/*##############################################################################

    Copyright (C) 2011 HPCC Systems.

    All rights reserved. This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
############################################################################## */

#include "platform.h"

#include "jlib.hpp"
#include "jio.hpp"

#include "jmutex.hpp"
#include "jfile.hpp"
#include "jlog.hpp"
#include "jregexp.hpp"
#include "gitfile.hpp"
#include "archive.hpp"

#ifdef _USE_LIBARCHIVE

#include <sys/stat.h>
#include <archive.h>
#include <archive_entry.h>

/*
 * Direct access to files in zip archives (and other libarchive-supported formats), without needing to extract them first
 * Installs hooks into createIFile, spotting filenames of the form /my/directory/myfile.zip/{password}/path/within/archive
 */

#define ARCHIVE_SIGNATURE "[.]{zip|tar|tar[.]gz|tgz}{$|"PATHSEPSTR"}"

static RegExpr *signature;
static SpinLock *lock;

static const char *splitName(const char *fileName)
{
    if (!fileName)
        return NULL;
    SpinBlock b(*lock);
    const char *sig = signature->find(fileName);
    if (sig)
        return sig+signature->findlen();
    else
        return NULL;
}

static void splitArchivedFileName(const char *fullName, StringAttr &container, StringAttr &option, StringAttr &relPath)
{
    const char *tail = splitName(fullName);
    assertex(tail);
    size_t containerLen = tail-fullName;
    if (fullName[containerLen-1]==PATHSEPCHAR)
        containerLen--;
    container.set(fullName, containerLen);
    if (*tail=='{')
    {
        tail++;
        const char *end = strchr(tail, '}');
        if (!end)
            throw MakeStringException(0, "Invalid archive-embedded filename - no matching } found");
        option.set(tail, end - tail);
        tail = end+1;
        if (*tail==PATHSEPCHAR)
            tail++;
        else if (*tail != 0)
            throw MakeStringException(0, "Invalid archive-embedded filename - " PATHSEPSTR " expected after }");
    }
    else
        option.clear();
    if (tail && *tail)
    {
        StringBuffer s(tail);
        s.replace(PATHSEPCHAR, '/');
        relPath.set(s);
    }
    else
        relPath.clear();
}

static StringBuffer & buildArchivedFileName(StringBuffer &fullname, const char *archiveFile, const char *option, const char *relPath)
{
    fullname.append(archiveFile);
    if (option && *option)
        fullname.append(PATHSEPCHAR).append('{').append(option).append('}');
    if (relPath && *relPath)
        fullname.append(PATHSEPCHAR).append(relPath);
    return fullname;
}

IDirectoryIterator *createArchiveDirectoryIterator(const char *gitFileName, const char *mask, bool sub, bool includeDirs);

// Wrapper around libarchive's archive_entry struct to ensure we free them at right time
// Because not clear whether safe to use a struct archive_entry object after the archive has been closed,
// we copy the info we need out of them into something we CAN be sure of the lifespan of

class ArchiveEntry : public CInterface, implements IInterface
{
public:
    IMPLEMENT_IINTERFACE;
    ArchiveEntry(struct archive_entry *entry)
    {
        mode = archive_entry_filetype(entry);
        filesize = archive_entry_size(entry);
        path.set(archive_entry_pathname(entry));
    }
    bool isDir() const
    {
        return S_ISDIR(mode);
    }
    inline offset_t size()
    {
        return filesize;
    }
    const char *pathname()
    {
        return path.get();
    }
private:
    unsigned mode;
    offset_t filesize;
    StringAttr path;
};

// IFileIO implementation for reading out of libarchive-supported archives
// Because of the nature of the libarchive this may not be efficient for some archive formats
// Have to read through the entire archive directory to find the bit you want, it seems
// It's possible that we could add some seek support to at least avoid having to do so twice?

class ArchiveFileIO : public CInterface, implements IFileIO
{
public:
    IMPLEMENT_IINTERFACE;
    ArchiveFileIO(const char *_fullName) : fullName(_fullName)
    {
        // Sadly it seems we can't use a saved entry to read data from an archive. We have to open a new archive
        // object and scan through until we find the matching file, in order to extract it.
        StringAttr container, option, relpath;
        splitArchivedFileName(_fullName, container, option, relpath);
        curPos = 0;
        lastPos = 0;
        curBuffSize = 0;
        curBuff = NULL;
        archive = archive_read_new();
        archive_read_support_format_all(archive);
        archive_read_support_compression_all(archive);
        int retcode = archive_read_open_filename(archive, container, 10240);
        if (retcode == ARCHIVE_OK)
        {
            struct archive_entry *entry = archive_entry_new();
            while (archive_read_next_header2(archive, entry) == ARCHIVE_OK)
            {
                const char *filename = archive_entry_pathname(entry);
                if (strcmp(filename, relpath.get())==0)
                {
                    fileSize = archive_entry_size(entry);
                    break;
                }
            }
            archive_entry_free(entry);
        }
    }
    ~ArchiveFileIO()
    {
        archive_read_finish(archive);
    }

