/*

 * ngtcp2

 *

 * Copyright (c) 2018 ngtcp2 contributors

 *

 * Permission is hereby granted, free of charge, to any person obtaining

 * a copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sublicense, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

#include "ngtcp2_vec.h"

#include <string.h>

#include <assert.h>

#include "ngtcp2_str.h"

ngtcp2_vec *ngtcp2_vec_init(ngtcp2_vec *vec, const uint8_t *base, size_t len) {

  *vec = (ngtcp2_vec){

    .base = (uint8_t *)base,

    .len = len,

  };

  return vec;

}

uint64_t ngtcp2_vec_len(const ngtcp2_vec *vec, size_t n) {

  size_t i;

  size_t res = 0;

  for (i = 0; i < n; ++i) {

    res += vec[i].len;

  }

  return res;

}

int64_t ngtcp2_vec_len_varint(const ngtcp2_vec *vec, size_t n) {

  uint64_t res = 0;

  size_t len;

  size_t i;

  for (i = 0; i < n; ++i) {

    len = vec[i].len;

    if (len > NGTCP2_MAX_VARINT - res) {

      return -1;

    }

    res += len;

  }

  return (int64_t)res;

}

ngtcp2_ssize ngtcp2_vec_split(ngtcp2_vec *dst, size_t *pdstcnt, ngtcp2_vec *src,

                              size_t *psrccnt, size_t left, size_t maxcnt) {

  size_t i;

  size_t srccnt = *psrccnt;

  size_t nmove;

  size_t extra = 0;

  for (i = 0; i < srccnt; ++i) {

    if (left >= src[i].len) {

      left -= src[i].len;

      continue;

    }

    if (*pdstcnt && src[srccnt - 1].base + src[srccnt - 1].len == dst[0].base) {

      if (*pdstcnt + srccnt - i - 1 > maxcnt) {

        return -1;

      }

      dst[0].len += src[srccnt - 1].len;

      dst[0].base = src[srccnt - 1].base;

      extra = src[srccnt - 1].len;

      --srccnt;

    } else if (*pdstcnt + srccnt - i > maxcnt) {

      return -1;

    }

    if (left == 0) {

      *psrccnt = i;

    } else {

      *psrccnt = i + 1;

    }

    nmove = srccnt - i;

    if (nmove) {

      memmove(dst + nmove, dst, sizeof(ngtcp2_vec) * (*pdstcnt));

      *pdstcnt += nmove;

      memcpy(dst, src + i, sizeof(ngtcp2_vec) * nmove);

    }

    ngtcp2_vec_drop(&dst[0], left);

    src[i].len = left;

    if (nmove == 0) {

      extra -= left;

    }

    return (ngtcp2_ssize)(ngtcp2_vec_len(dst, nmove) + extra);

  }

  return 0;

}

size_t ngtcp2_vec_merge(ngtcp2_vec *dst, size_t *pdstcnt, ngtcp2_vec *src,

                        size_t *psrccnt, size_t left, size_t maxcnt) {

  size_t orig_left = left;

  size_t i = 0;

  ngtcp2_vec *a, *b;

  assert(maxcnt);

  if (*pdstcnt == 0) {

    if (*psrccnt == 0) {

      return 0;

    }

    a = &dst[0];

    b = &src[0];

    if (left < b->len) {

      a->len = left;

      a->base = b->base;

      ngtcp2_vec_drop(b, left);

      return left;

    }

    *a = *b;

    ++*pdstcnt;

    left -= b->len;

    i = 1;

  }

  for (; left && i < *psrccnt; ++i) {

    a = &dst[*pdstcnt - 1];

    b = &src[i];

    if (left < b->len) {

      if (a->base + a->len == b->base) {

        a->len += left;

      } else if (*pdstcnt == maxcnt) {

        break;

      } else {

        dst[*pdstcnt] = (ngtcp2_vec){

          .base = b->base,

          .len = left,

        };

        ++*pdstcnt;

      }

      ngtcp2_vec_drop(b, left);

      left = 0;

      break;

    }

    if (a->base + a->len == b->base) {

      a->len += b->len;

    } else if (*pdstcnt == maxcnt) {

      break;

    } else {

      dst[(*pdstcnt)++] = *b;

    }

    left -= b->len;

  }

  memmove(src, src + i, sizeof(ngtcp2_vec) * (*psrccnt - i));

  *psrccnt -= i;

  return orig_left - left;

}

size_t ngtcp2_vec_copy_at_most(ngtcp2_vec *dst, size_t dstcnt,

                               const ngtcp2_vec *src, size_t srccnt,

                               size_t left) {

  size_t i, j;

  for (i = 0, j = 0; left > 0 && i < srccnt && j < dstcnt;) {

    if (src[i].len == 0) {

      ++i;

      continue;

    }

    if (src[i].len > left) {

      dst[j] = (ngtcp2_vec){

        .base = src[i].base,

        .len = left,

      };

      return j + 1;

    }

    dst[j] = src[i];

    left -= dst[j].len;

    ++i;

    ++j;

  }

  return j;

}

void ngtcp2_vec_copy(ngtcp2_vec *dst, const ngtcp2_vec *src, size_t cnt) {

  memcpy(dst, src, sizeof(ngtcp2_vec) * cnt);

}

void ngtcp2_vec_split_at(ngtcp2_vec *dst, ngtcp2_vec *src, size_t offset) {

  assert(offset < src->len);

  *dst = (ngtcp2_vec){

    .base = src->base + offset,

    .len = src->len - offset,

  };

  src->len = offset;

}