//! Custom error type.

use std::io::Error as IoError;
use std::str::Utf8Error;

use base64::DecodeError;
use kuska_handshake::async_std::Error as HandshakeError;
use kuska_ssb::api::Error as ApiError;
use kuska_ssb::feed::Error as FeedError;
use kuska_ssb::rpc::Error as RpcError;
use serde_json::Error as JsonError;

/// A custom error type encapsulating all possible errors for this library.
/// `From` implementations are provided for external error types, allowing
/// the `?` operator to be used on functions which return `Result<_, GolgiError>`.
#[derive(Debug)]
pub enum GolgiError {
    /// Failed to decode base64.
    DecodeBase64(DecodeError),
    /// IO error with context.
    Io {
        /// The underlying IO error.
        source: IoError,
        /// Description of the error context.
        context: String,
    },
    /// Scuttlebutt secret handshake error.
    Handshake(HandshakeError),
    /// Kuska SSB API error.
    Api(ApiError),
    /// Kuska SSB feed error.
    Feed(FeedError),
    /// Kuska SSB RPC error.
    Rpc(RpcError),
    /// Go-sbot error.
    Sbot(String),
    /// SSB sigil-link error.
    SigilLink(String),
    /// JSON serialization or deserialization error.
    SerdeJson(JsonError),
    /// Error decoding typed SSB message from content.
    ContentType(String),
    /// Error decoding UTF8 string from bytes
    Utf8Parse {
        /// The underlying parse error.
        source: Utf8Error,
    },
}

impl std::error::Error for GolgiError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match *self {
            GolgiError::DecodeBase64(ref err) => Some(err),
            GolgiError::Io { ref source, .. } => Some(source),
            GolgiError::Handshake(_) => None,
            GolgiError::Api(ref err) => Some(err),
            GolgiError::Feed(ref err) => Some(err),
            GolgiError::Rpc(ref err) => Some(err),
            GolgiError::Sbot(_) => None,
            GolgiError::SigilLink(_) => None,
            GolgiError::SerdeJson(ref err) => Some(err),
            GolgiError::ContentType(_) => None,
            GolgiError::Utf8Parse { ref source } => Some(source),
        }
    }
}

impl std::fmt::Display for GolgiError {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        match *self {
            // TODO: add context (what were we trying to decode?)
            GolgiError::DecodeBase64(_) => write!(f, "Failed to decode base64"),
            GolgiError::Io { ref context, .. } => write!(f, "IO error: {}", context),
            GolgiError::Handshake(ref err) => write!(f, "Handshake failure: {}", err),
            GolgiError::Api(ref err) => write!(f, "SSB API failure: {}", err),
            GolgiError::Feed(ref err) => write!(f, "SSB feed error: {}", err),
            // TODO: improve this variant with a context message
            // then have the core display msg be: "SSB RPC error: {}", context
            GolgiError::Rpc(ref err) => write!(f, "SSB RPC failure: {}", err),
            GolgiError::Sbot(ref err) => write!(f, "Sbot encountered an error: {}", err),
            GolgiError::SigilLink(ref context) => write!(f, "SSB blob ID error: {}", context),
            GolgiError::SerdeJson(_) => write!(f, "Failed to serialize JSON slice"),
            //GolgiError::WhoAmI(ref err) => write!(f, "{}", err),
            GolgiError::ContentType(ref err) => write!(
                f,
                "Failed to decode typed message from SSB message content: {}",
                err
            ),
            GolgiError::Utf8Parse { source } => {
                write!(f, "Failed to deserialize UTF8 from bytes: {}", source)
            }
        }
    }
}

impl From<DecodeError> for GolgiError {
    fn from(err: DecodeError) -> Self {
        GolgiError::DecodeBase64(err)
    }
}

impl From<HandshakeError> for GolgiError {
    fn from(err: HandshakeError) -> Self {
        GolgiError::Handshake(err)
    }
}

impl From<ApiError> for GolgiError {
    fn from(err: ApiError) -> Self {
        GolgiError::Api(err)
    }
}

impl From<FeedError> for GolgiError {
    fn from(err: FeedError) -> Self {
        GolgiError::Feed(err)
    }
}

impl From<RpcError> for GolgiError {
    fn from(err: RpcError) -> Self {
        GolgiError::Rpc(err)
    }
}

impl From<JsonError> for GolgiError {
    fn from(err: JsonError) -> Self {
        GolgiError::SerdeJson(err)
    }
}

impl From<Utf8Error> for GolgiError {
    fn from(err: Utf8Error) -> Self {
        GolgiError::Utf8Parse { source: err }
    }
}