servers/src/plugins/loader.rs

use std::{fs, path::Path, sync::Arc};

use libloading::{Library, Symbol};
use tracing::{info, trace};

use crate::{commands, plugins::Registrar};

use super::{PluginManager, PluginManagerType};

/// Plugins and Commands loader
pub fn loader() -> anyhow::Result<PluginManagerType> {
    let config_dir = "./plugins";

    // if config directory doesn't exists, create it
    if !Path::new(config_dir).exists() {
        fs::create_dir_all(config_dir)?;
    }

    // get path to .so lib from command argument
    let paths = fs::read_dir(config_dir)?;

    // create a plugin manager
    let mut plugin_manager = PluginManager::new();

    // register default commands
    for command in commands::register_commands() {
        plugin_manager.commands.push(command)
    }

    // for all plugin in directory
    for path in paths {
        // get library file path
        let path = path?.path();
        let plugin_path = path.to_str().unwrap();

        info!("Loading plugin `{}`", plugin_path);

        // loading library from .so is unsafe
        unsafe {
            // load library
            // Box::new and Box::leak must be there because if it isn't there it throws a segmentation fault
            let lib = Box::leak(Box::new(Library::new(&path)?));

            // get function `plugin_entry` from library
            trace!("Finding symbol `plugin_entry` in `{}`", plugin_path);
            let func: Symbol<unsafe extern "C" fn(&mut dyn Registrar) -> ()> =
                lib.get(b"plugin_entry")?;

            // execute initial plugin function
            trace!(
                "Running function `plugin_entry` from plugin `{}`",
                plugin_path
            );
            func(&mut plugin_manager);
        }
    }

    // return a `PluginManager`
    Ok(Arc::new(plugin_manager))
}