#include "libmain/shared.hh"

#include <algorithm>
#include <cctype>
#include <csignal>
#include <cstdlib>
#include <exception>
#include <iostream>
#include <mutex>
#include <utility>

#include <glog/logging.h>
#include <openssl/crypto.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>

#include "libstore/globals.hh"
#include "libstore/store-api.hh"
#include "libutil/util.hh"

namespace nix {

static bool gcWarning = true;

void printGCWarning() {
  if (!gcWarning) {
    return;
  }

  static bool haveWarned = false;
  if (!haveWarned) {
    haveWarned = true;
    LOG(WARNING) << "you did not specify '--add-root'; "
                 << "the result might be removed by the garbage collector";
  }
}

void printMissing(const ref<Store>& store, const PathSet& paths) {
  unsigned long long downloadSize;
  unsigned long long narSize;
  PathSet willBuild;
  PathSet willSubstitute;
  PathSet unknown;
  store->queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize,
                      narSize);
  printMissing(store, willBuild, willSubstitute, unknown, downloadSize,
               narSize);
}

void printMissing(const ref<Store>& store, const PathSet& willBuild,
                  const PathSet& willSubstitute, const PathSet& unknown,
                  unsigned long long downloadSize, unsigned long long narSize) {
  if (!willBuild.empty()) {
    LOG(INFO) << "these derivations will be built:";
    Paths sorted = store->topoSortPaths(willBuild);
    reverse(sorted.begin(), sorted.end());
    for (auto& i : sorted) {
      LOG(INFO) << "  " << i;
    }
  }

  if (!willSubstitute.empty()) {
    LOG(INFO) << "these paths will be fetched ("
              << (downloadSize / (1024.0 * 1024.0)) << " MiB download, "
              << (narSize / (1024.0 * 1024.0)) << "MiB unpacked):";

    for (auto& i : willSubstitute) {
      LOG(INFO) << i;
    }
  }

  if (!unknown.empty()) {
    LOG(INFO) << "don't know how to build these paths"
              << (settings.readOnlyMode
                      ? " (may be caused by read-only store access)"
                      : "")
              << ":";

    for (auto& i : unknown) {
      LOG(INFO) << i;
    }
  }
}

std::string getArg(const std::string& opt, Strings::iterator& i,
                   const Strings::iterator& end) {
  ++i;
  if (i == end) {
    throw UsageError(format("'%1%' requires an argument") % opt);
  }

  return *i;
}

#if OPENSSL_VERSION_NUMBER < 0x10101000L
/* OpenSSL is not thread-safe by default - it will randomly crash
   unless the user supplies a mutex locking function. So let's do
   that. */
static std::vector<std::mutex> opensslLocks;

static void opensslLockCallback(int mode, int type, const char* file,
                                int line) {
  if (mode & CRYPTO_LOCK)
    opensslLocks[type].lock();
  else
    opensslLocks[type].unlock();
}
#endif

static void sigHandler(int signo) {}

void initNix() {
  /* Turn on buffering for cerr. */
#if HAVE_PUBSETBUF
  static char buf[1024];
  std::cerr.rdbuf()->pubsetbuf(buf, sizeof(buf));
#endif

#if OPENSSL_VERSION_NUMBER < 0x10101000L
  /* Initialise OpenSSL locking. */
  opensslLocks = std::vector<std::mutex>(CRYPTO_num_locks());
  CRYPTO_set_locking_callback(opensslLockCallback);
#endif

  loadConfFile();

  startSignalHandlerThread();

  /* Reset SIGCHLD to its default. */
  struct sigaction act;
  sigemptyset(&act.sa_mask);
  act.sa_handler = SIG_DFL;
  act.sa_flags = 0;
  if (sigaction(SIGCHLD, &act, nullptr) != 0) {
    throw SysError("resetting SIGCHLD");
  }

