/*
 * nghttp2 - HTTP/2 C Library
 *
 * Copyright (c) 2012 Tatsuhiro Tsujikawa
 *
 * 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 "util.h"

#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>

#include <nghttp2/nghttp2.h>

#include "timegm.h"

namespace nghttp2 {

namespace util {

const char DEFAULT_STRIP_CHARSET[] = "\r\n\t ";

const char UPPER_XDIGITS[] = "0123456789ABCDEF";

bool isAlpha(const char c)
{
  return ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z');
}

bool isDigit(const char c)
{
  return '0' <= c && c <= '9';
}

bool isHexDigit(const char c)
{
  return isDigit(c) || ('A' <= c && c <= 'F') || ('a' <= c && c <= 'f');
}

bool inRFC3986UnreservedChars(const char c)
{
  static const char unreserved[] = { '-', '.', '_', '~' };
  return isAlpha(c) || isDigit(c) ||
    std::find(&unreserved[0], &unreserved[4], c) != &unreserved[4];
}

std::string percentEncode(const unsigned char* target, size_t len)
{
  std::string dest;
  for(size_t i = 0; i < len; ++i) {
    unsigned char c = target[i];

    if(inRFC3986UnreservedChars(c)) {
      dest += c;
    } else {
      dest += "%";
      dest += UPPER_XDIGITS[c >> 4];
      dest += UPPER_XDIGITS[(c & 0x0f)];
    }
  }
  return dest;
}

std::string percentEncode(const std::string& target)
{
  return percentEncode(reinterpret_cast<const unsigned char*>(target.c_str()),
                       target.size());
}

bool in_token(char c)
{
  static const char extra[] = {
    '!', '#', '$', '%', '&', '\'', '*', '+', '-', '.', '^', '_', '`', '|', '~'
  };

  return isAlpha(c) || isDigit(c) ||
    std::find(&extra[0], &extra[sizeof(extra)], c) != &extra[sizeof(extra)];
}

std::string percent_encode_token(const std::string& target)
{
  auto len = target.size();
  std::string dest;

  for(size_t i = 0; i < len; ++i) {
    unsigned char c = target[i];

    if(c != '%' && in_token(c)) {
      dest += c;
    } else {
      dest += "%";
      dest += UPPER_XDIGITS[c >> 4];
      dest += UPPER_XDIGITS[(c & 0x0f)];
    }
  }
  return dest;
}

std::string percentDecode
(std::string::const_iterator first, std::string::const_iterator last)
{
  std::string result;
  for(; first != last; ++first) {
    if(*first == '%') {
      if(first+1 != last && first+2 != last &&
         isHexDigit(*(first+1)) && isHexDigit(*(first+2))) {
        std::string numstr(first+1, first+3);
        result += strtol(numstr.c_str(), 0, 16);
        first += 2;
      } else {
        result += *first;
      }
    } else {
      result += *first;
    }
  }
  return result;
}

std::string quote_string(const std::string& target)
{
  auto cnt = std::count(std::begin(target), std::end(target), '"');

  if(cnt == 0) {
    return target;
  }

  std::string res;
  res.reserve(target.size() + cnt);

  for(auto c : target) {
    if(c == '"') {
      res += "\\\"";
    } else {
      res += c;
    }
  }

  return res;
}

namespace {
template<typename Iterator>
Iterator cpydig(Iterator d, int n, size_t len)
{
  auto p = d + len - 1;

  do {
    *p-- = (n % 10) + '0';
    n /= 10;
  } while(p >= d);

  return d + len;
}
} // namespace

namespace {
const char *MONTH[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                        "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
const char *DAY_OF_WEEK[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri",
                              "Sat" };
} // namespace

std::string http_date(time_t t)
{
  struct tm tms;
  std::string res;

  if(gmtime_r(&t, &tms) == nullptr) {
    return res;
  }

  /* Sat, 27 Sep 2014 06:31:15 GMT */
  res.resize(29);

  auto p = std::begin(res);

  auto s = DAY_OF_WEEK[tms.tm_wday];
  p = std::copy(s, s + 3, p);
  *p++ = ',';
  *p++ = ' ';
  p = cpydig(p, tms.tm_mday, 2);
  *p++ = ' ';
  s = MONTH[tms.tm_mon];
  p = std::copy(s, s + 3, p);
  *p++ = ' ';
  p = cpydig(p, tms.tm_year + 1900, 4);
  *p++ = ' ';
  p = cpydig(p, tms.tm_hour, 2);
  *p++ = ':';
  p = cpydig(p, tms.tm_min, 2);
  *p++ = ':';
  p = cpydig(p, tms.tm_sec, 2);
  s = " GMT";
  p = std::copy(s, s + 4, p);

