optly.h

/*
  optly.h — v2.3.1
  Single-header command line argument parser for C.

  Features
  --------
  * STB-style single-header library
  * Commands and command-specific flags
  * Long flags (--verbose)
  * Short flags (-v)
  * Batched short flags (-abc)
  * Inline flag values (--threads=4)
  * Separate flag values (--threads 4)
  * Typed flag values
  * Positional arguments
  * Optional commands
  * Optional flags
  * No dynamic memory allocation
  * Portable C (C99)

  Basic Usage
  -----------

    #define OPTLY_IMPLEMENTATION
    #include "optly.h"

    // You need to define "main" command, which is your application.
    // Note: If you compile with `gcc` with flag `-pedantic` this will fire warning.
    //       To suppress it have static variables for flags, commands and enum flag values separately,
    //       or move cmd to runtime (to `main` function)
    static OptlyCommand cmd = {

      // Name will be used in usage. If you set is as NULL it will be argv[0]
      .name = NULL,

      // If not null, then it will be used in usage
      .description = NULL,

      // This is your "top-level global" flags. They should be specified before any command (./app --thread 2 -v)
      .flags = (OptlyFlag[]){
        // Long (full name)   short name   description (for usage)  Default value           Flag value  type
        { "verbose",          'v',         "Enable verbose output", .value.as_bool = false, .type = OPTLY_TYPE_BOOL   },

        // Values are unions, so you need to specify member of value with correct type some way
        { "threads",          't',         "Worker threads", false, {.as_uint32 = 4},       OPTLY_TYPE_UINT32 },

        // Flag arrays should alwasy ends with NULL_FLAG. Try to not forget about it :)
        NULL_FLAG,
      },

      // This is your commands. (git `commit`, docker `compose` `up`)
      .commands = (OptlyCommand[]){

        // Instead of defining whole struct manually you can use helper functions
        optly_command("run", "Runs server",

          // optly_flags macro deals with type castings and closing array with NULL_FLAG
          optly_flags(

            // This is *command* flag. `./app -p 8080 run` will not work, but `./app run -p 8080` will
            optly_flag_uint16("port", 'p', "Server port", .value.as_uint16 = 8080)

            // NOTE: this flag and 'verbose' GLOBAL flag are not the same
            // `./app -v run` - enables global -v flag
            // `./app run -v` - enables command -v flag
            optly_flag_bool("verbose", 'v', "Enable verbose output for worker", .value.as_bool = false)
          ),

          // This is subcommands of command "run"
          optly_commands(

            // `./app run check` subcommand have no description, flags or subcommands.
            //  NULL is here to suppress warning about not providing argument in variadic macro
            optly_command("check", NULL),

            // `./app run dump_config` subcommands
            optly_command("dump_config",

              // We skipped description, so we need to specify fileds now
              .flags = optly_flags(
                optly_flag_bool("color", 'c', "Show colors", .value.as_bool = false)
              )
            )
          ),

          // Positioanl arguments can be defined lilke this
          optly_positionals(optly_positional("address", "Address to listen on", .min = 0, .max = 1)),
        ),
      }
    };

    int main(int argc, char **argv) {
      optly_parse_args(argc, argv, &cmd);

      printf("Verbose: %s\n", optly_flag_value_bool(&cmd, "verbose") ? "true" : "false");
      printf("Threads: %u\n", optly_flag_value_uint32(&cmd, "threads"));

      if (!cmd.next_command) {
        return 0;
      }

      printf("Command: %s\n", cmd.next_command->name);

      printf("Verbose: %s\n", optly_flag_value_bool(cmd.next_command, "verbose") ? "true" : "false");
      printf("Port: %u\n", optly_flag_value_uint16(cmd.next_command, "port"));

      if (cmd.next_command->next_command) {
        printf("Command: %s\n", cmd.next_command->next_command->name);
      }

      OptlyPositional *address = optly_get_positional(&cmd, "address");

      if (address && address->count == 1) {
        printf("Address: %s\n", address->values[1]);
      } else {
        printf("Address: 0.0.0.0\n");
      }
    }

  Commands
  --------

  Commands are positional tokens that do not begin with '-'.

    app build
    app run

  Each command may define its own flags.

  Flags
  -----

  Flags may be long or short.

    --verbose
    -v

  Flags may have values.

    --threads=4
    --threads 4
    -t 4

  Short flags can be batched.

    -abc  ->  -a -b -c

  Positional Arguments
  --------------------

  Any non-flag tokens after command selection are stored as positional arguments.

    app build file1 file2

  Access:

  Named positional: (can have many valies inside)

    Positional *pos = optly_get_positional(&cmd, "name");

  Or directly through command:

    for (OptlyPositional *p = cmd.positionals; p->name; p++) {
      // ...
    }

  Help and version command/flag generation
  ----------------------------

  You can define

    #define OPTLY_GEN_HELP_FLAG
    #define OPTLY_GEN_HELP_COMMAND

  to generate help flag `--help | -h` and/or help command `help cmd`, or

  #define OPTLY_GEN_VERSION_FLAG
  #define OPTLY_GEN_VERSION_COMMAND

  to generate version flag `--version | -v` and/or version command `version`.

  If help/version command/flag would be found during parsing usage would be
  automatically called and `exit(0)` is called.

  Note that user defined flags with `-h`/`-v` would interfere with generated flags.

  Error and logging handling
  --------------

  This library always logs errors internally using OPTLY_LOG.

  Instead of failing on first error, Optly now accumulates all errors during parsing.

