#ifndef LIB_SHADER_FILE_HPP
#define LIB_SHADER_FILE_HPP

#include <string>
#include <sstream>
#include <vector>
#include <stdint.h>

#if defined(WIN32) || defined(WIN64)
#  include <windows.h>
#elif defined(LINUX)
#  include <dlfcn.h>
#else
#   error "unknown operation system"
#endif

/**********************************************************************************************************************************/
/* public interface                                                                                                               */
/**********************************************************************************************************************************/
namespace lsf
{
    enum LogLevel
    {
        llDebug     = 0,
        llInfo      = 1,
        llWarning   = 2,
        llError     = 3,
    };
    
    enum ErrorCode
    {
        errNone                         = 0x00000000,
        errNotInit                      = 0x00000001,
        errInvalidHandleShaderFile      = 0x00000010,
        errInvalidHandleShaderGenerator = 0x00000011,
        errInvalidGeneratorName         = 0x00000020,
        errInvalidPropertyIndex         = 0x00000021,
        errInvalidPropertyName          = 0x00000022,
        errGeneratorNotAssignedToFile   = 0x00000023,
        errUnknownIdentfifier           = 0x00001000,
        errDuplicateIdentifier          = 0x00001001,
        errOutOfRange                   = 0x00001002,
        errInvalidIdentifier            = 0x00001003,
        errInvalidParamterCount         = 0x00001004,
        errInvalidParamter              = 0x00001005,
        errUnexpectedToken              = 0x00001006,
        errInvalidToken                 = 0x00001007,
        errExpressionInternal           = 0x00001008,
        errExpression                   = 0x00001009,
        errShaderPartInternal           = 0x0000100a,
        errShaderPart                   = 0x0000100b,
        errInvalidLibraryName           = 0x00002000,
        errInvalidLibraryHandle         = 0x00002001,
        errInvalidMethodName            = 0x00002002,
        errUnknown                      = 0xffffffff,
    };
    
    /** class to load and manage shared library */
    class Library
    {
        friend class ShaderFile;
        friend class Generator;
        
    public:
        #if defined(WIN32) || defined(WIN64)
            typedef HMODULE Handle; //!< shader file handle
        #elif defined(LINUX)
            #error "linux is not supported yet"
        #else
            #error "unknown operation system"
        #endif

    private:
        struct Impl;        //!< struct that implements the libraries methods
        Impl*   _impl;      //!< struct that implements the libraries methods
        Handle  _handle;    //!< handle of shared library        
    
    public:
        /** get last error code 
         * @return  error code of last failed operation */
        ErrorCode getLastErrorCode() const;
        
        /** get last error message
         * @return  error message of last failed operation */
        std::string getLastErrorMsg() const;
        
        /** get last error trace
         * @return  error trace of last failed operation */
        std::string getLastErrorTrace() const;
        
        /** constructor 
         * @param libName   name of shared library file */
        Library(std::string libName);
        
        /** destructor */
        virtual ~Library();
        
    private:
        /** deleted copy constructor */
        Library(const Library& that) { };
    };
    
    /** class to manage a shader file */ 
    class ShaderFile
    {
    public: 
        typedef void* Handle;               //!< shader file handle
    
    private:
        const Library::Impl&    _impl;      //!< struct that implements the libraries methods
        Handle                  _handle;    //!< handle of this shader file
    
    protected:
        /** method to log messages from shader file and code generation
         * @param logLevel  level of the log message
         * @param msg       message to write log log */ 
        virtual void logMsg(LogLevel logLevel, const std::string& msg);
    
    public:
        /** get shader file handle
         * @return  handle of this shader file */
        Handle getHandle() const;
        
        /** get library 
         * @return  library object this shader file is attached to */
        const Library& getLibrary() const;
        
        /** load shader file from a given file
         * @param filename  file to load shader code from */
        void loadFromFile(std::string filename);
        
        /** save shader file to a given file
         * @param filename  file to save shader code to */
        void saveToFile(std::string filename) const;
        
        /** constructor 
         * @param library   library this shader file is attached to */
        ShaderFile(const Library& library);
        