  /* Install a dummy SIGUSR1 handler for use with pthread_kill(). */
  act.sa_handler = sigHandler;
  if (sigaction(SIGUSR1, &act, nullptr) != 0) {
    throw SysError("handling SIGUSR1");
  }

  /* Register a SIGSEGV handler to detect stack overflows. */
  detectStackOverflow();

  /* There is no privacy in the Nix system ;-)  At least not for
     now.  In particular, store objects should be readable by
     everybody. */
  umask(0022);

  /* Initialise the PRNG. */
  struct timeval tv;
  gettimeofday(&tv, nullptr);
  srandom(tv.tv_usec);
}

LegacyArgs::LegacyArgs(
    const std::string& programName,
    std::function<bool(Strings::iterator& arg, const Strings::iterator& end)>
        parseArg)
    : MixCommonArgs(programName), parseArg(std::move(parseArg)) {
  mkFlag()
      .longName("no-build-output")
      .shortName('Q')
      .description("do not show build output")
      .set(&settings.verboseBuild, false);

  mkFlag()
      .longName("keep-failed")
      .shortName('K')
      .description("keep temporary directories of failed builds")
      .set(&(bool&)settings.keepFailed, true);

  mkFlag()
      .longName("keep-going")
      .shortName('k')
      .description("keep going after a build fails")
      .set(&(bool&)settings.keepGoing, true);

  mkFlag()
      .longName("fallback")
      .description("build from source if substitution fails")
      .set(&(bool&)settings.tryFallback, true);

  auto intSettingAlias = [&](char shortName, const std::string& longName,
                             const std::string& description,
                             const std::string& dest) {
    mkFlag<unsigned int>(shortName, longName, description, [=](unsigned int n) {
      settings.set(dest, std::to_string(n));
    });
  };

  intSettingAlias(0, "cores",
                  "maximum number of CPU cores to use inside a build", "cores");
  intSettingAlias(0, "max-silent-time",
                  "number of seconds of silence before a build is killed",
                  "max-silent-time");
  intSettingAlias(0, "timeout", "number of seconds before a build is killed",
                  "timeout");

  mkFlag(0, "readonly-mode", "do not write to the Nix store",
         &settings.readOnlyMode);

  mkFlag(0, "no-gc-warning", "disable warning about not using '--add-root'",
         &gcWarning, false);

  mkFlag()
      .longName("store")
      .label("store-uri")
      .description("URI of the Nix store to use")
      .dest(&(std::string&)settings.storeUri);
}

bool LegacyArgs::processFlag(Strings::iterator& pos, Strings::iterator end) {
  if (MixCommonArgs::processFlag(pos, end)) {
    return true;
  }
  bool res = parseArg(pos, end);
  if (res) {
    ++pos;
  }
  return res;
}

bool LegacyArgs::processArgs(const Strings& args, bool finish) {
  if (args.empty()) {
    return true;
  }
  assert(args.size() == 1);
  Strings ss(args);
  auto pos = ss.begin();
  if (!parseArg(pos, ss.end())) {
    throw UsageError(format("unexpected argument '%1%'") % args.front());
  }
  return true;
}

void parseCmdLine(
    int argc, char** argv,
    std::function<bool(Strings::iterator& arg, const Strings::iterator& end)>
        parseArg) {
  parseCmdLine(baseNameOf(argv[0]), argvToStrings(argc, argv),
               std::move(parseArg));
}

void parseCmdLine(
    const std::string& programName, const Strings& args,
    std::function<bool(Strings::iterator& arg, const Strings::iterator& end)>
        parseArg) {
  LegacyArgs(programName, std::move(parseArg)).parseCmdline(args);
}

void printVersion(const std::string& programName) {
  std::cout << format("%1% (Tvix) %2%") % programName % nixVersion << std::endl;

