| 1 | package utils |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "flag" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | "net" |
| 10 | "os" |
| 11 | "os/signal" |
| 12 | "strconv" |
| 13 | "strings" |
| 14 | "syscall" |
| 15 | "time" |
| 16 | ) |
| 17 | |
| 18 | type CommandFunc func([]string) error |
| 19 | type IntEnvParser func(string, int) int |
| 20 | type boolFlagValue interface{ IsBoolFlag() bool } |
| 21 | |
| 22 | func trimmedEnv(name string) string { |
| 23 | return strings.TrimSpace(os.Getenv(name)) |
| 24 | } |
| 25 | |
| 26 | func resolveStringEnv(fallback string, envNames ...string) string { |
| 27 | value := fallback |
| 28 | for _, envName := range envNames { |
| 29 | if envValue := trimmedEnv(envName); envValue != "" { |
| 30 | value = envValue |
| 31 | break |
| 32 | } |
| 33 | } |
| 34 | return value |
| 35 | } |
| 36 | |
| 37 | func resolveBoolEnv(fallback bool, envNames ...string) bool { |
| 38 | for _, envName := range envNames { |
| 39 | raw := trimmedEnv(envName) |
| 40 | if raw == "" { |
| 41 | continue |
| 42 | } |
| 43 | parsed, err := strconv.ParseBool(raw) |
| 44 | if err != nil { |
| 45 | return fallback |
| 46 | } |
| 47 | return parsed |
| 48 | } |
| 49 | return fallback |
| 50 | } |
| 51 | |
| 52 | func resolveIntEnv(fallback int, parse IntEnvParser, envNames ...string) int { |
| 53 | if parse == nil { |
| 54 | parse = func(raw string, fallback int) int { |
| 55 | v, err := strconv.Atoi(strings.TrimSpace(raw)) |
| 56 | if err != nil { |
| 57 | return fallback |
| 58 | } |
| 59 | return v |
| 60 | } |
| 61 | } |
| 62 | for _, envName := range envNames { |
| 63 | raw := trimmedEnv(envName) |
| 64 | if raw == "" { |
| 65 | continue |
| 66 | } |
| 67 | return parse(raw, fallback) |
| 68 | } |
| 69 | return fallback |
| 70 | } |
| 71 | |
| 72 | func ParsePortNumber(raw string, fallback int) int { |
| 73 | raw = strings.TrimSpace(raw) |
| 74 | if raw == "" { |
| 75 | return fallback |
| 76 | } |
| 77 | port, err := strconv.Atoi(raw) |
| 78 | if err != nil || port < 1 || port > 65535 { |
| 79 | return fallback |
| 80 | } |
| 81 | return port |
| 82 | } |
| 83 | |
| 84 | func ParseOptionalPortNumber(raw string, fallback int) int { |
| 85 | raw = strings.TrimSpace(raw) |
| 86 | if raw == "" { |
| 87 | return fallback |
| 88 | } |
| 89 | if raw == "0" { |
| 90 | return 0 |
| 91 | } |
| 92 | return ParsePortNumber(raw, fallback) |
| 93 | } |
| 94 | |
| 95 | func DurationOrDefault(v, fallback time.Duration) time.Duration { |
| 96 | if v > 0 { |
| 97 | return v |
| 98 | } |
| 99 | return fallback |
| 100 | } |
| 101 | |
| 102 | func IntOrDefault(v, fallback int) int { |
| 103 | if v > 0 { |
| 104 | return v |
| 105 | } |
| 106 | return fallback |
| 107 | } |
| 108 | |
| 109 | func StringOrDefault(v, fallback string) string { |
| 110 | if v != "" { |
| 111 | return v |
| 112 | } |
| 113 | return fallback |
| 114 | } |
| 115 | |
| 116 | func StringFlag(fs *flag.FlagSet, target *string, name, fallback, usage string) { |
| 117 | ensureFlagSet(fs).StringVar(target, name, fallback, usage) |
| 118 | } |
| 119 | |
| 120 | func StringFlagEnv(fs *flag.FlagSet, target *string, name, fallback, usage string, envNames ...string) { |