        /** destructor */
        virtual ~ShaderFile();
     
    private:
        /** deleted copy constructor */
        ShaderFile(const ShaderFile& that);
        
    public:
        /** callback method for log messages 
         * @param logLevel  log level of the log message
         * @param msg       log message
         * @param userargs  user defined arguments */
        static void __stdcall logCallback(const LogLevel loglevel, const char* msg, void* userargs);
    };
    
    /** class to manage a shader code generator */
    class Generator
    {
    public:
        typedef void* Handle;                       //!< shader generator handle
        typedef std::vector<std::string> StringVec; //!< vector of strings
        
    private:
        const Library::Impl&    _impl;              //!< struct that implements the libraries methods
        const ShaderFile&       _shaderFile;        //!< shader file the generator is attached to
        std::string             _name;              //!< name of this generator
        Handle                  _handle;            //!< handle of this generator
        StringVec               _propertyNames;     //!< vector with all known properties 
    
    public:
        /** get generator name
         * @return name of this generator */
        std::string getName() const;
        
        /** get generator handle
         * @return handle of this generator */
        Handle getHandle() const;
        
        /** get shader file this generator is attached to
         * @return shader file this genrator is attached to */
        const ShaderFile& getShaderFile() const;
        
        /** get a vector of all known properties
         * @return vecotr with all known properties */
        const StringVec& getPropertyNames() const;
        
        /** get the value of a single property by its name
         * @param name      name of the property
         * @return          value of the property */
        std::string getProperty(const std::string& name) const;
        
        /** get the value of a single property by its index
         * @param index     index of the property (see getPropertyNames() to get the index of a property) 
         * @return          value of the property */
        std::string getProperty(int index) const;
        
        /** set the value of a single property by its name
         * @param name      name of the property
         * @param value     value of the property */
        void setProperty(const std::string& name, const std::string& value);
        
        /** set the value of a single property by its index
         * @param index     index of the property (see getPropertyNames() to get the index of a property) 
         * @param value     value of the property */
        void setProperty(int index, const std::string& value);
        
        /** generate the shader code with the current property setup 
         * @return generated shader code */
        std::string generateCode() const;
        
        /** constructor 
         * @param shaderFile    shader file this generator is attached to
         * @param name          name of a valid generator inside the shaderFile */
        Generator(const ShaderFile& shaderFile, std::string name);
        
        /** destructor */ 
        virtual ~Generator();
        
    private:
        /** deleted copy constructor */
        Generator(const Generator& that);
    };
    
    /** object to handle error inside this library */ 
    class Exception : public std::exception
    {
    private:
        std::string _message;   //!< error message
        ErrorCode   _errorCode; //!< suitable error code to the error message
        
    public:
        /** get error code 
         * @return error code of this exception */
        ErrorCode getErrorCode() const;
        
        /** get error message
         * @return error message of this exception */
        std::string getMessage() const;
        
        /** @return error message of this exception */
        virtual const char* what() const throw();

        /** constructor */
        Exception(std::string message, ErrorCode errorCode = errUnknown);
        
        /** destructor */
        ~Exception() throw();
    };
}




/**********************************************************************************************************************************/
/* private implementation                                                                                                         */
/**********************************************************************************************************************************/
#if defined(WIN32) || defined(WIN64)
lsf::Library::Handle libOpen(const char* name)
    { return LoadLibrary(name); };

template <typename T>
T getAddr(lsf::Library::Handle handle, const char* name)
{ 
    FARPROC tmp = GetProcAddress(handle, name);
    return reinterpret_cast<T>(tmp); 
};

int libClose(lsf::Library::Handle handle)
    { return FreeLibrary(handle); };

#elif defined(LINUX)
#  include <dlfcn.h>
#  error "linux is not supported yet"
#else
#   error "unknown operation system"
#endif

