Moved internal/ to pkg/ to make building external plugins possible

pkg/generator/generator.go

@@ -0,0 +1,320 @@
+package generator
+
+import (
+	"bytes"
+	"fmt"
+	"maps"
+	"os"
+	"path/filepath"
+	"plugin"
+
+	configurator "github.com/OpenCHAMI/configurator/internal"
+	"github.com/OpenCHAMI/configurator/internal/util"
+	"github.com/nikolalohinski/gonja/v2"
+	"github.com/nikolalohinski/gonja/v2/exec"
+	"github.com/sirupsen/logrus"
+)
+
+type Mappings map[string]any
+type FileMap map[string][]byte
+type FileList [][]byte
+
+// Generator interface used to define how files are created. Plugins can
+// be created entirely independent of the main driver program.
+type Generator interface {
+	GetName() string
+	GetVersion() string
+	GetDescription() string
+	Generate(config *configurator.Config, opts ...util.Option) (FileMap, error)
+}
+
+// Params defined and used by the "generate" subcommand.
+type Params struct {
+	Args        []string
+	PluginPaths []string
+	Target      string
+	Verbose     bool
+}
+
+// Converts the file outputs from map[string][]byte to map[string]string.
+func ConvertContentsToString(f FileMap) map[string]string {
+	n := make(map[string]string, len(f))
+	for k, v := range f {
+		n[k] = string(v)
+	}
+	return n
+}
+
+// Loads files without applying any Jinja 2 templating.
+func LoadFiles(paths ...string) (FileMap, error) {
+	var outputs = FileMap{}
+	for _, path := range paths {
+		expandedPaths, err := filepath.Glob(path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to glob path: %v", err)
+		}
+		for _, expandedPath := range expandedPaths {
+			info, err := os.Stat(expandedPath)
+			if err != nil {
+				fmt.Println(err)
+				return nil, fmt.Errorf("failed to stat file or directory: %v", err)
+			}
+			// skip any directories found
+			if info.IsDir() {
+				continue
+			}
+			b, err := os.ReadFile(expandedPath)
+			if err != nil {
+				return nil, fmt.Errorf("failed to read file: %v", err)
+			}
+
+			outputs[expandedPath] = b
+		}
+	}
+
+	return outputs, nil
+}
+
+// Loads a single generator plugin given a single file path.
+func LoadPlugin(path string) (Generator, error) {
+	// skip loading plugin if path is a directory with no error
+	if isDir, err := util.IsDirectory(path); err == nil && isDir {
+		return nil, nil
+	} else if err != nil {
+		return nil, fmt.Errorf("failed to test if path is directory: %v", err)
+	}
+
+	// try and open the plugin
+	p, err := plugin.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open plugin: %v", err)
+	}
+
+	// load the "Generator" symbol from plugin
+	symbol, err := p.Lookup("Generator")
+	if err != nil {
+		return nil, fmt.Errorf("failed to look up symbol at path '%s': %v", path, err)
+	}
+
+	// assert that the plugin loaded has a valid generator
+	gen, ok := symbol.(Generator)
+	if !ok {
+		return nil, fmt.Errorf("failed to load the correct symbol type at path '%s'", path)
+	}
+	return gen, nil
+}
+
+// Loads all generator plugins in a given directory.
+//
+// Returns a map of generators. Each generator can be accessed by the name
+// returned by the generator.GetName() implemented.
+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)
+	for _, item := range items {
+		if item.IsDir() {
+			subitems, _ := os.ReadDir(item.Name())
+			for _, subitem := range subitems {
+				if !subitem.IsDir() {
+					gen, err := LoadPlugin(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 := LoadPlugin(dirpath + item.Name())
+			if err != nil {
+				fmt.Printf("failed to load plugin: %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
+}
+
+// Option to specify "target" in parameter map. This is used to set which generator
+// to use to generate a config file.
+func WithTarget(target string) util.Option {
+	return func(p util.Params) {
+		if p != nil {
+			p["target"] = target
+		}
+	}
+}
+
+// Option to specify "type" in parameter map. This is not currently used.
+func WithType(_type string) util.Option {
+	return func(p util.Params) {
+		if p != nil {
+			p["type"] = _type
+		}
+	}
+}
+
+// Option to a specific client to include in implementing plugin generator.Generate().
+//
+// NOTE: This may be changed to pass some kind of client interface as an argument in
+// the future instead.
+func WithClient(client configurator.SmdClient) util.Option {
+	return func(p util.Params) {
+		p["client"] = client
+	}
+}
+
+// Helper function to get client in generator.Generate() plugin implementations.
