#pragma once

#include <chrono>
#include <future>
#include <string>
#include <unordered_set>

#include <absl/status/status.h>
#include <absl/strings/str_split.h>

#include "libstore/pathlocks.hh"
#include "libstore/sqlite.hh"
#include "libstore/store-api.hh"
#include "libutil/sync.hh"
#include "libutil/util.hh"

namespace nix {

/* Nix store and database schema version.  Version 1 (or 0) was Nix <=
   0.7.  Version 2 was Nix 0.8 and 0.9.  Version 3 is Nix 0.10.
   Version 4 is Nix 0.11.  Version 5 is Nix 0.12-0.16.  Version 6 is
   Nix 1.0.  Version 7 is Nix 1.3. Version 10 is 2.0. */
const int nixSchemaVersion = 10;

struct Derivation;

struct OptimiseStats {
  unsigned long filesLinked = 0;
  unsigned long long bytesFreed = 0;
  unsigned long long blocksFreed = 0;
};

class LocalStore : public LocalFSStore {
 private:
  /* Lock file used for upgrading. */
  AutoCloseFD globalLock;

  struct State {
    /* The SQLite database object. */
    SQLite db;

    /* Some precompiled SQLite statements. */
    SQLiteStmt stmtRegisterValidPath;
    SQLiteStmt stmtUpdatePathInfo;
    SQLiteStmt stmtAddReference;
    SQLiteStmt stmtQueryPathInfo;
    SQLiteStmt stmtQueryReferences;
    SQLiteStmt stmtQueryReferrers;
    SQLiteStmt stmtInvalidatePath;
    SQLiteStmt stmtAddDerivationOutput;
    SQLiteStmt stmtQueryValidDerivers;
    SQLiteStmt stmtQueryDerivationOutputs;
    SQLiteStmt stmtQueryPathFromHashPart;
    SQLiteStmt stmtQueryValidPaths;

    /* The file to which we write our temporary roots. */
    AutoCloseFD fdTempRoots;

    /* The last time we checked whether to do an auto-GC, or an
       auto-GC finished. */
    std::chrono::time_point<std::chrono::steady_clock> lastGCCheck;

    /* Whether auto-GC is running. If so, get gcFuture to wait for
       the GC to finish. */
    bool gcRunning = false;
    std::shared_future<void> gcFuture;

    /* How much disk space was available after the previous
       auto-GC. If the current available disk space is below
       minFree but not much below availAfterGC, then there is no
       point in starting a new GC. */
    uint64_t availAfterGC = std::numeric_limits<uint64_t>::max();

    std::unique_ptr<PublicKeys> publicKeys;
  };

  Sync<State, std::recursive_mutex> _state;

 public:
  PathSetting realStoreDir_;

  const Path realStoreDir;
  const Path dbDir;
  const Path linksDir;
  const Path reservedPath;
  const Path schemaPath;
  const Path trashDir;
  const Path tempRootsDir;
  const Path fnTempRoots;

 private:
  Setting<bool> requireSigs{
      (Store*)this, settings.requireSigs, "require-sigs",
      "whether store paths should have a trusted signature on import"};

  const PublicKeys& getPublicKeys();

 public:
  // Hack for build-remote.cc.
  // TODO(tazjin): remove this when we've got gRPC
  PathSet locksHeld =
      absl::StrSplit(getEnv("NIX_HELD_LOCKS").value_or(""),
                     absl::ByAnyChar(" \t\n\r"), absl::SkipEmpty());

  /* Initialise the local store, upgrading the schema if
     necessary. */
  LocalStore(const Params& params);

  ~LocalStore();

  /* Implementations of abstract store API methods. */

  std::string getUri() override;

  bool isValidPathUncached(const Path& path) override;

  PathSet queryValidPaths(const PathSet& paths, SubstituteFlag maybeSubstitute =
                                                    NoSubstitute) override;

  PathSet queryAllValidPaths() override;

  void queryPathInfoUncached(
      const Path& path,
      Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept override;

  void queryReferrers(const Path& path, PathSet& referrers) override;

  PathSet queryValidDerivers(const Path& path) override;

  PathSet queryDerivationOutputs(const Path& path) override;

  StringSet queryDerivationOutputNames(const Path& path) override;

  Path queryPathFromHashPart(const std::string& hashPart) override;

  PathSet querySubstitutablePaths(const PathSet& paths) override;

  void querySubstitutablePathInfos(const PathSet& paths,
                                   SubstitutablePathInfos& infos) override;

  void addToStore(const ValidPathInfo& info, Source& source, RepairFlag repair,
                  CheckSigsFlag checkSigs,
                  std::shared_ptr<FSAccessor> accessor) override;

  Path addToStore(const std::string& name, const Path& srcPath, bool recursive,
                  HashType hashAlgo, PathFilter& filter,
                  RepairFlag repair) override;

  /* Like addToStore(), but the contents of the path are contained
     in `dump', which is either a NAR serialisation (if recursive ==
     true) or simply the contents of a regular file (if recursive ==
     false). */
  Path addToStoreFromDump(const std::string& dump, const std::string& name,
                          bool recursive = true, HashType hashAlgo = htSHA256,
                          RepairFlag repair = NoRepair);

