Resolve entered command routes to canonical paths

route.go

@@ -0,0 +1,96 @@
+package commandkit
+
+import (
+	"strings"
+
+	"gitea.maximumdirect.net/eric/CommandKit/internal/commandpath"
+)
+
+type routeKind uint8
+
+const (
+	routeUnknown routeKind = iota
+	routeCanonical
+	routeDiscovery
+)
+
+type routeResult struct {
+	kind          routeKind
+	args          []string
+	enteredPath   commandpath.Path
+	canonicalPath commandpath.Path
+	discoveryPath commandpath.Path
+}
+
+func resolveEnteredRoute(args []string, snapshot *routingSnapshot) routeResult {
+	path, trailing := commandPathTokens(args)
+	result := routeResult{kind: routeUnknown}
+	if snapshot == nil {
+		result.args = append(append([]string(nil), path...), trailing...)
+		result.enteredPath = path.Clone()
+		return result
+	}
+
+	resolved, origins := snapshot.aliases.ResolveWithProvenance(path)
+	trace := traceCanonicalPath(snapshot.canonical, resolved)
+	switch {
+	case trace.exact != nil:
+		result.kind = routeCanonical
+		result.canonicalPath = trace.exact.path.Clone()
+	case trace.operandOwner != nil:
+		result.kind = routeCanonical
+		result.canonicalPath = trace.operandOwner.path.Clone()
+	}
+
+	if result.kind == routeCanonical {
+		result.enteredPath = enteredEndpoint(path, origins, len(result.canonicalPath))
+	} else if len(path) == 0 {
+		result.kind = routeCanonical
+	} else if discovery, ok := findDiscoveryPath(snapshot.discoveryFlags, path); ok {
+		result.kind = routeDiscovery
+		result.discoveryPath = discovery
+		result.enteredPath = discovery.Clone()
+	} else {
+		result.enteredPath = path.Clone()
+	}
+
+	result.args = make([]string, 0, len(resolved)+len(trailing))
+	result.args = append(result.args, resolved...)
+	result.args = append(result.args, trailing...)
+	return result
+}
+
+func commandPathTokens(args []string) (commandpath.Path, []string) {
+	end := len(args)
+	for index, token := range args {
+		if token == "--" || (token != "-" && strings.HasPrefix(token, "-")) {
+			end = index
+			break
+		}
+	}
+	path := make(commandpath.Path, end)
+	copy(path, args[:end])
+	return path, append([]string(nil), args[end:]...)
+}
+
+func enteredEndpoint(path commandpath.Path, origins [][]int, canonicalLength int) commandpath.Path {
+	inputLength := 0
+	for _, componentOrigins := range origins[:canonicalLength] {
+		for _, origin := range componentOrigins {
+			if origin+1 > inputLength {
+				inputLength = origin + 1
+			}
+		}
+	}
+	return path[:inputLength].Clone()
+}
+
+func findDiscoveryPath(contexts map[string]resolvedFlagAliases, path commandpath.Path) (commandpath.Path, bool) {
+	for length := len(path); length > 0; length-- {
+		prefix := path[:length]
+		if _, exists := contexts[prefix.Key()]; exists {
+			return prefix.Clone(), true
+		}
+	}
+	return nil, false
+}