#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 <fcntl.h>
#include <errno.h>

/* The tests are included into the same translation unit as the program,
   so we can access the internal static function pointers and wrappers.
   We must select a valid mode (base64) for basenc (BASE_TYPE == 42). */

static void select_base64_mode(void)
{
#if BASE_TYPE == 42
  /* Select base64 mode by wiring the function pointers. */
  base_length = base64_length_wrapper;
  required_padding = base64_required_padding;
  isubase = isubase64;
  base_encode = base64_encode;

  base_decode_ctx_init = base64_decode_ctx_init_wrapper;
  base_decode_ctx = base64_decode_ctx_wrapper;
  base_decode_ctx_finalize = decode_ctx_finalize;

  has_padding = base64_ctx_has_padding;
  get_pending_length = base64_ctx_get_pending_length;
#else
  /* For other BASE_TYPEs, these are compile-time bound, nothing to do. */
#endif
}

/* Helper to run do_decode in a child process, capturing output and exit code. */
static int run_do_decode_case(const char *input, size_t input_len,
                              bool ignore_garbage,
                              char **out_buf, size_t *out_len)
{
  select_base64_mode();

  /* Create a temporary input file. */
  char tmpl[] = "/tmp/basenc_test_XXXXXX";
  int fd = mkstemp(tmpl);
  if (fd < 0) {
    perror("mkstemp");
    return -1;
  }

  ssize_t written = 0;
  while ((size_t)written < input_len) {
    ssize_t w = write(fd, input + written, input_len - written);
    if (w < 0) {
      if (errno == EINTR) continue;
      perror("write");
      close(fd);
      unlink(tmpl);
      return -1;
    }
    written += w;
  }
  if (lseek(fd, 0, SEEK_SET) < 0) {
    perror("lseek");
    close(fd);
    unlink(tmpl);
    return -1;
  }

  FILE *in_fp = fdopen(fd, "rb");
  if (!in_fp) {
    perror("fdopen");
    close(fd);
    unlink(tmpl);
    return -1;
  }

  /* Pipe for capturing output. */
  int pipefd[2];
  if (pipe(pipefd) != 0) {
    perror("pipe");
    fclose(in_fp);
    unlink(tmpl);
    return -1;
  }

  fflush(stdout);
    fflush(stderr);
    pid_t pid = fork();
  if (pid < 0) {
    perror("fork");
    fclose(in_fp);
    close(pipefd[0]);
    close(pipefd[1]);
    unlink(tmpl);
    return -1;
  }

  if (pid == 0) {
    /* Child: call do_decode, writing output to pipe write-end. */
    close(pipefd[0]);
    FILE *out_fp = fdopen(pipefd[1], "wb");
    if (!out_fp) {
      _exit(127);
    }

    /* Call the target function; it will exit the process. */
    do_decode(in_fp, tmpl, out_fp, ignore_garbage);

    /* Not reached */
    _exit(126);
  }

  /* Parent: clean up and collect output. */
  close(pipefd[1]);
  /* We can unlink the temp file now; child has the file handle open. */
  unlink(tmpl);
  fclose(in_fp); /* Close parent's handle; child still has its own. */

  /* Read all data from the pipe into a dynamically sized buffer. */
  size_t cap = 1024;
  size_t used = 0;
  char *buf = (char *)malloc(cap);
  if (!buf) {
    close(pipefd[0]);
    /* Reap child to avoid zombie. */
    int st; waitpid(pid, &st, 0);
    return -1;
  }

  for (;;) {
    if (used == cap) {
      size_t new_cap = cap * 2;
      char *new_buf = (char *)realloc(buf, new_cap);
      if (!new_buf) {
        free(buf);
        close(pipefd[0]);
        int st; waitpid(pid, &st, 0);
        return -1;
      }
      buf = new_buf;
      cap = new_cap;
    }
    ssize_t r = read(pipefd[0], buf + used, cap - used);
    if (r > 0) {
      used += (size_t)r;
      continue;
    } else if (r == 0) {
      break; /* EOF */
    } else {
      if (errno == EINTR) continue;
      /* On read error, still proceed to collect exit status. */
      break;
    }
  }
  close(pipefd[0]);

  int status = 0;
  if (waitpid(pid, &status, 0) < 0) {
    free(buf);
    return -1;
  }

