#ifndef HECLDATABASE_HPP
#define HECLDATABASE_HPP

#include <iterator>
#include <string>
#include <functional>
#include <vector>
#include <map>
#include <unordered_map>
#include <memory>
#include <atomic>
#include <stdexcept>
#include <stdint.h>

#include <Athena/IStreamReader.hpp>

#include "HECL.hpp"

namespace HECL
{
namespace Database
{

/**
 * @brief Nodegraph class for gathering dependency-resolved objects for packaging
 */
class PackageDepsgraph
{
public:
    struct Node
    {
        enum
        {
            NODE_DATA,
            NODE_GROUP
        } type;
        SystemString path;
        class ObjectBase* projectObj;
        Node* sub;
        Node* next;
    };
private:
    friend class Project;
    std::vector<Node> m_nodes;
public:
    const Node* getRootNode() const {return &m_nodes[0];}
};

/**
 * @brief Subclassed by dataspec entries to manage per-game aspects of the data pipeline
 *
 * The DataSpec class manages interfaces for unpackaging, cooking, and packaging
 * of data for interacting with a specific system/game-engine.
 */
class IDataSpec
{
public:
    struct ExtractPassInfo
    {
        SystemString srcpath;
        ProjectPath subpath;
    };
    virtual bool canExtract(const ExtractPassInfo& info) {(void)info;return false;}
    virtual void doExtract(const ExtractPassInfo& info) {(void)info;}

    struct PackagePassInfo
    {
        PackageDepsgraph& depsgraph;
        ProjectPath subpath;
    };
    virtual bool canPackage(const PackagePassInfo& info) {(void)info;return false;}
    virtual void doPackage(const PackagePassInfo& info) {(void)info;}
};

/**
 * @brief IDataSpec registry entry
 */
struct DataSpecEntry
{
    SystemString name;
    SystemString desc;
    std::function<IDataSpec*(void)> factory;
};
extern const HECL::Database::DataSpecEntry DATA_SPEC_REGISTRY[];

/**
 * @brief Base object to subclass for integrating with key project operations
 *
 * All project objects are provided with IDataObject pointers to their database
 * entries. Subclasses register themselves with a type registry so instances
 * are automatically constructed when performing operations like cooking and packaging.
 *
 * DO NOT CONSTRUCT THIS OR SUBCLASSES DIRECTLY!!
 */
class ObjectBase
{
    friend class Project;
    SystemString m_path;
protected:

    /**
     * @brief Byte-order of target system
     */
    enum DataEndianness
    {
        DE_NONE,
        DE_BIG, /**< Big-endian (PowerPC) */
        DE_LITTLE /**< Little-endian (Intel) */
    };

    /**
     * @brief Data-formats of target system
     */
    enum DataPlatform
    {
        DP_NONE,
        DP_GENERIC, /**< Scanline textures and 3-way shader bundle (GLSL, HLSL, SPIR-V) */
        DP_REVOLUTION, /**< Tiled textures and GX register buffers */
        DP_CAFE /**< Swizzled textures and R700 shader objects */
    };

    typedef std::function<void(const void* data, size_t len)> FDataAppender;

    /**
     * @brief Optional private method implemented by CProjectObject subclasses to cook objects
     * @param dataAppender subclass calls this function zero or more times to provide cooked-data linearly
     * @param endianness byte-order to target
     * @param platform data-formats to target
     * @return true if cook succeeded
     *
     * This method is called during IProject::cookPath().
     * Part of the cooking process may include embedding database-refs to dependencies.
     * This method should store the 64-bit value provided by IDataObject::id() when doing this.
     */
    virtual bool _cookObject(FDataAppender dataAppender,
                             DataEndianness endianness, DataPlatform platform)
    {(void)dataAppender;(void)endianness;(void)platform;return true;}

    typedef std::function<void(ObjectBase*)> FDepAdder;

