//===-- ExperimentalDependencyGraph.cpp ------------------------------------==//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "swift/Driver/ExperimentalDependencyDriverGraph.h"
// Next two includes needed for reporting errors opening dot file for writing.
#include "swift/AST/DiagnosticsFrontend.h"
#include "swift/AST/FileSystem.h"
#include "swift/Basic/ReferenceDependencyKeys.h"
#include "swift/Basic/Statistic.h"
#include "swift/Demangling/Demangle.h"
#include "swift/Driver/Job.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/YAMLParser.h"
#include "llvm/Support/raw_ostream.h"

// Definitions for the portion experimental dependency system used by the
// driver.

using namespace swift;

using namespace swift::experimental_dependencies;
using namespace swift::driver;

//==============================================================================
// MARK: Interfacing to Compilation
//==============================================================================

using LoadResult = experimental_dependencies::DependencyGraphImpl::LoadResult;

LoadResult ModuleDepGraph::loadFromPath(const Job *Cmd, StringRef path,
                                        DiagnosticEngine &diags) {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-loadFromPath");

  if (driverDotFileBasePath.empty()) {
    driverDotFileBasePath = path;
    llvm::sys::path::remove_filename(driverDotFileBasePath);
    llvm::sys::path::append(driverDotFileBasePath, "driver");
  }

  auto buffer = llvm::MemoryBuffer::getFile(path);
  if (!buffer)
    return LoadResult::HadError;
  auto r = loadFromBuffer(Cmd, *buffer.get());
  if (emitExperimentalDependencyDotFileAfterEveryImport)
    emitDotFileForJob(diags, Cmd);
  if (verifyExperimentalDependencyGraphAfterEveryImport)
    verify();
  return r;
}

LoadResult ModuleDepGraph::loadFromBuffer(const Job *job,
                                          llvm::MemoryBuffer &buffer) {

  Optional<SourceFileDepGraph> sourceFileDepGraph =
      SourceFileDepGraph::loadFromBuffer(buffer);
  if (!sourceFileDepGraph)
    return DependencyGraphImpl::LoadResult::HadError;
  addIndependentNode(job);
  return integrate(sourceFileDepGraph.getValue());
}

bool ModuleDepGraph::isMarked(const Job *cmd) const {
  return cascadingJobs.count(getSwiftDeps(cmd));
}

void ModuleDepGraph::markTransitive(
    SmallVectorImpl<const Job *> &visited, const Job *job,
    ModuleDepGraph::MarkTracer *visitTracer) {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-markTransitive");
  std::unordered_set<const ModuleDepGraphNode *> visitedNodeSet;
  const StringRef swiftDeps = getSwiftDeps(job);
  // Do the traversal.
  for (auto &fileAndNode : nodeMap[swiftDeps]) {
    checkTransitiveClosureForCascading(visitedNodeSet, fileAndNode.second, visitTracer);
  }
  // Copy back visited jobs.
  std::unordered_set<std::string> visitedSwiftDeps;
  for (const ModuleDepGraphNode *n : visitedNodeSet) {
    if (!n->getSwiftDeps().hasValue())
      continue;
    const std::string &swiftDeps = n->getSwiftDeps().getValue();
    if (visitedSwiftDeps.insert(swiftDeps).second) {
      assert(n->assertImplementationMustBeInAFile());
      ensureJobIsTracked(swiftDeps);
      visited.push_back(getJob(swiftDeps));
    }
  }
}

bool ModuleDepGraph::markIntransitive(const Job *node) {
  return cascadingJobs.insert(getSwiftDeps(node)).second;
}

void ModuleDepGraph::addIndependentNode(const Job *job) {
  // No need to create any nodes; that will happen when the swiftdeps file is
  // read. Just record the correspondence.
  jobsBySwiftDeps.insert(std::make_pair(getSwiftDeps(job), job));
}

std::vector<std::string> ModuleDepGraph::getExternalDependencies() const {
  return std::vector<std::string>(externalDependencies.begin(),
                                  externalDependencies.end());
}