| 121 | ensureFlagSet(fs).StringVar(target, name, resolveStringEnv(fallback, envNames...), flagUsage(usage, envNames...)) |
| 122 | } |
| 123 | |
| 124 | func BoolFlag(fs *flag.FlagSet, target *bool, name string, fallback bool, usage string) { |
| 125 | ensureFlagSet(fs).BoolVar(target, name, fallback, usage) |
| 126 | } |
| 127 | |
| 128 | func BoolFlagEnv(fs *flag.FlagSet, target *bool, name string, fallback bool, usage string, envNames ...string) { |
| 129 | ensureFlagSet(fs).BoolVar(target, name, resolveBoolEnv(fallback, envNames...), flagUsage(usage, envNames...)) |
| 130 | } |
| 131 | |
| 132 | func IntFlagEnv(fs *flag.FlagSet, target *int, name string, fallback int, parse IntEnvParser, usage string, envNames ...string) { |
| 133 | ensureFlagSet(fs).IntVar(target, name, resolveIntEnv(fallback, parse, envNames...), flagUsage(usage, envNames...)) |
| 134 | } |
| 135 | |
| 136 | func RepeatedStringFlag(fs *flag.FlagSet, target *[]string, name, usage string) { |
| 137 | ensureFlagSet(fs).Func(name, usage, func(value string) error { |
| 138 | if target == nil { |
| 139 | return nil |
| 140 | } |
| 141 | *target = append(*target, value) |
| 142 | return nil |
| 143 | }) |
| 144 | } |
| 145 | |
| 146 | func ensureFlagSet(fs *flag.FlagSet) *flag.FlagSet { |
| 147 | if fs != nil { |
| 148 | return fs |
| 149 | } |
| 150 | return flag.CommandLine |
| 151 | } |
| 152 | |
| 153 | func flagUsage(usage string, envNames ...string) string { |
| 154 | names := make([]string, 0, len(envNames)) |
| 155 | for _, envName := range envNames { |
| 156 | envName = strings.TrimSpace(envName) |
| 157 | if envName != "" { |
| 158 | names = append(names, envName) |
| 159 | } |
| 160 | } |
| 161 | if len(names) == 0 { |
| 162 | return usage |
| 163 | } |
| 164 | var envUsage string |
| 165 | switch len(names) { |
| 166 | case 1: |
| 167 | envUsage = names[0] |
| 168 | case 2: |
| 169 | envUsage = names[0] + " or " + names[1] |
| 170 | default: |
| 171 | envUsage = strings.Join(names[:len(names)-1], ", ") + ", or " + names[len(names)-1] |
| 172 | } |
| 173 | if strings.TrimSpace(usage) == "" { |
| 174 | return "(env: " + envUsage + ")" |
| 175 | } |
| 176 | return usage + " (env: " + envUsage + ")" |
| 177 | } |
| 178 | |
| 179 | func SignalContext() (context.Context, context.CancelFunc) { |
| 180 | return signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGHUP) |
| 181 | } |
| 182 | |
| 183 | func RunCommands( |
| 184 | args []string, |
| 185 | stdout io.Writer, |
| 186 | stderr io.Writer, |
| 187 | usage func(io.Writer), |
| 188 | commands map[string]CommandFunc, |
| 189 | ) error { |
| 190 | defaultCommand, hasDefaultCommand := commands[""] |
| 191 | if len(args) == 0 { |
| 192 | if hasDefaultCommand { |
| 193 | return defaultCommand(nil) |
| 194 | } |
| 195 | if usage != nil { |
| 196 | usage(stdout) |
| 197 | } |
| 198 | return nil |
| 199 | } |
| 200 | |
| 201 | command := strings.TrimSpace(args[0]) |
| 202 | switch { |
| 203 | case command == "help": |
| 204 | if runCommand, ok := commands[command]; ok { |
| 205 | return runCommand(args[1:]) |
| 206 | } |
| 207 | if usage != nil { |
| 208 | usage(stdout) |