  `optly_parse_args()` returns an `OptlyErrors` struct:

    OptlyErrors errs = optly_parse_args(argc, argv, &cmd);

    for (size_t i = 0; i < optly_errors_count(&errs); i++) {
      OptlyError e = optly_errors_at(&errs, i);
      printf("Error: %s", optly_error_message(e.kind));

      if (e.arg) {
        printf(" (%s)", e.arg);
      }

      printf("\n");
    }

  Each error may include optional context, which could be - flag, value, command or positional name

  By default, Optly will call `exit()` if any errors occurred.

  To disable this behavior:

    #define OPTLY_NO_EXIT

  This is useful for:
  - testing
  - custom error handling

  The best way to control logging is to use Logcie library (https://github.com/strongleong/logcie).
  Or have a look at OPTLY_LOG family of macros.

  Licese
  ------

  MIT/Public domain - choose whitchever you prefer
*/

#ifndef OPTLY_H
#define OPTLY_H

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#ifndef OPTLYDEF
#define OPTLYDEF
#endif  // OPTLYDEF

// Versioning macros
#define OPTLY_VERSION_MAJOR         2
#define OPTLY_VERSION_MINOR         3
#define OPTLY_VERSION_RELEASE       1
#define OPTLY_VERSION_NUMBER        (OPTLY_VERSION_MAJOR * 100 * 100 + OPTLY_VERSION_MINOR * 100 + OPTLY_VERSION_RELEASE)
#define OPTLY_VERSION_FULL          OPTLY_VERSION_MAJOR.OPTLY_VERSION_MINOR.OPTLY_VERSION_RELEASE
#define OPTLY_QUOTE(str)            #str
#define OPTLY_EXPAND_AND_QUOTE(str) OPTLY_QUOTE(str)
#define OPTLY_VERSION_STRING        OPTLY_EXPAND_AND_QUOTE(OPTLY_VERSION_FULL)

// If you need more that 64 positional arguments per ONE command
// you should look in the mirror really deep
#ifndef OPTLY_MAX_POSITIONALS
#define OPTLY_MAX_POSITIONALS 64
#endif

#ifndef OPTLY_FLAG_BUFFER_LENGTH
#define OPTLY_FLAG_BUFFER_LENGTH 256
#endif

#ifndef OPTLY_MAX_ERRORS
#define OPTLY_MAX_ERRORS 32
#endif

#ifndef OPTLY_HELP_SHORT_FLAG
#define OPTLY_HELP_SHORT_FLAG "-h"
#endif

#ifndef OPTLY_VERSION_SHORT_FLAG
#define OPTLY_VERSION_SHORT_FLAG "-v"
#endif

typedef enum OptlyFlagType {
  OPTLY_TYPE_BOOL,
  OPTLY_TYPE_CHAR,
  OPTLY_TYPE_STRING,
  OPTLY_TYPE_INT8,
  OPTLY_TYPE_INT16,
  OPTLY_TYPE_INT32,
  OPTLY_TYPE_INT64,
  OPTLY_TYPE_UINT8,
  OPTLY_TYPE_UINT16,
  OPTLY_TYPE_UINT32,
  OPTLY_TYPE_UINT64,
  OPTLY_TYPE_FLOAT,
  OPTLY_TYPE_DOUBLE,
  OPTLY_TYPE_ENUM,
} OptlyFlagType;

typedef union OptlyFlagValue {
  bool as_bool;

  char   as_char;
  char  *as_string;
  char **as_enum;

  int8_t  as_int8;
  int16_t as_int16;
  int32_t as_int32;
  int64_t as_int64;

  uint8_t  as_uint8;
  uint16_t as_uint16;
  uint32_t as_uint32;
  uint64_t as_uint64;

  float  as_float;
  double as_double;
} OptlyFlagValue;

typedef struct {
  char *fullname;
  char  shortname;
  char *description;

  bool required;
  bool present;

  OptlyFlagValue value;
  OptlyFlagType  type;
} OptlyFlag;

typedef struct {
  char *name;
  char *description;

  size_t min;
  size_t max;

  char  *values[OPTLY_MAX_POSITIONALS];
  size_t count;
} OptlyPositional;

typedef struct OptlyCommand OptlyCommand;

struct OptlyCommand {
  char *name;
  char *description;

  OptlyFlag       *flags;
  OptlyCommand    *commands;
  OptlyPositional *positionals;

  OptlyCommand *next_command;
};

typedef enum OptlyErrorKind {
  OPTLY_OK = 0,
  OPTLY_ERR_UNKNOWN_FLAG,
  OPTLY_ERR_UNKNOWN_COMMAND,
  OPTLY_ERR_MISSING_VALUE,
  OPTLY_ERR_INVALID_VALUE,
  OPTLY_ERR_MISSING_REQUIRED,
  OPTLY_ERR_POSITIONAL_TOO_FEW,
  OPTLY_ERR_POSITIONAL_TOO_MANY,
  OPTLY_ERR_DUPLICATE_VARIADIC,
  OPTLY_ERR_BATCH_NON_BOOL,
  Count_OptlyError
} OptlyErrorKind;

typedef struct OptlyError {
  OptlyErrorKind kind;
  const char    *arg;
} OptlyError;

typedef struct OptlyErrors {
  OptlyError items[OPTLY_MAX_ERRORS];
  size_t     count;
} OptlyErrors;

OPTLYDEF size_t      optly_errors_count(const OptlyErrors *errs);
OPTLYDEF OptlyError  optly_errors_at(const OptlyErrors *errs, size_t i);
OPTLYDEF const char *optly_error_message(OptlyErrorKind err);
OPTLYDEF void        optly_error_print(const OptlyErrors *errs);

#define NULL_FLAG       {.fullname = NULL, .shortname = 0, .value = {.as_int64 = 0}, .type = 0}
#define NULL_COMMAND    {.name = NULL, .flags = NULL}
#define NULL_POSITIONAL {.name = NULL}

