6661,
    /// P1-5 3.7.2.4.3 - RESET_EVENT
    ResetEvent = 6662,
    /// P1-5 3.7.2.4.4 - WAIT_EVENT
    WaitEvent = 6663,
    /// P1-5 3.7.2.4.5 - GET_EVENT_ID
    GetEventId = 6664,
    /// P1-5 3.7.2.4.6 - GET_EVENT_STATUS
    GetEventStatus = 6665,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.7.2.1.1 - CREATE_MUTEX
    CreateMutex = 6676,
    /// P1-5 3.7.2.1.2 - ACQUIRE_MUTEX
    AcquireMutex = 6677,
    /// P1-5 3.7.2.1.3 - RELEASE_MUTEX
    ReleaseMutex = 6678,
    /// P1-5 3.7.2.1.4 - RESET_MUTEX
    ResetMutex = 6679,
    /// P1-5 3.7.2.1.5 - GET_MUTEX_ID
    GetMutexId = 6680,
    /// P1-5 3.7.2.1.6 - GET_MUTEX_STATUS
    GetMutexStatus = 6681,
    /// P1-5 3.7.2.1.7 - GET_PROCIESS_MUTEX_STATE
    GetProciessMutexState = 6682,
    /////////////////////
    //* 10 Free Spaces */
    /////////////////////
    /// P1-5 3.8.2.1 - REPORT_APPLICATION_MESSAGE
    ReportApplicationMessage = 6693,
    /// P1-5 3.8.2.2 - CREATE_ERROR_HANDLER
    CreateErrorHandler = 6694,
    /// P1-5 3.8.2.3 - GET_ERROR_STATUS
    GetErrorStatus = 6695,
    /// P1-5 3.8.2.4 - RAISE_APPLICATION_ERROR
    RaiseApplicationError = 6696,
    /// P1-5 3.8.2.5 - CONFIGURE_ERROR_HANDLER
    ConfigureErrorHandler = 6697,
}
}

#[derive(Debug, PartialEq)]
pub struct SyscallRequest {
    pub id: ApexSyscall,
    pub params: Vec<u64>,
}

#[derive(Debug, PartialEq)]
pub struct SyscallResponse {
    pub id: ApexSyscall,
    pub status: u64,
}

impl SyscallRequest {
    /// Serializes a SyscallRequest into its binary representation
    ///
    /// The format for serializing a SyscallRequest is defined as follows:
    /// ```text
    /// id [u64]
    /// nparams [u8]
    /// params [u64 * nparams]
    /// ```
    ///
    /// All integers are encoded in native endian.
    pub fn serialize(&self) -> Result<Vec<u8>> {
        let mut serialized: Vec<u8> = Vec::new();
        serialized.write_u64::<NativeEndian>(self.id as u64)?;
        serialized.write_u8(self.params.len().try_into()?)?;
        for &param in &self.params {
            serialized.write_u64::<NativeEndian>(param)?;
        }

        Ok(serialized)
    }

    /// Deserializes a serialized SyscallRequest back into its internal
    /// representation
    pub fn deserialize(serialized: &Vec<u8>) -> Result<Self> {
        let mut serialized: &[u8] = serialized;

        let id = ApexSyscall::from_u64(serialized.read_u64::<NativeEndian>()?)
            .ok_or(anyhow!("deserialization of ApexSyscall failed"))?;

        let nparams = serialized.read_u8()?;
        let mut params: Vec<u64> = Vec::with_capacity(nparams as usize);
        for _ in 0..nparams {
            params.push(serialized.read_u64::<NativeEndian>()?);
        }

        Ok(SyscallRequest { id, params })
    }
}

impl SyscallResponse {
    /// Serializes a SyscallResponse into its binary representation
    ///
    /// The format for serializing a SyscallResponse is defined as follows:
    /// ```text
    /// id [u64]
    /// status [u64]
    /// ```
    ///
    /// All integers are encoded in native endian.
    pub fn serialize(&self) -> Result<Vec<u8>> {
        let mut serialized: Vec<u8> = Vec::new();
        serialized.write_u64::<NativeEndian>(self.id as u64)?;
        serialized.write_u64::<NativeEndian>(self.status)?;

        Ok(serialized)
    }

    /// Deserializes a serialized SyscallResponse back into its internal
    /// representation
    pub fn deserialize(serialized: &Vec<u8>) -> Result<Self> {
        let mut serialized: &[u8] = serialized;

        let id = ApexSyscall::from_u64(serialized.read_u64::<NativeEndian>()?)
            .ok_or(anyhow!("deserialization of ApexSyscall failed"))?;
        let status = serialized.read_u64::<NativeEndian>()?;

        Ok(SyscallResponse { id, status })
    }
}

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

    #[test]
    fn test_serialize_request() {
        let request = SyscallRequest {
            id: ApexSyscall::Start,
            params: vec![1, 2, 3],
        };
        let serialized = request.serialize().unwrap();
        let mut serialized: &[u8] = &serialized;

        let id = serialized.read_u64::<NativeEndian>().unwrap();
        assert_eq!(id, ApexSyscall::Start as u64);

        let nparams = serialized.read_u8().unwrap();
        assert_eq!(nparams, 3);

        let params = [
            serialized.read_u64::<NativeEndian>().unwrap(),
            serialized.read_u64::<NativeEndian>().unwrap(),
            serialized.read_u64::<NativeEndian>().unwrap(),
        ];
        assert_eq!(params, [1, 2, 3]);
        assert!(serialized.is_empty());
    }

    #[test]
    fn test_serialize_response() {
        let response = SyscallResponse {
            id: ApexSyscall::Start,
            status: 42,
        };
        let serialized = response.serialize().unwrap();
        let mut serialized: &[u8] = &serialized;

        let id = serialized.read_u64::<NativeEndian>().unwrap();
        assert_eq!(id, ApexSyscall::Start as u64);

        let status = serialized.read_u64::<NativeEndian>().unwrap();
        assert_eq!(status, 42);
        assert!(serialized.is_empty());
    }

    #[test]
    fn test_deserialize_request() {
        let request = SyscallRequest {
            id: ApexSyscall::Start,
            params: vec![1, 2, 3],
        };
        let serialized = request.serialize().unwrap();
        let deserialized = SyscallRequest::deserialize(&serialized).unwrap();
        assert_eq!(request, deserialized);
        assert!(!serialized.is_empty());
    }

    #[test]
    fn test_deserialize_response() {
        let response = SyscallResponse {
            id: ApexSyscall::Start,
            status: 42,
        };
        let serialized = response.serialize().unwrap();
        let deserialized = SyscallResponse::deserialize(&serialized).unwrap();
        assert_eq!(response, deserialized);
        assert!(!serialized.is_empty());
    }
}