  return res;
}

time_t parse_http_date(const std::string& s)
{
  tm tm;
  memset(&tm, 0, sizeof(tm));
  char* r = strptime(s.c_str(), "%a, %d %b %Y %H:%M:%S GMT", &tm);
  if(r == 0) {
    return 0;
  }
  return timegm(&tm);
}

bool startsWith(const std::string& a, const std::string& b)
{
  return startsWith(a.begin(), a.end(), b.begin(), b.end());
}

bool istartsWith(const std::string& a, const std::string& b)
{
  return istartsWith(a.begin(), a.end(), b.begin(), b.end());
}

namespace {
void streq_advance(const char **ap, const char **bp)
{
  for(; **ap && **bp && lowcase(**ap) == lowcase(**bp); ++*ap, ++*bp);
}
} // namespace

bool istartsWith(const char *a, const char* b)
{
  if(!a || !b) {
    return false;
  }
  streq_advance(&a, &b);
  return !*b;
}

bool endsWith(const std::string& a, const std::string& b)
{
  return endsWith(a.begin(), a.end(), b.begin(), b.end());
}

bool strieq(const std::string& a, const std::string& b)
{
  if(a.size() != b.size()) {
    return false;
  }
  for(size_t i = 0; i < a.size(); ++i) {
    if(lowcase(a[i]) != lowcase(b[i])) {
      return false;
    }
  }
  return true;
}

bool strieq(const char *a, const char *b)
{
  if(!a || !b) {
    return false;
  }
  for(; *a && *b && lowcase(*a) == lowcase(*b); ++a, ++b);
  return !*a && !*b;
}

bool strieq(const char *a, const uint8_t *b, size_t bn)
{
  if(!a || !b) {
    return false;
  }
  const uint8_t *blast = b + bn;
  for(; *a && b != blast && lowcase(*a) == lowcase(*b); ++a, ++b);
  return !*a && b == blast;
}

int strcompare(const char *a, const uint8_t *b, size_t bn)
{
  assert(a && b);
  const uint8_t *blast = b + bn;
  for(; *a && b != blast; ++a, ++b) {
    if(*a < *b) {
      return -1;
    } else if(*a > *b) {
      return 1;
    }
  }
  if(!*a && b == blast) {
    return 0;
  } else if(b == blast) {
    return 1;
  } else {
    return -1;
  }
}

bool strifind(const char *a, const char *b)
{
  if(!a || !b) {
    return false;
  }
  for(size_t i = 0; a[i]; ++i) {
    const char *ap = &a[i], *bp = b;
    for(; *ap && *bp && lowcase(*ap) == lowcase(*bp); ++ap, ++bp);
    if(!*bp) {
      return true;
    }
  }
  return false;
}

char upcase(char c)
{
  if('a' <= c && c <= 'z') {
    return c-'a'+'A';
  } else {
    return c;
  }
}

namespace {
const char LOWER_XDIGITS[] = "0123456789abcdef";
} // namespace

std::string format_hex(const unsigned char *s, size_t len)
{
  std::string res;
  res.resize(len * 2);

  for(size_t i = 0; i < len; ++i) {
    unsigned char c = s[i];

    res[i * 2] = LOWER_XDIGITS[c >> 4];
    res[i * 2 + 1] = LOWER_XDIGITS[c & 0x0f];
  }
  return res;
}

void to_token68(std::string& base64str)
{
  for(auto i = std::begin(base64str); i != std::end(base64str); ++i) {
    switch(*i) {
    case '+':
      *i = '-';
      break;
    case '/':
      *i = '_';
      break;
    case '=':
      base64str.erase(i, std::end(base64str));
      return;
    }
  }
  return;
}

void to_base64(std::string& token68str)
{
  for(auto i = std::begin(token68str); i != std::end(token68str); ++i) {
    switch(*i) {
    case '-':
      *i = '+';
      break;
    case '_':
      *i = '/';
      break;
    }
  }
  if(token68str.size() & 0x3) {
    token68str.append(4 - (token68str.size() & 0x3), '=');
  }
  return;
}

void inp_strlower(std::string& s)
{
  for(auto i = std::begin(s); i != std::end(s); ++i) {
    if('A' <= *i && *i <= 'Z') {
      *i = (*i) - 'A' + 'a';
    }
  }
}

