#include "../../unity/unity.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <limits.h>

/* Access program-internal variables and functions since this file is included
   into the same translation unit. We will use:
   - interrupt_handler(int)
   - make_filename(int) indirectly via files/variables
   - delete_all_files, etc. are called by interrupt_handler
   - variables: filename_space, prefix, suffix, digits, files_created, remove_files
*/

/* Dummy signal handler counter */
static volatile sig_atomic_t g_test_signal_count = 0;

static void test_dummy_handler(int sig)
{
  (void)sig;
  g_test_signal_count++;
}

/* Choose a signal whose default action is non-terminating so that raising it
   after setting SIG_DFL will not abort the test process. */
static int pick_safe_signal(void)
{
#ifdef SIGCHLD
  return SIGCHLD; /* default is ignore */
#elif defined(SIGURG)
  return SIGURG;  /* default is ignore */
#elif defined(SIGWINCH)
  return SIGWINCH; /* default is ignore */
#elif defined(SIGCONT)
  return SIGCONT; /* default is continue */
#else
  /* As a last resort, use SIGCHLD value if available at runtime; otherwise,
     pick SIGCONT's typical value. But compilation should provide at least one. */
  return SIGCONT;
#endif
}

/* Create a temporary directory for the test; returns malloc'd path. */
static char* create_temp_dir(void)
{
  char templ[] = "/tmp/csplit_interrupt_test.XXXXXX";
  char *path = (char*)malloc(sizeof(templ));
  TEST_ASSERT_NOT_NULL_MESSAGE(path, "malloc failed for temp dir path");
  strcpy(path, templ);
  char *ret = mkdtemp(path);
  if (!ret)
  {
    free(path);
    TEST_FAIL_MESSAGE("mkdtemp failed to create temporary directory");
  }
  return path;
}

/* Join two path components, returning a freshly allocated string */
static char* path_join2(const char* a, const char* b)
{
  size_t la = strlen(a);
  size_t lb = strlen(b);
  size_t need = la + 1 + lb + 1;
  char *p = (char*)malloc(need);
  TEST_ASSERT_NOT_NULL_MESSAGE(p, "malloc failed in path_join2");
  memcpy(p, a, la);
  p[la] = '/';
  memcpy(p + la + 1, b, lb);
  p[la + 1 + lb] = '\0';
  return p;
}

/* Prepare globals for filename generation.
   Allocates/replaces filename_space and sets prefix/suffix/digits/files_created. */
static void prepare_filename_env(const char* pre, const char* suf, int dig, int nfiles)
{
  /* filename_space should be large enough; allocate a generous buffer */
  if (filename_space)
  {
    free((void*)filename_space);
    filename_space = NULL;
  }
  filename_space = (char*)malloc(1024);
  TEST_ASSERT_NOT_NULL_MESSAGE((void*)filename_space, "malloc failed for filename_space");

  /* Set prefix and suffix */
  /* prefix is char const * volatile; suffix is char * volatile */
  prefix = pre;
  if (suffix)
  {
    free((void*)suffix);
    suffix = NULL;
  }
  if (suf)
  {
    char *s = (char*)malloc(strlen(suf) + 1);
    TEST_ASSERT_NOT_NULL(s);
    strcpy(s, suf);
    suffix = s;
  }
  else
  {
    suffix = NULL;
  }
  digits = dig;
  files_created = nfiles;
}

/* Create N files based on current prefix/suffix/digits and return an array
   of allocated strings containing their paths. */
static char** create_numbered_files(int n)
{
  char **names = (char**)calloc(n, sizeof(char*));
  TEST_ASSERT_NOT_NULL_MESSAGE(names, "calloc failed for file names array");

  for (int i = 0; i < n; i++)
  {
    char *name = strdup(make_filename(i));
    TEST_ASSERT_NOT_NULL_MESSAGE(name, "strdup failed on make_filename");
    FILE *fp = fopen(name, "w");
    if (!fp)
    {
      /* Clean up partially created files on error */
      for (int j = 0; j <= i; j++)
      {
        if (names[j]) { unlink(names[j]); free(names[j]); }
      }
      free(names);
      TEST_FAIL_MESSAGE("Failed to create test file");
    }
    fclose(fp);
    names[i] = name;
  }
  return names;
}

static void free_names_and_dir(char **names, int n, const char* dir)
{
  if (names)
  {
    for (int i = 0; i < n; i++)
    {
      if (names[i]) free(names[i]);
    }
    free(names);
  }
  if (dir)
  {
    rmdir(dir);
  }
}

/* Unity required hooks */
void setUp(void)
{
  /* Nothing */
}
void tearDown(void)
{
  /* Ensure we don't leave a bad signal handler behind */
  int sig = pick_safe_signal();
  signal(sig, SIG_DFL);

