Resolve command context for completion

completion_context.go

@@ -0,0 +1,80 @@
+package commandkit
+
+import (
+	"strings"
+
+	internalcobra "gitea.maximumdirect.net/eric/CommandKit/internal/cobra"
+	commandmeta "gitea.maximumdirect.net/eric/CommandKit/internal/commandmeta"
+	"gitea.maximumdirect.net/eric/CommandKit/internal/commandpath"
+)
+
+type completionContext struct {
+	route           routeResult
+	command         *commandmeta.Command
+	aliases         []commandmeta.FlagAlias
+	completed       []string
+	tail            []string
+	current         string
+	commandPosition bool
+}
+
+func resolveCompletionContext(snapshot *routingSnapshot, completed []string, current string) completionContext {
+	context := completionContext{completed: append([]string(nil), completed...), current: current}
+	if snapshot == nil {
+		return context
+	}
+	context.route = resolveEnteredRoute(completed, snapshot)
+	switch context.route.kind {
+	case routeCanonical:
+		context.command = completionCommand(snapshot.metadata, context.route.canonicalPath)
+		if context.command == nil || len(context.route.args) < len(context.route.canonicalPath) {
+			context.command = nil
+			return context
+		}
+		context.tail = append([]string(nil), context.route.args[len(context.route.canonicalPath):]...)
+		context.aliases = snapshot.flagAliases[context.route.canonicalPath.Key()].neutralRecords()
+		context.commandPosition = len(context.tail) == 0
+	case routeDiscovery:
+		context.command = &commandmeta.Command{CoreFlags: commandmeta.ReportingFlags()}
+		context.tail = append([]string(nil), context.route.args...)
+		context.aliases = snapshot.discoveryFlags[context.route.discoveryPath.Key()].neutralRecords()
+	}
+	return context
+}
+
+func completionCommand(root *commandmeta.Command, path commandpath.Path) *commandmeta.Command {
+	current := root
+	for _, name := range path {
+		if current == nil {
+			return nil
+		}
+		var next *commandmeta.Command
+		for _, child := range current.Children {
+			if child.Name == name {
+				next = child
+				break
+			}
+		}
+		current = next
+	}
+	return current
+}
+
+func completionChildren(snapshot *routingSnapshot, context completionContext) []commandmeta.CompletionChoice {
+	if snapshot == nil || context.command == nil || !context.commandPosition {
+		return nil
+	}
+	var choices []commandmeta.CompletionChoice
+	for _, child := range context.command.Children {
+		if !strings.HasPrefix(child.Name, context.current) || (len(context.route.canonicalPath) == 0 && child.Name == internalcobra.CompletionQueryToken) {
+			continue
+		}
+		entered := append(append([]string(nil), context.completed...), child.Name)
+		route := resolveEnteredRoute(entered, snapshot)
+		intended := append(context.route.canonicalPath.Clone(), child.Name)
+		if route.kind == routeCanonical && route.canonicalPath.Equal(intended) {
+			choices = append(choices, commandmeta.CompletionChoice{Value: child.Name, Description: child.Summary})
+		}
+	}
+	return choices
+}