namespace {
// Calculates Damerau–Levenshtein distance between c-string a and b
// with given costs.  swapcost, subcost, addcost and delcost are cost
// to swap 2 adjacent characters, substitute characters, add character
// and delete character respectively.
int levenshtein
(const char* a,
 const char* b,
 int swapcost,
 int subcost,
 int addcost,
 int delcost)
{
  int alen = strlen(a);
  int blen = strlen(b);
  auto dp = std::vector<std::vector<int>>(3, std::vector<int>(blen+1));
  for(int i = 0; i <= blen; ++i) {
    dp[1][i] = i;
  }
  for(int i = 1; i <= alen; ++i) {
    dp[0][0] = i;
    for(int j = 1; j <= blen; ++j) {
      dp[0][j] = dp[1][j-1]+(a[i-1] == b[j-1] ? 0 : subcost);
      if(i >= 2 && j >= 2 && a[i-1] != b[j-1] &&
         a[i-2] == b[j-1] && a[i-1] == b[j-2]) {
        dp[0][j] = std::min(dp[0][j], dp[2][j-2]+swapcost);
      }
      dp[0][j] = std::min(dp[0][j],
                          std::min(dp[1][j]+delcost, dp[0][j-1]+addcost));
    }
    std::rotate(std::begin(dp), std::begin(dp)+2, std::end(dp));
  }
  return dp[1][blen];
}
} // namespace

void show_candidates(const char *unkopt, option *options)
{
  for(; *unkopt == '-'; ++unkopt);
  if(*unkopt == '\0') {
    return;
  }
  int prefix_match = 0;
  auto unkoptlen = strlen(unkopt);
  auto cands = std::vector<std::pair<int, const char*>>();
  for(size_t i = 0; options[i].name != nullptr; ++i) {
    auto optnamelen = strlen(options[i].name);
    // Use cost 0 for prefix match
    if(istartsWith(options[i].name, options[i].name + optnamelen,
                   unkopt, unkopt + unkoptlen)) {
      if(optnamelen == unkoptlen) {
        // Exact match, then we don't show any condidates.
        return ;
      }
      ++prefix_match;
      cands.emplace_back(0, options[i].name);
      continue;
    }
    // Use cost 0 for suffix match, but match at least 3 characters
    if(unkoptlen >= 3 &&
       iendsWith(options[i].name, options[i].name + optnamelen,
                 unkopt, unkopt + unkoptlen)) {
      cands.emplace_back(0, options[i].name);
      continue;
    }
    // cost values are borrowed from git, help.c.
    int sim = levenshtein(unkopt, options[i].name, 0, 2, 1, 3);
    cands.emplace_back(sim, options[i].name);
  }
  if(prefix_match == 1 || cands.empty()) {
    return;
  }
  std::sort(std::begin(cands), std::end(cands));
  int threshold = cands[0].first;
  // threshold value is a magic value.
  if(threshold > 6) {
    return;
  }
  std::cerr << "\nDid you mean:\n";
  for(auto& item : cands) {
    if(item.first > threshold) {
      break;
    }
    std::cerr << "\t--" << item.second << "\n";
  }
}

bool has_uri_field(const http_parser_url &u, http_parser_url_fields field)
{
  return u.field_set & (1 << field);
}

bool fieldeq(const char *uri1, const http_parser_url &u1,
             const char *uri2, const http_parser_url &u2,
             http_parser_url_fields field)
{
  if(!has_uri_field(u1, field)) {
    if(!has_uri_field(u2, field)) {
      return true;
    } else {
      return false;
    }
  } else if(!has_uri_field(u2, field)) {
    return false;
  }
  if(u1.field_data[field].len != u2.field_data[field].len) {
    return false;
  }
  return memcmp(uri1+u1.field_data[field].off,
                uri2+u2.field_data[field].off,
                u1.field_data[field].len) == 0;
}

bool fieldeq(const char *uri, const http_parser_url &u,
             http_parser_url_fields field,
             const char *t)
{
  if(!has_uri_field(u, field)) {
    if(!t[0]) {
      return true;
    } else {
      return false;
    }
  } else if(!t[0]) {
    return false;
  }
  int i, len = u.field_data[field].len;
  const char *p = uri+u.field_data[field].off;
  for(i = 0; i < len && t[i] && p[i] == t[i]; ++i);
  return i == len && !t[i];
}

std::string get_uri_field(const char *uri, const http_parser_url &u,
                          http_parser_url_fields field)
{
  if(util::has_uri_field(u, field)) {
    return std::string(uri+u.field_data[field].off,
                       u.field_data[field].len);
  } else {
    return "";
  }
}

uint16_t get_default_port(const char *uri, const http_parser_url &u)
{
  if(util::fieldeq(uri, u, UF_SCHEMA, "https")) {
    return 443;
  } else if(util::fieldeq(uri, u, UF_SCHEMA, "http")) {
    return 80;
  } else {
    return 443;
  }
}

bool porteq(const char *uri1, const http_parser_url &u1,
            const char *uri2, const http_parser_url &u2)
{
  uint16_t port1, port2;
  port1 = util::has_uri_field(u1, UF_PORT) ?
    u1.port : get_default_port(uri1, u1);
  port2 = util::has_uri_field(u2, UF_PORT) ?
    u2.port : get_default_port(uri2, u2);
  return port1 == port2;
}