  // TODO(tazjin): figure out what the fuck this is
  /*if (verbosity > lvlInfo) {
    Strings cfg;
#if HAVE_BOEHMGC
    cfg.push_back("gc");
#endif
#if HAVE_SODIUM
    cfg.push_back("signed-caches");
#endif
    std::cout << "Features: " << concatStringsSep(", ", cfg) << "\n";
    std::cout << "Configuration file: " << settings.nixConfDir + "/nix.conf"
              << "\n";
    std::cout << "Store directory: " << settings.nixStore << "\n";
    std::cout << "State directory: " << settings.nixStateDir << "\n";
    } */
  throw Exit();
}

void showManPage(const std::string& name) {
  restoreSignals();
  setenv("MANPATH", settings.nixManDir.c_str(), 1);
  execlp("man", "man", name.c_str(), nullptr);
  throw SysError(format("command 'man %1%' failed") % name.c_str());
}

int handleExceptions(const std::string& programName,
                     const std::function<void()>& fun) {
  ReceiveInterrupts receiveInterrupts;  // FIXME: need better place for this

  std::string error = ANSI_RED "error:" ANSI_NORMAL " ";
  try {
    try {
      fun();
    } catch (...) {
      /* Subtle: we have to make sure that any `interrupted'
         condition is discharged before we reach printMsg()
         below, since otherwise it will throw an (uncaught)
         exception. */
      setInterruptThrown();
      throw;
    }
  } catch (Exit& e) {
    return e.status;
  } catch (UsageError& e) {
    LOG(INFO) << e.what();
    LOG(INFO) << "Try '" << programName << " --help' for more information.";
    return 1;
  } catch (BaseError& e) {
    LOG(ERROR) << error << (settings.showTrace ? e.prefix() : "") << e.msg();
    if (!e.prefix().empty() && !settings.showTrace) {
      LOG(INFO) << "(use '--show-trace' to show detailed location information)";
    }
    return static_cast<int>(e.status);
  } catch (std::bad_alloc& e) {
    LOG(ERROR) << error << "failed to allocate: " << e.what();
    return 1;
  } catch (std::exception& e) {
    LOG(ERROR) << error << e.what();
    return 1;
  }

  return 0;
}

RunPager::RunPager() {
  if (isatty(STDOUT_FILENO) == 0) {
    return;
  }
  char* pager = getenv("NIX_PAGER");
  if (pager == nullptr) {
    pager = getenv("PAGER");
  }
  if (pager && (std::string(pager) == "" || std::string(pager) == "cat")) {
    return;
  }

  Pipe toPager;
  toPager.create();

  pid = startProcess([&]() {
    if (dup2(toPager.readSide.get(), STDIN_FILENO) == -1) {
      throw SysError("dupping stdin");
    }
    if (getenv("LESS") == nullptr) {
      setenv("LESS", "FRSXMK", 1);
    }
    restoreSignals();
    if (pager != nullptr) {
      execl("/bin/sh", "sh", "-c", pager, nullptr);
    }
    execlp("pager", "pager", nullptr);
    execlp("less", "less", nullptr);
    execlp("more", "more", nullptr);
    throw SysError(format("executing '%1%'") % pager);
  });

  pid.setKillSignal(SIGINT);

  if (dup2(toPager.writeSide.get(), STDOUT_FILENO) == -1) {
    throw SysError("dupping stdout");
  }
}

RunPager::~RunPager() {
  try {
    if (pid != Pid(-1)) {
      std::cout.flush();
      close(STDOUT_FILENO);
      pid.wait();
    }
  } catch (...) {
    ignoreException();
  }
}

std::string showBytes(unsigned long long bytes) {
  return (format("%.2f MiB") % (bytes / (1024.0 * 1024.0))).str();
}

PrintFreed::~PrintFreed() {
  if (show) {
    std::cout << format("%1% store paths deleted, %2% freed\n") %
                     results.paths.size() % showBytes(results.bytesFreed);
  }
}

Exit::~Exit() = default;

}  // namespace nix