use std::io::{Error as IoError, Write};
use std::process::{Command, Stdio};
use std::{env, str, thread};

use crate::error::Result;

/// Runs the given OS command and returns the output as string.
///
/// Use `input` parameter to specify a text to write to stdin.
/// Environment variables are set accordingly to `envs`.
pub fn run(command: &str, input: Option<String>, envs: Vec<(&str, &str)>) -> Result<String> {
    log::trace!("Running command: {:?}", command);
    let mut child = if cfg!(target_os = "windows") {
        Command::new("cmd")
            .envs(envs)
            .args(["/C", command])
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .current_dir(env::current_dir()?)
            .spawn()
    } else {
        Command::new("sh")
            .envs(envs)
            .args(["-c", command])
            .stdin(Stdio::piped())
            .stdout(Stdio::piped())
            .current_dir(env::current_dir()?)
            .spawn()
    }?;
    if let Some(input) = input {
        let mut stdin = child
            .stdin
            .take()
            .ok_or_else(|| IoError::other("stdin is not captured"))?;
        thread::spawn(move || {
            stdin
                .write_all(input.as_bytes())
                .expect("Failed to write to stdin");
        });
    }
    let output = child.wait_with_output()?;
    if output.status.success() {
        Ok(str::from_utf8(&output.stdout)?.to_string())
    } else {
        for output in [output.stdout, output.stderr] {
            let output = str::from_utf8(&output)?.to_string();
            if !output.is_empty() {
                log::error!("{}", output);
            }
        }
        Err(IoError::other(format!("command exited with {:?}", output.status)).into())
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    #[cfg(target_family = "unix")]
    fn run_os_command() -> Result<()> {
        assert_eq!(
            "eroc-ffilc-tig",
            run("echo $APP_NAME | rev", None, vec![(
                "APP_NAME",
                env!("CARGO_PKG_NAME")
            )])?
            .trim()
        );
        assert_eq!(
            "eroc-ffilc-tig",
            run("rev", Some(env!("CARGO_PKG_NAME").to_string()), vec![])?.trim()
        );
        assert_eq!("testing", run("echo 'testing'", None, vec![])?.trim());
        assert!(run("some_command", None, vec![]).is_err());
        Ok(())
    }
}
