path: root/plugin.go

package gui

// This is based off of the excellent example and documentation here:
// https://github.com/vladimirvivien/go-plugin-example
// There truly are great people in this world.
// It's a pleasure to be here with all of you

import (
	"embed"
	"errors"
	"os"
	"path/filepath"
	"plugin"

	"go.wit.com/log"
	"go.wit.com/widget"
)

var err error

type Symbol any

type aplug struct {
	count    int
	name     string
	filename string
	plug     *plugin.Plugin

	// set this to true if the plugin dies
	// TODO: remove the plugin from the pool
	dead bool

	// this tells the toolkit plugin how to send events
	// back here
	//
	// This is how we are passed information like a user clicking a button
	// or a user changing a dropdown menu or a checkbox
	//
	// From this channel, the information is then passed into the main program
	// Custom() function
	//
	Callback func(chan widget.Action)

	// This is how actions are sent to the toolkit.
	// For example:
	// If a program is using GTK, when a program tries to make a new button
	// "Open GIMP", then it would pass an action via this channel into the toolkit
	// plugin and the toolkit plugin would add a button to the parent widget
	//
	// each toolkit has it's own goroutine and each one is sent this
	// add button request
	//
	pluginChan    chan widget.Action
	PluginChannel func() chan widget.Action

	frozenChan    chan widget.Action
	FrozenChannel func() chan widget.Action
}

var allPlugins []*aplug

func (n *Node) LoadToolkit(name string) (*Node, error) {
	log.Log(PLUG, "LoadToolkit() START for name =", name)
	plug := initPlugin(name)
	if plug == nil {
		return n, errors.New("initPlugin(" + name + ") failed")
	}
	plug.dead = false

	log.Log(PLUG, "LoadToolkit() sending Toolkit Init action to the plugin channel")
	var a widget.Action
	a.ActionType = widget.ToolkitInit
	plug.pluginChan <- a
	// sleep(.5) // temp hack until chan communication is setup

	// TODO: find a new way to do this that is locking, safe and accurate
	me.rootNode.redraw(plug)
	log.Log(PLUG, "LoadToolkit() END for name =", name)
	return n, nil
}

// loads and initializes a toolkit (andlabs/ui, gocui, etc)
// attempts to locate the .so file
func initPlugin(name string) *aplug {
	log.Log(PLUG, "initPlugin() START")

	for _, aplug := range allPlugins {
		log.Log(PLUG, "initPlugin() already loaded toolkit plugin =", aplug.name)
		if aplug.name == name {
			log.Log(WARN, "initPlugin() SKIPPING", name, "as you can't load it twice")
			return nil
		}
	}

	return searchPaths(name)
}

// newPlug.PluginChannel = getPluginChannel(newPlug, "PluginChannel")
func getPluginChannel(p *aplug, funcName string) func() chan widget.Action {
	var newfunc func() chan widget.Action
	var ok bool
	var test plugin.Symbol

	test, err = p.plug.Lookup(funcName)
	if err != nil {
		log.Error(err, "DID NOT FIND: name =", test)
		return nil
	}

	newfunc, ok = test.(func() chan widget.Action)
	if !ok {
		log.Log(PLUG, "function name =", funcName, "names didn't map correctly. Fix the plugin name =", p.name)
		return nil
	}
	return newfunc
}

func sendCallback(p *aplug, funcName string) func(chan widget.Action) {
	var newfunc func(chan widget.Action)
	var ok bool
	var test plugin.Symbol

	test, err = p.plug.Lookup(funcName)
	if err != nil {
		log.Log(WARN, "sendCallback() err =", err)
		log.Log(WARN, "sendCallback() DID NOT FIND: name =", funcName)
		return nil
	}

	newfunc, ok = test.(func(chan widget.Action))
	if !ok {
		log.Log(PLUG, "function name =", funcName, "names didn't map correctly. Fix the plugin name =", p.name)
		return nil
	}
	return newfunc
}

