#include "../../unity/unity.h"
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>

/* base2msbf_encode is defined in the program source and included before this file. */

void setUp(void) {
  /* Setup code here, or leave empty */
}

void tearDown(void) {
  /* Cleanup code here, or leave empty */
}

/* Helper: manually encode a single byte to MSB-first bit string */
static void byte_to_bits_msb(unsigned char c, char out[9]) {
  for (int i = 0; i < 8; i++) {
    out[i] = (c & 0x80) ? '1' : '0';
    c <<= 1;
  }
  out[8] = '\0';
}

/* Helper: encode a buffer using the reference helper above */
static char *bytes_to_bits_msb(const unsigned char *in, size_t inlen) {
  size_t outlen = inlen * 8;
  char *res = (char *)malloc(outlen + 1);
  TEST_ASSERT_NOT_NULL(res);
  char *p = res;
  for (size_t i = 0; i < inlen; i++) {
    char tmp[9];
    byte_to_bits_msb(in[i], tmp);
    memcpy(p, tmp, 8);
    p += 8;
  }
  res[outlen] = '\0';
  return res;
}

void test_base2msbf_encode_empty_input_no_output(void) {
  char outbuf[16];
  /* prefill with sentinel */
  for (size_t i = 0; i < sizeof(outbuf); i++) outbuf[i] = 'X';

  const char inbuf[] = ""; /* inlen = 0 */
  base2msbf_encode(inbuf, (idx_t)0, outbuf, (idx_t)8);

  /* No output should be written; buffer remains unchanged */
  for (size_t i = 0; i < sizeof(outbuf); i++) {
    TEST_ASSERT_EQUAL_CHAR('X', outbuf[i]);
  }
}

void test_base2msbf_encode_single_byte_zero(void) {
  unsigned char inbuf[1] = {0x00};
  char outbuf[8 + 1];
  memset(outbuf, 0, sizeof(outbuf));

  base2msbf_encode((const char *)inbuf, (idx_t)1, outbuf, (idx_t)8);
  outbuf[8] = '\0';

  TEST_ASSERT_EQUAL_STRING("00000000", outbuf);
}

void test_base2msbf_encode_single_byte_ff(void) {
  unsigned char inbuf[1] = {0xFF};
  char outbuf[8 + 1];
  memset(outbuf, 0, sizeof(outbuf));

  base2msbf_encode((const char *)inbuf, (idx_t)1, outbuf, (idx_t)8);
  outbuf[8] = '\0';

  TEST_ASSERT_EQUAL_STRING("11111111", outbuf);
}

void test_base2msbf_encode_single_byte_a5(void) {
  unsigned char inbuf[1] = {0xA5}; /* 10100101 */
  char outbuf[8 + 1];
  memset(outbuf, 0, sizeof(outbuf));

  base2msbf_encode((const char *)inbuf, (idx_t)1, outbuf, (idx_t)8);
  outbuf[8] = '\0';

  TEST_ASSERT_EQUAL_STRING("10100101", outbuf);
}

void test_base2msbf_encode_single_byte_80(void) {
  unsigned char inbuf[1] = {0x80}; /* 10000000 */
  char outbuf[8 + 1];
  memset(outbuf, 0, sizeof(outbuf));

  base2msbf_encode((const char *)inbuf, (idx_t)1, outbuf, (idx_t)8);
  outbuf[8] = '\0';

  TEST_ASSERT_EQUAL_STRING("10000000", outbuf);
}

void test_base2msbf_encode_two_bytes_Hi(void) {
  const unsigned char inbuf[2] = {'H', 'i'}; /* 0x48, 0x69 */
  /* Expected: 0x48 -> 01001000, 0x69 -> 01101001 */
  const char *expected = "0100100001101001";

  char outbuf[16 + 1];
  memset(outbuf, 0, sizeof(outbuf));
  base2msbf_encode((const char *)inbuf, (idx_t)2, outbuf, (idx_t)16);
  outbuf[16] = '\0';

  TEST_ASSERT_EQUAL_STRING(expected, outbuf);
}

void test_base2msbf_encode_truncate_outlen_multiple_of_8(void) {
  const unsigned char inbuf[3] = {'A', 'B', 'C'}; /* 0x41, 0x42, 0x43 */
  /* Expect only first two bytes encoded because outlen==16 */
  const char *expected_first2 = "0100000101000010"; /* 'A' then 'B' */

  char outbuf[16 + 2];
  memset(outbuf, 0, sizeof(outbuf));
  outbuf[16] = 'Z'; /* sentinel */
  outbuf[17] = '\0';

  base2msbf_encode((const char *)inbuf, (idx_t)3, outbuf, (idx_t)16);

  outbuf[16] = '\0';
  TEST_ASSERT_EQUAL_STRING(expected_first2, outbuf);
  /* Ensure sentinel not overwritten beyond outlen */
  TEST_ASSERT_EQUAL_CHAR('Z', outbuf[16]);
}

void test_base2msbf_encode_outlen_zero_no_write(void) {
  const unsigned char inbuf[2] = {0x01, 0xFF};
  char outbuf[4];
  for (size_t i = 0; i < sizeof(outbuf); i++) outbuf[i] = 'Q';

  base2msbf_encode((const char *)inbuf, (idx_t)2, outbuf, (idx_t)0);

  for (size_t i = 0; i < sizeof(outbuf); i++) {
    TEST_ASSERT_EQUAL_CHAR('Q', outbuf[i]);
  }
}

void test_base2msbf_encode_reference_compare_randomish_pattern(void) {
  const unsigned char inbuf[] = {0x00, 0xFF, 0x12, 0xAB, 0x7E, 0x80, 0x01, 0xC3};
  size_t inlen = sizeof(inbuf);
  size_t outlen = inlen * 8;

  char *expected = bytes_to_bits_msb(inbuf, inlen);
  char *outbuf = (char *)malloc(outlen + 1);
  TEST_ASSERT_NOT_NULL(outbuf);
  memset(outbuf, 0, outlen + 1);

  base2msbf_encode((const char *)inbuf, (idx_t)inlen, outbuf, (idx_t)outlen);
  outbuf[outlen] = '\0';

  TEST_ASSERT_EQUAL_STRING(expected, outbuf);

  free(expected);
  free(outbuf);
}

int main(void) {
  UNITY_BEGIN();
  RUN_TEST(test_base2msbf_encode_empty_input_no_output);
  RUN_TEST(test_base2msbf_encode_single_byte_zero);
  RUN_TEST(test_base2msbf_encode_single_byte_ff);
  RUN_TEST(test_base2msbf_encode_single_byte_a5);
  RUN_TEST(test_base2msbf_encode_single_byte_80);
  RUN_TEST(test_base2msbf_encode_two_bytes_Hi);
  RUN_TEST(test_base2msbf_encode_truncate_outlen_multiple_of_8);
  RUN_TEST(test_base2msbf_encode_outlen_zero_no_write);
  RUN_TEST(test_base2msbf_encode_reference_compare_randomish_pattern);
  return UNITY_END();
}