// Add every (swiftdeps) use of the external dependency to uses.
void ModuleDepGraph::markExternal(SmallVectorImpl<const Job *> &uses,
                                  StringRef externalDependency) {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-markExternal");
  // TODO move nameForDep into key
  // These nodes will depend on the *interface* of the external Decl.
  DependencyKey key =
      DependencyKey::createDependedUponKey<NodeKind::externalDepend>(
          externalDependency.str());
  // collect answers into useSet
  std::unordered_set<std::string> visitedSet;
  for (const DependencyKey &keyOfUse : usesByDef[key]) {
    nodeMap.forEachValueMatching(
        keyOfUse, [&](const std::string &, ModuleDepGraphNode *n) {
          const Job *job = getJob(n->getSwiftDeps());
          if (isMarked(job))
            return;
          uses.push_back(job);
          markTransitive(uses, job);
        });
  }
}

//==============================================================================
// MARK: Integrating SourceFileDepGraph into ModuleDepGraph
//==============================================================================

LoadResult ModuleDepGraph::integrate(const SourceFileDepGraph &g) {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-integrate");

  StringRef swiftDeps = g.getSwiftDepsFromSourceFileProvide();
  // When done, disappearedNodes contains the nodes which no longer exist.
  auto disappearedNodes = nodeMap[swiftDeps];
  // When done, changeDependencyKeys contains a list of keys that changed
  // as a result of this integration.
  auto changedNodes = std::unordered_set<DependencyKey>();

  g.forEachNode([&](const SourceFileDepGraphNode *integrand) {
    integrateUsesByDef(integrand, g);
    const auto key = integrand->getKey();
    Optional<ModuleDepGraphNode *> preexistingNodeInPlace =
        integrand->getIsProvides() ? nodeMap.find(swiftDeps, key) : None;
    if (preexistingNodeInPlace)
      disappearedNodes.erase(key);
    const bool changed = integrateSourceFileDepGraphNode(
        integrand, swiftDeps, preexistingNodeInPlace);
    if (changed)
      changedNodes.insert(key);

    // Track externalDependencies so Compilation can check them.
    if (integrand->getKey().getKind() == NodeKind::externalDepend)
      externalDependencies.insert(integrand->getKey().getName());
  });

  for (auto &p : disappearedNodes) {
    changedNodes.insert(p.second->getKey());
    removeNode(p.second);
  }

  // TODO: use changedKeys sometime, for instance by returning them
  // as part of return value so that the driver can only mark from them.
  return changedNodes.empty() ? LoadResult::UpToDate
                              : LoadResult::AffectsDownstream;
}

bool ModuleDepGraph::integrateSourceFileDepGraphNode(
    const SourceFileDepGraphNode *integrand,
    StringRef swiftDepsOfSourceFileGraph,
    const Optional<ModuleDepGraphNode *> preexistingNodeInPlace) {

  const auto key = integrand->getKey();

  const Optional<ModuleDepGraphNode *> preexistingExpat =
      preexistingNodeInPlace ? None : nodeMap.find("", key);

  const size_t preexistingCount = nodeMap[key].size();

  assert((!preexistingExpat || preexistingCount == 1) &&
         "If there is an expat, must not be any Decls in files.");

  const bool dupsExistInOtherFiles =
      !preexistingNodeInPlace && !preexistingExpat && preexistingCount;

  return integrand->getIsProvides()
             ? integrateFrontendDeclNode(integrand, swiftDepsOfSourceFileGraph,
                                         preexistingNodeInPlace,
                                         preexistingExpat)
             : integrateFrontendExpatNode(integrand, preexistingNodeInPlace,
                                          preexistingExpat,
                                          dupsExistInOtherFiles);
}

bool ModuleDepGraph::integrateFrontendDeclNode(
    const SourceFileDepGraphNode *integrand,
    StringRef swiftDepsOfSourceFileGraph,
    const Optional<ModuleDepGraphNode *> preexistingNodeInPlace,
    const Optional<ModuleDepGraphNode *> preexistingExpat) {

  const auto key = integrand->getKey();
  if (preexistingNodeInPlace)
    return preexistingNodeInPlace.getValue()->integrateFingerprintFrom(
        integrand);

  if (preexistingExpat) {
    // Some other file depended on this, but didn't know where it was.
    moveNodeToDifferentFile(preexistingExpat.getValue(),
                            swiftDepsOfSourceFileGraph.str());
    preexistingExpat.getValue()->integrateFingerprintFrom(integrand);
    return true; // New Decl, assume changed
  }
  integrateByCreatingANewNode(integrand, swiftDepsOfSourceFileGraph.str());
  return true; // New node
}

bool ModuleDepGraph::integrateFrontendExpatNode(
    const SourceFileDepGraphNode *integrand,
    const Optional<ModuleDepGraphNode *> preexistingNodeInPlace,
    const Optional<ModuleDepGraphNode *> preexistingExpat,
    bool dupsExistInOtherFiles) {