/*
This searches in the following order for the plugin .so files:

	/usr/lib/go-gui-toolkits/
	~/go/src/go.wit.com/toolkits/
	/usr/lib/local/go-gui-toolkits/

	TODO: plugin.Open() seem to always fail after the first attempt fails
*/
func searchPaths(name string) *aplug {
	var filename string
	var pfile []byte
	var err error
	var p *aplug

	// try the filename from the command line first
	if argGui.GuiFile != "" {
		p = initToolkit(name, argGui.GuiFile)
		if p != nil {
			log.Log(NOW, "gui.Init() loaded ok!", argGui.GuiFile)
			return p
		}
	}

	// check for custom toolkit builds. This looks:
	// with 'go build':       ~/go/src/go.wit.com/toolkits/gocui/gocui.go
	// with 'make install':   ~/go/lib/go-gui/gocui.go
	//
	// TODO: use forge to find the "go.work" dir
	// TODO: fix 'go install' to support building plugins
	homeDir, err := os.UserHomeDir()
	if err != nil {
		log.Error(err, "os.UserHomeDir() error", err)
	} else {
		// first look in the toolkit build directory
		filename = homeDir + "/go/src/go.wit.com/toolkits/" + name + "/" + name + ".so"
		p = initToolkit(name, filename)
		if p != nil {
			log.Log(NOW, "gui.Init() loaded", filename, "ok!")
			return p
		}

		// this is the "default" location when built and installed locally
		filename = homeDir + "/go/lib/go-gui/" + name + ".so"
		p = initToolkit(name, filename)
		if p != nil {
			log.Log(NOW, "gui.Init() loaded", filename, "ok!")
			return p
		}
	}

	// try /usr/local/
	filename = "/usr/local/lib/go-gui/" + name + ".so"
	p = initToolkit(name, filename)
	if p != nil {
		log.Log(NOW, "gui.Init() loaded", filename, "ok!")
		return p
	}

	// try to load the embedded plugin file
	// TODO: fix the filename used in /tmp/
	resname := filepath.Join("resources/", name+".so")
	pfile, err = me.resFS.ReadFile(resname)
	if err == nil {
		tmpname := filepath.Join("/tmp/", name+".so")
		log.Log(WARN, "searchPaths() using toolkit embedded in executable")
		log.Log(WARN, "searchPaths() resource file", tmpname, resname, len(pfile))
		f, _ := os.OpenFile(tmpname, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
		f.Write(pfile)
		f.Close()
		p := initToolkit(name, tmpname)
		if p != nil {
			log.Log(NOW, "gui.Init() loaded", resname, "ok!")
			return p
		}
	} else {
		log.Log(INFO, "searchPaths()", resname, "was not embedded in the binary")
	}

	// attempt to write out the file from the internal resource
	// is this the same as above. todo: sort this out.
	filename = "resources/" + name + ".so"
	p = initToolkit(name, filename)
	if p != nil {
		log.Log(NOW, "gui.Init() loaded", filename, "ok!")
		return p
	}

	// This is the 'default' location
	// if you are a linux distribution package maintainer, please put the tookits here
	filename = "/usr/lib/go-gui-toolkits/" + name + ".so"
	p = initToolkit(name, filename)
	if p != nil {
		log.Log(NOW, "gui.Init() loaded", filename, "ok!")
		return p
	}

	return nil
}

// load module
// 1. open the shared object file to load the symbols
func initToolkit(name string, filename string) *aplug {
	/*
		if _, err := os.Stat(filename); err != nil {
			if os.IsNotExist(err) {
				log.Log(PLUG, "initToolkit() missing plugin", name, "as filename", filename)
				return nil
			}
		}
		log.Log(PLUG, "initToolkit() Found plugin", name, "as filename", filename)

		plug, err := plugin.Open(filename)
	*/
	if err := checkPluginViaSubprocess(filename); err != nil {
		log.Printf("initToolkit() subprocess load plugin failed: %v\n", err)
		return nil
	}

	plug, err := checkPlug(filename)
	if err != nil {
		// turn on PLUG debugging if something goes wrong
		PLUG.SetBool(true)
		log.Log(PLUG, "plugin.Open() err =", err)
		log.Log(PLUG, "initToolkit() FAILED =", filename)
		return nil
	}
	log.Log(PLUG, "initToolkit() SUCCESS loading plugin =", filename)

	var newPlug *aplug
	newPlug = new(aplug)
	newPlug.name = name
	newPlug.filename = filename
	newPlug.plug = plug

