Split up WissKI Instance code

internal/component/instances/wisski_prefix.go

@@ -0,0 +1,58 @@
+package instances
+
+import (
+	"errors"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/fsx"
+	"github.com/tkw1536/goprogram/stream"
+)
+
+// NoPrefix checks if this WissKI instance is excluded from generating prefixes.
+// TODO: Move this to the database!
+func (wisski *WissKI) NoPrefix() bool {
+	return fsx.IsFile(filepath.Join(wisski.FilesystemBase, "prefixes.skip"))
+}
+
+var errPrefixExecFailed = errors.New("PrefixConfig: Failed to call list_uri_prefixes")
+
+// PrefixConfig returns the prefix config belonging to this instance.
+func (wisski *WissKI) PrefixConfig() (config string, err error) {
+	// if the user requested to skip the prefix, then don't do anything with it!
+	if wisski.NoPrefix() {
+		return "", nil
+	}
+
+	var builder strings.Builder
+
+	// domain
+	builder.WriteString(wisski.URL().String() + ":")
+	builder.WriteString("\n")
+
+	// default prefixes
+	wu := stream.NewIOStream(&builder, nil, nil, 0)
+	code, err := wisski.Barrel().Exec(wu, "barrel", "/bin/bash", "/user_shell.sh", "-c", "drush php:script /wisskiutils/list_uri_prefixes.php")
+	if err != nil || code != 0 {
+		return "", errPrefixExecFailed
+	}
+
+	// custom prefixes
+	prefixPath := filepath.Join(wisski.FilesystemBase, "prefixes")
+	if fsx.IsFile(prefixPath) {
+		prefix, err := os.Open(prefixPath)
+		if err != nil {
+			return "", err
+		}
+		defer prefix.Close()
+		if _, err := io.Copy(&builder, prefix); err != nil {
+			return "", err
+		}
+		builder.WriteString("\n")
+	}
+
+	// and done!
+	return builder.String(), nil
+}