/* Library::Impl ******************************************************************************************************************/
struct lsf::Library::Impl
{
    typedef ShaderFile::Handle  (__stdcall *lsf_shader_file_create_t)               ();
    typedef void                (__stdcall *lsf_shader_file_log_callback_t)         (const LogLevel loglevel, const char* msg, void* userargs);
    typedef ErrorCode           (__stdcall *lsf_shader_file_set_log_callback_t)     (const ShaderFile::Handle handle, const lsf_shader_file_log_callback_t callback, void* userargs);
    typedef ErrorCode           (__stdcall *lsf_shader_file_load_from_file_t)       (const ShaderFile::Handle handle, const char* filename);
    typedef ErrorCode           (__stdcall *lsf_shader_file_save_to_file_t)         (const ShaderFile::Handle handle, const char* filename);
    typedef const char*         (__stdcall *lsf_shader_file_get_generator_names_t)  (const ShaderFile::Handle handle);
    typedef ErrorCode           (__stdcall *lsf_shader_file_destroy_t)              (const ShaderFile::Handle handle);
    
    typedef Generator::Handle   (__stdcall *lsf_generator_create_t)                 (const ShaderFile::Handle handle, const char* name);
    typedef const char*         (__stdcall *lsf_generator_get_property_names_t)     (const Generator::Handle handle);
    typedef const char*         (__stdcall *lsf_generator_get_property_t)           (const Generator::Handle handle, const int index);
    typedef const char*         (__stdcall *lsf_generator_get_property_by_name_t)   (const Generator::Handle handle, const char* name);
    typedef ErrorCode           (__stdcall *lsf_generator_set_property_t)           (const Generator::Handle handle, const int index, const char* value);
    typedef ErrorCode           (__stdcall *lsf_generator_set_property_by_name_t)   (const Generator::Handle handle, const char* name, const char* value);
    typedef const char*         (__stdcall *lsf_generator_generate_code_t)          (const Generator::Handle handle);
    typedef ErrorCode           (__stdcall *lsf_generator_destroy_t)                (const Generator::Handle handle);

    typedef ErrorCode           (__stdcall *lsf_init_t)                             ();
    typedef ErrorCode           (__stdcall *lsf_get_last_error_code_t)              ();
    typedef const char*         (__stdcall *lsf_get_last_error_msg_t)               ();
    typedef const char*         (__stdcall *lsf_get_last_error_trace_t)             ();
    typedef ErrorCode           (__stdcall *lsf_finish_t)                           ();

    const Library& library;

    lsf_shader_file_create_t                lsf_shader_file_create;
    lsf_shader_file_set_log_callback_t      lsf_shader_file_set_log_callback;
    lsf_shader_file_load_from_file_t        lsf_shader_file_load_from_file;
    lsf_shader_file_save_to_file_t          lsf_shader_file_save_to_file;
    lsf_shader_file_get_generator_names_t   lsf_shader_file_get_generator_names;
    lsf_shader_file_destroy_t               lsf_shader_file_destroy;

    lsf_generator_create_t                  lsf_generator_create;
    lsf_generator_get_property_names_t      lsf_generator_get_property_names;
    lsf_generator_get_property_t            lsf_generator_get_property;
    lsf_generator_get_property_by_name_t    lsf_generator_get_property_by_name;
    lsf_generator_set_property_t            lsf_generator_set_property;
    lsf_generator_set_property_by_name_t    lsf_generator_set_property_by_name;
    lsf_generator_generate_code_t           lsf_generator_generate_code;
    lsf_generator_destroy_t                 lsf_generator_destroy;

    lsf_init_t                              lsf_init;
    lsf_get_last_error_code_t               lsf_get_last_error_code;
    lsf_get_last_error_msg_t                lsf_get_last_error_msg;
    lsf_get_last_error_trace_t              lsf_get_last_error_trace;
    lsf_finish_t                            lsf_finish;
    
    Impl(const Library& library) :
        library                                 (library),
        
        lsf_shader_file_create                  (NULL),
        lsf_shader_file_set_log_callback        (NULL),
        lsf_shader_file_load_from_file          (NULL),
        lsf_shader_file_save_to_file            (NULL),
        lsf_shader_file_get_generator_names     (NULL),
        lsf_shader_file_destroy                 (NULL),
        
        lsf_generator_create                    (NULL),
        lsf_generator_get_property_names        (NULL),
        lsf_generator_get_property              (NULL),
        lsf_generator_get_property_by_name      (NULL),
        lsf_generator_set_property              (NULL),
        lsf_generator_set_property_by_name      (NULL),
        lsf_generator_generate_code             (NULL),
        lsf_generator_destroy                   (NULL),
        
        lsf_init                                (NULL),
        lsf_get_last_error_code                 (NULL),
        lsf_get_last_error_msg                  (NULL),
        lsf_get_last_error_trace                (NULL),
        lsf_finish                              (NULL)
        { };
};

