////////////////////////////////////////////////////////////////////////////////
// Copyright 2020 Google LLC.
//
// This software is licensed under the terms defined in the Widevine Master
// License Agreement. For a copy of this agreement, please contact
// widevine-licensing@google.com.
////////////////////////////////////////////////////////////////////////////////

// Example of Simulcrypt ECMG with custom entitlement key fetcher.

#include <netinet/in.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <unistd.h>

#include <cerrno>
#include <cstddef>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <ostream>
#include <string>

#include <cstdint>
#include "media_cas_packager_sdk/public/wv_cas_ecmg_client_handler.h"
#include "media_cas_packager_sdk/public/wv_cas_types.h"

namespace {

using widevine::cas::EcmgConfig;
using widevine::cas::EntitlementKeyInfo;
using widevine::cas::WvCasEcmgClientHandler;

constexpr int kServerPortNumber = 1234;
constexpr int kListenQueueSize = 20;
constexpr int kBufferSizeBytes = 2048;
constexpr unsigned char kTestECPrivateKey2Secp256r1[] = {
    0x30, 0x77, 0x02, 0x01, 0x01, 0x04, 0x20, 0x34, 0x9a, 0xf2, 0x95,
    0x94, 0xd4, 0xca, 0xb9, 0xa0, 0x81, 0xe4, 0x1c, 0xf5, 0xde, 0x8d,
    0x23, 0xf6, 0x79, 0xba, 0x3c, 0x6e, 0xc9, 0x0b, 0x56, 0x0f, 0x07,
    0x5e, 0x9f, 0xe9, 0x38, 0x18, 0xfc, 0xa0, 0x0a, 0x06, 0x08, 0x2a,
    0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, 0xa1, 0x44, 0x03, 0x42,
    0x00, 0x04, 0x7b, 0x2a, 0x61, 0x59, 0xe5, 0x1b, 0xb6, 0x30, 0x7b,
    0x59, 0x98, 0x42, 0x59, 0x37, 0xfb, 0x46, 0xfe, 0x53, 0xfe, 0x32,
    0xa1, 0x5c, 0x93, 0x36, 0x11, 0xb0, 0x5a, 0xae, 0xa4, 0x48, 0xe3,
    0x20, 0x12, 0xce, 0x78, 0xa7, 0x7f, 0xfd, 0x73, 0x5e, 0x09, 0x77,
    0x53, 0x77, 0x8f, 0xd6, 0x1b, 0x26, 0xfa, 0xc4, 0x2c, 0xc4, 0x11,
    0xfa, 0x72, 0x6a, 0xbe, 0x94, 0x78, 0x4d, 0x74, 0x20, 0x27, 0x86};

void BuildEcmgConfig(EcmgConfig* config) {
  config->delay_start = 200;     // in milliseconds.
  config->delay_stop = 200;      // in milliseconds.
  config->ecm_rep_period = 100;  // in milliseconds.
  config->max_comp_time = 100;   // in milliseconds.
  config->access_criteria_transfer_mode = 0;
  config->number_of_content_keys = 2;
  config->crypto_mode = widevine::cas::CryptoMode::kAesCtr;
  config->ecc_private_signing_key.assign(
      std::begin(kTestECPrivateKey2Secp256r1),
      std::end(kTestECPrivateKey2Secp256r1));
}

void PrintMessage(const std::string& description, const char* const message,
                  size_t length) {
  std::cout << description << std::endl;
  for (size_t i = 0; i < length; i++) {
    printf("'\\x%02x', ", static_cast<uint16_t>(*(message + i)));
    fflush(stdout);
  }
  printf("\n");
  fflush(stdout);
}

void ServeClient(int socket_fd, WvCasEcmgClientHandler* ecmg) {
  char request[kBufferSizeBytes];
  char response[kBufferSizeBytes];
  while (true) {
    bzero(request, kBufferSizeBytes);
    bzero(response, kBufferSizeBytes);
    size_t response_length = 0;
    size_t request_length = recv(socket_fd, request, kBufferSizeBytes, 0);
    if (request_length == 0) {
      std::cout << "No more request from client." << std::endl;
      return;
    }
    if (request_length < 0) {
      std::cerr << "Failed to receive request from client." << std::endl;
      return;
    }
    PrintMessage("Request", request, request_length);
    ecmg->HandleRequest(kBufferSizeBytes, request, kBufferSizeBytes, response,
                        &response_length);
    PrintMessage("Response", response, response_length);
    if (send(socket_fd, response, response_length, 0) < 0) {
      std::cerr << "Failed to send response to client." << std::endl;
      return;
    }
  }
}

std::vector<EntitlementKeyInfo> MyEntitlementKeyFetcherFun(uint16_t channel_id,
                                                           uint16_t stream_id,
                                                           uint16_t ecm_id) {
  // Fill the function to get entitlement keys based on the input parameters.
  // Potential step 1: Convert the input {channel_id, stream_id, ecm_id} to
  // EntitlementRequestParams defined in wv_cas_key_fetcher.h, such as
  // content_id, content provider, etc.
  // Potential step 2: Make the key fetch request. Refer to wv_cas_key_fetcher
  // and wv_cas_curl_key_fetcher for APIs that can fetch keys from Widevine
  // server with EntitlementRequestParams.

