// Copyright 2018 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#include "packager/file/http_file.h"

#include <gflags/gflags.h>
#include "packager/base/bind.h"
#include "packager/base/files/file_util.h"
#include "packager/base/logging.h"
#include "packager/base/strings/string_number_conversions.h"
#include "packager/base/strings/stringprintf.h"
#include "packager/base/synchronization/lock.h"
#include "packager/base/threading/worker_pool.h"

DEFINE_int32(libcurl_verbosity, 0,
             "Set verbosity level for libcurl.");
DEFINE_string(user_agent, "",
              "Set a custom User-Agent string for HTTP ingest.");
DEFINE_string(https_ca_file, "",
              "Absolute path to the Certificate Authority file for the "
              "server cert. PEM format");
DEFINE_string(https_cert_file, "",
              "Absolute path to client certificate file.");
DEFINE_string(https_cert_private_key_file, "",
              "Absolute path to the private Key file.");
DEFINE_string(https_cert_private_key_password, "",
              "Password to the private key file.");
DECLARE_uint64(io_cache_size);

namespace shaka {

// curl_ primitives stolen from `http_key_fetcher.cc`.
namespace {

const char kUserAgentString[] = "shaka-packager-uploader/0.1";

size_t AppendToString(char* ptr,
                      size_t size,
                      size_t nmemb,
                      std::string* response) {
  DCHECK(ptr);
  DCHECK(response);
  const size_t total_size = size * nmemb;
  response->append(ptr, total_size);
  return total_size;
}

}  // namespace

class LibCurlInitializer {
 public:
  LibCurlInitializer() {
    curl_global_init(CURL_GLOBAL_DEFAULT);
  }

  ~LibCurlInitializer() {
    curl_global_cleanup();
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(LibCurlInitializer);
};

/// Create a HTTP/HTTPS client
HttpFile::HttpFile(const char* file_name, const char* mode, bool https)
    : File(file_name),
      file_mode_(mode),
      user_agent_(FLAGS_user_agent),
      ca_file_(FLAGS_https_ca_file),
      cert_file_(FLAGS_https_cert_file),
      cert_private_key_file_(FLAGS_https_cert_private_key_file),
      cert_private_key_pass_(FLAGS_https_cert_private_key_password),
      timeout_in_seconds_(0),
      cache_(FLAGS_io_cache_size),
      scoped_curl(curl_easy_init(), &curl_easy_cleanup),
      task_exit_event_(base::WaitableEvent::ResetPolicy::AUTOMATIC,
                       base::WaitableEvent::InitialState::NOT_SIGNALED) {
  if (https) {
    resource_url_ = "https://" + std::string(file_name);
  } else {
    resource_url_ = "http://" + std::string(file_name);
  }

  static LibCurlInitializer lib_curl_initializer;

  // Setup libcurl scope
  if (!scoped_curl.get()) {
    LOG(ERROR) << "curl_easy_init() failed.";
    // return Status(error::HTTP_FAILURE, "curl_easy_init() failed.");
    delete this;
  }
}

HttpFile::HttpFile(const char* file_name, const char* mode)
    : HttpFile(file_name, mode, false)
{}

// Destructor
HttpFile::~HttpFile() {}

bool HttpFile::Open() {

  VLOG(1) << "Opening " << resource_url() << " with file mode \"" << file_mode_ << "\".";

  // Ignore read requests as they would truncate the target
  // file by propagating as zero-length PUT requests.
  // See also https://github.com/google/shaka-packager/issues/149#issuecomment-437203701
  if (file_mode_ == "r") {
    VLOG(1) << "HttpFile only supports write mode, skipping further operations";
    task_exit_event_.Signal();
    return false;
  }

