use std::rc::Rc;
use std::cell::{RefCell, RefMut};

use neovim_lib::{Neovim, NeovimApi};

use nvim::{NeovimClient, ErrorReport};

pub struct Manager {
    nvim: Option<Rc<RefCell<NeovimClient>>>,
}

impl Manager {
    pub fn new() -> Self {
        Manager { nvim: None }
    }

    pub fn initialize(&mut self, nvim: Rc<RefCell<NeovimClient>>) {
        self.nvim = Some(nvim);
    }

    fn nvim(&self) -> Option<RefMut<Neovim>> {
        let nvim_client = self.nvim.as_ref().unwrap();
        if nvim_client.borrow().is_initialized() {
            Some(RefMut::map(nvim_client.borrow_mut(), |n| n.nvim_mut()))
        } else {
            None
        }
    }

    pub fn get_state(&self) -> State {
        if let Some(mut nvim) = self.nvim() {
            let loaded_plug = nvim.eval("exists('g:loaded_plug')");
            loaded_plug
                .ok_and_report(&mut *nvim)
                .and_then(|loaded_plug| loaded_plug.as_i64())
                .map_or(State::Unknown, |loaded_plug| if loaded_plug > 0 {
                    State::AlreadyLoaded
                } else {
                    State::Unknown
                })
        } else {
            State::Unknown
        }
    }
}

pub enum State {
    Unknown,
    AlreadyLoaded,
}