    /**
     * @brief Optional private method implemented by CProjectObject subclasses to resolve dependencies
     * @param depAdder subclass calls this function zero or more times to register each dependency
     *
     * This method is called during IProject::packagePath().
     * Dependencies registered via this method will eventually have this method called on themselves
     * as well. This is a non-recursive operation, no need for subclasses to implement recursion-control.
     */
    virtual void _gatherDeps(FDepAdder depAdder)
    {(void)depAdder;}

public:
    ObjectBase(const SystemString& path)
    : m_path(path) {}

    inline const SystemString& getPath() const {return m_path;}

};


/**
 * @brief Main project interface
 *
 * Projects are intermediate working directories used for staging
 * resources in their ideal editor-formats. This interface exposes all
 * primary operations to perform on a given project.
 */
class Project
{
public:
    typedef std::vector<std::pair<const DataSpecEntry&, bool>> CompiledSpecs;
private:
    ProjectRootPath m_rootPath;
    CompiledSpecs m_compiledSpecs;
public:
    Project(const HECL::ProjectRootPath& rootPath);

    /**
     * @brief Configuration file handle
     *
     * Holds a path to a line-delimited textual configuration file;
     * opening a locked handle for read/write transactions
     */
    class ConfigFile
    {
        SystemString m_filepath;
        std::vector<std::string> m_lines;
        FILE* m_lockedFile = NULL;
    public:
        ConfigFile(const Project& project, const SystemString& name);
        const std::vector<std::string>& lockAndRead();
        void addLine(const std::string& line);
        void removeLine(const std::string& refLine);
        bool checkForLine(const std::string& refLine);
        void unlockAndDiscard();
        void unlockAndCommit();
    };
    ConfigFile m_specs;
    ConfigFile m_paths;
    ConfigFile m_groups;

    /**
     * @brief Index file handle
     *
     * Holds a path to a binary index file;
     * opening a locked handle for read/write transactions
     */
    class IndexFile
    {
        SystemString m_filepath;
        const Project& m_project;
        size_t m_maxPathLen = 0;
        size_t m_onlyUpdatedMaxPathLen = 0;
        FILE* m_lockedFile = NULL;
    public:
        class Entry
        {
            friend class IndexFile;
            ProjectPath m_path;
            HECL::Time m_lastModtime;
            bool m_updated = false;
            Entry(const ProjectPath& path, const HECL::Time& lastModtime)
            : m_path(path), m_lastModtime(lastModtime) {}
            Entry(const ProjectPath& path);
        };
    private:
        size_t m_updatedCount = 0;
        std::vector<Entry> m_entryStore;
        std::unordered_map<ProjectPath, Entry*> m_entryLookup;
    public:
        IndexFile(const Project& project);
        const std::vector<Entry>& lockAndRead();
        const std::vector<ProjectPath*> getChangedPaths();
        void addOrUpdatePath(const ProjectPath& path);
        void unlockAndDiscard();
        void unlockAndCommit(bool onlyUpdated=false);
    };
    IndexFile m_index;

    /**
     * @brief Internal packagePath() exception
     *
     * Due to the recursive nature of packagePath(), there are potential
     * pitfalls like infinite-recursion. HECL throws this whenever there
     * are uncooked dependencies or if the maximum dependency-recursion
     * limit is exceeded.
     */
    class PackageException : public std::runtime_error {};

    /**
     * @brief A rough description of how 'expensive' a given cook operation is
     *
     * This is used to provide pretty colors during the cook operation
     */
    enum Cost
    {
        C_NONE,
        C_LIGHT,
        C_MEDIUM,
        C_HEAVY
    };

    /**
     * @brief Register an optional callback to report log-messages using
     * @param logger logger-callback
     *
     * If this method is never called, all project operations will run silently.
     */
    void registerLogger(HECL::FLogger logger);