/* Library ************************************************************************************************************************/
template <typename T>
inline void loadProc(lsf::Library::Handle handle, T& proc, const char* name)
{
    proc = getAddr<T>(handle, name);
    if (!proc)
        throw lsf::Exception(std::string("unable to load method from library: ") + name, lsf::errInvalidMethodName);
}

lsf::ErrorCode lsf::Library::getLastErrorCode() const
    { return _impl->lsf_get_last_error_code(); }

std::string lsf::Library::getLastErrorMsg() const
    { return std::string(_impl->lsf_get_last_error_msg()); }
    
std::string lsf::Library::getLastErrorTrace() const
    { return std::string(_impl->lsf_get_last_error_trace()); }

lsf::Library::Library(std::string libName) :
    _impl(new Impl(*this))
{
    _handle = libOpen(libName.c_str());
    if (!_handle)
        throw Exception("unable to open shared library: " + libName, lsf::errInvalidLibraryName);
    
    loadProc(_handle, _impl->lsf_shader_file_create,                "lsf_ShaderFile_create");
    loadProc(_handle, _impl->lsf_shader_file_set_log_callback,      "lsf_ShaderFile_setLogCallback");
    loadProc(_handle, _impl->lsf_shader_file_load_from_file,        "lsf_ShaderFile_loadFromFile");
    loadProc(_handle, _impl->lsf_shader_file_save_to_file,          "lsf_ShaderFile_saveToFile");
    loadProc(_handle, _impl->lsf_shader_file_get_generator_names,   "lsf_ShaderFile_getGeneratorNames");
    loadProc(_handle, _impl->lsf_shader_file_destroy,               "lsf_ShaderFile_destroy");
    
    loadProc(_handle, _impl->lsf_generator_create,                  "lsf_Generator_create");
    loadProc(_handle, _impl->lsf_generator_get_property_names,      "lsf_Generator_getPropertyNames");
    loadProc(_handle, _impl->lsf_generator_get_property,            "lsf_Generator_getProperty");
    loadProc(_handle, _impl->lsf_generator_get_property_by_name,    "lsf_Generator_getPropertyByName");
    loadProc(_handle, _impl->lsf_generator_set_property,            "lsf_Generator_setProperty");
    loadProc(_handle, _impl->lsf_generator_set_property_by_name,    "lsf_Generator_setPropertyByName");
    loadProc(_handle, _impl->lsf_generator_generate_code,           "lsf_Generator_generateCode");
    loadProc(_handle, _impl->lsf_generator_destroy,                 "lsf_Generator_destroy");
    
    loadProc(_handle, _impl->lsf_init,                              "lsf_init");
    loadProc(_handle, _impl->lsf_get_last_error_code,               "lsf_getLastErrorCode");
    loadProc(_handle, _impl->lsf_get_last_error_msg,                "lsf_getLastErrorMsg");
    loadProc(_handle, _impl->lsf_get_last_error_trace,              "lsf_getLastErrorTrace");
    loadProc(_handle, _impl->lsf_finish,                            "lsf_finish");
    
    ErrorCode err = _impl->lsf_init();
    if (err != lsf::errNone)
        throw Exception("unable to initialize library", err);
}

lsf::Library::~Library()
{
    if (_impl)
    {
        _impl->lsf_finish();
        delete _impl;
        _impl = NULL;
    }
    if (_handle)
    {
        libClose(_handle);
        _handle = NULL;
    }    
}

/* ShaderFile *********************************************************************************************************************/
void lsf::ShaderFile::logMsg(LogLevel logLevel, const std::string& msg)
    { /* DUMMY */ }
    
inline lsf::ShaderFile::Handle lsf::ShaderFile::getHandle() const
    { return _handle; }

inline const lsf::Library& lsf::ShaderFile::getLibrary() const
    { return _impl.library; }

void lsf::ShaderFile::loadFromFile(std::string filename)
{
    ErrorCode err = _impl.lsf_shader_file_load_from_file(_handle, filename.c_str());
    if (err != errNone)
        throw Exception("unable to load file", err);
}

