post megre cleanup.

server/internal/plugins/dependency.go

@@ -0,0 +1,133 @@
+package plugins
+
+import (
+	"fmt"
+
+	"github.com/rs/zerolog"
+
+	"github.com/demodesk/neko/pkg/types"
+)
+
+type dependency struct {
+	plugin    types.Plugin
+	dependsOn []*dependency
+	invoked   bool
+	logger    zerolog.Logger
+}
+
+func (a *dependency) findPlugin(name string) (*dependency, bool) {
+	if a == nil {
+		return nil, false
+	}
+
+	if a.plugin.Name() == name {
+		return a, true
+	}
+
+	for _, dep := range a.dependsOn {
+		plug, ok := dep.findPlugin(name)
+		if ok {
+			return plug, true
+		}
+	}
+
+	return nil, false
+}
+
+func (a *dependency) startPlugin(pm types.PluginManagers) error {
+	if a.invoked {
+		return nil
+	}
+
+	a.invoked = true
+
+	for _, do := range a.dependsOn {
+		if err := do.startPlugin(pm); err != nil {
+			return fmt.Errorf("plugin's '%s' dependency: %w", a.plugin.Name(), err)
+		}
+	}
+
+	err := a.plugin.Start(pm)
+	if err != nil {
+		return fmt.Errorf("plugin '%s' failed to start: %w", a.plugin.Name(), err)
+	}
+
+	a.logger.Info().Str("plugin", a.plugin.Name()).Msg("plugin started")
+	return nil
+}
+
+type dependiencies struct {
+	deps   map[string]*dependency
+	logger zerolog.Logger
+}
+
+func (d *dependiencies) addPlugin(plugin types.Plugin) error {
+	pluginName := plugin.Name()
+
+	plug, ok := d.deps[pluginName]
+	if !ok {
+		plug = &dependency{}
+	} else if plug.plugin != nil {
+		return fmt.Errorf("plugin '%s' already added", pluginName)
+	}
+
+	plug.plugin = plugin
+	plug.logger = d.logger
+	d.deps[pluginName] = plug
+
+	dplug, ok := plugin.(types.DependablePlugin)
+	if !ok {
+		return nil
+	}
+
+	for _, depName := range dplug.DependsOn() {
+		dependsOn, ok := d.deps[depName]
+		if !ok {
+			dependsOn = &dependency{}
+		} else if dependsOn.plugin != nil {
+			// if there is a cyclical dependency, break it and return error
+			if tdep, ok := dependsOn.findPlugin(pluginName); ok {
+				dependsOn.dependsOn = nil
+				delete(d.deps, pluginName)
+				return fmt.Errorf("cyclical dependency detected: '%s' <-> '%s'", pluginName, tdep.plugin.Name())
+			}
+		}
+
+		plug.dependsOn = append(plug.dependsOn, dependsOn)
+		d.deps[depName] = dependsOn
+	}
+
+	return nil
+}
+
+func (d *dependiencies) findPlugin(name string) (*dependency, bool) {
+	for _, dep := range d.deps {
+		plug, ok := dep.findPlugin(name)
+		if ok {
+			return plug, true
+		}
+	}
+	return nil, false
+}
+
+func (d *dependiencies) start(pm types.PluginManagers) error {
+	for _, dep := range d.deps {
+		if err := dep.startPlugin(pm); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (d *dependiencies) forEach(f func(*dependency) error) error {
+	for _, dep := range d.deps {
+		if err := f(dep); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (d *dependiencies) len() int {
+	return len(d.deps)
+}