    virtual size32_t read(offset_t pos, size32_t len, void * _data)
    {
        // NOTE - we don't support multithreaded access (the sequential-only restriction would make that tricky anyway)
        if (pos < lastPos)
            throw MakeStringException(0, "Only sequential access to contained file %s supported", fullName.get());
        byte *data = (byte *) _data;
        lastPos = pos;
        size32_t lenRequested = len;
        while (len > 0 & pos < fileSize)
        {
            if (pos >= curPos+curBuffSize)
            {
                int ret = archive_read_data_block(archive, &curBuff, &curBuffSize, &curPos);
                if (ret != ARCHIVE_OK)
                {
                    if (ret == ARCHIVE_EOF)
                        break;  // This shouldn't happen if the quoted fileSize was accurate...
                    else
                        throw MakeStringException(0, "Read error reading contained file %s", fullName.get());
                }
            }
            else
            {
                // Copy as much of the current request as we can fulfil from this block
                offset_t buffOffset = (pos - curPos);
                size_t copyLen = (curBuffSize - buffOffset) > len ? len : curBuffSize - buffOffset;  // careful for overflows, we are mixing 64/32bit values
                if (curBuff)
                    memcpy(data, ((const byte *) curBuff) + buffOffset, copyLen);
                else
                    memset(data, 0, copyLen);  // Sparse areas of compressed files may be represented with NULL buffers
                data += copyLen;
                len -= copyLen;
                pos += copyLen;
            }
        }
        return lenRequested - len;
    }
    virtual offset_t size()
    {
        return fileSize;
    }
    virtual void close()
    {
    }

    // Write methods not implemented - this is a read-only file
    virtual size32_t write(offset_t pos, size32_t len, const void * data)
    {
        throwUnexpected();
    }
    virtual offset_t appendFile(IFile *file,offset_t pos=0,offset_t len=(offset_t)-1)
    {
        throwUnexpected();
    }
    virtual void setSize(offset_t size)
    {
        throwUnexpected();
    }
    virtual void flush()
    {
        throwUnexpected();
    }
protected:
    struct archive *archive;
    offset_t fileSize;
#if ARCHIVE_VERSION_NUMBER < 3000000
    off_t curPos;
#else
    unsigned __int64 curPos;
#endif
    offset_t lastPos;
    size_t curBuffSize;
    const void *curBuff;
    StringAttr fullName;
};

// IFile implementation for reading out of libarchive-supported archives
// These use the struct_archive_entry objects allocated in the directory iterator
// in the hope they might be useful for directly seeking to the file to be extracted
// at some point.

class ArchiveFile : public CInterface, implements IFile
{
public:
    IMPLEMENT_IINTERFACE;
    ArchiveFile(const char *_fileName, ArchiveEntry *_entry)
    : fullName(_fileName),entry(_entry)
    {
    }
    virtual bool exists()
    {
        return entry != NULL;
    }
    virtual bool getTime(CDateTime * createTime, CDateTime * modifiedTime, CDateTime * accessedTime)
    {
        UNIMPLEMENTED; // MORE - maybe could implement if required
    }
    virtual fileBool isDirectory()
    {
        if (!entry)
            return notFound;
        return entry->isDir() ? foundYes : foundNo;
    }
    virtual fileBool isFile()
    {
        if (!entry)
            return notFound;
        return entry->isDir() ? foundNo : foundYes;
    }
    virtual fileBool isReadOnly()
    {
        if (!entry)
            return notFound;
        return foundYes;
    }
    virtual IFileIO * open(IFOmode mode)
    {
        assertex(mode==IFOread && entry != NULL);
        return new ArchiveFileIO(fullName.str());
    }
    virtual IFileAsyncIO * openAsync(IFOmode mode)
    {
        UNIMPLEMENTED;
    }
    virtual IFileIO * openShared(IFOmode mode, IFSHmode shmode)
    {
        assertex(mode==IFOread && entry != NULL);
        return new ArchiveFileIO(fullName.str());
    }
    virtual const char * queryFilename()
    {
        return fullName.str();
    }
    virtual offset_t size()
    {
        if (!entry)
            return 0;
        return entry->size();
    }

