use std::{process, path::PathBuf, fmt::Display, fs};

#[derive(Debug, Clone)]
pub struct CommandError {
    output: process::Output,
    log_path: PathBuf,
}

impl CommandError {
    pub fn new(output: process::Output, log_path: PathBuf) -> Self {
        Self {
            output, log_path
        }
    }
}

impl Display for CommandError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let log_path = fs::canonicalize(&self.log_path)
            .map(|p| p.to_str()
                 .map(String::from)
                 .unwrap_or(format!("[path not valid utf-8: {:?}]", p)))
            .unwrap_or_else(|e| format!("[invalid path; reason: {}]", e));

        write!(
            f,
            "Command exited with non-zero exit code ({}). Logs can be viewed at {}\nExcerpt from stderr:\n----\n",
            self.output.status.code()
                              .map(|n| i32::to_string(&n))
                              .unwrap_or("??".to_owned()),
            log_path
        )?;

        let buf: Vec<_> = self.output.stderr.rsplit(|b| *b == b'\n').take(10).collect();

        for line in buf.into_iter().rev() {
            write!(f, "{}\n", String::from_utf8(line.to_vec()).unwrap_or(String::from("[LINE NOT VALID UTF-8]")))?;
        }

        write!(f, "----\n")?;

        Ok(())
    }
}