  const auto key = integrand->getKey();

  if (dupsExistInOtherFiles || preexistingExpat) {
    // Integrand is a dependency from another file, and we already have a def
    // node for that. Nothing to be done.
    assert(!integrand->getFingerprint().hasValue() &&
           "If extra-file dependencies were to have fingerprints, would need "
           "to do something more.");
    return false;
  }
  if (preexistingNodeInPlace) {
    // Something was deleted from this file, but it still depends on that
    // (baseName). Also, at this point there is no other matching node.
    preexistingNodeInPlace.getValue()->integrateFingerprintFrom(integrand);
    moveNodeToDifferentFile(preexistingNodeInPlace.getValue(), None);
  } else
    integrateByCreatingANewNode(integrand, None);
  return true;
}

ModuleDepGraphNode *ModuleDepGraph::integrateByCreatingANewNode(
    const SourceFileDepGraphNode *integrand,
    const Optional<std::string> swiftDepsForNewNode) {
  const auto &key = integrand->getKey();
  ModuleDepGraphNode *newNode = new ModuleDepGraphNode(
      key, integrand->getFingerprint(), swiftDepsForNewNode);
  addToMap(newNode);
  return newNode;
}

void ModuleDepGraph::integrateUsesByDef(const SourceFileDepGraphNode *n,
                                        const SourceFileDepGraph &g) {
  const auto &def = n->getKey();
  auto &uses = usesByDef[def];
  g.forEachUseOf(n, [&](const SourceFileDepGraphNode *useNode) {
    const auto &use = useNode->getKey();
    if (use != def)
      uses.insert(use);
  });
}

void ModuleDepGraph::removeNode(ModuleDepGraphNode *n) {
  eraseNodeFromMap(n);
  delete n;
}

//==============================================================================
// MARK: ModuleDepGraph access
//==============================================================================

void ModuleDepGraph::forEachUseOf(
    const ModuleDepGraphNode *def,
    function_ref<void(const ModuleDepGraphNode *)> fn) {
  auto iter = usesByDef.find(def->getKey());
  if (iter == usesByDef.end())
    return;
  for (const DependencyKey &useKey : iter->second)
    forEachMatchingNode(useKey, fn);
}

void ModuleDepGraph::forEachNode(
    function_ref<void(const ModuleDepGraphNode *)> fn) const {
  nodeMap.forEachEntry([&](const std::string &, const DependencyKey &,
                           ModuleDepGraphNode *n) { fn(n); });
}

void ModuleDepGraph::forEachMatchingNode(
    const DependencyKey &key,
    function_ref<void(const ModuleDepGraphNode *)> fn) const {
  nodeMap.forEachValueMatching(
      key, [&](const std::string &, ModuleDepGraphNode *n) { fn(n); });
}

void ModuleDepGraph::forEachArc(
    function_ref<void(const ModuleDepGraphNode *, const ModuleDepGraphNode *)>
        fn) const {
  /// Use find instead of [] because this is const
  for (const auto &defUse : usesByDef)
    forEachMatchingNode(defUse.first, [&](const ModuleDepGraphNode *defNode) {
      for (const auto &useKey : defUse.second)
        forEachMatchingNode(useKey, [&](const ModuleDepGraphNode *useNode) {
          fn(defNode, useNode);
        });
    });
}

//==============================================================================
// MARK: ModuleDepGraph traversal
//==============================================================================

// Could be faster by passing in a file, not a node, but we are trying for
// generality.
// The status quo system doesn't traverse past "Marked" nodes.
// I'm not sure that will be safe when we get fingerprints.
// Seems like no harm, just more time spent, by traversing through "Marked"
// nodes.
void ModuleDepGraph::checkTransitiveClosureForCascading(
    std::unordered_set<const ModuleDepGraphNode *> &visited,
    const ModuleDepGraphNode *potentiallyCascadingDef,
    MarkTracer *tracer
  ) {
  // Cycle recording and check.
  if (!visited.insert(potentiallyCascadingDef).second)
    return;
  // Moved this out of the following loop for effieciency.
  assert(potentiallyCascadingDef->getSwiftDeps().hasValue() &&
         "Should only call me for Decl nodes.");
  tracer->pushDef(potentiallyCascadingDef);
  forEachUseOf(potentiallyCascadingDef, [&](const ModuleDepGraphNode *u) {
    tracer->foundUse(u);
    if (u->getKey().isInterface() && u->getSwiftDeps().hasValue()) {
      // An interface depends on something. Thus, if that something changes
      // the interface must be recompiled. But if an interface changes, then
      // anything using that interface must also be recompiled.
      // So, the job containing the interface "cascades", in other words
      // whenever that job gets recompiled, anything depending on it
      // (since we don't have interface-specific dependency info as of Dec.
      // 2018) must be recompiled.
      rememberThatJobCascades(u->getSwiftDeps().getValue());
      tracer->foundCascadingUse(u);
    }
    checkTransitiveClosureForCascading(visited, u, tracer);
    tracer->popUse(u);
  });
}

