use std::env;

use pico_args::Arguments;

use crate::{
	env::TMUX,
	error,
	flag::Flags,
	util::session_name
};

pub struct State<'a> {
	pub args: &'a mut Arguments,
	pub flags: Flags,

	pub session: bool,
	tmux_var: Option<String>,
	pub title: Option<String>
}

impl State<'_> {

	pub fn new(args: &mut Arguments) -> State {
		let flags = Flags::from(args);
		let tmux_var = env::var(TMUX).ok();
		let session = tmux_var.is_some();
		let title = if session { session_name() } else { None };

		State {
			args,
			flags,
			session,
			tmux_var,
			title
		}
	}

	pub fn nest_init(&self) {
		if self.flags.nested {
			if self.session { env::set_var(TMUX, ""); }		//	nesting & session	=> ok
			else { error::not_nesting(); }					//	nesting & !session	=> error
		} else if self.session { error::prevent_nest(); }	//	!nesting & session	=> error
															//	!nesting & !session	=> ok
	}

	pub fn nest_deinit(&self) {
		if self.flags.nested && self.session {
			env::set_var(TMUX, self.tmux_var.as_ref().unwrap());
		}
	}

	pub fn session_enforce(&self, cmd: &'static str) {
		if !self.session { error::not_in_session(cmd); }
	}

	pub fn target(&mut self) -> Option<String> { self.args.subcommand().unwrap_or(None) }
}