reef 0.0.28

use super::errors::*;
use regex::Regex;
use std::path::{Path, PathBuf};

pub fn shebang(path: &Path) -> Result<String> {
    let text = std::fs::read_to_string(path)
        .chain_err(|| ErrorKind::ShebangNotFound(path.to_path_buf()))?;
    let re = Regex::new(r"#!\s*([/:\.\w\-]+)")
        .chain_err(|| ErrorKind::ShebangNotFound(path.to_path_buf()))?;
    match re.captures(&text) {
        Some(caps) => {
            if caps.len() > 1 {
                Ok(caps[1].to_string())
            } else {
                Err(Error::from_kind(ErrorKind::ShebangNotFound(
                    path.to_path_buf(),
                )))
            }
        }
        None => Err(Error::from_kind(ErrorKind::ShebangNotFound(
            path.to_path_buf(),
        ))),
    }
}

pub fn which(name: &str) -> Result<PathBuf> {
    let extensions = vec!["", ".exe", ".bat"];
    for ext in extensions.iter() {
        let exe_name = format!("{}{}", name, ext);
        match which_exact(&exe_name) {
            Some(path) => {
                return Ok(path);
            }
            None => {}
        };
    }
    Err(Error::from_kind(ErrorKind::UnrecognizedCommand(
        name.to_string(),
    )))
}

fn which_exact(name: &str) -> Option<PathBuf> {
    std::env::var_os("PATH").and_then(|paths| {
        std::env::split_paths(&paths)
            .filter_map(|dir| {
                let full_path = dir.join(&name);
                if full_path.is_file() {
                    Some(full_path)
                } else {
                    None
                }
            })
            .next()
    })
}