//! Arg parsing and process info
use super::*;
use std::fmt;

lazy_static!{
    static ref EXEC: String = std::env::args().next().unwrap();
}

pub fn program_name() -> &'static str
{
    &EXEC[..]
}

/// Program usage
#[derive(Debug)]
pub struct Usage;

impl Usage
{
    pub fn print_and_exit(self, code: i32) -> !
    {
	if code == 0 {
	    print!("{}", self);
	} else {
	    eprint!("{}", self);
	}
	std::process::exit(code)
    }
}

fn splash(f: &mut fmt::Formatter<'_>) -> fmt::Result
{
    writeln!(f, "transfer v{} - simple network file transfer", env!("CARGO_PKG_VERSION"))?;
    writeln!(f, " written by {} with <3. License GPL3+", env!("CARGO_PKG_AUTHORS"))?;
    writeln!(f, "")
}

impl fmt::Display for Usage
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
    {
	splash(f)?;
	
	writeln!(f, "Usage: {} --send <bind> [SEND OPTIONS] <file...>", program_name())?;
	writeln!(f, "Usage: {} --recv <endpoint> [RECV OPTIONS] <output...>", program_name())?;
	writeln!(f, "\nSEND OPTIONS:")?;
	writeln!(f, " -e\t\t\tEncrypt file(s)")?;
	writeln!(f, " -c\t\t\tCompress files")?;
	writeln!(f, " --buffer-size <bytes>\tSize of file buffer")?;
	writeln!(f, " -a\t\t\tSend file names")?;
	writeln!(f, " -1\t\t\tExit after 1 client has been served")?;
	writeln!(f, " -k\t\t\tSupport continuation of failed downloads")?;

	writeln!(f, "\nRECV OPTIONS:")?;
	writeln!(f, " -i\t\t\tAsk before starting downloads")?;
	writeln!(f, " -k\t\t\tContinue a previously started download")?;
	
	Ok(())
    }
}