// Created on: 2008-01-20
// Created by: Alexander A. BORODIN
// Copyright (c) 2008-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _Font_FontMgr_HeaderFile
#define _Font_FontMgr_HeaderFile

#include <Standard.hxx>
#include <Standard_Transient.hxx>
#include <Font_NListOfSystemFont.hxx>
#include <Font_StrictLevel.hxx>
#include <Font_UnicodeSubset.hxx>
#include <NCollection_DataMap.hxx>
#include <NCollection_IndexedMap.hxx>
#include <NCollection_Shared.hxx>
#include <TColStd_SequenceOfHAsciiString.hxx>

class TCollection_HAsciiString;
class NCollection_Buffer;

DEFINE_STANDARD_HANDLE(Font_FontMgr, Standard_Transient)

//! Collects and provides information about available fonts in system.
class Font_FontMgr : public Standard_Transient
{
  DEFINE_STANDARD_RTTIEXT(Font_FontMgr, Standard_Transient)
public:

  //! Return global instance of font manager.
  Standard_EXPORT static Handle(Font_FontMgr) GetInstance();

  //! Return font aspect as string.
  static const char* FontAspectToString (Font_FontAspect theAspect)
  {
    switch (theAspect)
    {
      case Font_FontAspect_UNDEFINED:  return "undefined";
      case Font_FontAspect_Regular:    return "regular";
      case Font_FontAspect_Bold:       return "bold";
      case Font_FontAspect_Italic:     return "italic";
      case Font_FontAspect_BoldItalic: return "bold-italic";
    }
    return "invalid";
  }

  //! Return flag to use fallback fonts in case if used font does not include symbols from specific Unicode subset; TRUE by default.
  Standard_EXPORT static Standard_Boolean& ToUseUnicodeSubsetFallback();

public:

  //! Return the list of available fonts.
  void AvailableFonts (Font_NListOfSystemFont& theList) const
  {
    for (Font_FontMap::Iterator aFontIter (myFontMap); aFontIter.More(); aFontIter.Next())
    {
      theList.Append (aFontIter.Value());
    }
  }

  //! Return the list of available fonts.
  Font_NListOfSystemFont GetAvailableFonts() const
  {
    Font_NListOfSystemFont aList;
    AvailableFonts (aList);
    return aList;
  }

  //! Returns sequence of available fonts names
  Standard_EXPORT void GetAvailableFontsNames (TColStd_SequenceOfHAsciiString& theFontsNames) const;
  
  //! Returns font that match given parameters.
  //! If theFontName is empty string returned font can have any FontName.
  //! If theFontAspect is Font_FA_Undefined returned font can have any FontAspect.
  //! If theFontSize is "-1" returned font can have any FontSize.
  Standard_EXPORT Handle(Font_SystemFont) GetFont (const Handle(TCollection_HAsciiString)& theFontName, const Font_FontAspect theFontAspect, const Standard_Integer theFontSize) const;

  //! Returns font that match given name or NULL if such font family is NOT registered.
  //! Note that unlike FindFont(), this method ignores font aliases and does not look for fall-back.
  Standard_EXPORT Handle(Font_SystemFont) GetFont (const TCollection_AsciiString& theFontName) const;

  //! Tries to find font by given parameters.
  //! If the specified font is not found tries to use font names mapping.
  //! If the requested family name not found -> search for any font family with given aspect and height.
  //! If the font is still not found, returns any font available in the system.
  //! Returns NULL in case when the fonts are not found in the system.
  //! @param theFontName    [in]       font family to find or alias name
  //! @param theStrictLevel [in]       search strict level for using aliases and fallback
  //! @param theFontAspect  [in] [out] font aspect to find (considered only if family name is not found);
  //!                                  can be modified if specified font alias refers to another style (compatibility with obsolete aliases)
  //! @param theDoFailMsg   [in]       put error message on failure into default messenger
  Standard_EXPORT Handle(Font_SystemFont) FindFont (const TCollection_AsciiString& theFontName,
                                                    Font_StrictLevel theStrictLevel,
                                                    Font_FontAspect& theFontAspect,
                                                    Standard_Boolean theDoFailMsg = Standard_True) const;

