/*
  Copyright 2019-2021 David Robillard <d@drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "int_math.h"
#include "read_utils.h"
#include "write_utils.h"

#include "exess/exess.h"

#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

ExessResult
exess_read_long(int64_t* const out, const char* const str)
{
  *out = 0;

  // Read leading sign if present
  size_t i    = skip_whitespace(str);
  int    sign = 1;
  if (str[i] == '-') {
    sign = -1;
    ++i;
  } else if (str[i] == '+') {
    ++i;
  }

  // Read digits
  uint64_t    magnitude = 0;
  ExessResult r         = exess_read_ulong(&magnitude, str + i);
  if (r.status > EXESS_EXPECTED_END) {
    return result(r.status, i + r.count);
  }

  i += r.count;

  if (sign > 0) {
    if (magnitude > (uint64_t)INT64_MAX) {
      return result(EXESS_OUT_OF_RANGE, i);
    }

    *out = (int64_t)magnitude;
    return end_read(EXESS_SUCCESS, str, i);
  }

  const uint64_t min_magnitude = (uint64_t)(-(INT64_MIN + 1)) + 1;
  if (magnitude > min_magnitude) {
    return result(EXESS_OUT_OF_RANGE, i);
  }

  if (magnitude == min_magnitude) {
    *out = INT64_MIN;
  } else {
    *out = -(int64_t)magnitude;
  }

  return end_read(r.status, str, i);
}

static size_t
exess_long_string_length(const int64_t value)
{
  if (value == INT64_MIN) {
    return 20;
  }

  if (value < 0) {
    return 1u + exess_num_digits((uint64_t)-value);
  }

  return exess_num_digits((uint64_t)value);
}

ExessResult
exess_write_long(const int64_t value, const size_t buf_size, char* const buf)
{
  if (!buf) {
    return result(EXESS_SUCCESS, exess_long_string_length(value));
  }

  if (value == INT64_MIN) {
    return end_write(
      EXESS_SUCCESS,
      buf_size,
      buf,
      write_string(20, "-9223372036854775808", buf_size, buf, 0));
  }

  const bool     is_negative = value < 0;
  const uint64_t abs_value   = (uint64_t)(is_negative ? -value : value);

  size_t      i = (is_negative) ? write_char('-', buf_size, buf, 0) : 0;
  ExessResult r = write_digits(abs_value, buf_size, buf, i);

  return end_write(r.status, buf_size, buf, i + r.count);
}