// NOTE: Forcing designated initializer for automatically zero-initializing missing fields
#define optly_flag(name, ...)        \
  (OptlyFlag) {                      \
    .fullname = (name), __VA_ARGS__, \
    .present  = false                \
  }

#define optly_command(namme, ...) \
  (OptlyCommand) {                \
    .name = (namme), __VA_ARGS__  \
  }

#define optly_flags(...)   \
  (OptlyFlag[]) {          \
    __VA_ARGS__, NULL_FLAG \
  }
#define optly_commands(...)   \
  (OptlyCommand[]) {          \
    __VA_ARGS__, NULL_COMMAND \
  }

#define optly_positional(namme, ...) \
  (OptlyPositional) {                \
    .name = (namme), __VA_ARGS__     \
  }
#define optly_positionals(...)   \
  (OptlyPositional[]) {          \
    __VA_ARGS__, NULL_POSITIONAL \
  }

#define optly_flag_bool(name, ...)   optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_BOOL)
#define optly_flag_char(name, ...)   optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_CHAR)
#define optly_flag_string(name, ...) optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_STRING)
#define optly_flag_int8(name, ...)   optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_INT8)
#define optly_flag_int16(name, ...)  optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_INT16)
#define optly_flag_int32(name, ...)  optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_INT32)
#define optly_flag_int64(name, ...)  optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_INT64)
#define optly_flag_uint8(name, ...)  optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_UINT8)
#define optly_flag_uint16(name, ...) optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_UINT16)
#define optly_flag_uint32(name, ...) optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_UINT32)
#define optly_flag_uint64(name, ...) optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_UINT64)
#define optly_flag_float(name, ...)  optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_FLOAT)
#define optly_flag_double(name, ...) optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_DOUBLE)
#define optly_flag_enum(name, ...)   optly_flag(name, __VA_ARGS__, .type = OPTLY_TYPE_ENUM)

#define optly_enum_values(default, ...) \
  .value.as_enum = (char *[]) {         \
    default, __VA_ARGS__, NULL          \
  }

#if defined(OPTLY_GEN_VERSION_FLAG) || defined(OPTLY_GEN_VERSION_COMMAND)
OPTLYDEF OptlyErrors optly_parse_args(int argc, char *argv[], OptlyCommand *main_cmd, const char *version);
#else
OPTLYDEF OptlyErrors optly_parse_args(int argc, char *argv[], OptlyCommand *main_cmd);
#endif

OPTLYDEF bool             optly_is_command(OptlyCommand *command, const char *name);
OPTLYDEF const OptlyFlag *optly_get_flag(const OptlyFlag *flags, const char *name);
OPTLYDEF OptlyPositional *optly_get_positional(OptlyCommand *command, const char *name);

OPTLYDEF void optly_usage(OptlyCommand *command);

static inline bool optly_is_flag_null(const OptlyFlag *flag) {
  return flag == NULL || (flag->fullname == NULL && flag->shortname == 0);
}

static inline bool optly_is_command_null(const OptlyCommand *cmd) {
  return cmd == NULL || cmd->name == NULL;
}

inline OPTLYDEF bool             optly_flag_value_bool(const OptlyCommand *command, const char *name);
inline OPTLYDEF char             optly_flag_value_char(const OptlyCommand *command, const char *name);
inline OPTLYDEF char            *optly_flag_value_string(const OptlyCommand *command, const char *name);
inline OPTLYDEF int8_t           optly_flag_value_int8(const OptlyCommand *command, const char *name);
inline OPTLYDEF int16_t          optly_flag_value_int16(const OptlyCommand *command, const char *name);
inline OPTLYDEF int32_t          optly_flag_value_int32(const OptlyCommand *command, const char *name);
inline OPTLYDEF int64_t          optly_flag_value_int64(const OptlyCommand *command, const char *name);
inline OPTLYDEF uint8_t          optly_flag_value_uint8(const OptlyCommand *command, const char *name);
inline OPTLYDEF uint16_t         optly_flag_value_uint16(const OptlyCommand *command, const char *name);
inline OPTLYDEF uint32_t         optly_flag_value_uint32(const OptlyCommand *command, const char *name);
inline OPTLYDEF uint64_t         optly_flag_value_uint64(const OptlyCommand *command, const char *name);
inline OPTLYDEF float            optly_flag_value_float(const OptlyCommand *command, const char *name);
inline OPTLYDEF double           optly_flag_value_double(const OptlyCommand *command, const char *name);
inline OPTLYDEF OptlyPositional *optly_get_positional(OptlyCommand *command, const char *name);

#endif  // OPTLY_H

// -----------------------------------

#ifdef OPTLY_IMPLEMENTATION

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

// Logcie integration

#ifndef OPTLY_LOG
#ifdef LOGCIE
#ifdef LOGCIE_VA_LOGS
#define OPTLY_LOG(level, ...) LOGCIE_##level##_VA(__VA_ARGS__)
#else
#define OPTLY_LOG(level, ...) LOGCIE_##level(__VA_ARGS__)
#endif
#else
#define OPTLY_LOG(level, ...)                \
  do {                                       \
    fprintf(stderr, #level ": "__VA_ARGS__); \
    fprintf(stderr, "\n");                   \
  } while (0)
#endif
#endif

