/*
 * This file is part of Moonlight Embedded.
 *
 * Copyright (C) 2015 Iwan Timmer
 *
 * Moonlight is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Moonlight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Moonlight; if not, see <http://www.gnu.org/licenses/>.
 */

#include "http.h"
#include "xml.h"

#include "limelight-common/Limelight.h"

#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/err.h>

static const char *uniqueFileName = "uniqueid.dat";
static const char *certificateFileName = "client.pem";
static const char *keyFileName = "key.pem";

static char unique_id[17];
static X509 *cert;
static char cert_hex[4096];
static EVP_PKEY *privateKey;

static bool paired;
static int currentGame;

static void client_load_unique_id() {
  FILE *fd = fopen(uniqueFileName, "r");
  if (fd == NULL) {
    unsigned char unique_data[16];
    RAND_bytes(unique_data, 16);
    for (int i = 0; i < 16; i += 2) {
      sprintf(unique_id + i, "%02x", unique_data[i]);
    }
    fd = fopen(uniqueFileName, "w");
    fwrite(unique_id, 16, 1, fd);
  } else {
    fread(unique_id, 16, 1, fd);
  }
  fclose(fd);
  unique_id[16] = 0;
}

static void client_load_cert() {
  FILE *fd = fopen(certificateFileName, "r");
  if (fd == NULL) {
    fprintf(stderr, "Can't open certificate file");
    exit(-1);
  }

  if (!(cert = PEM_read_X509(fd, NULL, NULL, NULL))) {
    printf("Error loading cert into memory.\n");
    exit(-1);
  }

  rewind(fd);

  int c;
  int length = 0;
  while ((c = fgetc(fd)) != EOF) {
    sprintf(cert_hex + length, "%02x", c);
    length += 2;
  }
  cert_hex[length] = 0;

  fclose(fd);

  fd = fopen(keyFileName, "r");
  PEM_read_PrivateKey(fd, &privateKey, NULL, NULL);
  fclose(fd);
}

static void client_load_server_status(const char *address) {
  char url[4096];
  sprintf(url, "https://%s:47984/serverinfo?uniqueid=%s", address, unique_id);

  struct http_data *data = http_create_data();
  http_request(url, data);

  char *pairedText = NULL;
  char *currentGameText = NULL;
  xml_search(data->memory, data->size, "currentgame", &currentGameText);
  xml_search(data->memory, data->size, "PairStatus", &pairedText);
  http_free_data(data);

  paired = pairedText != NULL && strcmp(pairedText, "1") == 0;
  currentGame = currentGameText == NULL ? 0 : atoi(currentGameText);

  free(pairedText);
  free(currentGameText);
}

static void bytes_to_hex(unsigned char *in, char *out, size_t len) {
  for (int i = 0; i < len; i++) {
    sprintf(out + i * 2, "%02x", in[i]);
  }
  out[len * 2] = 0;
}

static int sign_it(const char *msg, size_t mlen, unsigned char **sig, size_t *slen, EVP_PKEY *pkey) {
  int result = -1;

  *sig = NULL;
  *slen = 0;

  EVP_MD_CTX *ctx = EVP_MD_CTX_create();
  if (ctx == NULL) {
    printf("EVP_MD_CTX_create failed, error 0x%lx\n", ERR_get_error());
    return -1;
  }

  const EVP_MD *md = EVP_get_digestbyname("SHA256");
  if (md == NULL) {
    printf("EVP_get_digestbyname failed, error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  int rc = EVP_DigestInit_ex(ctx, md, NULL);
  if (rc != 1) {
    printf("EVP_DigestInit_ex failed, error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  rc = EVP_DigestSignInit(ctx, NULL, md, NULL, pkey);
  if (rc != 1) {
    printf("EVP_DigestSignInit failed, error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  rc = EVP_DigestSignUpdate(ctx, msg, mlen);
  if (rc != 1) {
    printf("EVP_DigestSignUpdate failed, error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  size_t req = 0;
  rc = EVP_DigestSignFinal(ctx, NULL, &req);
  if (rc != 1) {
    printf("EVP_DigestSignFinal failed (1), error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  if (!(req > 0)) {
    printf("EVP_DigestSignFinal failed (2), error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  *sig = OPENSSL_malloc(req);
  if (*sig == NULL) {
    printf("OPENSSL_malloc failed, error 0x%lx\n", ERR_get_error());
    goto cleanup;
  }

  *slen = req;
  rc = EVP_DigestSignFinal(ctx, *sig, slen);
  if (rc != 1) {
    printf("EVP_DigestSignFinal failed (3), return code %d, error 0x%lx\n", rc,
           ERR_get_error());
    goto cleanup;
  }

  if (req != *slen) {
    printf("EVP_DigestSignFinal failed, mismatched signature sizes %ld, %ld\n",
           req, *slen);
    goto cleanup;
  }

  result = 1;

cleanup:
  EVP_MD_CTX_destroy(ctx);
  ctx = NULL;

  return !!result;
}

static void client_pair(const char *address) {
  char url[4096];

  char pin[5];
  sprintf(pin, "%d%d%d%d", (int)random() % 10, (int)random() % 10, (int)random() % 10, (int)random() % 10);
  printf("Please enter the following PIN on the target PC: %s\n", pin);

  unsigned char salt_data[16];
  char salt_hex[33];
  RAND_bytes(salt_data, 16);
  bytes_to_hex(salt_data, salt_hex, 16);

