package tomo

import "os"
import "plugin"
import "path/filepath"

var pluginPaths []string

func loadPlugins () {
	for _, dir := range pluginPaths {
		if dir != "" {
			loadPluginsFrom(dir)
		}
	}
}

func loadPluginsFrom (dir string) {
	entries, err := os.ReadDir(dir)
	// its no big deal if one of the dirs doesn't exist
	if err != nil { return }

	for _, entry := range entries {
		if entry.IsDir() { continue }
		if filepath.Ext(entry.Name()) != ".so" { continue }
		pluginPath := filepath.Join(dir, entry.Name())
		loadPlugin(pluginPath)
	}
}

func loadPlugin (path string) {
	die := func (reason string) {
		println("tomo: could not load plugin at", path + ":", reason)
	}

	plugin, err := plugin.Open(path)
	if err != nil {
		die(err.Error())
		return
	}

	// check for and obtain basic plugin functions
	name, ok := extract[func () string](plugin, "Name")
	if !ok { die("does not implement Name() string"); return }
	_, ok = extract[func () string](plugin, "Description")
	if !ok { die("does not implement Description() string"); return }

	println("tomo: loaded plugin", name())
}

func extract[T any] (plugin *plugin.Plugin, name string) (value T, ok bool) {
	symbol, err := plugin.Lookup(name)
	if err != nil { return }
	value, ok = symbol.(T)
	return
}