  //! Tries to find font by given parameters.
  Handle(Font_SystemFont) FindFont (const TCollection_AsciiString& theFontName,
                                    Font_FontAspect& theFontAspect) const
  {
    return FindFont (theFontName, Font_StrictLevel_Any, theFontAspect);
  }

  //! Tries to find fallback font for specified Unicode subset.
  //! Returns NULL in case when fallback font is not found in the system.
  //! @param theSubset     [in] Unicode subset
  //! @param theFontAspect [in] font aspect to find
  Standard_EXPORT Handle(Font_SystemFont) FindFallbackFont (Font_UnicodeSubset theSubset,
                                                            Font_FontAspect theFontAspect) const;

  //! Read font file and retrieve information from it (the list of font faces).
  Standard_EXPORT Standard_Boolean CheckFont (NCollection_Sequence<Handle(Font_SystemFont)>& theFonts,
                                              const TCollection_AsciiString& theFontPath) const;

  //! Read font file and retrieve information from it.
  Standard_EXPORT Handle(Font_SystemFont) CheckFont (const Standard_CString theFontPath) const;
  
  //! Register new font.
  //! If there is existing entity with the same name and properties but different path
  //! then font will be overridden or ignored depending on theToOverride flag.
  Standard_EXPORT Standard_Boolean RegisterFont (const Handle(Font_SystemFont)& theFont,
                                                 const Standard_Boolean theToOverride);

  //! Register new fonts.
  Standard_Boolean RegisterFonts (const NCollection_Sequence<Handle(Font_SystemFont)>& theFonts,
                                  const Standard_Boolean theToOverride)
  {
    Standard_Boolean isRegistered = Standard_False;
    for (NCollection_Sequence<Handle(Font_SystemFont)>::Iterator aFontIter (theFonts); aFontIter.More(); aFontIter.Next())
    {
      isRegistered = RegisterFont (aFontIter.Value(), theToOverride) || isRegistered;
    }
    return isRegistered;
  }

public:

  //! Return flag for tracing font aliases usage via Message_Trace messages; TRUE by default.
  Standard_Boolean ToTraceAliases() const { return myToTraceAliases; }

  //! Set flag for tracing font alias usage; useful to trace which fonts are actually used.
  //! Can be disabled to avoid redundant messages with Message_Trace level.
  void SetTraceAliases (Standard_Boolean theToTrace) { myToTraceAliases = theToTrace; }

  //! Return font names with defined aliases.
  //! @param theAliases [out] alias names
  Standard_EXPORT void GetAllAliases (TColStd_SequenceOfHAsciiString& theAliases) const;

  //! Return aliases to specified font name.
  //! @param theFontNames [out] font names associated with alias name
  //! @param theAliasName [in]  alias name
  Standard_EXPORT void GetFontAliases (TColStd_SequenceOfHAsciiString& theFontNames,
                                       const TCollection_AsciiString& theAliasName) const;

  //! Register font alias.
  //!
  //! Font alias allows using predefined short-cuts like Font_NOF_MONOSPACE or Font_NOF_SANS_SERIF,
  //! and defining several fallback fonts like Font_NOF_CJK ("cjk") or "courier" for fonts,
  //! which availability depends on system.
  //!
  //! By default, Font_FontMgr registers standard aliases, which could be extended or replaced by application
  //! basing on better knowledge of the system or basing on additional fonts packaged with application itself.
  //! Aliases are defined "in advance", so that they could point to non-existing fonts,
  //! and they are resolved dynamically on request - first existing font is returned in case of multiple aliases to the same name.
  //!
  //! @param theAliasName [in] alias name or name of another font to be used as alias
  //! @param theFontName  [in] font to be used as substitution for alias
  //! @return FALSE if alias has been already registered
  Standard_EXPORT bool AddFontAlias (const TCollection_AsciiString& theAliasName,
                                     const TCollection_AsciiString& theFontName);

