//! Dynamic tracing system that tends to be real-time.

#![warn(missing_docs)]

mod config;
mod env;
mod supervisor;
mod tracers;

pub use rill_engine as engine;
pub use rill_protocol as protocol;
pub use rill_server as server;
pub use tracers::*;

use anyhow::Error;
use meio::thread::ScopedRuntime;
use once_cell::sync::Lazy;
use std::sync::Mutex;

static INSTALLED: Lazy<Mutex<Option<RillRate>>> = Lazy::new(|| Mutex::new(None));

/// The tracer.
pub struct RillRate {
    _scoped: ScopedRuntime,
}

impl RillRate {
    /// Creates an instance of `RillRate` tracer using environment vars.
    pub fn from_env(app_name: impl ToString) -> Result<Self, Error> {
        use supervisor::RillRate;
        let actor = RillRate::new(app_name.to_string());
        let _scoped = meio::thread::spawn(actor)?;
        Ok(Self { _scoped })
    }

    /// Create and install an instance of `RillRate` into the global cell.
    /// The provider will be alive and available until the `uninstall` method call.
    pub fn install(app_name: impl ToString) -> Result<(), Error> {
        let instance = Self::from_env(app_name)?;
        // TODO: Metod like `Option::swap` instad?
        let mut cell = INSTALLED
            .lock()
            .map_err(|err| Error::msg(err.to_string()))?;
        *cell = Some(instance);
        Ok(())
    }

    /// Uninstalling of the installed `RillRate` instance.
    pub fn uninstall() -> Result<(), Error> {
        INSTALLED
            .lock()
            .map_err(|err| Error::msg(err.to_string()))?
            .take();
        Ok(())
    }
}