| 209 | } |
| 210 | return nil |
| 211 | case command == "-h" || command == "--help": |
| 212 | if usage != nil { |
| 213 | usage(stdout) |
| 214 | } |
| 215 | return nil |
| 216 | case command == "" || strings.HasPrefix(command, "-"): |
| 217 | if hasDefaultCommand { |
| 218 | return defaultCommand(args) |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | runCommand, ok := commands[command] |
| 223 | if !ok { |
| 224 | if usage != nil { |
| 225 | usage(stderr) |
| 226 | } |
| 227 | return fmt.Errorf("unknown command %q", command) |
| 228 | } |
| 229 | return runCommand(args[1:]) |
| 230 | } |
| 231 | |
| 232 | func NewFlagSet(name string, usage func(io.Writer)) *flag.FlagSet { |
| 233 | fs := flag.NewFlagSet(name, flag.ContinueOnError) |
| 234 | fs.SetOutput(io.Discard) |
| 235 | if usage != nil { |
| 236 | fs.Usage = func() { |
| 237 | usage(fs.Output()) |
| 238 | } |
| 239 | } |
| 240 | return fs |
| 241 | } |
| 242 | |
| 243 | func ParseFlagSet(fs *flag.FlagSet, args []string, usage func(io.Writer)) error { |
| 244 | args = normalizeFlagArgs(fs, args) |
| 245 | if len(args) == 1 && (args[0] == "help" || args[0] == "-h" || args[0] == "--help") { |
| 246 | if usage != nil { |
| 247 | usage(os.Stdout) |
| 248 | } |
| 249 | return flag.ErrHelp |
| 250 | } |
| 251 | if err := fs.Parse(args); err != nil { |
| 252 | if errors.Is(err, flag.ErrHelp) { |
| 253 | if usage != nil { |
| 254 | usage(os.Stdout) |
| 255 | } |
| 256 | return flag.ErrHelp |
| 257 | } |
| 258 | if usage != nil { |
| 259 | usage(os.Stderr) |
| 260 | } |
| 261 | return err |
| 262 | } |
| 263 | return nil |
| 264 | } |
| 265 | |
| 266 | func normalizeFlagArgs(fs *flag.FlagSet, args []string) []string { |
| 267 | if fs == nil || len(args) < 2 { |
| 268 | return args |
| 269 | } |
| 270 | |
| 271 | flags := make([]string, 0, len(args)) |
| 272 | positionals := make([]string, 0, len(args)) |
| 273 | |
| 274 | for i := 0; i < len(args); i++ { |
| 275 | arg := strings.TrimSpace(args[i]) |
| 276 | if arg == "" || arg == "-" || !strings.HasPrefix(arg, "-") { |
| 277 | positionals = append(positionals, args[i]) |
| 278 | continue |
| 279 | } |
| 280 | if arg == "--" { |
| 281 | positionals = append(positionals, args[i+1:]...) |
| 282 | break |
| 283 | } |
| 284 | |
| 285 | name := strings.TrimLeft(strings.TrimSpace(arg), "-") |
| 286 | if name == "" { |
| 287 | positionals = append(positionals, args[i]) |
| 288 | continue |
| 289 | } |
| 290 | hasInlineValue := false |
| 291 | if cut, _, ok := strings.Cut(name, "="); ok { |
| 292 | name = strings.TrimSpace(cut) |
| 293 | hasInlineValue = true |
| 294 | } |
| 295 | if name == "" { |
| 296 | positionals = append(positionals, args[i]) |
| 297 | continue |
| 298 | } |
| 299 | |
| 300 | flags = append(flags, args[i]) |
| 301 | |
| 302 | flagDef := fs.Lookup(name) |
| 303 | if hasInlineValue || flagDef == nil { |
| 304 | continue |
| 305 | } |
| 306 | boolValue, ok := flagDef.Value.(boolFlagValue) |
| 307 | if ok && boolValue.IsBoolFlag() { |
| 308 | if i+1 < len(args) { |
| 309 | next := strings.TrimSpace(args[i+1]) |
| 310 | if _, err := strconv.ParseBool(next); err == nil { |
| 311 | flags[len(flags)-1] = args[i] + "=" + next |
