new-gui/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 (
	"os"
	"plugin"

	"git.wit.org/wit/gui/toolkit"
)

var err error
type Symbol any

type aplug struct {
	// Ok bool
	name string
	filename string
	plug *plugin.Plugin
	sym *plugin.Symbol
	LoadOk bool
	InitOk bool
	MainOk bool

	Init func()
	// TODO: make Main() main() and never allow the user to call it
	// run plugin.Main() when the plugin is loaded
	Main func(func ())	// this never returns. Each plugin must have it's own goroutine
	// Queue func(func ())	// Should this return right away? Should it wait (can it wait?)
	Quit func()
	// NewWindow func(*toolkit.Widget)

	// simplifies passing to the plugin
	// Send func(*toolkit.Widget, *toolkit.Widget)

	// should replace Send()
	Action func(*toolkit.Action)
}

var allPlugins []*aplug

// loads and initializes a toolkit (andlabs/ui, gocui, etc)
func LoadToolkit(name string) bool {
	var newPlug aplug

	log(debugGui, "gui.LoadToolkit() START")
	newPlug.LoadOk = false

	for _, aplug := range allPlugins {
		log(debugGui, "gui.LoadToolkit() already loaded toolkit plugin =", aplug.name)
		if (aplug.name == name) {
			log(debugGui, "gui.LoadToolkit() SKIPPING")
			return true
		}
	}

	// locate the shared library file
	filename := name + ".so"
	loadPlugin(&newPlug, filename)
	if (newPlug.plug == nil) {
		log(true, "attempt to find plugin", filename, "failed")
		return false
	}
	// newPlug.Ok = true
	newPlug.name = name

	// deprecate Init(?)
	newPlug.Init = loadFuncE(&newPlug, "Init")

	// should make a goroutine that never exits
	newPlug.Main  = loadFuncF(&newPlug, "Main")

	// should send things to the goroutine above
	// newPlug.Queue = loadFuncF(&newPlug, "Queue")

	// unload the plugin and restore state
	newPlug.Quit = loadFuncE(&newPlug, "Quit")

	// Sends instructions like "Add", "Delete", "Disable", etc
	// Sends a widget (button, checkbox, etc) and it's parent widget
	newPlug.Action = loadFuncA(&newPlug, "Action")

	allPlugins = append(allPlugins, &newPlug)

	log(debugPlugin, "gui.LoadToolkit() END", newPlug.name, filename)
	newPlug.Init()
	newPlug.LoadOk = true
	return true
}

// TODO: All these functions need to be done a smarter way
// but I haven't worked out the golang syntax to make it smarter
func loadFuncE(p *aplug, funcName string) func() {
	var newfunc func()
	var ok bool
	var test plugin.Symbol

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

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

func loadFunc2(p *aplug, funcName string) func(*toolkit.Widget, *toolkit.Widget) {
	var newfunc func(*toolkit.Widget, *toolkit.Widget)
	var ok bool
	var test plugin.Symbol

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

	newfunc, ok = test.(func(*toolkit.Widget, *toolkit.Widget))
	if !ok {
		log(debugGui, "function name =", funcName, "names didn't map correctly. Fix the plugin name =", p.name)
		return nil
	}
	return newfunc
}

// does this fix loadFuncE problems?
// TODO: still need to move to channels here
func loadFuncA(p *aplug, funcName string) func(*toolkit.Action) {
	var newfunc func(*toolkit.Action)
	var ok bool
	var test plugin.Symbol

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

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

// This is probably dangerous and should never be done
// executing arbitrary functions will cause them to run inside the goroutine that
// the GUI toolkit itself is running in. TODO: move to channels here
func loadFuncF(p *aplug, funcName string) func(func ()) {
	var newfunc func(func ())
	var ok bool
	var test plugin.Symbol

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

	newfunc, ok = test.(func(func ()))
	if !ok {
		log(debugGui, "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:
		./toolkit/
		~/go/src/go.wit.org/gui/toolkit/
		/usr/lib/go-gui/
*/
func loadPlugin(p *aplug, name string) {
	var filename string

	homeDir, err := os.UserHomeDir()
	if err != nil {
		log(logError, "loadPlugin() error. exiting here?")
		return
	}

	// attempt to write out the file from the internal resource
	filename = "toolkit/" + name
	p.plug = loadfile(filename)
	if (p.plug != nil) {
		p.filename = filename
		return
	}

	filename = homeDir + "/go/src/git.wit.org/wit/gui/toolkit/" + name
	p.plug = loadfile(filename)
	if (p.plug != nil) {
		p.filename = filename
		return
	}

	filename = "/usr/lib/go-gui/" + name
	p.plug = loadfile(filename)
	if (p.plug != nil) {
		p.filename = filename
		return
	}
	return
}

// load module
// 1. open the shared object file to load the symbols
func loadfile(filename string) *plugin.Plugin {
	plug, err := plugin.Open(filename)
	if err != nil {
		log(debugGui, "plugin FAILED =", filename, err)
		return nil
	}
	log(debugGui, "plugin WORKED =", filename)
	log(true, "loading plugin", filename, "worked")
	return plug
}

// Sends a widget and what to do with it to the plugin
// parent = n, child = c

// THIS COPIES THE WIDGET STRUCT 2023/03/16 as it's not crashing. Queue() is also being used
// never mind that comment. no it doesn't
func newaction(a *toolkit.Action, n *Node, where *Node) {
	if (n != nil) {
		a.Widget = &n.widget
		a.WidgetId = n.id
		a.WidgetType = n.widget.Type
		a.ActionType = a.ActionType
	}
	// action(&a, newNode, n)
	// newaction(&a, newNode, n)

	if (where != nil) {
		log(debugGui, "Action() START on where X,Y, Next X,Y =", where.Name, where.X, where.Y, where.NextX, where.NextY)
		a.ParentId = where.id
		switch where.widget.Type {
		case toolkit.Grid:
			// where.Dump(true)
			log(debugGui, "Action() START on Grid (X,Y)", where.X, where.Y, "put next thing at (X,Y) =", where.NextX, where.NextY)
			//
			// fix values here if they are invalid. Index starts at 1
			if (where.NextX < 1) {
				where.NextX = 1
			}
			if (where.NextY < 1) {
				where.NextY = 1
			}
			//
			a.X = where.NextX
			a.Y = where.NextY
			log(debugGui, "Action() END   on Grid (X,Y)", where.X, where.Y, "put next thing at (X,Y) =", where.NextX, where.NextY)
		default:
		}
	}

	for _, aplug := range allPlugins {
		log(debugPlugin, "Action() aplug =", aplug.name, "Action type=", a.ActionType)
		if (aplug.Action == nil) {
			log(debugPlugin, "Failed Action() == nil for", aplug.name)
			continue
		}
		aplug.Action(a)
	}
	// increment where to put the next widget in a grid or table
	if (where != nil) {
		switch where.widget.Type {
		case toolkit.Grid:
			log(logInfo, "Action() START size (X,Y)", where.X, where.Y, "put next thing at (X,Y) =", where.NextX, where.NextY)
			where.NextY += 1
			if (where.NextY > where.Y) {
				where.NextX += 1
				where.NextY = 1
			}
			log(logInfo, "Action() END size (X,Y)", where.X, where.Y, "put next thing at (X,Y) =", where.NextX, where.NextY)
		default:
		}
	}
}