// A simple program to reproduce the output of "locale -a" with the
// //third_party/glibc_locale supported locales.

#include <ctype.h>
#include <locale.h>
#include <stdio.h>
#include <string.h>

#include <set>
#include <string>

#include "third_party/glibc_locales/glibc_locales.h"
#include "third_party/glibc_locales/supported_locales.h"

void help() {
  printf("We only support 'locale -a'.\n\n");
  printf("This program prints a list of locales that are supported by\n");
  printf("both the glibc_locales library and the underlying glibc\n");
  printf("implementation, in a format matching glibc's locale -a output.\n");
}

int main(int argc, char **argv) {
  // Check that we are called as "locale -a".  Return a nonzero exit code
  // unless we are called as "locale --help".
  if ((argc != 2) || strcmp("-a", argv[1])) {
    help();
    return (argc != 2 || strcmp("--help", argv[1]));
  }

  // Loop over all locales supported by the glibc_locales library.
  std::set<std::string> locales = {UTF_LOCALES, NONUTF_LOCALES, "C", "POSIX"};
  for (const std::string &name : locales) {
    // Does glibc like this locale?  If not, don't print it.
    google_locale_t locale = google_newlocale(LC_ALL, name.c_str(), NULL, 1);
    if (locale == NULL) continue;

    // Normalize any codeset name; e.g. replace "UTF-8" with "utf8".
    std::string normalized;
    bool in_codeset = false;
    for (const char &c : name) {
      if (in_codeset) {
        if (c == '@')
          in_codeset = false;
        else if (!isalnum(c))
          continue;
        normalized.push_back(tolower(c));
      } else {
        if (c == '.') in_codeset = true;
        normalized.push_back(c);
      }
    }

    printf("%s\n", normalized.c_str());
  }
}