| 312 | i++ |
| 313 | } |
| 314 | } |
| 315 | continue |
| 316 | } |
| 317 | if i+1 >= len(args) { |
| 318 | continue |
| 319 | } |
| 320 | i++ |
| 321 | flags = append(flags, args[i]) |
| 322 | } |
| 323 | |
| 324 | return append(flags, positionals...) |
| 325 | } |
| 326 | |
| 327 | func OptionalSingleArg(args []string, name string) (string, error) { |
| 328 | switch len(args) { |
| 329 | case 0: |
| 330 | return "", nil |
| 331 | case 1: |
| 332 | return strings.TrimSpace(args[0]), nil |
| 333 | default: |
| 334 | return "", fmt.Errorf("only one %s is supported", strings.TrimSpace(name)) |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | func RequireNoArgs(args []string, command string) error { |
| 339 | if len(args) == 0 { |
| 340 | return nil |
| 341 | } |
| 342 | return fmt.Errorf("%s does not accept positional arguments", strings.TrimSpace(command)) |
| 343 | } |
| 344 | |
| 345 | func NormalizeLoopbackTarget(raw string) (string, error) { |
| 346 | raw = strings.TrimSpace(raw) |
| 347 | if raw == "" { |
| 348 | return "", nil |
| 349 | } |
| 350 | if port, ok := strings.CutPrefix(raw, ":"); ok { |
| 351 | if _, err := strconv.Atoi(port); err == nil { |
| 352 | return net.JoinHostPort("127.0.0.1", port), nil |
| 353 | } |
| 354 | } |
| 355 | if _, err := strconv.Atoi(raw); err == nil { |
| 356 | return net.JoinHostPort("127.0.0.1", raw), nil |
| 357 | } |
| 358 | return NormalizeTargetAddr(raw) |
| 359 | } |
| 360 | |
| 361 | // HelpTopic maps a subcommand name to its usage printer. |
| 362 | type HelpTopic struct { |
| 363 | Name string |
| 364 | Usage func(io.Writer) |
| 365 | } |
| 366 | |
| 367 | // MakeHelpCommand returns a CommandFunc that dispatches help topics. |
| 368 | // Topics are matched in order; the slice provides deterministic output. |
| 369 | func MakeHelpCommand(rootUsage func(io.Writer), topics []HelpTopic) CommandFunc { |
| 370 | return func(args []string) error { |
| 371 | if len(args) == 0 { |
| 372 | rootUsage(os.Stdout) |
| 373 | return nil |
| 374 | } |
| 375 | if len(args) > 1 { |
| 376 | rootUsage(os.Stderr) |
| 377 | return errors.New("only one help topic is supported") |
| 378 | } |
| 379 | topic := strings.TrimSpace(args[0]) |
| 380 | switch topic { |
| 381 | case "", "help", "-h", "--help": |
| 382 | rootUsage(os.Stdout) |
| 383 | return nil |
| 384 | } |
| 385 | for _, t := range topics { |
| 386 | if t.Name == topic { |
| 387 | t.Usage(os.Stdout) |
| 388 | return nil |
| 389 | } |
| 390 | } |
| 391 | rootUsage(os.Stderr) |
| 392 | return fmt.Errorf("unknown help topic %q", topic) |
| 393 | } |
| 394 | } |
| 395 | |
| 396 | func WriteCommandUsage(w io.Writer, usage []string, examples []string) { |
| 397 | if w == nil { |
| 398 | return |
| 399 | } |
| 400 | if len(usage) > 0 { |
| 401 | fmt.Fprintln(w, "Usage:") |
| 402 | for _, line := range usage { |
| 403 | fmt.Fprintln(w, " "+strings.TrimSpace(line)) |
| 404 | } |
| 405 | } |
| 406 | if len(examples) == 0 { |
| 407 | return |
| 408 | } |
| 409 | fmt.Fprintln(w) |
| 410 | fmt.Fprintln(w, "Examples:") |
| 411 | for _, line := range examples { |
| 412 | fmt.Fprintln(w, " "+strings.TrimSpace(line)) |
| 413 | } |
| 414 | } |