Feat: UDP 框架

cmd/udppeer/interactive.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var errUDPEmptyCommand = errors.New("interactive command is empty")
+
+type udpInteractiveCommand struct {
+	name  string
+	to    string
+	value string
+}
+
+func parseUDPInteractiveCommand(line string) (udpInteractiveCommand, error) {
+	commandName, rest, ok := cutUDPField(strings.TrimSpace(line))
+	if !ok {
+		return udpInteractiveCommand{}, errUDPEmptyCommand
+	}
+
+	switch strings.ToLower(commandName) {
+	case "help", "h", "?":
+		return udpInteractiveCommand{name: "help"}, nil
+	case "quit", "exit":
+		return udpInteractiveCommand{name: "quit"}, nil
+	case "text":
+		to, body, err := parseUDPTargetValue(rest, "text")
+		if err != nil {
+			return udpInteractiveCommand{}, err
+		}
+		return udpInteractiveCommand{name: "text", to: to, value: body}, nil
+	case "file":
+		to, path, err := parseUDPTargetValue(rest, "file")
+		if err != nil {
+			return udpInteractiveCommand{}, err
+		}
+		return udpInteractiveCommand{name: "file", to: to, value: path}, nil
+	default:
+		return udpInteractiveCommand{}, fmt.Errorf("unknown command %q; type help for usage", commandName)
+	}
+}
+
+func parseUDPTargetValue(rest, commandName string) (string, string, error) {
+	to, value, ok := cutUDPField(strings.TrimSpace(rest))
+	if !ok {
+		return "", "", fmt.Errorf("%s command requires a target peer and payload", commandName)
+	}
+	if strings.TrimSpace(value) == "" {
+		return "", "", fmt.Errorf("%s command requires a non-empty payload", commandName)
+	}
+
+	return to, strings.TrimSpace(value), nil
+}
+
+func cutUDPField(input string) (string, string, bool) {
+	trimmed := strings.TrimSpace(input)
+	if trimmed == "" {
+		return "", "", false
+	}
+
+	for i, r := range trimmed {
+		if r == ' ' || r == '\t' {
+			return trimmed[:i], strings.TrimSpace(trimmed[i+1:]), true
+		}
+	}
+
+	return trimmed, "", true
+}