#define SHIFT_ARG(argv, argc) (++(argv), --(argc))

static const char *error_messages[] = {
  [OPTLY_OK]                      = "No error",
  [OPTLY_ERR_UNKNOWN_FLAG]        = "Unknown flag",
  [OPTLY_ERR_UNKNOWN_COMMAND]     = "Unknown command",
  [OPTLY_ERR_MISSING_VALUE]       = "Flag requires a value",
  [OPTLY_ERR_INVALID_VALUE]       = "Invalid value for flag",
  [OPTLY_ERR_MISSING_REQUIRED]    = "Required flag is not present",
  [OPTLY_ERR_POSITIONAL_TOO_FEW]  = "Not enough positional arguments",
  [OPTLY_ERR_POSITIONAL_TOO_MANY] = "Too many positional arguments",
  [OPTLY_ERR_DUPLICATE_VARIADIC]  = "Duplicate variadic positional",
  [OPTLY_ERR_BATCH_NON_BOOL]      = "Cannot batch non-boolean flags",
};

OPTLYDEF const char *optly_error_message(OptlyErrorKind err) {
#if __STDC_VERSION__ >= 201112L  // Check for C11 support
  static_assert(Count_OptlyError == 10, "Forgot to update optly_error_message");
#else
  assert(Count_OptlyError == 10 && "Forgot to update optly_error_message");
#endif

  assert(err >= OPTLY_OK && err < Count_OptlyError);
  return error_messages[err];
}

OPTLYDEF void optly_error_print(const OptlyErrors *errs) {
  for (size_t i = 0; i < errs->count; i++) {
    fprintf(stdout, "ERROR: %s (%s)\n", optly_error_message(errs->items[i].kind), errs->items[i].arg);
  }
}

static void optly__push_error(OptlyErrors *errs, OptlyErrorKind err, const char *arg) {
  if (!errs) {
    return;
  }

  if (errs->count < OPTLY_MAX_ERRORS) {
    errs->items[errs->count++] = (OptlyError){err, arg};
  }
}

#ifdef OPTLY_NO_EXIT
#define OPTLY_EXIT(errs, code)
#else
#define OPTLY_EXIT(errs, code) \
  do { exit(code); } while (0)
#endif

OPTLYDEF size_t optly_errors_count(const OptlyErrors *errs) {
  return errs ? errs->count : 0;
}

OPTLYDEF OptlyError optly_errors_at(const OptlyErrors *errs, size_t i) {
  return errs->items[i];
}

static bool optly__has_flags(OptlyCommand *cmd) {
  return cmd && cmd->flags && !optly_is_flag_null(cmd->flags);
}

static bool optly__has_commands(OptlyCommand *cmd) {
  return cmd && cmd->commands && !optly_is_command_null(cmd->commands);
}

static bool optly__has_positionals(OptlyCommand *cmd) {
  return cmd && cmd->positionals && cmd->positionals->name;
}

static void optly__usage_positionals_signature(OptlyPositional *pos) {
  if (!pos) return;

  for (; pos->name; pos++) {
    bool required = pos->min > 0;
    bool variadic = pos->max == 0 || pos->max > 1;

    if (required)
      fprintf(stderr, " <%s%s>", pos->name, variadic ? "..." : "");
    else
      fprintf(stderr, " [%s%s]", pos->name, variadic ? "..." : "");
  }
}

static void optly__usage_signature(OptlyCommand *cmd) {
  fprintf(stderr, "Usage: %s", cmd->name);

  if (optly__has_flags(cmd))
    fprintf(stderr, " [FLAGS]");

  if (optly__has_positionals(cmd))
    optly__usage_positionals_signature(cmd->positionals);

  if (optly__has_commands(cmd))
    fprintf(stderr, " <COMMAND>");

  fprintf(stderr, "\n");
}

static uint8_t type_name_pad = 8;

static const char *optly__flag_type_name(OptlyFlagType type) {
  switch (type) {
    case OPTLY_TYPE_BOOL:   return "";
    case OPTLY_TYPE_CHAR:   return "<char>";
    case OPTLY_TYPE_STRING: return "<str>";
    case OPTLY_TYPE_INT8:   return "<i8>";
    case OPTLY_TYPE_INT16:  return "<i16>";
    case OPTLY_TYPE_INT32:  return "<i32>";
    case OPTLY_TYPE_INT64:  return "<i64>";
    case OPTLY_TYPE_UINT8:  return "<u8>";
    case OPTLY_TYPE_UINT16: return "<u16>";
    case OPTLY_TYPE_UINT32: return "<u32>";
    case OPTLY_TYPE_UINT64: return "<u64>";
    case OPTLY_TYPE_FLOAT:  return "<float>";
    case OPTLY_TYPE_DOUBLE: return "<double>";
    case OPTLY_TYPE_ENUM:   return "<enum>";
  }

  return "";
}

static size_t optly__flag_print_width(OptlyFlag *flags) {
  size_t max = 0;

  for (OptlyFlag *flag = flags; !optly_is_flag_null(flag); flag++) {
    size_t len = 0;

    if (flag->shortname) {
      len += 2;
    }

    if (flag->fullname) {
      len += strlen(flag->fullname) + 3;
    }

    if (len > max) {
      max = len;
    }
  }

  return max;
}

static void optly__print_default_value(OptlyFlag *flag) {
  if (flag->type == OPTLY_TYPE_BOOL) return;

  fprintf(stderr, " (default: ");

  switch (flag->type) {
    case OPTLY_TYPE_CHAR:   fprintf(stderr, "%c", flag->value.as_char); break;
    case OPTLY_TYPE_STRING: fprintf(stderr, "%s", flag->value.as_string); break;
    case OPTLY_TYPE_INT8:   fprintf(stderr, "%d", flag->value.as_int8); break;
    case OPTLY_TYPE_INT16:  fprintf(stderr, "%d", flag->value.as_int16); break;
    case OPTLY_TYPE_INT32:  fprintf(stderr, "%d", flag->value.as_int32); break;
    case OPTLY_TYPE_INT64:  fprintf(stderr, "%lld", (long long)flag->value.as_int64); break;
    case OPTLY_TYPE_UINT8:  fprintf(stderr, "%u", flag->value.as_uint8); break;
    case OPTLY_TYPE_UINT16: fprintf(stderr, "%u", flag->value.as_uint16); break;
    case OPTLY_TYPE_UINT32: fprintf(stderr, "%u", flag->value.as_uint32); break;
    case OPTLY_TYPE_UINT64: fprintf(stderr, "%llu", (unsigned long long)flag->value.as_uint64); break;
    case OPTLY_TYPE_FLOAT:  fprintf(stderr, "%f", flag->value.as_float); break;
    case OPTLY_TYPE_DOUBLE: fprintf(stderr, "%f", flag->value.as_double); break;
    default:                break;
  }