// Directory functions
    virtual IDirectoryIterator *directoryFiles(const char *mask, bool sub, bool includeDirs)
    {
        if (isDirectory() != foundYes || (mask && !*mask))   // Empty mask string means matches nothing - NULL means matches everything
            return createNullDirectoryIterator();
        else
        {
            StringBuffer dirName(fullName);
            dirName.append(PATHSEPCHAR);
            return createArchiveDirectoryIterator(dirName, mask, sub, includeDirs);
        }
    }
    virtual bool getInfo(bool &_isdir,offset_t &_size,CDateTime &_modtime)
    {
        _isdir = isDirectory()==foundYes;
        _size = size();
        _modtime.clear(); // MORE could probably do better
        return true; // MORE should this be false if not existing?
    }

    // Not going to be implemented - this IFile interface is too big..
    virtual bool setTime(const CDateTime * createTime, const CDateTime * modifiedTime, const CDateTime * accessedTime) { UNIMPLEMENTED; }
    virtual bool remove() { UNIMPLEMENTED; }
    virtual void rename(const char *newTail) { UNIMPLEMENTED; }
    virtual void move(const char *newName) { UNIMPLEMENTED; }
    virtual void setReadOnly(bool ro) { UNIMPLEMENTED; }
    virtual bool setCompression(bool set) { UNIMPLEMENTED; }
    virtual offset_t compressedSize() { UNIMPLEMENTED; }
    virtual unsigned getCRC() { UNIMPLEMENTED; }
    virtual void setCreateFlags(unsigned cflags) { UNIMPLEMENTED; }
    virtual void setShareMode(IFSHmode shmode) { UNIMPLEMENTED; }
    virtual bool createDirectory() { UNIMPLEMENTED; }
    virtual IDirectoryDifferenceIterator *monitorDirectory(
                                  IDirectoryIterator *prev=NULL,    // in (NULL means use current as baseline)
                                  const char *mask=NULL,
                                  bool sub=false,
                                  bool includedirs=false,
                                  unsigned checkinterval=60*1000,
                                  unsigned timeout=(unsigned)-1,
                                  Semaphore *abortsem=NULL)  { UNIMPLEMENTED; }
    virtual void copySection(const RemoteFilename &dest, offset_t toOfs=(offset_t)-1, offset_t fromOfs=0, offset_t size=(offset_t)-1, ICopyFileProgress *progress=NULL) { UNIMPLEMENTED; }
    virtual void copyTo(IFile *dest, size32_t buffersize=0x100000, ICopyFileProgress *progress=NULL, bool usetmp=false) { UNIMPLEMENTED; }
    virtual IMemoryMappedFile *openMemoryMapped(offset_t ofs=0, memsize_t len=(memsize_t)-1, bool write=false)  { UNIMPLEMENTED; }
    virtual void treeCopyTo(IFile *dest,IpSubNet &subnet,IpAddress &resfrom,bool usetmp=false) { UNIMPLEMENTED; }


protected:
    StringBuffer fullName;
    Linked<ArchiveEntry> entry;
};

extern REMOTE_API IFile *createIFileInArchive(const char *containedFileName)
{
    StringBuffer fname(containedFileName);
    assertex(fname.length());
    removeTrailingPathSepChar(fname);
    StringBuffer dirPath, dirTail;
    splitFilename(fname.str(), &dirPath, &dirPath, &dirTail, &dirTail);

    Owned<IDirectoryIterator> dir = createArchiveDirectoryIterator(dirPath.str(), dirTail.str(), false, true);
    if (dir->first())
    {
        Linked<IFile> file = &dir->query();
        assertex(!dir->next());
        return file.getClear();
    }
    else
        return new ArchiveFile(containedFileName, NULL);
}

