/******************************************************************************
 *
 * Project:  CPL - Common Portability Library
 * Purpose:  Implement VSI large file api for archive files.
 * Author:   Even Rouault, even.rouault at spatialys.com
 *
 ******************************************************************************
 * Copyright (c) 2010-2014, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "cpl_port.h"
#include "cpl_vsi_virtual.h"

#include <cstring>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <ctime>
#include <map>
#include <set>
#include <string>
#include <utility>
#include <vector>

#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_multiproc.h"
#include "cpl_string.h"
#include "cpl_vsi.h"

//! @cond Doxygen_Suppress

static bool IsEitherSlash(char c)
{
    return c == '/' || c == '\\';
}

/************************************************************************/
/*                    ~VSIArchiveEntryFileOffset()                      */
/************************************************************************/

VSIArchiveEntryFileOffset::~VSIArchiveEntryFileOffset()
{
}

/************************************************************************/
/*                        ~VSIArchiveReader()                           */
/************************************************************************/

VSIArchiveReader::~VSIArchiveReader()
{
}

/************************************************************************/
/*                        ~VSIArchiveContent()                          */
/************************************************************************/

VSIArchiveContent::~VSIArchiveContent()
{
    for (int i = 0; i < nEntries; i++)
    {
        delete entries[i].file_pos;
        CPLFree(entries[i].fileName);
    }
    CPLFree(entries);
}

/************************************************************************/
/*                   VSIArchiveFilesystemHandler()                      */
/************************************************************************/

VSIArchiveFilesystemHandler::VSIArchiveFilesystemHandler()
{
    hMutex = nullptr;
}

/************************************************************************/
/*                   ~VSIArchiveFilesystemHandler()                     */
/************************************************************************/

VSIArchiveFilesystemHandler::~VSIArchiveFilesystemHandler()

{
    for (const auto &iter : oFileList)
    {
        delete iter.second;
    }

    if (hMutex != nullptr)
        CPLDestroyMutex(hMutex);
    hMutex = nullptr;
}

/************************************************************************/
/*                       GetStrippedFilename()                          */
/************************************************************************/

static CPLString GetStrippedFilename(const CPLString &osFileName, bool &bIsDir)
{
    bIsDir = false;
    const char *fileName = osFileName.c_str();

    // Remove ./ pattern at the beginning of a filename.
    if (fileName[0] == '.' && fileName[1] == '/')
    {
        fileName += 2;
        if (fileName[0] == '\0')
            return CPLString();
    }

    char *pszStrippedFileName = CPLStrdup(fileName);
    char *pszIter = nullptr;
    for (pszIter = pszStrippedFileName; *pszIter; pszIter++)
    {
        if (*pszIter == '\\')
            *pszIter = '/';
    }

    const size_t nLen = strlen(fileName);
    bIsDir = nLen > 0 && fileName[nLen - 1] == '/';
    if (bIsDir)
    {
        // Remove trailing slash.
        pszStrippedFileName[nLen - 1] = '\0';
    }
    CPLString osRet(pszStrippedFileName);
    CPLFree(pszStrippedFileName);
    return osRet;
}

/************************************************************************/
/*                       GetContentOfArchive()                          */
/************************************************************************/

const VSIArchiveContent *
VSIArchiveFilesystemHandler::GetContentOfArchive(const char *archiveFilename,
                                                 VSIArchiveReader *poReader)
{
    CPLMutexHolder oHolder(&hMutex);

    VSIStatBufL sStat;
    if (VSIStatL(archiveFilename, &sStat) != 0)
        return nullptr;

    if (oFileList.find(archiveFilename) != oFileList.end())
    {
        VSIArchiveContent *content = oFileList[archiveFilename];
        if (static_cast<time_t>(sStat.st_mtime) > content->mTime ||
            static_cast<vsi_l_offset>(sStat.st_size) != content->nFileSize)
        {
            CPLDebug("VSIArchive",
                     "The content of %s has changed since it was cached",
                     archiveFilename);
            delete content;
            oFileList.erase(archiveFilename);
        }
        else
        {
            return content;
        }
    }

    bool bMustClose = poReader == nullptr;
    if (poReader == nullptr)
    {
        poReader = CreateReader(archiveFilename);
        if (!poReader)
            return nullptr;
    }

    if (poReader->GotoFirstFile() == FALSE)
    {
        if (bMustClose)
            delete (poReader);
        return nullptr;
    }