void lsf::ShaderFile::saveToFile(std::string filename) const
{
    ErrorCode err = _impl.lsf_shader_file_load_from_file(_handle, filename.c_str());
    if (err != errNone)
        throw Exception("unable to load file", err);
}

lsf::ShaderFile::ShaderFile(const Library& library) :
    _impl(*library._impl)
{
    _handle = _impl.lsf_shader_file_create();
    if (!_handle)
        throw Exception(_impl.lsf_get_last_error_msg(), _impl.lsf_get_last_error_code());
    ErrorCode err = _impl.lsf_shader_file_set_log_callback(_handle, &ShaderFile::logCallback, this);
    if (err != errNone)
        logMsg(llWarning, "unable to register log callback");
}

lsf::ShaderFile::~ShaderFile()
{
    _impl.lsf_shader_file_destroy(_handle);
    _handle = NULL;
}

void lsf::ShaderFile::logCallback(const lsf::LogLevel loglevel, const char* msg, void* userargs)
{
    static_cast<ShaderFile*>(userargs)->logMsg(loglevel, std::string(msg)); 
}

/* Generator **********************************************************************************************************************/
inline std::string lsf::Generator::getName() const
    { return _name; };
    
inline lsf::Generator::Handle lsf::Generator::getHandle() const
    { return _handle; };
    
inline const lsf::ShaderFile& lsf::Generator::getShaderFile() const
    { return _shaderFile; };
    
inline const lsf::Generator::StringVec& lsf::Generator::getPropertyNames() const
    { return _propertyNames; };
        
std::string lsf::Generator::getProperty(const std::string& name) const
{
    const char* ret = _impl.lsf_generator_get_property_by_name(_handle, name.c_str());
    if (!ret)
        throw Exception(_impl.lsf_get_last_error_msg(), _impl.lsf_get_last_error_code());
    return std::string(ret);
}

std::string lsf::Generator::getProperty(int index) const
{
    const char* ret = _impl.lsf_generator_get_property(_handle, index);
    if (!ret)
        throw Exception(_impl.lsf_get_last_error_msg(), _impl.lsf_get_last_error_code());
    return std::string(ret);
}

void lsf::Generator::setProperty(const std::string& name, const std::string& value)
{
    ErrorCode err = _impl.lsf_generator_set_property_by_name(_handle, name.c_str(), value.c_str());
    if (err != errNone)
        throw Exception(_impl.lsf_get_last_error_msg(), err);
}

void lsf::Generator::setProperty(int index, const std::string& value)
{
    ErrorCode err = _impl.lsf_generator_set_property(_handle, index, value.c_str());
    if (err != errNone)
        throw Exception(_impl.lsf_get_last_error_msg(), err);
}

std::string lsf::Generator::generateCode() const
{
    const char* ret = _impl.lsf_generator_generate_code(_handle);
    if (!ret)
        throw Exception(_impl.lsf_get_last_error_msg(), _impl.lsf_get_last_error_code());
    return std::string(ret);
}

lsf::Generator::Generator(const ShaderFile& shaderFile, std::string name) :
    _shaderFile (shaderFile),
    _impl       (*shaderFile.getLibrary()._impl),
    _name       (name)
{
    _handle = _impl.lsf_generator_create(_shaderFile.getHandle(), _name.c_str());
    if (!_handle)
        throw Exception(_impl.lsf_get_last_error_msg(), _impl.lsf_get_last_error_code());
    const char* propertyNames = _impl.lsf_generator_get_property_names(_handle);
    if (propertyNames)
    {
        std::stringstream ss(propertyNames);
        std::string item;
        while (std::getline(ss, item, '\x10'))
            _propertyNames.push_back(item);
    }
}

lsf::Generator::~Generator()
{
    _impl.lsf_generator_destroy(_handle);
    _handle = NULL;
}

/* Exception **********************************************************************************************************************/
inline lsf::ErrorCode lsf::Exception::getErrorCode() const
    { return _errorCode; }

inline std::string lsf::Exception::getMessage() const
    { return _message; }

const char* lsf::Exception::what() const throw()
    { return _message.c_str(); };

lsf::Exception::Exception(std::string message, ErrorCode errorCode) : 
    _message    (message),
    _errorCode  (errorCode)
    { }

lsf::Exception::~Exception() throw()
    { }

#endif /* LIB_SHADER_FILE_HPP */