#include "derivations.hh"
#include "globals.hh"
#include "local-store.hh"
#include "parsed-derivations.hh"
#include "store-api.hh"
#include "thread-pool.hh"

namespace nix {

void Store::computeFSClosure(const PathSet& startPaths, PathSet& paths_,
                             bool flipDirection, bool includeOutputs,
                             bool includeDerivers) {
  struct State {
    size_t pending;
    PathSet& paths;
    std::exception_ptr exc;
  };

  Sync<State> state_(State{0, paths_, 0});

  std::function<void(const Path&)> enqueue;

  std::condition_variable done;

  enqueue = [&](const Path& path) -> void {
    {
      auto state(state_.lock());
      if (state->exc) return;
      if (state->paths.count(path)) return;
      state->paths.insert(path);
      state->pending++;
    }

    queryPathInfo(
        path, {[&, path](std::future<ref<ValidPathInfo>> fut) {
          // FIXME: calls to isValidPath() should be async

          try {
            auto info = fut.get();

            if (flipDirection) {
              PathSet referrers;
              queryReferrers(path, referrers);
              for (auto& ref : referrers)
                if (ref != path) enqueue(ref);

              if (includeOutputs)
                for (auto& i : queryValidDerivers(path)) enqueue(i);

              if (includeDerivers && isDerivation(path))
                for (auto& i : queryDerivationOutputs(path))
                  if (isValidPath(i) && queryPathInfo(i)->deriver == path)
                    enqueue(i);

            } else {
              for (auto& ref : info->references)
                if (ref != path) enqueue(ref);

              if (includeOutputs && isDerivation(path))
                for (auto& i : queryDerivationOutputs(path))
                  if (isValidPath(i)) enqueue(i);

              if (includeDerivers && isValidPath(info->deriver))
                enqueue(info->deriver);
            }

            {
              auto state(state_.lock());
              assert(state->pending);
              if (!--state->pending) done.notify_one();
            }

          } catch (...) {
            auto state(state_.lock());
            if (!state->exc) state->exc = std::current_exception();
            assert(state->pending);
            if (!--state->pending) done.notify_one();
          };
        }});
  };

  for (auto& startPath : startPaths) enqueue(startPath);

  {
    auto state(state_.lock());
    while (state->pending) state.wait(done);
    if (state->exc) std::rethrow_exception(state->exc);
  }
}

void Store::computeFSClosure(const Path& startPath, PathSet& paths_,
                             bool flipDirection, bool includeOutputs,
                             bool includeDerivers) {
  computeFSClosure(PathSet{startPath}, paths_, flipDirection, includeOutputs,
                   includeDerivers);
}

void Store::queryMissing(const PathSet& targets, PathSet& willBuild_,
                         PathSet& willSubstitute_, PathSet& unknown_,
                         unsigned long long& downloadSize_,
                         unsigned long long& narSize_) {
  Activity act(*logger, lvlDebug, actUnknown,
               "querying info about missing paths");

  downloadSize_ = narSize_ = 0;

  ThreadPool pool;

  struct State {
    PathSet done;
    PathSet &unknown, &willSubstitute, &willBuild;
    unsigned long long& downloadSize;
    unsigned long long& narSize;
  };

  struct DrvState {
    size_t left;
    bool done = false;
    PathSet outPaths;
    DrvState(size_t left) : left(left) {}
  };

  Sync<State> state_(State{PathSet(), unknown_, willSubstitute_, willBuild_,
                           downloadSize_, narSize_});

  std::function<void(Path)> doPath;

  auto mustBuildDrv = [&](const Path& drvPath, const Derivation& drv) {
    {
      auto state(state_.lock());
      state->willBuild.insert(drvPath);
    }

    for (auto& i : drv.inputDrvs)
      pool.enqueue(
          std::bind(doPath, makeDrvPathWithOutputs(i.first, i.second)));
  };

  auto checkOutput = [&](const Path& drvPath, ref<Derivation> drv,
                         const Path& outPath, ref<Sync<DrvState>> drvState_) {
    if (drvState_->lock()->done) return;

    SubstitutablePathInfos infos;
    querySubstitutablePathInfos({outPath}, infos);

    if (infos.empty()) {
      drvState_->lock()->done = true;
      mustBuildDrv(drvPath, *drv);
    } else {
      {
        auto drvState(drvState_->lock());
        if (drvState->done) return;
        assert(drvState->left);
        drvState->left--;
        drvState->outPaths.insert(outPath);
        if (!drvState->left) {
          for (auto& path : drvState->outPaths)
            pool.enqueue(std::bind(doPath, path));
        }
      }
    }
  };

  doPath = [&](const Path& path) {
    {
      auto state(state_.lock());
      if (state->done.count(path)) return;
      state->done.insert(path);
    }

    DrvPathWithOutputs i2 = parseDrvPathWithOutputs(path);

    if (isDerivation(i2.first)) {
      if (!isValidPath(i2.first)) {
        // FIXME: we could try to substitute the derivation.
        auto state(state_.lock());
        state->unknown.insert(path);
        return;
      }

      Derivation drv = derivationFromPath(i2.first);
      ParsedDerivation parsedDrv(i2.first, drv);

      PathSet invalid;
      for (auto& j : drv.outputs)
        if (wantOutput(j.first, i2.second) && !isValidPath(j.second.path))
          invalid.insert(j.second.path);
      if (invalid.empty()) return;

      if (settings.useSubstitutes && parsedDrv.substitutesAllowed()) {
        auto drvState = make_ref<Sync<DrvState>>(DrvState(invalid.size()));
        for (auto& output : invalid)
          pool.enqueue(std::bind(checkOutput, i2.first,
                                 make_ref<Derivation>(drv), output, drvState));
      } else
        mustBuildDrv(i2.first, drv);

    } else {
      if (isValidPath(path)) return;

      SubstitutablePathInfos infos;
      querySubstitutablePathInfos({path}, infos);

      if (infos.empty()) {
        auto state(state_.lock());
        state->unknown.insert(path);
        return;
      }

      auto info = infos.find(path);
      assert(info != infos.end());

      {
        auto state(state_.lock());
        state->willSubstitute.insert(path);
        state->downloadSize += info->second.downloadSize;
        state->narSize += info->second.narSize;
      }

      for (auto& ref : info->second.references)
        pool.enqueue(std::bind(doPath, ref));
    }
  };

  for (auto& path : targets) pool.enqueue(std::bind(doPath, path));

  pool.process();
}

Paths Store::topoSortPaths(const PathSet& paths) {
  Paths sorted;
  PathSet visited, parents;

  std::function<void(const Path& path, const Path* parent)> dfsVisit;

  dfsVisit = [&](const Path& path, const Path* parent) {
    if (parents.find(path) != parents.end())
      throw BuildError(
          format("cycle detected in the references of '%1%' from '%2%'") %
          path % *parent);

    if (visited.find(path) != visited.end()) return;
    visited.insert(path);
    parents.insert(path);

    PathSet references;
    try {
      references = queryPathInfo(path)->references;
    } catch (InvalidPath&) {
    }

    for (auto& i : references)
      /* Don't traverse into paths that don't exist.  That can
         happen due to substitutes for non-existent paths. */
      if (i != path && paths.find(i) != paths.end()) dfsVisit(i, &path);

    sorted.push_front(path);
    parents.erase(path);
  };

  for (auto& i : paths) dfsVisit(i, nullptr);

  return sorted;
}

}  // namespace nix