// Emitting Dot file for ModuleDepGraph
// ===========================================

void ModuleDepGraph::emitDotFileForJob(DiagnosticEngine &diags,
                                       const Job *job) {
  emitDotFile(diags, getSwiftDeps(job));
}

void ModuleDepGraph::emitDotFile(DiagnosticEngine &diags, StringRef baseName) {
  unsigned seqNo = dotFileSequenceNumber[baseName]++;
  std::string fullName = baseName.str() + "." + std::to_string(seqNo) + ".dot";
  withOutputFile(diags, fullName, [&](llvm::raw_ostream &out) {
    emitDotFile(out);
    return false;
  });
}

void ModuleDepGraph::emitDotFile(llvm::raw_ostream &out) {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-emitDotFile");
  DotFileEmitter<ModuleDepGraph>(out, *this, true, false).emit();
}

//==============================================================================
// MARK: ModuleDepGraph debugging
//==============================================================================

void ModuleDepGraphNode::dump() const {
  DepGraphNode::dump();
  if (getSwiftDeps().hasValue())
    llvm::errs() << " swiftDeps: <" << getSwiftDeps().getValue() << ">\n";
  else
    llvm::errs() << " no swiftDeps\n";
}

bool ModuleDepGraph::verify() const {
  FrontendStatsTracer tracer(stats, "experimental-dependencies-verify");
  verifyNodeMapEntries();
  verifyCanFindEachJob();
  verifyEachJobIsTracked();

  return true;
}

void ModuleDepGraph::verifyNodeMapEntries() const {
  FrontendStatsTracer tracer(stats,
                             "experimental-dependencies-verifyNodeMapEntries");
  // TODO: disable when not debugging
  std::array<
      std::unordered_map<DependencyKey,
                         std::unordered_map<std::string, ModuleDepGraphNode *>>,
      2>
      nodesSeenInNodeMap;
  nodeMap.verify([&](const std::string &swiftDepsString,
                     const DependencyKey &key, ModuleDepGraphNode *n,
                     unsigned submapIndex) {
    verifyNodeMapEntry(nodesSeenInNodeMap, swiftDepsString, key, n,
                       submapIndex);
  });
}

void ModuleDepGraph::verifyNodeMapEntry(
    std::array<std::unordered_map<
                   DependencyKey,
                   std::unordered_map<std::string, ModuleDepGraphNode *>>,
               2> &nodesSeenInNodeMap,
    const std::string &swiftDepsString, const DependencyKey &key,
    ModuleDepGraphNode *n, const unsigned submapIndex) const {
  verifyNodeIsUniqueWithinSubgraph(nodesSeenInNodeMap, swiftDepsString, key, n,
                                   submapIndex);
  verifyNodeIsInRightEntryInNodeMap(swiftDepsString, key, n);
  key.verify();
  verifyExternalDependencyUniqueness(key);
}

void ModuleDepGraph::verifyNodeIsUniqueWithinSubgraph(
    std::array<std::unordered_map<
                   DependencyKey,
                   std::unordered_map<std::string, ModuleDepGraphNode *>>,
               2> &nodesSeenInNodeMap,
    const std::string &swiftDepsString, const DependencyKey &key,
    ModuleDepGraphNode *const n, const unsigned submapIndex) const {
  assert(submapIndex < nodesSeenInNodeMap.size() &&
         "submapIndex is out of bounds.");
  auto iterInserted = nodesSeenInNodeMap[submapIndex][n->getKey()].insert(
      std::make_pair(n->getSwiftDeps().hasValue() ? n->getSwiftDeps().getValue()
                                                  : std::string(),
                     n));
  if (!iterInserted.second) {
    llvm_unreachable("duplicate driver keys");
  }
}