    VSIArchiveContent *content = new VSIArchiveContent;
    content->mTime = sStat.st_mtime;
    content->nFileSize = static_cast<vsi_l_offset>(sStat.st_size);
    content->nEntries = 0;
    content->entries = nullptr;
    oFileList[archiveFilename] = content;

    std::set<CPLString> oSet;

    do
    {
        const CPLString osFileName = poReader->GetFileName();
        bool bIsDir = false;
        const CPLString osStrippedFilename =
            GetStrippedFilename(osFileName, bIsDir);
        if (osStrippedFilename.empty() || osStrippedFilename[0] == '/' ||
            osStrippedFilename.find("//") != std::string::npos)
        {
            continue;
        }

        if (oSet.find(osStrippedFilename) == oSet.end())
        {
            oSet.insert(osStrippedFilename);

            // Add intermediate directory structure.
            const char *pszBegin = osStrippedFilename.c_str();
            for (const char *pszIter = pszBegin; *pszIter; pszIter++)
            {
                if (*pszIter == '/')
                {
                    char *pszStrippedFileName2 = CPLStrdup(osStrippedFilename);
                    pszStrippedFileName2[pszIter - pszBegin] = 0;
                    if (oSet.find(pszStrippedFileName2) == oSet.end())
                    {
                        oSet.insert(pszStrippedFileName2);

                        content->entries =
                            static_cast<VSIArchiveEntry *>(CPLRealloc(
                                content->entries, sizeof(VSIArchiveEntry) *
                                                      (content->nEntries + 1)));
                        content->entries[content->nEntries].fileName =
                            pszStrippedFileName2;
                        content->entries[content->nEntries].nModifiedTime =
                            poReader->GetModifiedTime();
                        content->entries[content->nEntries].uncompressed_size =
                            0;
                        content->entries[content->nEntries].bIsDir = TRUE;
                        content->entries[content->nEntries].file_pos = nullptr;
#ifdef DEBUG_VERBOSE
                        const int nEntries = content->nEntries;
                        CPLDebug("VSIArchive",
                                 "[%d] %s : " CPL_FRMT_GUIB " bytes",
                                 content->nEntries + 1,
                                 content->entries[nEntries].fileName,
                                 content->entries[nEntries].uncompressed_size);
#endif
                        content->nEntries++;
                    }
                    else
                    {
                        CPLFree(pszStrippedFileName2);
                    }
                }
            }

            content->entries = static_cast<VSIArchiveEntry *>(
                CPLRealloc(content->entries,
                           sizeof(VSIArchiveEntry) * (content->nEntries + 1)));
            content->entries[content->nEntries].fileName =
                CPLStrdup(osStrippedFilename);
            content->entries[content->nEntries].nModifiedTime =
                poReader->GetModifiedTime();
            content->entries[content->nEntries].uncompressed_size =
                poReader->GetFileSize();
            content->entries[content->nEntries].bIsDir = bIsDir;
            content->entries[content->nEntries].file_pos =
                poReader->GetFileOffset();
#ifdef DEBUG_VERBOSE
            CPLDebug("VSIArchive", "[%d] %s : " CPL_FRMT_GUIB " bytes",
                     content->nEntries + 1,
                     content->entries[content->nEntries].fileName,
                     content->entries[content->nEntries].uncompressed_size);
#endif
            content->nEntries++;
        }