void write_uri_field(std::ostream& o,
                     const char *uri, const http_parser_url &u,
                     http_parser_url_fields field)
{
  if(util::has_uri_field(u, field)) {
    o.write(uri+u.field_data[field].off, u.field_data[field].len);
  }
}

bool numeric_host(const char *hostname)
{
  struct addrinfo hints;
  struct addrinfo* res;
  memset(&hints, 0, sizeof(hints));
  hints.ai_family = AF_UNSPEC;
  hints.ai_flags = AI_NUMERICHOST;
  if(getaddrinfo(hostname, nullptr, &hints, &res)) {
    return false;
  }
  freeaddrinfo(res);
  return true;
}

int reopen_log_file(const char *path)
{
#if defined(__ANDROID__) || defined(ANDROID)
  int fd;

  if(strcmp("/proc/self/fd/1", path) == 0 ||
     strcmp("/proc/self/fd/2", path) == 0) {

    // We will get permission denied error when O_APPEND is used for
    // these paths.
    fd = open(path, O_WRONLY | O_CREAT | O_CLOEXEC,
              S_IRUSR | S_IWUSR | S_IRGRP);
  } else {
    fd = open(path, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC,
              S_IRUSR | S_IWUSR | S_IRGRP);
  }
#elif defined O_CLOEXEC

  auto fd = open(path, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC,
                 S_IRUSR | S_IWUSR | S_IRGRP);
#else // !O_CLOEXEC

  auto fd = open(path, O_WRONLY | O_APPEND | O_CREAT,
                 S_IRUSR | S_IWUSR | S_IRGRP);

  // We get race condition if execve is called at the same time.
  if(fd != -1) {
    fcntl(fd, F_SETFD, FD_CLOEXEC);
  }

#endif // !O_CLOEXEC

  if(fd == -1) {
    return -1;
  }

  return fd;
}

std::string ascii_dump(const uint8_t *data, size_t len)
{
  std::string res;

  for(size_t i = 0; i < len; ++i) {
    auto c = data[i];

    if(c >= 0x20 && c < 0x7f) {
      res += c;
    } else {
      res += ".";
    }
  }

  return res;
}

char* get_exec_path(int argc, char **const argv, const char *cwd)
{
  if(argc == 0 || cwd == nullptr) {
    return nullptr;
  }

  auto argv0 = argv[0];
  auto len = strlen(argv0);

  char *path;

  if(argv0[0] == '/') {
    path = static_cast<char*>(malloc(len + 1));
    memcpy(path, argv0, len + 1);
  } else {
    auto cwdlen = strlen(cwd);
    path = static_cast<char*>(malloc(len + 1 + cwdlen + 1));
    memcpy(path, cwd, cwdlen);
    path[cwdlen] = '/';
    memcpy(path + cwdlen + 1, argv0, len + 1);
  }

  return path;
}

bool check_path(const std::string& path)
{
  // We don't like '\' in path.
  return !path.empty() && path[0] == '/' &&
    path.find('\\') == std::string::npos &&
    path.find("/../") == std::string::npos &&
    path.find("/./") == std::string::npos &&
    !util::endsWith(path, "/..") && !util::endsWith(path, "/.");
}

int64_t to_time64(const timeval& tv)
{
  return tv.tv_sec * 1000000 + tv.tv_usec;
}

bool check_h2_is_selected(const unsigned char *proto, size_t len)
{
  return streq(NGHTTP2_PROTO_VERSION_ID, NGHTTP2_PROTO_VERSION_ID_LEN,
               proto, len);
}

std::vector<unsigned char> get_default_alpn()
{
  auto res = std::vector<unsigned char>(1 + NGHTTP2_PROTO_VERSION_ID_LEN);
  auto p = res.data();

  *p++ = NGHTTP2_PROTO_VERSION_ID_LEN;
  memcpy(p, NGHTTP2_PROTO_VERSION_ID, NGHTTP2_PROTO_VERSION_ID_LEN);

  return res;
}

std::string format_iso8601(const std::chrono::system_clock::time_point& tp)
{
  auto t = std::chrono::duration_cast<std::chrono::milliseconds>
    (tp.time_since_epoch());
  time_t sec = t.count() / 1000;

  tm tms;
  if(gmtime_r(&sec, &tms) == nullptr) {
    return "";
  }

  char buf[128];

  auto nwrite = strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%S", &tms);
  snprintf(&buf[nwrite], sizeof(buf) - nwrite, ".%03ldZ", t.count() % 1000);

  return buf;
}

} // namespace util

} // namespace nghttp2