  // The size of the returned vector must not exceed 2. When the vector size is
  // 2, one of them must be specified as even key and the other must be odd key.
  constexpr char track_types_hd[] = "HD";
  constexpr char entitlement_key_id_even[] = "fake_key_id1....";
  constexpr char entitlement_key_value_even[] =
      "fakefakefakefakefakefakefake1...";
  constexpr char entitlement_key_id_odd[] = "fake_key_id2....";
  constexpr char entitlement_key_value_odd[] =
      "fakefakefakefakefakefakefake2...";
  return {{track_types_hd, /*is_even_key=*/true, entitlement_key_id_even,
           entitlement_key_value_even},
          {track_types_hd, /*is_even_key=*/false, entitlement_key_id_odd,
           entitlement_key_value_odd}};
}

int create_listen_socket_fd() {
  // Server address.
  struct sockaddr_in server_address;
  bzero(reinterpret_cast<char*>(&server_address), sizeof(server_address));
  server_address.sin_family = AF_INET;
  server_address.sin_addr.s_addr = htonl(INADDR_ANY);
  server_address.sin_port = htons(kServerPortNumber);

  // Create a listening socket.
  int listen_socket_fd = socket(AF_INET, SOCK_STREAM, /* protocol= */ 0);
  if (listen_socket_fd < 0) {
    std::cerr << "Failed to open listening socket" << std::endl;
  }
  // Set SO_REUSEADDR on a socket to true (1).
  int optval = 1;
  setsockopt(listen_socket_fd, SOL_SOCKET, SO_REUSEADDR, &optval,
             sizeof(optval));
  // Bind address.
  if (bind(listen_socket_fd,
           reinterpret_cast<struct sockaddr*>(&server_address),
           sizeof(server_address)) < 0) {
    std::cerr << "Failed to bind on server socket" << std::endl;
  }
  return listen_socket_fd;
}

}  // namespace

int main(int argc, char** argv) {
  EcmgConfig ecmg_config;
  BuildEcmgConfig(&ecmg_config);

  int listen_socket_fd = create_listen_socket_fd();
  // Listen for connection from clients.
  std::cout << "Server listening ..." << std::endl << std::flush;
  int return_val = listen(listen_socket_fd, kListenQueueSize);
  switch (return_val) {
    case EADDRINUSE:
      std::cerr << "Another socket is already listening on the same port."
                << std::endl;
      break;
    case EBADF:
      std::cerr << "The argument sockfd is not a valid descriptor."
                << std::endl;
      break;
    case ENOTSOCK:
      std::cerr << "The argument sockfd is not a socket." << std::endl;
      break;
    case EOPNOTSUPP:
      std::cerr << "The socket is not of a type that supports the listen() "
                   "operation."
                << std::endl;
      break;
    default:
      break;
  }

  // While loop to serve different client connections.
  while (true) {
    struct sockaddr_in client_address;
    socklen_t client_address_size = sizeof(client_address);
    int client_socket_fd = accept(
        listen_socket_fd, reinterpret_cast<struct sockaddr*>(&client_address),
        &client_address_size);
    std::cout << "\nTCP connection " << client_socket_fd << " start"
              << std::endl;
    if (client_socket_fd < 0) {
      std::cerr << "Failed to accept connection request from client"
                << std::endl;
    } else {
      if (fork() == 0) {
        // Reaching here, I am in the child process.
        close(listen_socket_fd);
        WvCasEcmgClientHandler client_handler(ecmg_config);
        client_handler.SetCustomEntitlementKeyFetcherFunc(
            MyEntitlementKeyFetcherFun);
        ServeClient(client_socket_fd, &client_handler);
        std::cout << "\nTCP connection " << client_socket_fd << " closed"
                  << std::endl;
        close(client_socket_fd);
        // Terminate child process.
        exit(0);
      }
      // Reaching here, I am in parent process.
      close(client_socket_fd);
    }
    usleep(1000);
  }
  return 0;
}