feat(blogo,source,multi-sourcer): support for multiple sources, new multi-sourcer plugin

blogo/blogo.go

@@ -153,7 +153,7 @@ func (b *Blogo) Init() error {
 		b.Use(renderer)
 	}
 
-	fs, err := b.sources[0].Source() // TODO: Support for multiple sources (via another plugin or built-in, with prefixes or not)
+	fs, err := b.source()
 	if err != nil {
 		return errors.Join(errors.New("failed to source files"), err)
 	}
@@ -162,6 +162,42 @@ func (b *Blogo) Init() error {
 	return nil
 }
 
+func (b *Blogo) source() (fs.FS, error) {
+	log := b.log.With(slog.String("step", "SOURCING"))
+
+	if len(b.sources) == 1 {
+		log.Debug(
+			"Just one sources found, using it directly",
+			slog.String("plugin", b.sources[0].Name()),
+		)
+		return b.sources[0].Source()
+	}
+
+	log.Debug(
+		fmt.Sprintf(
+			"Multiple sources found, initializing built-in %q plugin",
+			multiSourcerPluginName,
+		),
+	)
+
+	multi := NewMultiSourcer(MultiSourcerOpts{
+		NotPanicOnInit:       true,
+		NotSkipOnFSError:     false,
+		NotSkipOnSourceError: false,
+		Logger:               log,
+	})
+
+	for _, s := range b.sources {
+		log.Debug("Adding plugin to multi-sourcer", slog.String("plugin", s.Name()))
+		multi.Use(s)
+	}
+
+	b.sources = make([]SourcerPlugin, 1)
+	b.sources[0] = multi
+
+	return b.sources[0].Source()
+}
+
 func (b *Blogo) render(src fs.File, w io.Writer) error {
 	log := b.log.With(slog.String("step", "RENDERING"))
 

blogo/sourcer.go

@@ -0,0 +1,133 @@
+package blogo
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"log/slog"
+)
+
+const multiSourcerPluginName = "blogo-multisourcer-sourcer"
+
+type MultiSourcer interface {
+	SourcerPlugin
+	Use(Plugin)
+}
+
+type multiSourcer struct {
+	sources []SourcerPlugin
+
+	panicOnInit       bool
+	skipOnSourceError bool
+	skipOnFSError     bool
+
+	log *slog.Logger
+}
+
+type MultiSourcerOpts struct {
+	NotPanicOnInit       bool
+	NotSkipOnSourceError bool
+	NotSkipOnFSError     bool
+
+	Logger *slog.Logger
+}
+
+func NewMultiSourcer(opts ...MultiSourcerOpts) MultiSourcer {
+	opt := MultiSourcerOpts{}
+	if len(opts) > 0 {
+		opt = opts[0]
+	}
+
+	if opt.Logger == nil {
+		opt.Logger = slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{}))
+	}
+	opt.Logger = opt.Logger.WithGroup(multiSourcerPluginName)
+
+	return &multiSourcer{
+		sources: []SourcerPlugin{},
+
+		panicOnInit:       !opt.NotPanicOnInit,
+		skipOnSourceError: !opt.NotSkipOnSourceError,
+		skipOnFSError:     !opt.NotSkipOnFSError,
+
+		log: opt.Logger,
+	}
+}
+
+func (p *multiSourcer) Name() string {
+	return multiSourcerPluginName
+}
+
+func (p *multiSourcer) Use(plugin Plugin) {
+	log := p.log.With(slog.String("plugin", plugin.Name()))
+
+	if plg, ok := plugin.(SourcerPlugin); ok {
+		log.Debug("Added renderer plugin")
+		p.sources = append(p.sources, plg)
+	} else {
+		m := fmt.Sprintf("failed to add plugin %q, since it doesn't implement SourcerPlugin", plugin.Name())
+		log.Error(m)
+		if p.panicOnInit {
+			panic(fmt.Sprintf("%s: %s", multiRendererPluginName, m))
+		}
+	}
+}
+
+func (p *multiSourcer) Source() (fs.FS, error) {
+	log := p.log
+
+	fileSystems := []fs.FS{}
+
+	for _, s := range p.sources {
+		log = log.With(slog.String("plugin", p.Name()))
+		log.Info("Sourcing file system of plugin")
+
+		f, err := s.Source()
+		if err != nil && p.skipOnSourceError {
+			log.Error(
+				"Failed to source file system of plugin, skipping",
+				slog.String("error", err.Error()),
+			)
+		} else if err != nil {
+			log.Error(
+				"Failed to source file system of plugin, returning error",
+				slog.String("error", err.Error()),
+			)
+			return f, err
+		}
+
+		fileSystems = append(fileSystems, f)
+	}
+
+	f := make([]fs.FS, len(fileSystems), len(fileSystems))
+	for i := range f {
+		f[i] = fileSystems[i]
+	}
+
+	return &multiSourcerFS{
+		fileSystems: f,
+		skipOnError: p.skipOnFSError,
+	}, nil
+}
+
+type multiSourcerFS struct {
+	fileSystems []fs.FS
+	skipOnError bool
+}
+
+func (mf *multiSourcerFS) Open(name string) (fs.File, error) {
+	for _, f := range mf.fileSystems {
+		file, err := f.Open(name)
+
+		if err != nil && !errors.Is(err, fs.ErrNotExist) && !mf.skipOnError {
+			return file, err
+		}
+
+		if err == nil {
+			return file, err
+		}
+	}
+
+	return nil, fs.ErrNotExist
+}