  Path addTextToStore(const std::string& name, const std::string& s,
                      const PathSet& references, RepairFlag repair) override;

  absl::Status buildPaths(std::ostream& log_sink, const PathSet& paths,
                          BuildMode build_mode) override;

  BuildResult buildDerivation(const Path& drvPath, const BasicDerivation& drv,
                              BuildMode buildMode) override;

  void ensurePath(const Path& path) override;

  void addTempRoot(const Path& path) override;

  void addIndirectRoot(const Path& path) override;

  void syncWithGC() override;

 private:
  typedef std::shared_ptr<AutoCloseFD> FDPtr;
  using FDs = std::list<FDPtr>;

  void findTempRoots(FDs& fds, Roots& roots, bool censor);

 public:
  Roots findRoots(bool censor) override;

  void collectGarbage(const GCOptions& options, GCResults& results) override;

  /* Optimise the disk space usage of the Nix store by hard-linking
     files with the same contents. */
  void optimiseStore(OptimiseStats& stats);

  void optimiseStore() override;

  /* Optimise a single store path. */
  void optimisePath(const Path& path);

  bool verifyStore(bool checkContents, RepairFlag repair) override;

  /* Register the validity of a path, i.e., that `path' exists, that
     the paths referenced by it exists, and in the case of an output
     path of a derivation, that it has been produced by a successful
     execution of the derivation (or something equivalent).  Also
     register the hash of the file system contents of the path.  The
     hash must be a SHA-256 hash. */
  void registerValidPath(const ValidPathInfo& info);

  void registerValidPaths(const ValidPathInfos& infos);

  unsigned int getProtocol() override;

  void vacuumDB();

  /* Repair the contents of the given path by redownloading it using
     a substituter (if available). */
  void repairPath(const Path& path);

  void addSignatures(const Path& storePath, const StringSet& sigs) override;

  /* If free disk space in /nix/store if below minFree, delete
     garbage until it exceeds maxFree. */
  void autoGC(bool sync = true);

 private:
  int getSchema();

  void openDB(State& state, bool create);

  void makeStoreWritable();

  static uint64_t queryValidPathId(State& state, const Path& path);

  uint64_t addValidPath(State& state, const ValidPathInfo& info,
                        bool checkOutputs = true);

  void invalidatePath(State& state, const Path& path);

  /* Delete a path from the Nix store. */
  void invalidatePathChecked(const Path& path);

  void verifyPath(const Path& path, const PathSet& store, PathSet& done,
                  PathSet& validPaths, RepairFlag repair, bool& errors);

  static void updatePathInfo(State& state, const ValidPathInfo& info);

  void upgradeStore6();
  void upgradeStore7();
  PathSet queryValidPathsOld();
  ValidPathInfo queryPathInfoOld(const Path& path);

  struct GCState;

  static void deleteGarbage(GCState& state, const Path& path);

  void tryToDelete(GCState& state, const Path& path);

  bool canReachRoot(GCState& state, PathSet& visited, const Path& path);

  void deletePathRecursive(GCState& state, const Path& path);

  static bool isActiveTempFile(const GCState& state, const Path& path,
                               const std::string& suffix);

  AutoCloseFD openGCLock(LockType lockType);

  void findRoots(const Path& path, unsigned char type, Roots& roots);

  void findRootsNoTemp(Roots& roots, bool censor);

  void findRuntimeRoots(Roots& roots, bool censor);

  void removeUnusedLinks(const GCState& state);

  Path createTempDirInStore();

  void checkDerivationOutputs(const Path& drvPath, const Derivation& drv);

  using InodeHash = std::unordered_set<ino_t>;

  InodeHash loadInodeHash();
  static Strings readDirectoryIgnoringInodes(const Path& path,
                                             const InodeHash& inodeHash);
  void optimisePath_(OptimiseStats& stats, const Path& path,
                     InodeHash& inodeHash);

  // Internal versions that are not wrapped in retry_sqlite.
  static bool isValidPath_(State& state, const Path& path);
  static void queryReferrers(State& state, const Path& path,
                             PathSet& referrers);

  /* Add signatures to a ValidPathInfo using the secret keys
     specified by the ‘secret-key-files’ option. */
  static void signPathInfo(ValidPathInfo& info);

  Path getRealStoreDir() override { return realStoreDir; }

  void createUser(const std::string& userName, uid_t userId) override;

  friend class DerivationGoal;
  friend class SubstitutionGoal;
};

using Inode = std::pair<dev_t, ino_t>;
using InodesSeen = std::set<Inode>;

/* "Fix", or canonicalise, the meta-data of the files in a store path
   after it has been built.  In particular:
   - the last modification date on each file is set to 1 (i.e.,
     00:00:01 1/1/1970 UTC)
   - the permissions are set of 444 or 555 (i.e., read-only with or
     without execute permission; setuid bits etc. are cleared)
   - the owner and group are set to the Nix user and group, if we're
     running as root. */
void canonicalisePathMetaData(const Path& path, uid_t fromUid,
                              InodesSeen& inodesSeen);
void canonicalisePathMetaData(const Path& path, uid_t fromUid);

void canonicaliseTimestampAndPermissions(const Path& path);

MakeError(PathInUse, Error);

}  // namespace nix