+func GetClient(params util.Params) *configurator.SmdClient {
+	return util.Get[configurator.SmdClient](params, "client")
+}
+
+// Helper function to get the target in generator.Generate() plugin implementations.
+func GetTarget(config *configurator.Config, key string) configurator.Target {
+	return config.Targets[key]
+}
+
+// Helper function to load all options set with With*() into parameter map.
+func GetParams(opts ...util.Option) util.Params {
+	params := util.Params{}
+	for _, opt := range opts {
+		opt(params)
+	}
+	return params
+}
+
+// Wrapper function to slightly abstract away some of the nuances with using gonja
+// into a single function call. This function is *mostly* for convenience and
+// simplication. If no paths are supplied, then no templates will be applied and
+// there will be no output.
+//
+// The "FileList" returns a slice of byte arrays in the same order as the argument
+// list supplied, but with the Jinja templating applied.
+func ApplyTemplates(mappings Mappings, contents ...[]byte) (FileList, error) {
+	var (
+		data    = exec.NewContext(mappings)
+		outputs = FileList{}
+	)
+
+	for _, b := range contents {
+		// load jinja template from file
+		t, err := gonja.FromBytes(b)
+		if err != nil {
+			return nil, fmt.Errorf("failed to read template from file: %v", err)
+		}
+
+		// execute/render jinja template
+		b := bytes.Buffer{}
+		if err = t.Execute(&b, data); err != nil {
+			return nil, fmt.Errorf("failed to execute: %v", err)
+		}
+		outputs = append(outputs, b.Bytes())
+	}
+
+	return outputs, nil
+}
+
+// Wrapper function similiar to "ApplyTemplates" but takes file paths as arguments.
+// This function will load templates from a file instead of using file contents.
+func ApplyTemplateFromFiles(mappings Mappings, paths ...string) (FileMap, error) {
+	var (
+		data    = exec.NewContext(mappings)
+		outputs = FileMap{}
+	)
+
+	for _, path := range paths {
+		// 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)
+		}
+
+		// execute/render jinja template
+		b := bytes.Buffer{}
+		if err = t.Execute(&b, data); err != nil {
+			return nil, fmt.Errorf("failed to execute: %v", err)
+		}
+		outputs[path] = b.Bytes()
+	}
+
+	return outputs, nil
+}
+
+// Main function to generate a collection of files as a map with the path as the key and
+// the contents of the file as the value. This function currently expects a list of plugin
+// paths to load all plugins within a directory. Then, each plugin's generator.Generate()
+// function is called for each target specified.
+//
+// This function is the corresponding implementation for the "generate" CLI subcommand.
+// It is also call when running the configurator as a service with the "/generate" route.
+//
+// TODO: Separate loading plugins so we can load them once when running as a service.
+func Generate(config *configurator.Config, params Params) (FileMap, error) {
+	// load generator plugins to generate configs or to print
+	var (
+		generators = make(map[string]Generator)
+		client     = configurator.NewSmdClient(
+			configurator.WithHost(config.SmdClient.Host),
+			configurator.WithPort(config.SmdClient.Port),
+			configurator.WithAccessToken(config.AccessToken),
+			configurator.WithCertPoolFile(config.CertPath),
+		)
+	)
+
+	// load all plugins from params
+	for _, path := range params.PluginPaths {
+		if params.Verbose {
+			fmt.Printf("loading plugins from '%s'\n", path)
+		}
+		gens, err := LoadPlugins(path)
+		if err != nil {
+			fmt.Printf("failed to load plugins: %v\n", err)
+			err = nil
+			continue
+		}
+
+		// add loaded generator plugins to set
+		maps.Copy(generators, gens)
+	}
+
+	// show available targets then exit
+	if len(params.Args) == 0 && params.Target == "" {
+		for g := range generators {
+			fmt.Printf("-- found generator plugin \"%s\"\n", g)
+		}
+		return nil, nil
+	}
+
+	if params.Target == "" {
+		logrus.Errorf("no target supplied (--target name)")
+	} else {
+		// run the generator plugin from target passed
+		gen := generators[params.Target]
+		if gen == nil {
+			return nil, fmt.Errorf("invalid generator target (%s)", params.Target)
+		}
+		return gen.Generate(
+			config,
+			WithTarget(gen.GetName()),
+			WithClient(client),
+		)
+	}
+	return nil, fmt.Errorf("an unknown error has occurred")
+}