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

/* Unity setUp/tearDown */
void setUp(void) {
  /* no-op */
}
void tearDown(void) {
  /* no-op */
}

/* Helper: build expected uppercase hex string for input bytes. */
static void build_expected_hex(const unsigned char *in, size_t inlen, char *out)
{
  static const char hex[16] = "0123456789ABCDEF";
  for (size_t i = 0; i < inlen; i++) {
    unsigned char c = in[i];
    out[2*i]     = hex[(c >> 4) & 0x0F];
    out[2*i + 1] = hex[c & 0x0F];
  }
}

/* Tests start here. */

void test_base16_encode_empty_input(void)
{
  char out[4];
  memset(out, 'X', sizeof out);
  /* inlen = 0, outlen arbitrary (even) */
  base16_encode("", 0, out, 4);
  /* Ensure output is unchanged */
  TEST_ASSERT_EQUAL_UINT8('X', (unsigned char)out[0]);
  TEST_ASSERT_EQUAL_UINT8('X', (unsigned char)out[1]);
  TEST_ASSERT_EQUAL_UINT8('X', (unsigned char)out[2]);
  TEST_ASSERT_EQUAL_UINT8('X', (unsigned char)out[3]);
}

void test_base16_encode_single_zero(void)
{
  unsigned char inb[1] = { 0x00 };
  char out[2];
  base16_encode((const char*)inb, 1, out, 2);
  TEST_ASSERT_EQUAL_MEMORY("00", out, 2);
}

void test_base16_encode_single_ff(void)
{
  unsigned char inb[1] = { 0xFF };
  char out[2];
  base16_encode((const char*)inb, 1, out, 2);
  TEST_ASSERT_EQUAL_MEMORY("FF", out, 2);
}

void test_base16_encode_mixed_bytes(void)
{
  unsigned char inb[] = { 0x12, 0xAB, 0xCD, 0xEF, 0x00, 0x90 };
  char out[12];
  char expected[12];
  build_expected_hex(inb, sizeof inb, expected);
  base16_encode((const char*)inb, (idx_t)(sizeof inb), out, (idx_t)sizeof out);
  TEST_ASSERT_EQUAL_MEMORY(expected, out, sizeof out);
  /* Explicit known expectation as an additional check */
  TEST_ASSERT_EQUAL_MEMORY("12ABCDEF0090", out, 12);
}

void test_base16_encode_partial_output_even(void)
{
  unsigned char inb[] = { 0x01, 0x02, 0x03, 0x04 };
  char out[10];
  memset(out, '?', sizeof out);

  /* Provide outlen for only 2 bytes (4 hex chars) */
  base16_encode((const char*)inb, 4, out, 4);

  /* Only first 2 input bytes should be encoded */
  TEST_ASSERT_EQUAL_MEMORY("0102", out, 4);
  /* Ensure no writes beyond the allowed region */
  for (size_t i = 4; i < sizeof out; i++) {
    TEST_ASSERT_EQUAL_UINT8('?', (unsigned char)out[i]);
  }
}

void test_base16_encode_full_range_0_to_255(void)
{
  unsigned char inb[256];
  for (size_t i = 0; i < 256; i++) inb[i] = (unsigned char)i;

  char out[512];
  char expected[512];
  build_expected_hex(inb, 256, expected);

  base16_encode((const char*)inb, (idx_t)256, out, (idx_t)512);
  TEST_ASSERT_EQUAL_MEMORY(expected, out, 512);
}

void test_base16_encode_large_deterministic_pattern(void)
{
  enum { N = 1024 };
  unsigned char *inb = (unsigned char*)malloc(N);
  TEST_ASSERT_NOT_NULL(inb);
  for (size_t i = 0; i < N; i++) inb[i] = (unsigned char)((i * 37u + 11u) & 0xFFu);

  char *out = (char*)malloc(2 * N);
  char *expected = (char*)malloc(2 * N);
  TEST_ASSERT_NOT_NULL(out);
  TEST_ASSERT_NOT_NULL(expected);

  build_expected_hex(inb, N, expected);
  base16_encode((const char*)inb, (idx_t)N, out, (idx_t)(2 * N));
  TEST_ASSERT_EQUAL_MEMORY(expected, out, 2 * N);

  free(expected);
  free(out);
  free(inb);
}

void test_base16_encode_no_trailing_nul_added(void)
{
  unsigned char inb[] = { 0xDE, 0xAD, 0xBE, 0xEF };
  size_t outbytes = sizeof(inb) * 2; /* exact */
  char *out = (char*)malloc(outbytes + 1);
  TEST_ASSERT_NOT_NULL(out);
  out[outbytes] = '#'; /* sentinel after the valid region */

  base16_encode((const char*)inb, (idx_t)sizeof inb, out, (idx_t)outbytes);

  /* Verify correct encoding and that sentinel is untouched */
  TEST_ASSERT_EQUAL_MEMORY("DEADBEEF", out, outbytes);
  TEST_ASSERT_EQUAL_UINT8('#', (unsigned char)out[outbytes]);

  free(out);
}

int main(void)
{
  UNITY_BEGIN();
  RUN_TEST(test_base16_encode_empty_input);
  RUN_TEST(test_base16_encode_single_zero);
  RUN_TEST(test_base16_encode_single_ff);
  RUN_TEST(test_base16_encode_mixed_bytes);
  RUN_TEST(test_base16_encode_partial_output_even);
  RUN_TEST(test_base16_encode_full_range_0_to_255);
  RUN_TEST(test_base16_encode_large_deterministic_pattern);
  RUN_TEST(test_base16_encode_no_trailing_nul_added);
  return UNITY_END();
}