use core::fmt::{self, Debug, Display};

use crate::protocol::{PacketParseError, ResponseWriterError};
use crate::util::managed_vec::CapacityError;

/// An error which may occur during a GDB debugging session.
#[derive(Debug)]
#[non_exhaustive]
pub enum GdbStubError<T, C> {
    /// Connection Error while reading request.
    ConnectionRead(C),
    /// Connection Error while writing response.
    ConnectionWrite(ResponseWriterError<C>),
    /// Client nack'd the last packet, but `gdbstub` doesn't implement
    /// re-transmission.
    ClientSentNack,
    /// GdbStub was not provided with a packet buffer in `no_std` mode
    /// (missing call to `with_packet_buffer`)
    MissingPacketBuffer,
    /// Packet cannot fit in the provided packet buffer.
    PacketBufferOverlow,
    /// Could not parse the packet into a valid command.
    PacketParse(PacketParseError),
    /// GDB client sent an unexpected packet.
    PacketUnexpected,
    /// GDB client sent a packet with too much data for the given target.
    TargetMismatch,
    /// Target threw a fatal error.
    TargetError(T),
    /// Target didn't report any active threads.
    NoActiveThreads,
    /// Resuming with a signal is not implemented yet. Consider opening a PR?
    ResumeWithSignalUnimplemented,
    /// Internal - A non-fatal error occurred (with errno-style error code)
    #[doc(hidden)]
    NonFatalError(u8),
}

impl<T, C> From<ResponseWriterError<C>> for GdbStubError<T, C> {
    fn from(e: ResponseWriterError<C>) -> Self {
        GdbStubError::ConnectionWrite(e)
    }
}

impl<A, T, C> From<CapacityError<A>> for GdbStubError<T, C> {
    fn from(_: CapacityError<A>) -> Self {
        GdbStubError::PacketBufferOverlow
    }
}

impl<T, C> Display for GdbStubError<T, C>
where
    C: Debug,
    T: Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        use self::GdbStubError::*;
        match self {
            ConnectionRead(e) => write!(f, "Connection Error while reading request: {:?}", e),
            ConnectionWrite(e) => write!(f, "Connection Error while writing response: {:?}", e),
            ClientSentNack => write!(f, "Client nack'd the last packet, but `gdbstub` doesn't implement re-transmission."),
            MissingPacketBuffer => write!(f, "GdbStub was not provided with a packet buffer in `no_std` mode (missing call to `with_packet_buffer`)"),
            PacketBufferOverlow => write!(f, "Packet too big for provided buffer!"),
            PacketParse(e) => write!(f, "Could not parse the packet into a valid command: {:?}", e),
            PacketUnexpected => write!(f, "Client sent an unexpected packet."),
            TargetMismatch => write!(f, "GDB client sent a packet with too much data for the given target."),
            TargetError(e) => write!(f, "Target threw a fatal error: {:?}", e),
            NoActiveThreads => write!(f, "Target didn't report any active threads."),
            ResumeWithSignalUnimplemented => write!(f, "Resuming with a signal is not implemented yet. Consider opening a PR?"),
            NonFatalError(_) => write!(f, "Internal - A non-fatal error occurred (with errno-style error code)"),
        }
    }
}

#[cfg(feature = "std")]
impl<T, C> std::error::Error for GdbStubError<T, C>
where
    C: Debug,
    T: Debug,
{
}