  // Run progressive upload in separate thread.
  base::WorkerPool::PostTask(
      FROM_HERE, base::Bind(&HttpFile::CurlPut, base::Unretained(this)),
      true  // task_is_slow
  );

  return true;
}

void HttpFile::CurlPut() {
  // Setup libcurl handle with HTTP PUT upload transfer mode.
  std::string request_body;
  Request(PUT, resource_url(), request_body, &response_body_);
}

bool HttpFile::Close() {
  VLOG(1) << "Closing " << resource_url() << ".";
  cache_.Close();
  task_exit_event_.Wait();
  delete this;
  return true;
}

int64_t HttpFile::Read(void* buffer, uint64_t length) {
  LOG(WARNING) << "HttpFile does not support Read().";
  return -1;
}

int64_t HttpFile::Write(const void* buffer, uint64_t length) {
  std::string url = resource_url();

  VLOG(2) << "Writing to " << url << ", length=" << length;

  // TODO: Implement retrying with exponential backoff, see
  // "widevine_key_source.cc"
  Status status;

  uint64_t bytes_written = cache_.Write(buffer, length);
  VLOG(3) << "PUT CHUNK bytes_written: " << bytes_written;
  return bytes_written;

  // Debugging based on response status
  /*
  if (status.ok()) {
    VLOG(1) << "Writing chunk succeeded";

  } else {
    VLOG(1) << "Writing chunk failed";
    if (!response_body.empty()) {
      VLOG(2) << "Response:\n" << response_body;
    }
  }
  */

  // Always signal success to the downstream pipeline
  return length;
}

int64_t HttpFile::Size() {
  VLOG(1) << "HttpFile does not support Size().";
  return -1;
}

bool HttpFile::Flush() {
  // Do nothing on Flush.
  return true;
}

bool HttpFile::Seek(uint64_t position) {
  VLOG(1) << "HttpFile does not support Seek().";
  return false;
}

bool HttpFile::Tell(uint64_t* position) {
  VLOG(1) << "HttpFile does not support Tell().";
  return false;
}

// Perform HTTP request
Status HttpFile::Request(HttpMethod http_method,
                         const std::string& url,
                         const std::string& data,
                         std::string* response) {

  // TODO: Sanity checks.
  // DCHECK(http_method == GET || http_method == POST);

  VLOG(1) << "Sending request to URL " << url;

  // Setup HTTP method and libcurl options
  SetupRequestBase(http_method, url, response);

  // Setup HTTP request headers and body
  SetupRequestData(data);

  // Perform HTTP request
  CURLcode res = curl_easy_perform(scoped_curl.get());

  // Assume successful request
  Status status = Status::OK;

  // Handle request failure
  if (res != CURLE_OK) {
    std::string method_text = method_as_text(http_method);
    std::string error_message = base::StringPrintf(
        "%s request for %s failed. Reason: %s.", method_text.c_str(),
        url.c_str(), curl_easy_strerror(res));
    if (res == CURLE_HTTP_RETURNED_ERROR) {
      long response_code = 0;
      curl_easy_getinfo(scoped_curl.get(), CURLINFO_RESPONSE_CODE, &response_code);
      error_message +=
          base::StringPrintf(" Response code: %ld.", response_code);
    }

    // Signal error to logfile
    LOG(ERROR) << error_message;

    // Signal error to caller
    status = Status(
        res == CURLE_OPERATION_TIMEDOUT ? error::TIME_OUT : error::HTTP_FAILURE,
        error_message);
  }

  // Signal task completion
  task_exit_event_.Signal();

  // Return request status to caller
  return status;
}

// Configure curl_ handle with reasonable defaults
void HttpFile::SetupRequestBase(HttpMethod http_method,
                                const std::string& url,
                                std::string* response) {
  response->clear();

  // Configure HTTP request method/verb
  switch (http_method) {
    case GET:
      curl_easy_setopt(scoped_curl.get(), CURLOPT_HTTPGET, 1L);
      break;
    case POST:
      curl_easy_setopt(scoped_curl.get(), CURLOPT_POST, 1L);
      break;
    case PUT:
      curl_easy_setopt(scoped_curl.get(), CURLOPT_PUT, 1L);
      break;
    case PATCH:
      curl_easy_setopt(scoped_curl.get(), CURLOPT_CUSTOMREQUEST, "PATCH");
      break;
  }

