Embedded javascript plugins (#1393)

pkg/plugin/js.go

@@ -0,0 +1,124 @@
+package plugin
+
+import (
+	"errors"
+	"path/filepath"
+	"sync"
+
+	"github.com/robertkrimen/otto"
+	"github.com/stashapp/stash/pkg/plugin/common"
+	"github.com/stashapp/stash/pkg/plugin/js"
+)
+
+var errStop = errors.New("stop")
+
+type jsTaskBuilder struct{}
+
+func (*jsTaskBuilder) build(task pluginTask) Task {
+	return &jsPluginTask{
+		pluginTask: task,
+	}
+}
+
+type jsPluginTask struct {
+	pluginTask
+
+	started   bool
+	waitGroup sync.WaitGroup
+	vm        *otto.Otto
+}
+
+func throw(vm *otto.Otto, str string) {
+	value, _ := vm.Call("new Error", nil, str)
+	panic(value)
+}
+
+func (t *jsPluginTask) onError(err error) {
+	errString := err.Error()
+	t.result = &common.PluginOutput{
+		Error: &errString,
+	}
+}
+
+func (t *jsPluginTask) makeOutput(o otto.Value) {
+	t.result = &common.PluginOutput{}
+
+	asObj := o.Object()
+	if asObj == nil {
+		return
+	}
+
+	t.result.Output, _ = asObj.Get("Output")
+	err, _ := asObj.Get("Error")
+	if !err.IsUndefined() {
+		errStr := err.String()
+		t.result.Error = &errStr
+	}
+}
+
+func (t *jsPluginTask) Start() error {
+	if t.started {
+		return errors.New("task already started")
+	}
+
+	t.started = true
+
+	if len(t.plugin.Exec) == 0 {
+		return errors.New("no script specified in exec")
+	}
+
+	scriptFile := t.plugin.Exec[0]
+
+	t.vm = otto.New()
+	pluginPath := t.plugin.getConfigPath()
+	script, err := t.vm.Compile(filepath.Join(pluginPath, scriptFile), nil)
+	if err != nil {
+		return err
+	}
+
+	input := t.buildPluginInput()
+
+	t.vm.Set("input", input)
+	js.AddLogAPI(t.vm, t.progress)
+	js.AddUtilAPI(t.vm)
+	js.AddGQLAPI(t.vm, t.gqlHandler)
+
+	t.vm.Interrupt = make(chan func(), 1)
+
+	t.waitGroup.Add(1)
+
+	go func() {
+		defer func() {
+			t.waitGroup.Done()
+
+			if caught := recover(); caught != nil {
+				if caught == errStop {
+					// TODO - log this
+					return
+				}
+			}
+		}()
+
+		output, err := t.vm.Run(script)
+
+		if err != nil {
+			t.onError(err)
+		} else {
+			t.makeOutput(output)
+		}
+	}()
+
+	return nil
+}
+
+func (t *jsPluginTask) Wait() {
+	t.waitGroup.Wait()
+}
+
+func (t *jsPluginTask) Stop() error {
+	// TODO - need another way of doing this that doesn't require panic
+	t.vm.Interrupt <- func() {
+		panic(errStop)
+	}
+	return nil
+}