#pragma once
///@file

#include "sqlite.hh"

#include "pathlocks.hh"
#include "store-api.hh"
#include "local-fs-store.hh"
#include "gc-store.hh"
#include "sync.hh"
#include "util.hh"

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


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 OptimiseStats
{
    unsigned long filesLinked = 0;
    uint64_t bytesFreed = 0;
    uint64_t blocksFreed = 0;
};

struct LocalStoreConfig : virtual LocalFSStoreConfig
{
    using LocalFSStoreConfig::LocalFSStoreConfig;

    Setting<bool> requireSigs{(StoreConfig*) this,
        settings.requireSigs,
        "require-sigs",
        "Whether store paths copied into this store should have a trusted signature."};

    Setting<bool> readOnly{(StoreConfig*) this,
        false,
        "read-only",
        R"(
          Allow this store to be opened when its [database](@docroot@/glossary.md#gloss-nix-database) is on a read-only filesystem.

          Normally Nix will attempt to open the store database in read-write mode, even for querying (when write access is not needed), causing it to fail if the database is on a read-only filesystem.

          Enable read-only mode to disable locking and open the SQLite database with the [`immutable` parameter](https://www.sqlite.org/c3ref/open.html) set.

          **Warning**
          Do not use this unless the filesystem is read-only.
          Using it when the filesystem is writable can cause incorrect query results or corruption errors if the database is changed by another process.
          While the filesystem the database resides on might appear to be read-only, consider whether another user or system might have write access to it.
        )"};

    const std::string name() override { return "Local Store"; }

    std::string doc() override;
};

class LocalStore : public virtual LocalStoreConfig, public virtual LocalFSStore, public virtual GcStore
{
private:

    /**
     * Lock file used for upgrading.
     */
    AutoCloseFD globalLock;

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

        struct Stmts;
        std::unique_ptr<Stmts> stmts;

        /**
         * 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> _state;

public:

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

private:

    const PublicKeys & getPublicKeys();

public:

    /**
     * Hack for build-remote.cc.
     */
    PathSet locksHeld;

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

    ~LocalStore();

    static std::set<std::string> uriSchemes()
    { return {}; }

    /**
     * Implementations of abstract store API methods.
     */

    std::string getUri() override;

    bool isValidPathUncached(const StorePath & path) override;

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

    StorePathSet queryAllValidPaths() override;

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

    void queryReferrers(const StorePath & path, StorePathSet & referrers) override;

    StorePathSet queryValidDerivers(const StorePath & path) override;

    std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path) override;

    std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;

    StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

    bool pathInfoIsUntrusted(const ValidPathInfo &) override;
    bool realisationIsUntrusted(const Realisation & ) override;

    void addToStore(const ValidPathInfo & info, Source & source,
        RepairFlag repair, CheckSigsFlag checkSigs) override;

    StorePath addToStoreFromDump(Source & dump, std::string_view name,
        FileIngestionMethod method, HashType hashAlgo, RepairFlag repair, const StorePathSet & references) override;

    StorePath addTextToStore(
        std::string_view name,
        std::string_view s,
        const StorePathSet & references,
        RepairFlag repair) override;

    void addTempRoot(const StorePath & path) override;

private:

    void createTempRootsFile();

    /**
     * The file to which we write our temporary roots.
     */
    Sync<AutoCloseFD> _fdTempRoots;

    /**
     * The global GC lock.
     */
    Sync<AutoCloseFD> _fdGCLock;

    /**
     * Connection to the garbage collector.
     */
    Sync<AutoCloseFD> _fdRootsSocket;

public:

    void addIndirectRoot(const Path & path) override;

private:

    void findTempRoots(Roots & roots, bool censor);

    AutoCloseFD openGCLock();

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. Optionally, test the encountered
     * symlinks for corruption.
     */
    void optimisePath(const Path & path, RepairFlag repair);

    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;

    std::optional<TrustedFlag> isTrustedClient() override;

    void vacuumDB();

    void addSignatures(const StorePath & 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);

    /**
     * Register the store path 'output' as the output named 'outputName' of
     * derivation 'deriver'.
     */
    void registerDrvOutput(const Realisation & info) override;
    void registerDrvOutput(const Realisation & info, CheckSigsFlag checkSigs) override;
    void cacheDrvOutputMapping(
        State & state,
        const uint64_t deriver,
        const std::string & outputName,
        const StorePath & output);

    std::optional<const Realisation> queryRealisation_(State & state, const DrvOutput & id);
    std::optional<std::pair<int64_t, Realisation>> queryRealisationCore_(State & state, const DrvOutput & id);
    void queryRealisationUncached(const DrvOutput&,
        Callback<std::shared_ptr<const Realisation>> callback) noexcept override;

    std::optional<std::string> getVersion() override;

private:

    /**
     * Retrieve the current version of the database schema.
     * If the database does not exist yet, the version returned will be 0.
     */
    int getSchema();

    void openDB(State & state, bool create);

    void makeStoreWritable();

    uint64_t queryValidPathId(State & state, const StorePath & path);

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

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

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

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

    std::shared_ptr<const ValidPathInfo> queryPathInfoInternal(State & state, const StorePath & path);

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

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

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

    void findRootsNoTemp(Roots & roots, bool censor);

    void findRuntimeRoots(Roots & roots, bool censor);

    std::pair<Path, AutoCloseFD> createTempDirInStore();

    typedef std::unordered_set<ino_t> InodeHash;

    InodeHash loadInodeHash();
    Strings readDirectoryIgnoringInodes(const Path & path, const InodeHash & inodeHash);
    void optimisePath_(Activity * act, OptimiseStats & stats, const Path & path, InodeHash & inodeHash, RepairFlag repair);

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

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

    // XXX: Make a generic `Store` method
    FixedOutputHash hashCAPath(
        const FileIngestionMethod & method,
        const HashType & hashType,
        const StorePath & path);

    FixedOutputHash hashCAPath(
        const FileIngestionMethod & method,
        const HashType & hashType,
        const Path & path,
        const std::string_view pathHash
    );

    void addBuildLog(const StorePath & drvPath, std::string_view log) override;

    friend struct LocalDerivationGoal;
    friend struct PathSubstitutionGoal;
    friend struct SubstitutionGoal;
    friend struct DerivationGoal;
};


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


/**
 * "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.
 *
 * If uidRange is not empty, this function will throw an error if it
 * encounters files owned by a user outside of the closed interval
 * [uidRange->first, uidRange->second].
 */
void canonicalisePathMetaData(
    const Path & path,
    std::optional<std::pair<uid_t, uid_t>> uidRange,
    InodesSeen & inodesSeen);
void canonicalisePathMetaData(
    const Path & path,
    std::optional<std::pair<uid_t, uid_t>> uidRange);

void canonicaliseTimestampAndPermissions(const Path & path);

MakeError(PathInUse, Error);

}