use std::io;
use thiserror::Error;
use tokio::sync::mpsc::error::SendError as MpscSendError;

pub type Result<T> = std::result::Result<T, Error>;

#[derive(Error, Debug, PartialEq)]
#[non_exhaustive]
pub enum Error {
    #[error("duplicated packet")]
    ErrDuplicated,
    #[error("SRTP master key is not long enough")]
    ErrShortSrtpMasterKey,
    #[error("SRTP master salt is not long enough")]
    ErrShortSrtpMasterSalt,
    #[error("no such SRTP Profile")]
    ErrNoSuchSrtpProfile,
    #[error("indexOverKdr > 0 is not supported yet")]
    ErrNonZeroKdrNotSupported,
    #[error("exporter called with wrong label")]
    ErrExporterWrongLabel,
    #[error("no config provided")]
    ErrNoConfig,
    #[error("no conn provided")]
    ErrNoConn,
    #[error("failed to verify auth tag")]
    ErrFailedToVerifyAuthTag,
    #[error("packet is too short to be rtcp packet")]
    ErrTooShortRtcp,
    #[error("payload differs")]
    ErrPayloadDiffers,
    #[error("started channel used incorrectly, should only be closed")]
    ErrStartedChannelUsedIncorrectly,
    #[error("stream has not been inited, unable to close")]
    ErrStreamNotInited,
    #[error("stream is already closed")]
    ErrStreamAlreadyClosed,
    #[error("stream is already inited")]
    ErrStreamAlreadyInited,
    #[error("failed to cast child")]
    ErrFailedTypeAssertion,

    #[error("index_over_kdr > 0 is not supported yet")]
    UnsupportedIndexOverKdr,
    #[error("SRTP Master Key must be len {0}, got {1}")]
    SrtpMasterKeyLength(usize, usize),
    #[error("SRTP Salt must be len {0}, got {1}")]
    SrtpSaltLength(usize, usize),
    #[error("SyntaxError: {0}")]
    ExtMapParse(String),
    #[error("ssrc {0} not exist in srtp_ssrc_state")]
    SsrcMissingFromSrtp(u32),
    #[error("srtp ssrc={0} index={1}: duplicated")]
    SrtpSsrcDuplicated(u32, u16),
    #[error("srtcp ssrc={0} index={1}: duplicated")]
    SrtcpSsrcDuplicated(u32, usize),
    #[error("ssrc {0} not exist in srtcp_ssrc_state")]
    SsrcMissingFromSrtcp(u32),
    #[error("Stream with ssrc {0} exists")]
    StreamWithSsrcExists(u32),
    #[error("Session RTP/RTCP type must be same as input buffer")]
    SessionRtpRtcpTypeMismatch,
    #[error("Session EOF")]
    SessionEof,
    #[error("too short SRTP packet: only {0} bytes, expected > {1} bytes")]
    SrtpTooSmall(usize, usize),
    #[error("too short SRTCP packet: only {0} bytes, expected > {1} bytes")]
    SrtcpTooSmall(usize, usize),
    #[error("failed to verify rtp auth tag")]
    RtpFailedToVerifyAuthTag,
    #[error("failed to verify rtcp auth tag")]
    RtcpFailedToVerifyAuthTag,
    #[error("SessionSRTP has been closed")]
    SessionSrtpAlreadyClosed,
    #[error("this stream is not a RTPStream")]
    InvalidRtpStream,
    #[error("this stream is not a RTCPStream")]
    InvalidRtcpStream,

    #[error("{0}")]
    Io(#[source] IoError),
    #[error("{0}")]
    KeyingMaterial(#[from] util::KeyingMaterialExporterError),
    #[error("mpsc send: {0}")]
    MpscSend(String),
    #[error("{0}")]
    Util(#[from] util::Error),
    #[error("{0}")]
    Rtcp(#[from] rtcp::Error),
    #[error("aes gcm: {0}")]
    AesGcm(#[from] aes_gcm::Error),

    #[error("{0}")]
    Other(String),
}

#[derive(Debug, Error)]
#[error("io error: {0}")]
pub struct IoError(#[from] pub io::Error);

// Workaround for wanting PartialEq for io::Error.
impl PartialEq for IoError {
    fn eq(&self, other: &Self) -> bool {
        self.0.kind() == other.0.kind()
    }
}

impl From<io::Error> for Error {
    fn from(e: io::Error) -> Self {
        Error::Io(IoError(e))
    }
}

// Because Tokio SendError is parameterized, we sadly lose the backtrace.
impl<T> From<MpscSendError<T>> for Error {
    fn from(e: MpscSendError<T>) -> Self {
        Error::MpscSend(e.to_string())
    }
}