'wdcli backup': Rework backup process

This commit reworks the backup process to dynamically find the list of
components.

internal/component/control/resolver.go

@@ -0,0 +1,61 @@
+package control
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"github.com/FAU-CDI/wdresolve"
+	"github.com/FAU-CDI/wdresolve/resolvers"
+	"github.com/tkw1536/goprogram/stream"
+)
+
+func (control Control) ResolverConfigPath() string {
+	return filepath.Join(control.Dir, control.ResolverFile)
+}
+
+func (control Control) resolver(io stream.IOStream) (p wdresolve.ResolveHandler, err error) {
+	p.TrustXForwardedProto = true
+
+	fallback := &resolvers.Regexp{
+		Data: map[string]string{},
+	}
+
+	// handle the default domain name!
+	domainName := control.Config.DefaultDomain
+	if domainName != "" {
+		fallback.Data[fmt.Sprintf("^https?://(.*)\\.%s", regexp.QuoteMeta(domainName))] = fmt.Sprintf("https://$1.%s", domainName)
+		io.Printf("registering default domain %s\n", domainName)
+	}
+
+	// handle the extra domains!
+	for _, domain := range control.Config.SelfExtraDomains {
+		fallback.Data[fmt.Sprintf("^https?://(.*)\\.%s", regexp.QuoteMeta(domain))] = fmt.Sprintf("https://$1.%s", domainName)
+		io.Printf("registering legacy domain %s\n", domain)
+	}
+
+	// open the prefix file
+	prefixFile := control.ResolverConfigPath()
+	fs, err := os.Open(prefixFile)
+	io.Println("loading prefixes from ", prefixFile)
+	if err != nil {
+		return p, err
+	}
+	defer fs.Close()
+
+	// read the prefixes
+	// TODO: Do we want to load these without a file?
+	prefixes, err := resolvers.ReadPrefixes(fs)
+	if err != nil {
+		return p, err
+	}
+
+	// and use that as the resolver!
+	p.Resolver = resolvers.InOrder{
+		prefixes,
+		fallback,
+	}
+
+	return p, nil
+}