/*
 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/asn1.h>
#include <openssl/bytestring.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include <openssl/posix_time.h>

#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "internal.h"

int asn1_generalizedtime_to_tm(struct tm *tm, const ASN1_GENERALIZEDTIME *d) {
  if (d->type != V_ASN1_GENERALIZEDTIME) {
    return 0;
  }
  CBS cbs;
  CBS_init(&cbs, d->data, (size_t)d->length);
  if (!CBS_parse_generalized_time(&cbs, tm, /*allow_timezone_offset=*/0)) {
    return 0;
  }
  return 1;
}

int ASN1_GENERALIZEDTIME_check(const ASN1_GENERALIZEDTIME *d) {
  return asn1_generalizedtime_to_tm(NULL, d);
}

int ASN1_GENERALIZEDTIME_set_string(ASN1_GENERALIZEDTIME *s, const char *str) {
  size_t len = strlen(str);
  CBS cbs;
  CBS_init(&cbs, (const uint8_t *)str, len);
  if (!CBS_parse_generalized_time(&cbs, /*out_tm=*/NULL,
                                  /*allow_timezone_offset=*/0)) {
    return 0;
  }
  if (s != NULL) {
    if (!ASN1_STRING_set(s, str, len)) {
      return 0;
    }
    s->type = V_ASN1_GENERALIZEDTIME;
  }
  return 1;
}

ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_set(ASN1_GENERALIZEDTIME *s,
                                               int64_t posix_time) {
  return ASN1_GENERALIZEDTIME_adj(s, posix_time, 0, 0);
}

ASN1_GENERALIZEDTIME *ASN1_GENERALIZEDTIME_adj(ASN1_GENERALIZEDTIME *s,
                                               int64_t posix_time,
                                               int offset_day,
                                               long offset_sec) {
  struct tm data;
  if (!OPENSSL_posix_to_tm(posix_time, &data)) {
    return NULL;
  }

  if (offset_day || offset_sec) {
    if (!OPENSSL_gmtime_adj(&data, offset_day, offset_sec)) {
      return NULL;
    }
  }

  if (data.tm_year < 0 - 1900 || data.tm_year > 9999 - 1900) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_ILLEGAL_TIME_VALUE);
    return NULL;
  }

  char buf[16];
  int ret = snprintf(buf, sizeof(buf), "%04d%02d%02d%02d%02d%02dZ",
                     data.tm_year + 1900, data.tm_mon + 1, data.tm_mday,
                     data.tm_hour, data.tm_min, data.tm_sec);
  // |snprintf| must write exactly 15 bytes (plus the NUL) to the buffer.
  BSSL_CHECK(ret == static_cast<int>(sizeof(buf) - 1));

  int free_s = 0;
  if (s == NULL) {
    free_s = 1;
    s = ASN1_UTCTIME_new();
    if (s == NULL) {
      return NULL;
    }
  }

  if (!ASN1_STRING_set(s, buf, strlen(buf))) {
    if (free_s) {
      ASN1_UTCTIME_free(s);
    }
    return NULL;
  }
  s->type = V_ASN1_GENERALIZEDTIME;
  return s;
}