  fprintf(stderr, ")");
}

static size_t optly__command_print_width(OptlyCommand *commands) {
  size_t max = 0;

  for (OptlyCommand *cmd = commands; !optly_is_command_null(cmd); cmd++) {
    size_t len = strlen(cmd->name);

    if (len > max) {
      max = len;
    }
  }

  return max;
}

static void optly__usage_commands_list(OptlyCommand *commands) {
  if (!commands) return;

  fprintf(stderr, "\nCOMMANDS\n");
  size_t pad = optly__command_print_width(commands);

  for (OptlyCommand *cmd = commands; !optly_is_command_null(cmd); cmd++) {
    fprintf(stderr, "  %-*s  %s\n", (int)pad, cmd->name, cmd->description ? cmd->description : "");
  }

#ifdef OPTLY_GEN_HELP_COMMAND
  fprintf(stderr, "  %-*s  %s\n", (int)pad, "help", "Show help for command");
#endif

#ifdef OPTLY_GEN_VERSION_COMMAND
  fprintf(stderr, "  %-*s  %s\n", (int)pad, "version", "Show app version");
#endif
}

static void optly__usage_flags(OptlyFlag *flags) {
  if (!flags) return;

  fprintf(stderr, "\nFLAGS\n");

  size_t pad = optly__flag_print_width(flags);

  for (OptlyFlag *flag = flags; !optly_is_flag_null(flag); flag++) {
    char buf[OPTLY_FLAG_BUFFER_LENGTH + 16];

    // const char *type = optly__flag_type_name(flag->type);
    char type_buf[OPTLY_FLAG_BUFFER_LENGTH];

    if (flag->type == OPTLY_TYPE_ENUM && flag->value.as_enum) {
      char **vals = flag->value.as_enum;

      size_t offset = 0;
      offset += snprintf(type_buf + offset, sizeof(type_buf) - offset, "[");

      for (char **v = vals + 1; *v; v++) {
        offset += snprintf(type_buf + offset, sizeof(type_buf) - offset, "%s", *v);
        if (*(v + 1)) {
          offset += snprintf(type_buf + offset, sizeof(type_buf) - offset, "|");
        }
      }

      snprintf(type_buf + offset, sizeof(type_buf) - offset, "]");
    } else {
      snprintf(type_buf, sizeof(type_buf), "%s", optly__flag_type_name(flag->type));
    }

    const char *type = type_buf;

    if (flag->shortname && flag->fullname) {
      snprintf(buf, sizeof(buf), "-%c --%s %s", flag->shortname, flag->fullname, type);
    } else if (flag->fullname) {
      snprintf(buf, sizeof(buf), "--%s %s", flag->fullname, type);
    } else {
      snprintf(buf, sizeof(buf), "-%c %s", flag->shortname, type);
    }

    fprintf(stderr, "  %-*s  %s", (int)pad + type_name_pad, buf, flag->description ? flag->description : "");

    if (flag->required) {
      fprintf(stderr, " (required)");
    } else if (flag->type == OPTLY_TYPE_ENUM && flag->value.as_enum) {
      if (flag->value.as_enum[0]) {
        fprintf(stderr, " (default: %s)", flag->value.as_enum[0]);
      }
    } else if (flag->value.as_string != NULL) {
      optly__print_default_value(flag);
    }

    fprintf(stderr, "\n");
  }

#ifdef OPTLY_GEN_HELP_FLAG
  fprintf(stderr, "\n  %-*s  Show this message\n", (int)pad + type_name_pad, "-h --help");
#endif

#ifdef OPTLY_GEN_VERSION_FLAG
  fprintf(stderr, "  %-*s  Show version\n", (int)pad + type_name_pad, "-v --version");
#endif
}

static void optly__usage_positionals(OptlyPositional *pos) {
  if (!pos) return;

  fprintf(stderr, "\nPOSITIONAL ARGUMENTS\n");

  for (; pos->name; pos++) {
    if (pos->max == 0) {
      fprintf(stderr, "  %s  (%zu.. values)\n", pos->name, pos->min);
    } else {
      fprintf(stderr, "  %s  (%zu..%zu values)\n", pos->name, pos->min, pos->max);
    }
  }
}

OPTLYDEF void optly_usage(OptlyCommand *command) {
  if (command->description) {
    fprintf(stderr, "%s\n\n", command->description);
  }

  optly__usage_signature(command);

  optly__usage_commands_list(command->commands);
  optly__usage_positionals(command->positionals);
  optly__usage_flags(command->flags);

#ifdef OPTLY_GET_HELP_COMMAND
  fprintf(stderr, "\nRun '%s help <command>' for more information.\n", command->name);
#endif
}

/**
 * Check if argument matches a flag definition.
 */
static bool optly__flag_matches(const char *arg, const OptlyFlag *flag) {
  bool is_short = arg[1] != '-';

  return (!is_short && strcmp(arg + 2, flag->fullname) == 0) ||
         (is_short && (arg[1] == flag->shortname));
}