  //! Unregister font alias.
  //! @param theAliasName [in] alias name or name of another font to be used as alias;
  //!                          all aliases will be removed in case of empty name
  //! @param theFontName  [in] font to be used as substitution for alias;
  //!                          all fonts will be removed in case of empty name
  //! @return TRUE if alias has been removed
  Standard_EXPORT bool RemoveFontAlias (const TCollection_AsciiString& theAliasName,
                                        const TCollection_AsciiString& theFontName);

public:

  //! Collects available fonts paths.
  Standard_EXPORT void InitFontDataBase();

  //! Clear registry. Can be used for testing purposes.
  Standard_EXPORT void ClearFontDataBase();

  //! Return DejaVu font as embed a single fallback font.
  //! It can be used in cases when there is no own font file.
  //! Note: result buffer is readonly and should not be changed,
  //!       any data modification can lead to unpredictable consequences.
  Standard_EXPORT static Handle(NCollection_Buffer) EmbedFallbackFont();

private:
  
  //! Creates empty font manager object
  Standard_EXPORT Font_FontMgr();

private:

  //! Map storing registered fonts.
  class Font_FontMap : public NCollection_IndexedMap<Handle(Font_SystemFont), Font_SystemFont>
  {
  public:
    //! Empty constructor.
    Font_FontMap() {}

    //! Try finding font with specified parameters or the closest one.
    //! @param theFontName [in] font family to find (or empty string if family name can be ignored)
    //! @return best match font or NULL if not found
    Handle(Font_SystemFont) Find (const TCollection_AsciiString& theFontName) const;

  public:
    //! Computes a hash code for the system font, in the range [1, theUpperBound]. Based on Font Family, so that the
    //! whole family with different aspects can be found within the same bucket of some map
    //! @param theHExtendedString the handle referred to extended string which hash code is to be computed
    //! @param theUpperBound the upper bound of the range a computing hash code must be within
    //! @return a computed hash code, in the range [1, theUpperBound]
    static Standard_Integer HashCode (const Handle (Font_SystemFont) & theSystemFont,
                                      const Standard_Integer           theUpperBound)
    {
      return ::HashCode (theSystemFont->FontKey(), theUpperBound);
    }

    //! Matching two instances, for Map interface.
    static bool IsEqual (const Handle(Font_SystemFont)& theFont1,
                         const Handle(Font_SystemFont)& theFont2)
    {
      return theFont1->IsEqual (theFont2);
    }

  };

  //! Structure defining font alias.
  struct Font_FontAlias
  {
    TCollection_AsciiString FontName;
    Font_FontAspect         FontAspect;

    Font_FontAlias (const TCollection_AsciiString& theFontName, Font_FontAspect theFontAspect = Font_FontAspect_UNDEFINED) : FontName (theFontName), FontAspect (theFontAspect) {}
    Font_FontAlias() : FontAspect (Font_FontAspect_UNDEFINED) {}
  };

  //! Sequence of font aliases.
  typedef NCollection_Shared< NCollection_Sequence<Font_FontAlias> > Font_FontAliasSequence;

  //! Register font alias.
  void addFontAlias (const TCollection_AsciiString& theAliasName,
                     const Handle(Font_FontAliasSequence)& theAliases,
                     Font_FontAspect theAspect = Font_FontAspect_UNDEFINED);

private:

  Font_FontMap myFontMap;
  NCollection_DataMap<TCollection_AsciiString, Handle(Font_FontAliasSequence)> myFontAliases;
  Handle(Font_FontAliasSequence) myFallbackAlias;
  Standard_Boolean myToTraceAliases;

};

#endif // _Font_FontMgr_HeaderFile