class ArchiveDirectoryIterator : public CInterface, implements IDirectoryIterator
{
public:
    IMPLEMENT_IINTERFACE;
    ArchiveDirectoryIterator(const char *_containedFileName, const char *_mask, bool _sub, bool _includeDirs)
    : mask(_mask), sub(_sub), includeDirs(_includeDirs)
    {
        splitArchivedFileName(_containedFileName, container, option, relDir);
        curIndex = 0;
    }
    virtual StringBuffer &getName(StringBuffer &buf)
    {
        assertex(curFile);
        return buf.append(curFile->queryFilename());
    }
    virtual bool isDir()
    {
        assertex(curFile);
        return curFile->isDirectory();
    }
    virtual __int64 getFileSize()
    {
        assertex(curFile);
        return curFile->size();
    }
    virtual bool getModifiedTime(CDateTime &ret)
    {
        UNIMPLEMENTED;
    }
    virtual bool first()
    {
        curFile.clear();
        entries.kill();
        curIndex = 0;
        struct archive *archive = archive_read_new();
        archive_read_support_format_all(archive);
        archive_read_support_compression_all(archive);
        int retcode = archive_read_open_filename(archive, container, 10240);
        if (retcode == ARCHIVE_OK)
        {
            struct archive_entry *entry = archive_entry_new();
            while (archive_read_next_header2(archive, entry) == ARCHIVE_OK)
            {
                unsigned mode = archive_entry_filetype(entry);
                bool isDir = S_ISDIR(mode);
                if (includeDirs || !isDir)
                {
                    const char *filename = archive_entry_pathname(entry);
                    if (memcmp(filename, relDir.get(), relDir.length())==0)
                    {
                        StringBuffer tail(filename + relDir.length());
                        if (tail.length())
                        {
                            if (tail.charAt(tail.length()-1)=='/' || tail.charAt(tail.length()-1)==PATHSEPCHAR)
                                tail.remove(tail.length()-1, 1);
                        }
                        else
                        {
                            assert(isDir);
                            tail.append(".");
                        }
                        // Strip off a trailing /, then check that there is no / in the tail
                        if (strchr(tail, PATHSEPCHAR) == NULL &&  (!mask.length() || WildMatch(tail, mask, false)))
                        {
                            DBGLOG("found file %s %s %s", container.get(), relDir.get(), tail.str());
                            entries.append(*new ArchiveEntry(entry));
                        }
                    }
                }
            }
            archive_entry_free(entry);
        }
        archive_read_finish(archive);
        return next();
    }

    virtual bool next()
    {
        if (entries.isItem(curIndex))
        {
            ArchiveEntry &entry = entries.item(curIndex);
            curIndex++;
            const char *filename = entry.pathname();
            StringBuffer containedFileName;
            buildArchivedFileName(containedFileName, container, option, filename);
            removeTrailingPathSepChar(containedFileName);
            curFile.setown(new ArchiveFile(containedFileName, &entry));
            return true;
        }
        else
        {
            curFile.clear();
            return false;
        }
    }
    virtual bool isValid()  { return curFile != NULL; }
    virtual IFile & query() { return *curFile; }
protected:
    StringAttr container;
    StringAttr option;
    StringAttr relDir;
    StringAttr mask;
    Owned<IFile> curFile;
    unsigned curIndex;
    IArrayOf<ArchiveEntry> entries;  // The entries that matched
    bool includeDirs;
    bool sub;

};

IDirectoryIterator *createArchiveDirectoryIterator(const char *gitFileName, const char *mask, bool sub, bool includeDirs)
{
    assertex(sub==false);  // I don't know what it means!
    return new ArchiveDirectoryIterator(gitFileName, mask, sub, includeDirs);
}

class CArchiveFileHook : public CInterface, implements IContainedFileHook
{
public:
    IMPLEMENT_IINTERFACE;
    virtual IFile * createIFile(const char *fileName)
    {
        if (isArchiveFileName(fileName))
            return createIFileInArchive(fileName);
        else
            return NULL;
    }

protected:
    static bool isArchiveFileName(const char *fileName)
    {
        if (fileName)
            return splitName(fileName) != NULL;
        return false;
    }
} *archiveFileHook;

extern REMOTE_API void installArchiveFileHook()
{
    SpinBlock b(*lock); // Probably overkill!
    if (!archiveFileHook)
    {
        archiveFileHook = new CArchiveFileHook;
        addContainedFileHook(archiveFileHook);
    }
}

extern REMOTE_API void removeArchiveFileHook()
{
    SpinBlock b(*lock); // Probably overkill!
    if (archiveFileHook)
    {
        removeContainedFileHook(archiveFileHook);
        archiveFileHook = NULL;
    }
}

MODULE_INIT(INIT_PRIORITY_REMOTE_RMTFILE)
{
    lock = new SpinLock;
    signature = new RegExpr(ARCHIVE_SIGNATURE);
    archiveFileHook = NULL;
    return true;
}

MODULE_EXIT()
{
    removeArchiveFileHook();
    delete signature;
    delete lock;
    ::Release(archiveFileHook);
}
#else
extern REMOTE_API void installArchiveFileHook()
{
}

extern REMOTE_API void removeArchiveFileHook()
{
}
extern REMOTE_API IFile *createIFileInArchive(const char *containedFileName)
{
    throw MakeStringException(0, "System was built without archive file support");
}
#endif