  /* Reset globals to a safe state between tests */
  remove_files = false;
  if (suffix)
  {
    free((void*)suffix);
    suffix = NULL;
  }
  prefix = NULL;
  if (filename_space)
  {
    free((void*)filename_space);
    filename_space = NULL;
  }
  files_created = 0;
}

/* Test 1: remove_files = true, suffix not used, files are deleted and handler reset */
static void test_interrupt_handler_deletes_files_and_resets_handler(void)
{
  int sig = pick_safe_signal();
  g_test_signal_count = 0;

  char *dir = create_temp_dir();
  char *pre = path_join2(dir, "xx"); /* prefix like /tmp/.../xx */

  prepare_filename_env(pre, NULL, 2, 3);
  remove_files = true;

  char **names = create_numbered_files(3);

  /* Install a dummy handler first */
  signal(sig, test_dummy_handler);

  /* Call the handler under test */
  interrupt_handler(sig);

  /* The dummy handler should not have been invoked */
  TEST_ASSERT_EQUAL_INT_MESSAGE(0, g_test_signal_count, "dummy handler invoked unexpectedly");

  /* files_created should be reset to 0 by delete_all_files(true) */
  TEST_ASSERT_EQUAL_INT(0, files_created);

  /* All files should be deleted */
  for (int i = 0; i < 3; i++)
  {
    int rc = access(names[i], F_OK);
    TEST_ASSERT_EQUAL_INT_MESSAGE(-1, rc, "Expected file to be deleted");
    TEST_ASSERT_EQUAL_INT_MESSAGE(ENOENT, errno, "Expected ENOENT for deleted file");
  }

  /* Raising the signal again should not hit our dummy handler either (still default) */
  g_test_signal_count = 0;
  raise(sig);
  TEST_ASSERT_EQUAL_INT_MESSAGE(0, g_test_signal_count, "dummy handler invoked after reset");

  /* Cleanup */
  free_names_and_dir(names, 3, dir);
  free(pre);
}

/* Test 2: remove_files = false; files remain and handler reset; use suffix format */
static void test_interrupt_handler_keeps_files_when_remove_files_false(void)
{
  int sig = pick_safe_signal();
  g_test_signal_count = 0;

  char *dir = create_temp_dir();
  char *pre = path_join2(dir, "part");

  /* Use a suffix format to exercise that path: part + "%03d" */
  prepare_filename_env(pre, "%03d", 2, 2);
  remove_files = false;

  char **names = create_numbered_files(2);

  /* Sanity: expect the files exist now */
  for (int i = 0; i < 2; i++)
  {
    int rc = access(names[i], F_OK);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "Expected file to exist before handler");
  }

  /* Install dummy handler and call interrupt_handler */
  signal(sig, test_dummy_handler);
  interrupt_handler(sig);

  /* Dummy handler should not be invoked */
  TEST_ASSERT_EQUAL_INT(0, g_test_signal_count);

  /* files_created should remain unchanged (2) since remove_files == false */
  TEST_ASSERT_EQUAL_INT(2, files_created);

  /* Files should still exist */
  for (int i = 0; i < 2; i++)
  {
    int rc = access(names[i], F_OK);
    TEST_ASSERT_EQUAL_INT_MESSAGE(0, rc, "File should not have been deleted");
  }

  /* Raising again should not hit our dummy handler (it's been reset to default) */
  g_test_signal_count = 0;
  raise(sig);
  TEST_ASSERT_EQUAL_INT(0, g_test_signal_count);

  /* Cleanup: manually unlink files and dir */
  for (int i = 0; i < 2; i++)
  {
    unlink(names[i]);
  }
  free_names_and_dir(names, 2, dir);
  free(pre);
}

/* Test 3: zero files; ensure no crash and handler reset */
static void test_interrupt_handler_zero_files(void)
{
  int sig = pick_safe_signal();
  g_test_signal_count = 0;

  char *dir = create_temp_dir();
  char *pre = path_join2(dir, "xx");

  prepare_filename_env(pre, NULL, 2, 0);
  remove_files = true;

  signal(sig, test_dummy_handler);
  interrupt_handler(sig);

  TEST_ASSERT_EQUAL_INT(0, g_test_signal_count);
  TEST_ASSERT_EQUAL_INT(0, files_created);

  /* Raising again should not hit our dummy handler */
  g_test_signal_count = 0;
  raise(sig);
  TEST_ASSERT_EQUAL_INT(0, g_test_signal_count);

  /* Cleanup */
  rmdir(dir);
  free(pre);
  free(dir);
}

int main(void)
{
  UNITY_BEGIN();
  RUN_TEST(test_interrupt_handler_deletes_files_and_resets_handler);
  RUN_TEST(test_interrupt_handler_keeps_files_when_remove_files_false);
  RUN_TEST(test_interrupt_handler_zero_files);
  return UNITY_END();
}