#include "../../unity/unity.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>

/* Unity required hooks */
void setUp(void) {
  /* Force a consistent locale for help text */
  setenv("LC_ALL", "C", 1);
  setenv("LANGUAGE", "C", 1);
  setenv("LANG", "C", 1);
}

void tearDown(void) {
  /* nothing */
}

/* Helper to read all data from fd into a malloc'd buffer; NUL-terminate. */
static int read_all_fd(int fd, char **out_buf, size_t *out_len) {
  size_t cap = 1024;
  size_t len = 0;
  char *buf = (char *)malloc(cap + 1);
  if (!buf) return -1;

  for (;;) {
    if (len == cap) {
      size_t ncap = cap * 2;
      char *nbuf = (char *)realloc(buf, ncap + 1);
      if (!nbuf) {
        free(buf);
        return -1;
      }
      buf = nbuf;
      cap = ncap;
    }
    ssize_t n = read(fd, buf + len, cap - len);
    if (n < 0) {
      if (errno == EINTR) continue;
      free(buf);
      return -1;
    }
    if (n == 0) break;
    len += (size_t)n;
  }
  buf[len] = '\0';
  *out_buf = buf;
  if (out_len) *out_len = len;
  return 0;
}

/* Run usage(status_arg) in a child, capturing stdout, stderr, and exit status.
   Returns NULL on success, or a malloc'd error message string on failure. */
static char *run_usage_capture(int status_arg,
                               char **out_stdout, size_t *out_stdout_len,
                               char **out_stderr, size_t *out_stderr_len,
                               int *out_exit_code) {
  int out_pipe[2] = {-1,-1};
  int err_pipe[2] = {-1,-1};
  if (pipe(out_pipe) < 0) {
    char *msg;
    asprintf(&msg, "pipe(out) failed: %s", strerror(errno));
    return msg;
  }
  if (pipe(err_pipe) < 0) {
    close(out_pipe[0]); close(out_pipe[1]);
    char *msg;
    asprintf(&msg, "pipe(err) failed: %s", strerror(errno));
    return msg;
  }

  fflush(stdout);
    fflush(stderr);
    pid_t pid = fork();
  if (pid < 0) {
    close(out_pipe[0]); close(out_pipe[1]);
    close(err_pipe[0]); close(err_pipe[1]);
    char *msg;
    asprintf(&msg, "fork failed: %s", strerror(errno));
    return msg;
  }

  if (pid == 0) {
    /* Child: redirect stdout/stderr */
    /* Ensure locale is C for predictable output */
    setenv("LC_ALL", "C", 1);
    setenv("LANGUAGE", "C", 1);
    setenv("LANG", "C", 1);

    /* Connect pipes */
    if (dup2(out_pipe[1], STDOUT_FILENO) < 0) _exit(255);
    if (dup2(err_pipe[1], STDERR_FILENO) < 0) _exit(255);

    /* Close fds not needed in child */
    close(out_pipe[0]); close(out_pipe[1]);
    close(err_pipe[0]); close(err_pipe[1]);

    /* Call the function under test; it will exit(status_arg). */
    usage(status_arg);

    /* Should not reach here; ensure child terminates */
    _exit(254);
  }

  /* Parent: close write ends, read outputs */
  close(out_pipe[1]);
  close(err_pipe[1]);

  char *captured_out = NULL;
  char *captured_err = NULL;
  size_t len_out = 0, len_err = 0;

  int rc_out = read_all_fd(out_pipe[0], &captured_out, &len_out);
  int rc_err = read_all_fd(err_pipe[0], &captured_err, &len_err);

  close(out_pipe[0]);
  close(err_pipe[0]);

  int wstatus = 0;
  pid_t w = waitpid(pid, &wstatus, 0);
  if (w < 0) {
    free(captured_out);
    free(captured_err);
    char *msg;
    asprintf(&msg, "waitpid failed: %s", strerror(errno));
    return msg;
  }

  if (rc_out != 0 || rc_err != 0) {
    free(captured_out);
    free(captured_err);
    char *msg;
    asprintf(&msg, "read_all_fd failed (out=%d, err=%d)", rc_out, rc_err);
    return msg;
  }