    /**
     * @brief Get the path of the project's root-directory
     * @param absolute return as absolute-path
     * @return project root path
     *
     * Self explanatory
     */
    inline const ProjectRootPath& getProjectRootPath() const {return m_rootPath;}

    /**
     * @brief Add given file(s) to the database
     * @param path file or pattern within project
     * @return true on success
     *
     * This method blocks while object hashing takes place
     */
    bool addPaths(const std::vector<ProjectPath>& paths);

    /**
     * @brief Remove a given file or file-pattern from the database
     * @param paths file(s) or pattern(s) within project
     * @param recursive traverse into matched subdirectories
     * @return true on success
     *
     * This method will not delete actual working files from the project
     * directory. It will delete associated cooked objects though.
     */
    bool removePaths(const std::vector<ProjectPath>& paths, bool recursive=false);

    /**
     * @brief Register a working sub-directory as a Dependency Group
     * @param path directory to register as Dependency Group
     * @return true on success
     *
     * Dependency Groups are used at runtime to stage burst load-transactions.
     * They may only be added to directories and will automatically claim
     * subdirectories as well.
     *
     * Cooked objects in dependency groups will be packaged contiguously
     * and automatically duplicated if shared with other dependency groups.
     * This contiguous storage makes for optimal loading from slow block-devices
     * like optical drives.
     */
    bool addGroup(const ProjectPath& path);

    /**
     * @brief Unregister a working sub-directory as a dependency group
     * @param path directory to unregister as Dependency Group
     * @return true on success
     */
    bool removeGroup(const ProjectPath& path);

    /**
     * @brief Return map populated with dataspecs targetable by this project interface
     * @return Platform map with name-string keys and enable-status values
     */
    inline const CompiledSpecs& getDataSpecs() {return m_compiledSpecs;}

    /**
     * @brief Enable persistent user preference for particular spec string(s)
     * @param specs String(s) representing unique spec(s) from listDataSpecs
     * @return true on success
     */
    bool enableDataSpecs(const std::vector<SystemString>& specs);

    /**
     * @brief Disable persistent user preference for particular spec string(s)
     * @param specs String(s) representing unique spec(s) from listDataSpecs
     * @return true on success
     */
    bool disableDataSpecs(const std::vector<SystemString>& specs);

    /**
     * @brief Begin cook process for specified directory
     * @param path directory of intermediates to cook
     * @param feedbackCb a callback to run reporting cook-progress
     * @param recursive traverse subdirectories to cook as well
     * @return true on success
     *
     * Object cooking is generally an expensive process for large projects.
     * This method blocks execution during the procedure, with periodic
     * feedback delivered via feedbackCb.
     */
    bool cookPath(const ProjectPath& path,
                  std::function<void(SystemString&, Cost, unsigned)> feedbackCb,
                  bool recursive=false);

    /**
     * @brief Interrupts a cook in progress (call from SIGINT handler)
     *
     * Database corruption is bad! sqlite is pretty robust at avoiding data corruption,
     * but HECL spreads its data objects through the filesystem; this ensures that
     * those objects are cleanly finalized or discarded before stopping.
     *
     * Note that this method returns immediately; the resumed cookPath()
     * call will return as quickly as possible.
     */
    void interruptCook();

    /**
     * @brief Delete cooked objects for directory
     * @param path directory of intermediates to clean
     * @param recursive traverse subdirectories to clean as well
     * @return true on success
     *
     * Developers understand how useful 'clean' is. While ideally not required,
     * it's useful for verifying that a rebuild from ground-up is doable.
     */
    bool cleanPath(const ProjectPath& path, bool recursive=false);

    /**
     * @brief Constructs a full depsgraph of the project-subpath provided
     * @param path Subpath of project to root depsgraph at
     * @return Populated depsgraph ready to traverse
     */
    PackageDepsgraph buildPackageDepsgraph(const ProjectPath& path);

};

}
}

#endif // HECLDATABASE_HPP