use std::fmt;
use std::path::PathBuf;

use crate::error::BabyError;

#[derive(Debug)]
pub enum ServerError {
    Unimplemented(&'static str),
    Unauthorised {
        scheme: &'static str,
        reason: String,
    },
    InvalidRequest(String),
    PayloadTooLarge {
        cap_bytes: u64,
        actual_bytes: u64,
    },
    Io {
        path: PathBuf,
        source: std::io::Error,
    },
    Pipe(String),
    Backend(BabyError),
    Cancelled,
}

impl fmt::Display for ServerError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Unimplemented(what) => write!(f, "not yet implemented: {}", what),
            Self::Unauthorised { scheme, reason } => {
                write!(f, "unauthorised ({scheme}): {}", reason)
            }
            Self::InvalidRequest(msg) => write!(f, "invalid server request: {}", msg),
            Self::PayloadTooLarge {
                cap_bytes,
                actual_bytes,
            } => write!(
                f,
                "output exceeds cap: {} bytes > {} bytes cap",
                actual_bytes, cap_bytes
            ),
            Self::Io { path, source } => {
                write!(f, "io error at `{}`: {}", path.display(), source)
            }
            Self::Pipe(msg) => write!(f, "server pipe error: {}", msg),
            Self::Backend(err) => write!(f, "backend error: {}", err),
            Self::Cancelled => write!(f, "server stream was cancelled"),
        }
    }
}

impl std::error::Error for ServerError {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            Self::Io { source, .. } => Some(source),
            Self::Backend(err) => Some(err),
            _ => None,
        }
    }
}

impl From<BabyError> for ServerError {
    fn from(err: BabyError) -> Self {
        Self::Backend(err)
    }
}

impl From<std::io::Error> for ServerError {
    fn from(source: std::io::Error) -> Self {
        Self::Io {
            path: PathBuf::new(),
            source,
        }
    }
}

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