/**
 * Find a flag by argument.
 */
static OptlyFlag *optly__find_flag(const char *arg, OptlyFlag *flags) {
  for (OptlyFlag *f = flags; !optly_is_flag_null(f); f++) {
    if (optly__flag_matches(arg, f)) {
      return f;
    }
  }

  return NULL;
}

static void optly__flag_set_value(OptlyFlag *flag, char *value, OptlyErrors *errs) {
  assert(flag);

  if (flag->type != OPTLY_TYPE_BOOL && !value) {
    OPTLY_LOG(FATAL, "Flag --%s requires value", flag->fullname);
    optly__push_error(errs, OPTLY_ERR_MISSING_VALUE, flag->fullname);
    return;
  }

  if (flag->type != OPTLY_TYPE_ENUM) {
    flag->value.as_int64 = 0;
  }

  char *end = "";

  switch (flag->type) {
    case OPTLY_TYPE_CHAR:   flag->value.as_char = *value; break;
    case OPTLY_TYPE_STRING: flag->value.as_string = value; break;
    case OPTLY_TYPE_INT8:   flag->value.as_int8 = strtoll(value, &end, 10); break;
    case OPTLY_TYPE_INT16:  flag->value.as_int16 = strtoll(value, &end, 10); break;
    case OPTLY_TYPE_INT32:  flag->value.as_int32 = strtoll(value, &end, 10); break;
    case OPTLY_TYPE_INT64:  flag->value.as_int64 = strtoll(value, &end, 10); break;
    case OPTLY_TYPE_UINT8:  flag->value.as_uint8 = strtoull(value, &end, 10); break;
    case OPTLY_TYPE_UINT16: flag->value.as_uint16 = strtoull(value, &end, 10); break;
    case OPTLY_TYPE_UINT32: flag->value.as_uint32 = strtoull(value, &end, 10); break;
    case OPTLY_TYPE_UINT64: flag->value.as_uint64 = strtoull(value, &end, 10); break;
    case OPTLY_TYPE_FLOAT:  flag->value.as_float = strtof(value, &end); break;
    case OPTLY_TYPE_DOUBLE: flag->value.as_double = strtod(value, &end); break;
    case OPTLY_TYPE_BOOL:   flag->value.as_bool = true; break;
    case OPTLY_TYPE_ENUM:   {
      char **vals  = flag->value.as_enum;
      bool   valid = false;

      for (char **v = vals + 1; *v; v++) {
        if (strcmp(*v, value) == 0) {
          valid = true;
          break;
        }
      }

      if (!valid) {
        OPTLY_LOG(ERROR, "Invalid enum value '%s' for --%s", value, flag->fullname);
        optly__push_error(errs, OPTLY_ERR_INVALID_VALUE, value);
        return;
      }

      flag->value.as_enum[0] = value;
      break;
    }
  }

  if (*end != '\0') {
    OPTLY_LOG(ERROR, "Argument '%s' is not a number (%s)", flag->fullname, value);
    optly__push_error(errs, OPTLY_ERR_INVALID_VALUE, value);
    return;
  }

  flag->present = true;
}

inline static bool optly__is_help_flag(char *arg) {
  return strcmp(arg, "--help") == 0 ||
         strcmp(arg, OPTLY_HELP_SHORT_FLAG) == 0 ||
         (strlen(arg) > 2 &&
          arg[0] == '-' &&
          arg[1] != '-' &&
          strchr(arg, OPTLY_HELP_SHORT_FLAG[1]) != NULL);
}

inline static bool optly__is_version_flag(char *arg) {
  return strcmp(arg, "--version") == 0 ||
         strcmp(arg, OPTLY_VERSION_SHORT_FLAG) == 0 ||
         (strlen(arg) > 2 &&
          arg[0] == '-' &&
          arg[1] != '-' &&
          strchr(arg, OPTLY_VERSION_SHORT_FLAG[1]) != NULL);
}

static void optly__parse_batch_flags(char *arg, OptlyFlag *flags, OptlyErrors *errs) {
  if (strchr(arg, '=') != NULL) {
    return;
  }

  for (char *c = &arg[1]; *c; c++) {
    char sarg[3];
    snprintf(sarg, sizeof(sarg), "-%c", *c);

    OptlyFlag *flag = optly__find_flag(sarg, flags);

    if (!flag) {
      OPTLY_LOG(WARN, "Unknown short flag: %s", sarg);
      optly__push_error(errs, OPTLY_ERR_UNKNOWN_FLAG, sarg);

      continue;
    }

    if (flag->type != OPTLY_TYPE_BOOL) {
      OPTLY_LOG(WARN, "cannot batch non-boolean flags (invalid flag in %s)", sarg);
      optly__push_error(errs, OPTLY_ERR_BATCH_NON_BOOL, &flag->shortname);
      continue;
    }

    flag->value.as_bool = true;
    flag->present       = true;
  }

  return;
}

static void optly__parse_long_flags(char ***argv_ptr, int *argc_ptr, OptlyFlag *flags, OptlyErrors *errs) {
  char **argv = *argv_ptr;
  int    argc = *argc_ptr;

  if (!argv || argc <= 0 || !*argv) {
    return;
  }

  char *arg = *argv;

  char *value = NULL;
  char *eq    = strchr(arg, '=');
  char  tmp[OPTLY_FLAG_BUFFER_LENGTH];

  if (eq) {
    size_t len = strlen(arg);

    if (len >= sizeof(tmp)) {
      len = sizeof(tmp) - 1;
    }

    memcpy(tmp, arg, len);

    tmp[len]  = '\0';
    char *eq2 = strchr(tmp, '=');
    *eq2      = '\0';

    arg   = tmp;
    value = eq + 1;
  }

  OptlyFlag *flag = optly__find_flag(arg, flags);

  if (!flag) {
    OPTLY_LOG(WARN, "Unknown flag: %s", arg);
    // NOTE: We can't save arg for later because it can point to local tmp (if arg was in form --flag=value)
    optly__push_error(errs, OPTLY_ERR_UNKNOWN_FLAG, *argv);
    return;
  }

  flag->present = true;

  if (!value && flag->type != OPTLY_TYPE_BOOL && argv[1] && argv[1][0] != '-') {
    value = argv[1];
    SHIFT_ARG(argv, argc);
  }

  optly__flag_set_value(flag, value, errs);

