extern crate clap;
use clap::{App, Arg};
use isatty::stdout_isatty;
use std::env;
use std::fs::File;
use std::io::{prelude::*, BufReader};
use std::path::Path;

fn current_args() -> String {
    let mut out = String::from("osenv");
    for argument in env::args().skip(1) {
        out += format!(" {}", argument).as_str();
    }
    out
}

fn main() -> std::io::Result<()> {
    #[cfg(target_os = "macos")]
    static OS_DEFAULT_SHELL: &str = "sh";
    #[cfg(target_os = "linux")]
    static OS_DEFAULT_SHELL: &str = "sh";
    #[cfg(target_os = "windows")]
    static OS_DEFAULT_SHELL: &str = "ps1";

    let cmd = App::new("osenv")
        .version("0.1")
        .author("Alessandro Gatti <hamcha@crunchy.rocks>")
        .about("Cross-platform env helper")
        .arg(
            Arg::with_name("directory")
                .short("d")
                .long("directory")
                .value_name("DIRECTORY")
                .help("Directory to scan for .env files")
                .default_value(".")
                .takes_value(true),
        )
        .arg(
            Arg::with_name("file")
                .short("f")
                .long("file")
                .value_name("ENVFILE")
                .help("Env file")
                .default_value(".env")
                .takes_value(true),
        )
        .arg(
            Arg::with_name("environment")
                .short("e")
                .long("env")
                .value_name("ENVIRONMENT")
                .help("If provided, will look for .env.ENVIRONMENT")
                .takes_value(true),
        )
        .arg(
            Arg::with_name("shell")
                .short("s")
                .long("shell")
                .help("Output format")
                .takes_value(true)
                .default_value(OS_DEFAULT_SHELL)
                .possible_values(&["ps1", "sh"]),
        )
        .get_matches();

    let dir = cmd.value_of("directory").unwrap();
    let file = cmd.value_of("file").unwrap();
    let env = cmd.value_of("environment");
    let shell = cmd.value_of("shell").unwrap();

    // If -env was specified, add it as a suffix
    let filename = if env.is_some() {
        format!("{}.{}", file, env.unwrap())
    } else {
        String::from(file)
    };

    // Join directory and file
    let path = Path::new(dir).join(filename);

    if !path.exists() {
        println!("{}: file not found", path.display());
        std::process::exit(1);
    }

    let file = File::open(path)?;
    let reader = BufReader::new(file);

    // Print help messages if printing to terminal
    if stdout_isatty() {
        match shell {
            "ps1" => println!("#\n# It looks like you are not running osenv properly\n# The proper command on Powershell is:\n#    {} | iex\n# Hope this helps!\n#", current_args()),
            "sh" => println!("#\n# It looks like you are not running osenv properly\n# The proper command on unix shells is:\n#    eval $({})\n# Hope this helps!\n#", current_args()),
            _ => (),
        }
    }

    for line in reader.lines() {
        let envline = line.unwrap();
        let idx = envline.find('=');
        if idx.is_some() {
            match shell {
                "ps1" => {
                    // val needs to be shifted to remove the separator
                    println!(
                        "$env:{} = \"{}\"; ",
                        envline.get(..idx.unwrap()).unwrap(),
                        envline.get(idx.unwrap() + 1..).unwrap()
                    )
                }
                "sh" => println!("export {}", envline),
                _ => (),
            }
        }
    }

    Ok(())
}