  sprintf(url, "https://%s:47984/pair?uniqueid=%s&devicename=roth&updateState=1&phrase=getservercert&salt=%s&clientcert=%s", address, unique_id, salt_hex, cert_hex);
  struct http_data *data = http_create_data();
  http_request(url, data);

  unsigned char salt_pin[20];
  unsigned char aes_key_hash[20];
  AES_KEY aes_key;
  memcpy(salt_pin, salt_data, 16);
  memcpy(salt_pin+16, salt_pin, 4);
  SHA1(salt_pin, 20, aes_key_hash);
  AES_set_encrypt_key((unsigned char *)aes_key_hash, 128, &aes_key);

  unsigned char challenge_data[16];
  unsigned char challenge_enc[16];
  char challenge_hex[33];
  RAND_bytes(challenge_data, 16);
  AES_encrypt(challenge_data, challenge_enc, &aes_key);
  bytes_to_hex(challenge_enc, challenge_hex, 16);

  sprintf(url, "https://%s:47984/pair?uniqueid=%s&devicename=roth&updateState=1&clientchallenge=%s", address, unique_id, challenge_hex);
  http_request(url, data);

  char *result;
  xml_search(data->memory, data->size, "challengeresponse", &result);
  printf("Status %s\n", result);

  char challenge_response_data_enc[48];
  char challenge_response_data[48];
  for (int count = 0; count < strlen(result); count++) {
    sscanf(&result[count], "%2hhx", &challenge_response_data_enc[count / 2]);
  }
  free(result);

  for (int i = 0; i < 48; i += 16) {
    AES_decrypt(&challenge_response_data_enc[i], &challenge_response_data[i], &aes_key);
  }

  char client_secret_data[16];
  RAND_bytes(client_secret_data, 16);

  char challenge_response[16 + 256 + 16];
  char challenge_response_hash[32];
  char challenge_response_hash_enc[32];
  char challenge_response_hex[33];
  memcpy(challenge_response, challenge_response_data + 20, 16);
  memcpy(challenge_response + 16, cert->signature->data, 256);
  memcpy(challenge_response + 16 + 256, client_secret_data, 16);
  SHA1(challenge_response, 16 + 256 + 16, challenge_response_hash);

  for (int i = 0; i < 32; i += 16) {
    AES_encrypt(&challenge_response_hash[i], &challenge_response_hash_enc[i], &aes_key);
  }
  bytes_to_hex(challenge_response_hash_enc, challenge_response_hex, 32);

  sprintf(url, "https://%s:47984/pair?uniqueid=%s&devicename=roth&updateState=1&serverchallengeresp=%s", address, unique_id, challenge_response_hex);
  http_request(url, data);
  xml_search(data->memory, data->size, "pairingsecret", &result);

  char *signature = NULL;
  size_t s_len;
  if (!sign_it(client_secret_data, 16, &signature, &s_len, privateKey)) {
      fprintf(stderr, "Failed to sign data\n");
      exit(-1);
  }

  char client_pairing_secret[16 + 256];
  char client_pairing_secret_hex[(16 + 256) * 2 + 1];
  memcpy(client_pairing_secret, client_secret_data, 16);
  memcpy(client_pairing_secret + 16, signature, 256);
  bytes_to_hex(client_pairing_secret, client_pairing_secret_hex, 16 + 256);

  sprintf(url, "https://%s:47984/pair?uniqueid=%s&devicename=roth&updateState=1&clientpairingsecret=%s", address, unique_id, client_pairing_secret_hex);
  http_request(url, data);

  sprintf(url, "https://%s:47984/pair?uniqueid=%s&devicename=roth&updateState=1&phrase=pairchallenge", address, unique_id, challenge_response_hex);
  http_request(url, data);
  http_free_data(data);
}

struct app_list *client_applist(const char *address) {
  char url[4096];
  struct http_data *data = http_create_data();
  sprintf(url, "https://%s:47984/applist?uniqueid=%s", address, unique_id);
  http_request(url, data);
  struct app_list *list = xml_applist(data->memory, data->size);
  http_free_data(data);
  return list;
}

int client_get_app_id(const char *address, char *name) {
  struct app_list *list = client_applist(address);
  while (list != NULL) {
    if (strcmp(list->name, name) == 0)
      return list->id;

    list = list->next;
  }
  return -1;
}

void client_start_app(STREAM_CONFIGURATION *config, const char *address, int appId) {
  RAND_bytes(config->remoteInputAesKey, 16);
  memset(config->remoteInputAesIv, 0, 16);

  srand(time(NULL));
  char url[4096];
  u_int32_t rikeyid = 1;
  char rikey_hex[33];
  bytes_to_hex(config->remoteInputAesKey, rikey_hex, 16);

  struct http_data *data = http_create_data();
  if (currentGame == 0)
    sprintf(url, "https://%s:47984/launch?uniqueid=%s&appid=%d&mode=%dx%dx%d&additionalStates=1&sops=1&rikey=%s&rikeyid=%d&localAudioPlayMode=0", address, unique_id, appId, config->width, config->height, config->fps, rikey_hex, rikeyid);
  else
    sprintf(url, "https://%s:47984/resume?uniqueid=%s&rikey=%s&rikeyid=%d", address, unique_id, rikey_hex, rikeyid);

  http_request(url, data);
  http_free_data(data);
}

void client_init(const char *address) {
  http_init();
  client_load_unique_id();
  client_load_cert();

  client_load_server_status(address);
  if (!paired) {
    client_pair(address);
  }
}