  *argv_ptr = argv;
  *argc_ptr = argc;
}

/**
 * Parse flags from argv.
 */
static void optly__parse_flags(char ***argv_ptr, int *argc_ptr, OptlyFlag *flags, OptlyErrors *errs) {
  char **argv = *argv_ptr;
  int    argc = *argc_ptr;

  if (!argv || argc <= 0 || !*argv) {
    return;
  }

  char *arg = *argv;

  bool is_batch_short = (arg[0] == '-' && arg[1] != '-' && strlen(arg) > 2) && arg[2] != '=';

  if (is_batch_short) {
    optly__parse_batch_flags(arg, flags, errs);
  } else {
    optly__parse_long_flags(argv_ptr, argc_ptr, flags, errs);
  }
}

/**
 * Parse a command from argv.
 */
static OptlyCommand *optly__parse_command(const char *arg, OptlyCommand *commands) {
  for (OptlyCommand *cmd = commands; !optly_is_command_null(cmd); cmd++) {
    if (strcmp(arg, cmd->name) == 0) {
      return cmd;
    }
  }

  return NULL;
}

static void optly__push_positional(OptlyCommand *cmd, char *value) {
  if (!cmd->positionals) return;
  size_t pos_count = 0;

  for (OptlyPositional *p = cmd->positionals; p->name; p++) {
    pos_count++;

    // Ensure at least 1 arg in optioanl positional
    size_t min = p->min == 0 ? 1 : p->min;

    if (p->count < min) {
      p->values[p->count++] = value;
      return;
    }
  }

  OptlyPositional *last_p         = &cmd->positionals[pos_count - 1];
  last_p->values[last_p->count++] = value;

  for (size_t i = pos_count - 1; i > 1; i--) {
    OptlyPositional *p      = &cmd->positionals[i];
    OptlyPositional *p_prev = &cmd->positionals[i - 1];

    if (p->count > p->max && p->max != 0) {
      p_prev->values[p_prev->count++] = p->values[0];

      for (size_t i = 0; i < p->count - 1; i++) {
        p->values[i] = p->values[i + 1];
      }

      p->count--;
    }
  }
}

static void optly__validate_flags(OptlyCommand *cmd, OptlyErrors *errs) {
  for (OptlyFlag *flag = cmd->flags; !optly_is_flag_null(flag); flag++) {
    if (flag->required && !flag->present) {
      OPTLY_LOG(ERROR, "Required flag '--%s' is not present", flag->fullname);
      optly__push_error(errs, OPTLY_ERR_MISSING_REQUIRED, flag->fullname);
    }
  }
}

static void optly__validate_positionals(OptlyCommand *cmd, OptlyErrors *errs) {
  if (!cmd->positionals) {
    return;
  }

  bool infinite_found = false;

  for (OptlyPositional *pos = cmd->positionals; pos->name; pos++) {
    if (pos->max == 0) {
      if (infinite_found) {
        OPTLY_LOG(FATAL, "Positional '%s' allows infinite values, but another variadic positional already exists", pos->name);
        optly__push_error(errs, OPTLY_ERR_DUPLICATE_VARIADIC, pos->name);
        OPTLY_EXIT(&errs, OPTLY_ERR_DUPLICATE_VARIADIC);
      }

      infinite_found = true;
    }

    if (pos->count < pos->min) {
      OPTLY_LOG(ERROR, "Not enough values for positional '%s'", pos->name);
      optly__push_error(errs, OPTLY_ERR_POSITIONAL_TOO_FEW, pos->name);
    }

    if (pos->max != 0 && pos->count > pos->max) {
      OPTLY_LOG(ERROR, "Too many values for positional '%s'", pos->name);
      optly__push_error(errs, OPTLY_ERR_POSITIONAL_TOO_MANY, pos->name);
    }
  }
}

inline OPTLYDEF bool optly_is_command(OptlyCommand *command, const char *name) {
  return command && strcmp(command->name, name) == 0;
}

const OptlyFlag *optly_get_flag(const OptlyFlag *flags, const char *name) {
  for (const OptlyFlag *flag = flags; !optly_is_flag_null(flag); flag++) {
    if (strcmp(flag->fullname, name) == 0) {
      return flag;
    }
  }

  return NULL;
}

inline OPTLYDEF bool optly_flag_value_bool(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_bool : false;
}

inline OPTLYDEF char optly_flag_value_char(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_char : '\0';
}

inline OPTLYDEF char *optly_flag_value_string(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_string : "";
}

inline OPTLYDEF int8_t optly_flag_value_int8(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_int8 : 0;
}

inline OPTLYDEF int16_t optly_flag_value_int16(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_int16 : 0;
}

inline OPTLYDEF int32_t optly_flag_value_int32(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_int32 : 0;
}

inline OPTLYDEF int64_t optly_flag_value_int64(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_int64 : 0;
}

inline OPTLYDEF uint8_t optly_flag_value_uint8(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_uint8 : 0;
}

inline OPTLYDEF uint16_t optly_flag_value_uint16(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_uint16 : 0;
}

inline OPTLYDEF uint32_t optly_flag_value_uint32(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_uint32 : 0;
}

inline OPTLYDEF uint64_t optly_flag_value_uint64(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_uint64 : 0;
}

inline OPTLYDEF float optly_flag_value_float(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_float : 0;
}

