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#![cfg(feature = "command")]

use crate::IntoResult;
use std::{
    fmt::{self, Display},
    io,
    process::{Child, ExitStatus, Output},
};

#[derive(Debug)]
pub enum Error {
    SpawnFailed(io::Error),
    WaitFailed(ExitStatus),
    WaitWithOutputFailed(Output),
}

impl Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::SpawnFailed(err) => write!(f, "Failed to spawn child process: {}", err),
            Self::WaitFailed(status) => {
                write!(f, "Command didn't complete successfully, ")?;
                if let Some(exit_code) = status.code() {
                    write!(f, "exiting with code {}.", exit_code)
                } else {
                    write!(f, "but returned no exit code.")
                }
            }
            Self::WaitWithOutputFailed(Output { status, stderr, .. }) => {
                write!(f, "{} ", Self::WaitFailed(status.to_owned()))?;
                if !stderr.is_empty() {
                    write!(f, "stderr contents: {}", String::from_utf8_lossy(stderr))
                } else {
                    write!(f, "stderr was empty.")
                }
            }
        }
    }
}

impl From<io::Error> for Error {
    fn from(err: io::Error) -> Self {
        Self::SpawnFailed(err)
    }
}

impl From<ExitStatus> for Error {
    fn from(status: ExitStatus) -> Self {
        Self::WaitFailed(status)
    }
}

impl From<Output> for Error {
    fn from(output: Output) -> Self {
        Self::WaitWithOutputFailed(output)
    }
}

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

impl IntoResult<(), Error> for ExitStatus {
    fn into_result(self) -> Result<()> {
        self.success().into_result().map_err(|()| self.into())
    }
}

impl IntoResult<(), Error> for io::Result<ExitStatus> {
    fn into_result(self) -> Result<()> {
        self.map_err(Into::into).and_then(IntoResult::into_result)
    }
}

impl IntoResult<Output, Error> for io::Result<Output> {
    fn into_result(self) -> Result<Output> {
        self.map_err(Into::into)
            .and_then(|output| output.status.into_result().map(|_| output))
    }
}

impl IntoResult<Child, Error> for io::Result<Child> {
    fn into_result(self) -> Result<Child> {
        self.map_err(Into::into)
    }
}