/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <cstdlib>
#include <cstdint>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <string>
#include <vector>

#include <zlib.h>

#include "pingsender.h"

using std::ifstream;
using std::ios;
using std::string;
using std::vector;

namespace PingSender {

// Operate in std::string because nul bytes will be preserved
bool IsValidDestination(std::string aHost) {
  static const std::string kValidDestinations[] = {
      "localhost",
      "incoming.telemetry.mozilla.org",
  };
  for (auto destination : kValidDestinations) {
    if (aHost == destination) {
      return true;
    }
  }
  return false;
}

bool IsValidDestination(char* aHost) {
  return IsValidDestination(std::string(aHost));
}

/**
 * This shared function returns a Date header string for use in HTTP requests.
 * See "RFC 7231, section 7.1.1.2: Date" for its specifications.
 */
std::string GenerateDateHeader() {
  char buffer[128];
  std::time_t t = std::time(nullptr);
  strftime(buffer, sizeof(buffer), "Date: %a, %d %b %Y %H:%M:%S GMT",
           std::gmtime(&t));
  return string(buffer);
}

std::string GzipCompress(const std::string& rawData) {
  z_stream deflater = {};

  // Use the maximum window size when compressing: this also tells zlib to
  // generate a gzip header.
  const int32_t kWindowSize = MAX_WBITS + 16;
  if (deflateInit2(&deflater, Z_DEFAULT_COMPRESSION, Z_DEFLATED, kWindowSize, 8,
                   Z_DEFAULT_STRATEGY) != Z_OK) {
    PINGSENDER_LOG("ERROR: Could not initialize zlib deflating\n");
    return "";
  }

  // Initialize the output buffer. The size of the buffer is the same
  // as defined by the ZIP_BUFLEN macro in Gecko.
  const uint32_t kBufferSize = 4 * 1024 - 1;
  unsigned char outputBuffer[kBufferSize];
  deflater.next_out = outputBuffer;
  deflater.avail_out = kBufferSize;

  // Let zlib know about the input data.
  deflater.avail_in = rawData.size();
  deflater.next_in =
      reinterpret_cast<Bytef*>(const_cast<char*>(rawData.c_str()));

  // Compress and append chunk by chunk.
  std::string gzipData;
  int err = Z_OK;

  while (deflater.avail_in > 0 && err == Z_OK) {
    err = deflate(&deflater, Z_NO_FLUSH);

    // Since we're using the Z_NO_FLUSH policy, zlib can decide how
    // much data to compress. When the buffer is full, we repeadetly
    // flush out.
    while (deflater.avail_out == 0) {
      gzipData.append(reinterpret_cast<const char*>(outputBuffer), kBufferSize);

      // Update the state and let the deflater know about it.
      deflater.next_out = outputBuffer;
      deflater.avail_out = kBufferSize;
      err = deflate(&deflater, Z_NO_FLUSH);
    }
  }

  // Flush the deflater buffers.
  while (err == Z_OK) {
    err = deflate(&deflater, Z_FINISH);
    size_t bytesToWrite = kBufferSize - deflater.avail_out;
    if (bytesToWrite == 0) {
      break;
    }
    gzipData.append(reinterpret_cast<const char*>(outputBuffer), bytesToWrite);
    deflater.next_out = outputBuffer;
    deflater.avail_out = kBufferSize;
  }

  // Clean up.
  deflateEnd(&deflater);

  if (err != Z_STREAM_END) {
    PINGSENDER_LOG("ERROR: There was a problem while compressing the ping\n");
    return "";
  }

  return gzipData;
}

class Ping {
 public:
  Ping(const string& aUrl, const string& aPath) : mUrl(aUrl), mPath(aPath) {}
  bool Send() const;
  bool Delete() const;

 private:
  string Read() const;

  const string mUrl;
  const string mPath;
};

bool Ping::Send() const {
  string ping(Read());

  if (ping.empty()) {
    PINGSENDER_LOG("ERROR: Ping payload is empty\n");
    return false;
  }

  // Compress the ping using gzip.
  string gzipPing(GzipCompress(ping));

  // In the unlikely event of failure to gzip-compress the ping, don't
  // attempt to send it uncompressed: Telemetry will pick it up and send
  // it compressed.
  if (gzipPing.empty()) {
    PINGSENDER_LOG("ERROR: Ping compression failed\n");
    return false;
  }

  if (!Post(mUrl, gzipPing)) {
    return false;
  }

  return true;
}

bool Ping::Delete() const {
  return !mPath.empty() && !std::remove(mPath.c_str());
}

string Ping::Read() const {
  string ping;
  ifstream file;

  file.open(mPath.c_str(), ios::in | ios::binary);

  if (!file.is_open()) {
    PINGSENDER_LOG("ERROR: Could not open ping file\n");
    return "";
  }

  do {
    char buff[4096];

    file.read(buff, sizeof(buff));

    if (file.bad()) {
      PINGSENDER_LOG("ERROR: Could not read ping contents\n");
      return "";
    }

    ping.append(buff, file.gcount());
  } while (!file.eof());

  return ping;
}

}  // namespace PingSender

using namespace PingSender;

int main(int argc, char* argv[]) {
  vector<Ping> pings;

  if ((argc >= 3) && ((argc - 1) % 2 == 0)) {
    for (int i = 1; i < argc; i += 2) {
      Ping ping(argv[i], argv[i + 1]);
      pings.push_back(ping);
    }
  } else {
    PINGSENDER_LOG(
        "Usage: pingsender URL1 PATH1 URL2 PATH2 ...\n"
        "Send the payloads stored in PATH<n> to the specified URL<n> using an "
        "HTTP POST\nmessage for each payload then delete the file after a "
        "successful send.\n");
    return EXIT_FAILURE;
  }

  ChangeCurrentWorkingDirectory(argv[2]);

  for (const auto& ping : pings) {
    if (!ping.Send()) {
      return EXIT_FAILURE;
    }

    if (!ping.Delete()) {
      PINGSENDER_LOG("ERROR: Could not delete the ping file\n");
      return EXIT_FAILURE;
    }
  }

  return EXIT_SUCCESS;
}