void ModuleDepGraph::verifyNodeIsInRightEntryInNodeMap(
    const std::string &swiftDepsString, const DependencyKey &key,
    const ModuleDepGraphNode *const n) const {
  const DependencyKey &nodeKey = n->getKey();
  const Optional<std::string> swiftDeps =
      swiftDepsString.empty() ? None : Optional<std::string>(swiftDepsString);
  assert(n->getSwiftDeps() == swiftDeps ||
         mapCorruption("Node misplaced for swiftDeps"));
  assert(nodeKey == key || mapCorruption("Node misplaced for key"));
}

void ModuleDepGraph::verifyExternalDependencyUniqueness(
    const DependencyKey &key) const {
  assert((key.getKind() != NodeKind::externalDepend ||
          externalDependencies.count(key.getName()) == 1) &&
         "Ensure each external dependency is tracked exactly once");
}

void ModuleDepGraph::verifyCanFindEachJob() const {
  FrontendStatsTracer tracer(stats,
                             "experimental-dependencies-verifyCanFindEachJob");
  for (const auto p : jobsBySwiftDeps) {
    getJob(p.first);
  }
}

void ModuleDepGraph::verifyEachJobIsTracked() const {
  FrontendStatsTracer tracer(
      stats, "experimental-dependencies-verifyEachJobIsTracked");
  nodeMap.forEachKey1(
      [&](const std::string &swiftDeps, const typename NodeMap::Key2Map &) {
        ensureJobIsTracked(swiftDeps);
      });
}

bool ModuleDepGraph::emitAndVerify(DiagnosticEngine &diags) {
  if (!driverDotFileBasePath.empty())
    emitDotFile(diags, driverDotFileBasePath);
  return verify();
}

//==============================================================================
// MARK: ModuleDepGraph::MarkTracer
//==============================================================================
void ModuleDepGraph::PathTracer::pushDef(const ModuleDepGraphNode* def) {
  if (path.empty()) path.push_back(def);
  else {assert(path.back() == def); }
}
void ModuleDepGraph::PathTracer::foundUse(const ModuleDepGraphNode* use) {
  path.push_back(use);
}
void ModuleDepGraph::PathTracer::foundCascadingUse(const ModuleDepGraphNode* use) {
  assert(path.back() == use);
  pathsByJob[job] = path;
  // copy path for use
}
void ModuleDepGraph::PathTracer::popUse(const ModuleDepGraphNode* use) {
  assert(path.back() == use);
  path.pop_back();
}

/// Dump the path that led to \p node.
void  ModuleDepGraph::PathTracer::printPath(
                                            raw_ostream &out,
                                            const driver::Job* jobToBeBuilt,
                                            llvm::function_ref<void(raw_ostream &, driver::Job*)> printItem
                                            ) const {
#error What?!
//  for (const Entry &entry : Table.lookup(item)) {
//    out << "\t";
//    printItem(entry.Node);
//    if (entry.KindMask.contains(DependencyKind::TopLevelName)) {
//      out << " provides top-level name '" << entry.Name << "'\n";
//
//    } else if (entry.KindMask.contains(DependencyKind::NominalType)) {
//      SmallString<64> name{entry.Name};
//      if (name.front() == 'P')
//        name.push_back('_');
//      out << " provides type '"
//      << swift::Demangle::demangleTypeAsString(name.str())
//      << "'\n";
//
//    } else if (entry.KindMask.contains(DependencyKind::NominalTypeMember)) {
//      SmallString<64> name{entry.Name};
//      size_t splitPoint = name.find('\0');
//      assert(splitPoint != StringRef::npos);
//
//      StringRef typePart;
//      if (name.front() == 'P') {
//        name[splitPoint] = '_';
//        typePart = name.str().slice(0, splitPoint+1);
//      } else {
//        typePart = name.str().slice(0, splitPoint);
//      }
//      StringRef memberPart = name.str().substr(splitPoint+1);
//
//      if (memberPart.empty()) {
//        out << " provides non-private members of type '"
//        << swift::Demangle::demangleTypeAsString(typePart)
//        << "'\n";
//      } else {
//        out << " provides member '" << memberPart << "' of type '"
//        << swift::Demangle::demangleTypeAsString(typePart)
//        << "'\n";
//      }
//    } else if (entry.KindMask.contains(DependencyKind::DynamicLookupName)) {
//      out << " provides AnyObject member '" << entry.Name << "'\n";
//
//    } else {
//      llvm_unreachable("not a dependency kind between nodes");
//    }
//  }
}