  // Configure HTTP request
  curl_easy_setopt(scoped_curl.get(), CURLOPT_URL, url.c_str());

  if (user_agent_.empty()) {
    curl_easy_setopt(scoped_curl.get(), CURLOPT_USERAGENT, kUserAgentString);
  } else {
    curl_easy_setopt(scoped_curl.get(), CURLOPT_USERAGENT, user_agent_.data());
  }

  curl_easy_setopt(scoped_curl.get(), CURLOPT_TIMEOUT, timeout_in_seconds_);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_FAILONERROR, 1L);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_FOLLOWLOCATION, 1L);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_WRITEFUNCTION, AppendToString);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_WRITEDATA, response);

  // HTTPS
  if (!cert_private_key_file_.empty() && !cert_file_.empty()) {
    curl_easy_setopt(scoped_curl.get(), CURLOPT_SSLKEY,
                     cert_private_key_file_.data());

    if (!cert_private_key_pass_.empty()) {
      curl_easy_setopt(scoped_curl.get(), CURLOPT_KEYPASSWD,
                       cert_private_key_pass_.data());
    }

    curl_easy_setopt(scoped_curl.get(), CURLOPT_SSLKEYTYPE, "PEM");
    curl_easy_setopt(scoped_curl.get(), CURLOPT_SSLCERTTYPE, "PEM");
    curl_easy_setopt(scoped_curl.get(), CURLOPT_SSLCERT, cert_file_.data());
  }
  if (!ca_file_.empty()) {
    // Host validation needs to be off when using self-signed certificates.
    curl_easy_setopt(scoped_curl.get(), CURLOPT_SSL_VERIFYHOST, 0L);
    curl_easy_setopt(scoped_curl.get(), CURLOPT_CAINFO, ca_file_.data());
  }

  // Propagate log level indicated by "--libcurl_verbosity" to libcurl.
  curl_easy_setopt(scoped_curl.get(), CURLOPT_VERBOSE, FLAGS_libcurl_verbosity);

}

// https://ec.haxx.se/callback-read.html
size_t read_callback(char* buffer, size_t size, size_t nitems, void* stream) {
  VLOG(3) << "read_callback";

  // Cast stream back to what is actually is
  // IoCache* cache = reinterpret_cast<IoCache*>(stream);
  IoCache* cache = (IoCache*)stream;
  VLOG(3) << "read_callback, cache: " << cache;

  // Copy cache content into buffer
  size_t length = cache->Read(buffer, size * nitems);
  VLOG(3) << "read_callback, length: " << length << "; buffer: " << buffer;
  return length;
}

// Configure curl_ handle for HTTP PUT upload
void HttpFile::SetupRequestData(const std::string& data) {

  // TODO: Sanity checks.
  // if (method == POST || method == PUT || method == PATCH)

  // Build list of HTTP request headers.
  struct curl_slist* headers = nullptr;

  headers = curl_slist_append(headers, "Content-Type: application/octet-stream");
  headers = curl_slist_append(headers, "Transfer-Encoding: chunked");

  // Don't stop on 200 OK responses.
  headers = curl_slist_append(headers, "Expect:");

  // Enable progressive upload with chunked transfer encoding.
  curl_easy_setopt(scoped_curl.get(), CURLOPT_READFUNCTION, read_callback);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_READDATA, &cache_);
  curl_easy_setopt(scoped_curl.get(), CURLOPT_UPLOAD, 1L);

  // Add HTTP request headers.
  curl_easy_setopt(scoped_curl.get(), CURLOPT_HTTPHEADER, headers);
}

// Return HTTP request method (verb) as string
std::string HttpFile::method_as_text(HttpMethod method) {
  std::string method_text = "UNKNOWN";
  switch (method) {
    case GET:
      method_text = "GET";
      break;
    case POST:
      method_text = "POST";
      break;
    case PUT:
      method_text = "PUT";
      break;
    case PATCH:
      method_text = "PATCH";
      break;
  }
  return method_text;
}

}  // namespace shaka