/* os_temp_dir() falls back when $TMPDIR is missing or read-only (Termux,
 * Android) and os_temp_dir_export() hands the choice to child processes.
 * Each case runs in a fresh fork because the choice is made once. */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#include "os_compat.h"

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

#ifndef _WIN32
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

static int nfail;

#define EXPECT(cond, msg)                                                      \
  do {                                                                         \
    if (!(cond)) {                                                             \
      fprintf(stderr, "FAIL %s:%d: %s\n", __FILE__, __LINE__, msg);            \
      nfail++;                                                                 \
    }                                                                          \
  } while (0)

/* Runs in a child: set the environment, then compare os_temp_dir(). */
static int pick_is(const char *tmpdir, const char *prefix, const char *want) {
  pid_t pid = fork();
  if (pid < 0)
    return 0;
  if (pid == 0) {
    if (tmpdir)
      setenv("TMPDIR", tmpdir, 1);
    else
      unsetenv("TMPDIR");
    if (prefix)
      setenv("PREFIX", prefix, 1);
    else
      unsetenv("PREFIX");
    char got[4096];
    if (os_temp_dir(got, sizeof(got)) != 0 || strcmp(got, want) != 0) {
      fprintf(stderr, "  TMPDIR=%s PREFIX=%s: got %s, want %s\n",
              tmpdir ? tmpdir : "(unset)", prefix ? prefix : "(unset)", got,
              want);
      _exit(1);
    }
    os_temp_dir_export();
    const char *t = getenv("TMPDIR");
    if (!t || strcmp(t, want) != 0)
      _exit(2);
    char f[4096];
    int fd = os_mkstemp(f, sizeof(f), "cst-t");
    if (fd < 0 || strncmp(f, want, strlen(want)) != 0)
      _exit(3);
    close(fd);
    unlink(f);
    _exit(0);
  }
  int st = 0;
  waitpid(pid, &st, 0);
  return WIFEXITED(st) && WEXITSTATUS(st) == 0;
}

int main(void) {
  const char *base = getenv("TMPDIR");
  char root[4096];
  snprintf(root, sizeof(root), "%s/cst-tmpdir-XXXXXX",
           base && base[0] ? base : "/tmp");
  if (!mkdtemp(root)) {
    puts("test_tmpdir: skipped (no writable temp dir to set up in)");
    return 0;
  }
  char ok[4200], prefix[4200], ptmp[4300], ro[4200], slash[4300];
  snprintf(ok, sizeof(ok), "%s/ok", root);
  snprintf(prefix, sizeof(prefix), "%s/usr", root);
  snprintf(ptmp, sizeof(ptmp), "%s/tmp", prefix);
  snprintf(ro, sizeof(ro), "%s/ro", root);
  snprintf(slash, sizeof(slash), "%s//", ok);
  mkdir(ok, 0700);
  mkdir(prefix, 0700);
  mkdir(ptmp, 0700);
  mkdir(ro, 0500);

  EXPECT(pick_is(ok, NULL, ok), "usable TMPDIR wins");
  EXPECT(pick_is(slash, NULL, ok), "trailing slashes trimmed");
  EXPECT(pick_is("/nonexistent/cst", prefix, ptmp),
         "missing TMPDIR falls back to $PREFIX/tmp");
  EXPECT(pick_is(NULL, prefix, ptmp), "unset TMPDIR uses $PREFIX/tmp");
  if (geteuid() != 0) {
    EXPECT(pick_is(ro, prefix, ptmp), "read-only TMPDIR is skipped");
    char tmp_ok[64] = "/tmp";
    if (access("/tmp", W_OK) == 0)
      EXPECT(pick_is(ro, NULL, tmp_ok), "read-only TMPDIR falls to /tmp");
  }

  rmdir(ro);
  rmdir(ptmp);
  rmdir(prefix);
  rmdir(ok);
  rmdir(root);
  if (nfail) {
    fprintf(stderr, "test_tmpdir: %d failure(s)\n", nfail);
    return 1;
  }
  puts("test_tmpdir: OK");
  return 0;
}
#else
int main(void) {
  puts("test_tmpdir: skipped on Windows");
  return 0;
}
#endif