  int exit_code = -1;
  if (WIFEXITED(wstatus)) {
    exit_code = WEXITSTATUS(wstatus);
  } else if (WIFSIGNALED(wstatus)) {
    free(captured_out);
    free(captured_err);
    char *msg;
    asprintf(&msg, "child terminated by signal %d", WTERMSIG(wstatus));
    return msg;
  } else {
    free(captured_out);
    free(captured_err);
    char *msg;
    asprintf(&msg, "child did not exit normally");
    return msg;
  }

  if (out_stdout) *out_stdout = captured_out; else free(captured_out);
  if (out_stderr) *out_stderr = captured_err; else free(captured_err);
  if (out_stdout_len) *out_stdout_len = len_out;
  if (out_stderr_len) *out_stderr_len = len_err;
  if (out_exit_code) *out_exit_code = exit_code;

  return NULL;
}

static int str_contains(const char *haystack, const char *needle) {
  if (!haystack || !needle) return 0;
  return strstr(haystack, needle) != NULL;
}

/* Tests */

void test_usage_success_outputs_help(void) {
  char *out = NULL, *err = NULL;
  size_t out_len = 0, err_len = 0;
  int exit_code = -1;

  char *msg = run_usage_capture(0, &out, &out_len, &err, &err_len, &exit_code);
  TEST_ASSERT_NULL_MESSAGE(msg, msg ? msg : "");

  /* Exit status must be 0 */
  TEST_ASSERT_EQUAL_INT(0, exit_code);

  /* Full help should go to stdout, not stderr */
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_TRUE(out_len > 0);
  TEST_ASSERT_NOT_NULL(err);
  TEST_ASSERT_EQUAL_UINT64(0, (unsigned long long)err_len);

  /* Check for key substrings in help text */
  TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "Usage:"), "Help text missing 'Usage:'");
  TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "Create named pipes"), "Help text missing description line");
  TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-m, --mode=MODE"), "Help text missing mode option");
  TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "--context"), "Help text missing context option");
  TEST_ASSERT_TRUE_MESSAGE(str_contains(out, "-Z"), "Help text missing -Z option");

  free(out);
  free(err);
}

void test_usage_nonzero_shows_try_help_and_exit_status_1(void) {
  char *out = NULL, *err = NULL;
  size_t out_len = 0, err_len = 0;
  int exit_code = -1;

  char *msg = run_usage_capture(1, &out, &out_len, &err, &err_len, &exit_code);
  TEST_ASSERT_NULL_MESSAGE(msg, msg ? msg : "");

  TEST_ASSERT_EQUAL_INT(1, exit_code);

  /* Expect message on stderr, none on stdout */
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_UINT64(0, (unsigned long long)out_len);
  TEST_ASSERT_NOT_NULL(err);
  TEST_ASSERT_TRUE(err_len > 0);

  TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "Try"), "stderr missing 'Try' message");
  TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "--help"), "stderr missing '--help' hint");

  free(out);
  free(err);
}

void test_usage_nonzero_propagates_exit_status_77(void) {
  char *out = NULL, *err = NULL;
  size_t out_len = 0, err_len = 0;
  int exit_code = -1;

  char *msg = run_usage_capture(77, &out, &out_len, &err, &err_len, &exit_code);
  TEST_ASSERT_NULL_MESSAGE(msg, msg ? msg : "");

  TEST_ASSERT_EQUAL_INT(77, exit_code);

  /* Same pattern: message on stderr, stdout empty */
  TEST_ASSERT_EQUAL_UINT64(0, (unsigned long long)out_len);
  TEST_ASSERT_TRUE(err_len > 0);
  TEST_ASSERT_TRUE_MESSAGE(str_contains(err, "--help"), "stderr missing '--help' hint");

  free(out);
  free(err);
}

/* Unity main */
int main(void) {
  UNITY_BEGIN();
  RUN_TEST(test_usage_success_outputs_help);
  RUN_TEST(test_usage_nonzero_shows_try_help_and_exit_status_1);
  RUN_TEST(test_usage_nonzero_propagates_exit_status_77);
  return UNITY_END();
}