  *out_buf = buf;
  *out_len = used;

  if (WIFEXITED(status))
    return WEXITSTATUS(status);
  else
    return 128; /* Abnormal termination. */
}

void setUp(void) {
  /* No global state to init beyond selecting base64 mode on each run. */
}

void tearDown(void) {
  /* Nothing to cleanup here. */
}

static void test_do_decode_base64_simple_no_padding(void)
{
  const char *enc = "TWFu"; /* "Man" */
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), false, &out, &out_len);
  TEST_ASSERT_EQUAL_INT(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(3, out_len);
  TEST_ASSERT_EQUAL_MEMORY("Man", out, 3);
  free(out);
}

static void test_do_decode_base64_with_padding(void)
{
  const char *enc = "TWE="; /* "Ma" */
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), false, &out, &out_len);
  TEST_ASSERT_EQUAL_INT(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(2, out_len);
  TEST_ASSERT_EQUAL_MEMORY("Ma", out, 2);
  free(out);
}

static void test_do_decode_base64_missing_padding_autopad(void)
{
  const char *enc = "TWE"; /* "Ma" without '='; finalize should auto-pad */
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), false, &out, &out_len);
  TEST_ASSERT_EQUAL_INT(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(2, out_len);
  TEST_ASSERT_EQUAL_MEMORY("Ma", out, 2);
  free(out);
}

static void test_do_decode_base64_ignore_garbage(void)
{
  /* Insert various garbage and newlines; with ignore_garbage it should decode. */
  const char *enc = "T?W!E=   \n"; /* Should reduce to "TWE=" -> "Ma" */
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), true, &out, &out_len);
  TEST_ASSERT_EQUAL_INT(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(2, out_len);
  TEST_ASSERT_EQUAL_MEMORY("Ma", out, 2);
  free(out);
}

static void test_do_decode_invalid_char_fails(void)
{
  const char *enc = "TW?="; /* Invalid '?' should cause failure without ignore-garbage */
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), false, &out, &out_len);
  TEST_ASSERT_NOT_EQUAL(0, ec);
  /* Output should be empty (no complete block decoded). */
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(0, out_len);
  free(out);
}

static void test_do_decode_incomplete_length_error(void)
{
  /* A single base64 character cannot be salvaged even with auto-padding. */
  const char *enc = "T";
  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, strlen(enc), false, &out, &out_len);
  TEST_ASSERT_NOT_EQUAL(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(0, out_len);
  free(out);
}

static void test_do_decode_large_multiblock(void)
{
  /* Build a large input exceeding a single DEC_BLOCKSIZE cycle.
     "TWFu" -> "Man". Repeat enough times. */
  const int repeats = 2000; /* 4*2000 = 8000 encoded bytes, > BASE_LENGTH(4200) */
  size_t enc_len = 4u * repeats;
  char *enc = (char *)malloc(enc_len);
  TEST_ASSERT_NOT_NULL(enc);
  for (int i = 0; i < repeats; i++) {
    memcpy(enc + 4u * i, "TWFu", 4);
  }

  char *out = NULL;
  size_t out_len = 0;
  int ec = run_do_decode_case(enc, enc_len, false, &out, &out_len);
  free(enc);

  TEST_ASSERT_EQUAL_INT(0, ec);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_EQUAL_size_t(3u * repeats, out_len);
  /* Spot check beginning, middle, and end segments for "Man". */
  TEST_ASSERT_EQUAL_MEMORY("Man", out, 3);
  TEST_ASSERT_EQUAL_MEMORY("Man", out + (3u * (repeats/2)), 3);
  TEST_ASSERT_EQUAL_MEMORY("Man", out + out_len - 3, 3);

  free(out);
}

int main(void)
{
  UNITY_BEGIN();

  RUN_TEST(test_do_decode_base64_simple_no_padding);
  RUN_TEST(test_do_decode_base64_with_padding);
  RUN_TEST(test_do_decode_base64_missing_padding_autopad);
  RUN_TEST(test_do_decode_base64_ignore_garbage);
  RUN_TEST(test_do_decode_invalid_char_fails);
  RUN_TEST(test_do_decode_incomplete_length_error);
  RUN_TEST(test_do_decode_large_multiblock);

  return UNITY_END();
}