inline OPTLYDEF double optly_flag_value_double(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_double : 0;
}

inline OPTLYDEF char *optly_flag_value_enum(const OptlyCommand *command, const char *name) {
  const OptlyFlag *flag = optly_get_flag(command->flags, name);
  return flag ? flag->value.as_enum[0] : NULL;
}

inline OPTLYDEF OptlyPositional *optly_get_positional(OptlyCommand *command, const char *name) {
  for (OptlyPositional *p = command->positionals; p->name; p++) {
    if (strcmp(p->name, name) == 0) {
      return p;
    }
  }

  return NULL;
}

#if defined(OPTLY_GEN_VERSION_FLAG) || defined(OPTLY_GEN_VERSION_COMMAND)
OPTLYDEF OptlyErrors optly_parse_args(int argc, char *argv[], OptlyCommand *main_cmd, const char *version) {
#else
OPTLYDEF OptlyErrors optly_parse_args(int argc, char *argv[], OptlyCommand *main_cmd) {
#endif
  assert(argc > 0);
  OptlyErrors errs = {0};

  if (main_cmd->name == NULL) {
    main_cmd->name = argv[0];
  }

  OptlyCommand *current_cmd     = main_cmd;
  bool          positional_only = false;

  SHIFT_ARG(argv, argc);

  while (argc > 0) {
    char *arg = *argv;

    if (!arg) {
      break;
    }

#ifdef OPTLY_GEN_HELP_FLAG
    if (optly__is_help_flag(arg)) {
      optly_usage(current_cmd);
      exit(0);
    }
#endif

#ifdef OPTLY_GEN_VERSION_FLAG
    if (optly__is_version_flag(arg)) {
      fprintf(stderr, "%s: %s\n", main_cmd->name, version);
      exit(0);
    }
#endif

    if (positional_only) {
      optly__push_positional(current_cmd, arg);
      SHIFT_ARG(argv, argc);
      continue;
    }

    if (strcmp(arg, "--") == 0) {
      positional_only = true;
      SHIFT_ARG(argv, argc);
      continue;
    }

    if (arg[0] == '-') {
      if (current_cmd->flags) {
        optly__parse_flags(&argv, &argc, current_cmd->flags, &errs);
      } else {
        // '--flag' argument is positional if no flags defined
        optly__push_positional(current_cmd, arg);
      }

      SHIFT_ARG(argv, argc);
      continue;
    }

    OptlyCommand *cmd = optly__parse_command(arg, current_cmd->commands);

#ifdef OPTLY_GEN_HELP_COMMAND
    if (strcmp(arg, "help") == 0) {
      SHIFT_ARG(argv, argc);

      OptlyCommand *target = current_cmd;

      if (argc > 0) {
        OptlyCommand *tmp = optly__parse_command(*argv, current_cmd->commands);
        if (!tmp) {
          OPTLY_LOG(ERROR, "Unknown command: %s", *argv);
          optly__push_error(&errs, OPTLY_ERR_UNKNOWN_COMMAND, *argv);
          OPTLY_EXIT(&errs, OPTLY_ERR_UNKNOWN_COMMAND);
        }

        target = tmp;
      }

      optly_usage(target);
      exit(0);
    }
#endif

#ifdef OPTLY_GEN_VERSION_COMMAND
    if (strcmp(arg, "version") == 0) {
      fprintf(stderr, "%s: %s\n", main_cmd->name, version);
      exit(0);
    }
#endif

    if (cmd) {
      current_cmd->next_command = cmd;
      current_cmd               = current_cmd->next_command;
    } else {
      if (current_cmd->positionals) {
        optly__push_positional(current_cmd, arg);
      } else {
        OPTLY_LOG(ERROR, "Unknown command %s", arg);
        optly__push_error(&errs, OPTLY_ERR_UNKNOWN_COMMAND, arg);
      }
    }

    SHIFT_ARG(argv, argc);
  }

  for (OptlyCommand *cmd = main_cmd; cmd; cmd = cmd->next_command) {
    optly__validate_flags(cmd, &errs);
    optly__validate_positionals(cmd, &errs);
  }

  current_cmd->next_command = NULL;

#ifndef OPTLY_NO_EXIT
  if (errs.count > 0) {
    exit(EXIT_FAILURE);
  }
#endif

  return errs;
}

#endif  // OPTLY_IMPLEMENTATION

// TODO: Types for variadics?
// TODO: Support different kind of numbers (0xBABA, 0123)?

/*
   ------------------------------------------------------------------------------
   This software is available under 2 licenses -- choose whichever you prefer.
   ------------------------------------------------------------------------------
   ALTERNATIVE A - MIT License
   Copyright (c) 2026 Nikita Chulkov nikita_chul@mail.ru
   Permission is hereby granted, free of charge, to any person obtaining a copy of
   this software and associated documentation files (the "Software"), to deal in
   the Software without restriction, including without limitation the rights to
   use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
   of the Software, and to permit persons to whom the Software is furnished to do
   so, subject to the following conditions:
   The above copyright notice and this permission notice shall be included in all
   copies or substantial portions of the Software.
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE.
   ------------------------------------------------------------------------------
   ALTERNATIVE B - Public Domain (www.unlicense.org)
   This is free and unencumbered software released into the public domain.
   Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
   software, either in source code form or as a compiled binary, for any purpose,
   commercial or non-commercial, and by any means.
   In jurisdictions that recognize copyright laws, the author or authors of this
   software dedicate any and all copyright interest in the software to the public
   domain. We make this dedication for the benefit of the public at large and to
   the detriment of our heirs and successors. We intend this dedication to be an
   overt act of relinquishment in perpetuity of all present and future rights to
   this software under copyright law.
   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   ------------------------------------------------------------------------------
*/