Rewrote generators to use plugin system with default plugins

internal/generator/generator.go

@@ -2,50 +2,162 @@ package generator
 
 import (
 	"bytes"
-
 	"fmt"
+	"os"
+	"plugin"
 
 	configurator "github.com/OpenCHAMI/configurator/internal"
+	"github.com/OpenCHAMI/configurator/internal/util"
 	"github.com/nikolalohinski/gonja/v2"
 	"github.com/nikolalohinski/gonja/v2/exec"
 )
 
-type Generator struct {
-	Type     string
-	Template string
+type Mappings = map[string]any
+type Generator interface {
+	GetName() string
+	GetGroups() []string
+	Generate(config *configurator.Config, opts ...util.Option) ([]byte, error)
 }
 
-func New() *Generator {
-	return &Generator{}
+func LoadPlugin(path string) (Generator, error) {
+	p, err := plugin.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load plugin: %v", err)
+	}
+
+	symbol, err := p.Lookup("Generator")
+	if err != nil {
+		return nil, fmt.Errorf("failed to look up symbol: %v", err)
+	}
+
+	gen, ok := symbol.(Generator)
+	if !ok {
+		return nil, fmt.Errorf("failed to load the correct symbol type")
+	}
+	return gen, nil
 }
 
-func (g *Generator) GenerateDNS(config *configurator.Config) {
-	// generate file using jinja template
-	// TODO: load template file for DNS
-	// TODO: substitute DNS data fetched from SMD
-	// TODO: print generated config file to STDOUT
+func LoadPlugins(dirpath string, opts ...util.Option) (map[string]Generator, error) {
+	// check if verbose option is supplied
+	var (
+		gens   = make(map[string]Generator)
+		params = util.GetParams(opts...)
+	)
+
+	items, _ := os.ReadDir(dirpath)
+	var LoadGenerator = func(path string) (Generator, error) {
+		// load each generator plugin
+		p, err := plugin.Open(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to load plugin: %v", err)
+		}
+
+		// lookup symbol in plugin
+		symbol, err := p.Lookup("Generator")
+		if err != nil {
+			return nil, fmt.Errorf("failed to look up symbol: %v", err)
+		}
+
+		// assert that the loaded symbol is the correct type
+		gen, ok := symbol.(Generator)
+		if !ok {
+			return nil, fmt.Errorf("failed to load the correct symbol type")
+		}
+		return gen, nil
+	}
+	for _, item := range items {
+		if item.IsDir() {
+			subitems, _ := os.ReadDir(item.Name())
+			for _, subitem := range subitems {
+				if !subitem.IsDir() {
+					gen, err := LoadGenerator(subitem.Name())
+					if err != nil {
+						fmt.Printf("failed to load generator in directory '%s': %v\n", item.Name(), err)
+						continue
+					}
+					if verbose, ok := params["verbose"].(bool); ok {
+						if verbose {
+							fmt.Printf("found plugin '%s'\n", item.Name())
+						}
+					}
+					gens[gen.GetName()] = gen
+				}
+			}
+		} else {
+			gen, err := LoadGenerator(dirpath + item.Name())
+			if err != nil {
+				fmt.Printf("failed to load generator: %v\n", err)
+				continue
+			}
+			if verbose, ok := params["verbose"].(bool); ok {
+				if verbose {
+					fmt.Printf("found plugin '%s'\n", dirpath+item.Name())
+				}
+			}
+			gens[gen.GetName()] = gen
+		}
+	}
+
+	return gens, nil
 }
 
-func (g *Generator) GenerateDHCP(config *configurator.Config, eths []configurator.EthernetInterface) ([]byte, error) {
-	// generate file using gonja template
-	path := config.TemplatePaths[g.Template]
-	fmt.Printf("path: %s\neth count: %v\n", path, len(eths))
+func WithTemplate(_template string) util.Option {
+	return func(p util.Params) {
+		if p != nil {
+			p["template"] = _template
+		}
+	}
+}
+
+func WithType(_type string) util.Option {
+	return func(p util.Params) {
+		if p != nil {
+			p["type"] = _type
+		}
+	}
+}
+
+func WithClient(client configurator.SmdClient) util.Option {
+	return func(p util.Params) {
+		p["client"] = client
+	}
+}
+
+// Syntactic sugar generic function to get parameter from util.Params.
+func Get[T any](params util.Params, key string) *T {
+	if v, ok := params[key].(T); ok {
+		return &v
+	}
+	return nil
+}
+
+// Helper function to get client in generator plugins.
+func GetClient(params util.Params) *configurator.SmdClient {
+	return Get[configurator.SmdClient](params, "client")
+}
+
+func GetParams(opts ...util.Option) util.Params {
+	params := util.Params{}
+	for _, opt := range opts {
+		opt(params)
+	}
+	return params
+}
+
+func Generate(g Generator, config *configurator.Config, opts ...util.Option) {
+	g.Generate(config, opts...)
+}
+
+func ApplyTemplate(path string, mappings map[string]any) ([]byte, error) {
+	data := exec.NewContext(mappings)
+
+	// load jinja template from file
 	t, err := gonja.FromFile(path)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read template from file: %v", err)
 	}
-	template := "# ========== GENERATED BY OCHAMI CONFIGURATOR ==========\n"
-	for _, eth := range eths {
-		if eth.Type == "NodeBMC" {
-			template += "dhcp-host=" + eth.MacAddress + "," + eth.ComponentId + "," + eth.IpAddresses[0].IpAddress + "\n"
-		} else {
-			template += "dhcp-host=" + eth.MacAddress + "," + eth.ComponentId + "," + eth.IpAddresses[0].IpAddress + "\n"
-		}
-	}
-	template += "# ======================================================"
-	data := exec.NewContext(map[string]any{
-		"hosts": template,
-	})
+
+	// execute/render jinja template
 	b := bytes.Buffer{}
 	if err = t.Execute(&b, data); err != nil {
 		return nil, fmt.Errorf("failed to execute: %v", err)