	// this tells the toolkit plugin how to send user events back to us
	// for things like: the user clicked on the 'Check IPv6'
	newPlug.Callback = sendCallback(newPlug, "Callback")

	// this let's us know where to send requests to the toolkit
	// for things like: add a new button called 'Check IPv6'
	newPlug.PluginChannel = getPluginChannel(newPlug, "PluginChannel")

	// add it to the list of plugins
	allPlugins = append(allPlugins, newPlug)

	// set the communication to the plugins
	newPlug.pluginChan = newPlug.PluginChannel()
	if newPlug.pluginChan == nil {
		log.Log(WARN, "initToolkit() ERROR PluginChannel() returned nil for plugin:", newPlug.name, filename)
		return nil
	}
	newPlug.Callback(me.guiChan)

	// test to see if this can be used to make fyne work
	newPlug.FrozenChannel = getPluginChannel(newPlug, "FrozenChannel")

	// set the communication to the plugins
	newPlug.frozenChan = newPlug.FrozenChannel()
	if newPlug.frozenChan == nil {
		log.Log(WARN, "initToolkit() ERROR FrozenChannel() returned nil for plugin:", newPlug.name)
	}

	log.Log(PLUG, "initToolkit() END", newPlug.name, filename)
	return newPlug
}

func (n *Node) InitEmbed(resFS embed.FS) *Node {
	me.resFS = resFS
	return n
}

func (n *Node) LoadToolkitEmbed(name string, b []byte) *Node {
	for _, aplug := range allPlugins {
		log.Log(PLUG, "LoadToolkitEmbed() already loaded toolkit plugin =", aplug.name)
		if aplug.name == name {
			log.Log(NOW, "LoadToolkitEmbed() SKIPPING", name, "as you can't load it twice")
			return n
		}
	}

	f, err := os.CreateTemp("", "sample."+name+".so")
	if err != nil {
		log.Error(err, "LoadToolkitEmbed() SKIPPING", name, "as you can't load it twice")
		return n
	}
	defer os.Remove(f.Name())
	f.Write(b)

	p := initToolkit(name, f.Name())
	if p == nil {
		log.Log(WARN, "LoadToolkitEmbed() embedded go file failed", name)
	}
	return n
}

func (n *Node) ListToolkits() {
	for _, aplug := range allPlugins {
		log.Log(WARN, "ListToolkits() has plugin =", aplug.name, "i =", aplug.count)
	}
}

// cleanly close all toolkits
func (n *Node) Close() {
	Exit()
}

func Exit() {
	log.Log(PLUG, "Closing all toolkits")
	for _, plug := range allPlugins {
		log.Log(PLUG, "Exit() found plugin", plug.name)
		var a widget.Action
		a.ActionType = widget.ToolkitClose
		plug.pluginChan <- a
	}
	allPlugins = nil
}

func (n *Node) CloseToolkit(name string) bool {
	log.Log(PLUG, "CloseToolkit() for name =", name)
	for i, plug := range allPlugins {
		log.Log(PLUG, "CloseToolkit() found", plug.name)
		if plug.name == name {
			log.Log(PLUG, "CloseToolkit() sending close", name)
			var a widget.Action
			a.ActionType = widget.ToolkitClose
			plug.pluginChan <- a
			allPlugins = append(allPlugins[:i], allPlugins[i+1:]...)
			return true
		}
	}
	return false
}