#ifndef CUSTOM_MUTATOR_HELPERS
#define CUSTOM_MUTATOR_HELPERS

#include "config.h"
#include "types.h"
#include <stdlib.h>

#define RAND_BELOW(limit) (rand() % (limit))

typedef struct{} afl_t;

static void surgical_havoc_mutate(u8 *out_buf, s32 begin, s32 end) {

  static s8  interesting_8[]  = {INTERESTING_8};
  static s16 interesting_16[] = {INTERESTING_8, INTERESTING_16};
  static s32 interesting_32[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32};

  switch (RAND_BELOW(12)) {

    case 0: {

      /* Flip a single bit somewhere. Spooky! */

      s32 bit_idx = ((RAND_BELOW(end - begin) + begin) << 3) + RAND_BELOW(8);

      out_buf[bit_idx >> 3] ^= 128 >> (bit_idx & 7);

      break;

    }

    case 1: {

      /* Set byte to interesting value. */

      u8 val = interesting_8[RAND_BELOW(sizeof(interesting_8))];
      out_buf[(RAND_BELOW(end - begin) + begin)] = val;

      break;

    }

    case 2: {

      /* Set word to interesting value, randomly choosing endian. */

      if (end - begin < 2) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 1) break;

      switch (RAND_BELOW(2)) {

        case 0:
          *(u16 *)(out_buf + byte_idx) =
              interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)];
          break;
        case 1:
          *(u16 *)(out_buf + byte_idx) =
              SWAP16(interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)]);
          break;

      }

      break;

    }

    case 3: {

      /* Set dword to interesting value, randomly choosing endian. */

      if (end - begin < 4) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 3) break;

      switch (RAND_BELOW(2)) {

        case 0:
          *(u32 *)(out_buf + byte_idx) =
              interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)];
          break;
        case 1:
          *(u32 *)(out_buf + byte_idx) =
              SWAP32(interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]);
          break;

      }

      break;

    }

    case 4: {

      /* Set qword to interesting value, randomly choosing endian. */

      if (end - begin < 8) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 7) break;

      switch (RAND_BELOW(2)) {

        case 0:
          *(u64 *)(out_buf + byte_idx) =
              (s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)];
          break;
        case 1:
          *(u64 *)(out_buf + byte_idx) =
              SWAP64((s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]);
          break;

      }

      break;

    }

    case 5: {

      /* Randomly subtract from byte. */

      out_buf[(RAND_BELOW(end - begin) + begin)] -= 1 + RAND_BELOW(ARITH_MAX);

      break;

    }

    case 6: {

      /* Randomly add to byte. */

      out_buf[(RAND_BELOW(end - begin) + begin)] += 1 + RAND_BELOW(ARITH_MAX);

      break;

    }

    case 7: {

      /* Randomly subtract from word, random endian. */

      if (end - begin < 2) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 1) break;

      if (RAND_BELOW(2)) {

        *(u16 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX);

      } else {

        u16 num = 1 + RAND_BELOW(ARITH_MAX);

        *(u16 *)(out_buf + byte_idx) =
            SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) - num);

      }

      break;

    }

    case 8: {

      /* Randomly add to word, random endian. */

      if (end - begin < 2) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 1) break;

      if (RAND_BELOW(2)) {

        *(u16 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX);

      } else {

        u16 num = 1 + RAND_BELOW(ARITH_MAX);

        *(u16 *)(out_buf + byte_idx) =
            SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) + num);

      }

      break;

    }

    case 9: {

      /* Randomly subtract from dword, random endian. */

      if (end - begin < 4) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 3) break;

      if (RAND_BELOW(2)) {

        *(u32 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX);

      } else {

        u32 num = 1 + RAND_BELOW(ARITH_MAX);

        *(u32 *)(out_buf + byte_idx) =
            SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) - num);

      }

      break;

    }

    case 10: {

      /* Randomly add to dword, random endian. */

      if (end - begin < 4) break;

      s32 byte_idx = (RAND_BELOW(end - begin) + begin);

      if (byte_idx >= end - 3) break;

      if (RAND_BELOW(2)) {

        *(u32 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX);

      } else {

        u32 num = 1 + RAND_BELOW(ARITH_MAX);

        *(u32 *)(out_buf + byte_idx) =
            SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) + num);

      }

      break;

    }

    case 11: {

      /* Just set a random byte to a random value. Because,
         why not. We use XOR with 1-255 to eliminate the
         possibility of a no-op. */

      out_buf[(RAND_BELOW(end - begin) + begin)] ^= 1 + RAND_BELOW(255);

      break;

    }

  }

}

#endif