    } while (poReader->GotoNextFile());

    if (bMustClose)
        delete (poReader);

    return content;
}

/************************************************************************/
/*                        FindFileInArchive()                           */
/************************************************************************/

int VSIArchiveFilesystemHandler::FindFileInArchive(
    const char *archiveFilename, const char *fileInArchiveName,
    const VSIArchiveEntry **archiveEntry)
{
    if (fileInArchiveName == nullptr)
        return FALSE;

    const VSIArchiveContent *content = GetContentOfArchive(archiveFilename);
    if (content)
    {
        for (int i = 0; i < content->nEntries; i++)
        {
            if (strcmp(fileInArchiveName, content->entries[i].fileName) == 0)
            {
                if (archiveEntry)
                    *archiveEntry = &content->entries[i];
                return TRUE;
            }
        }
    }
    return FALSE;
}

/************************************************************************/
/*                           CompactFilename()                          */
/************************************************************************/

static std::string CompactFilename(const char *pszArchiveInFileNameIn)
{
    std::string osRet(pszArchiveInFileNameIn);

    // Replace a/../b by b and foo/a/../b by foo/b.
    while (true)
    {
        size_t nSlashDotDot = osRet.find("/../");
        if (nSlashDotDot == std::string::npos || nSlashDotDot == 0)
            break;
        size_t nPos = nSlashDotDot - 1;
        while (nPos > 0 && osRet[nPos] != '/')
            --nPos;
        if (nPos == 0)
            osRet = osRet.substr(nSlashDotDot + strlen("/../"));
        else
            osRet = osRet.substr(0, nPos + 1) +
                    osRet.substr(nSlashDotDot + strlen("/../"));
    }
    return osRet;
}

/************************************************************************/
/*                           SplitFilename()                            */
/************************************************************************/

char *VSIArchiveFilesystemHandler::SplitFilename(const char *pszFilename,
                                                 CPLString &osFileInArchive,
                                                 int bCheckMainFileExists)
{
    // TODO(schwehr): Cleanup redundant calls to GetPrefix and strlen.
    if (strcmp(pszFilename, GetPrefix()) == 0)
        return nullptr;

    int i = 0;

    // Detect extended syntax: /vsiXXX/{archive_filename}/file_in_archive.
    if (pszFilename[strlen(GetPrefix()) + 1] == '{')
    {
        pszFilename += strlen(GetPrefix()) + 1;
        int nCountCurlies = 0;
        while (pszFilename[i])
        {
            if (pszFilename[i] == '{')
                nCountCurlies++;
            else if (pszFilename[i] == '}')
            {
                nCountCurlies--;
                if (nCountCurlies == 0)
                    break;
            }
            i++;
        }
        if (nCountCurlies > 0)
            return nullptr;
        char *archiveFilename = CPLStrdup(pszFilename + 1);
        archiveFilename[i - 1] = 0;

        bool bArchiveFileExists = false;
        if (!bCheckMainFileExists)
        {
            bArchiveFileExists = true;
        }
        else
        {
            CPLMutexHolder oHolder(&hMutex);

            if (oFileList.find(archiveFilename) != oFileList.end())
            {
                bArchiveFileExists = true;
            }
        }

        if (!bArchiveFileExists)
        {
            VSIStatBufL statBuf;
            VSIFilesystemHandler *poFSHandler =
                VSIFileManager::GetHandler(archiveFilename);
            if (poFSHandler->Stat(archiveFilename, &statBuf,
                                  VSI_STAT_EXISTS_FLAG |
                                      VSI_STAT_NATURE_FLAG) == 0 &&
                !VSI_ISDIR(statBuf.st_mode))
            {
                bArchiveFileExists = true;
            }
        }

        if (bArchiveFileExists)
        {
            if (IsEitherSlash(pszFilename[i + 1]))
            {
                osFileInArchive = CompactFilename(pszFilename + i + 2);
            }
            else if (pszFilename[i + 1] == '\0')
            {
                osFileInArchive = "";
            }
            else
            {
                CPLFree(archiveFilename);
                return nullptr;
            }

            // Remove trailing slash.
            if (!osFileInArchive.empty())
            {
                const char lastC = osFileInArchive.back();
                if (IsEitherSlash(lastC))
                    osFileInArchive.pop_back();
            }

            return archiveFilename;
        }

        CPLFree(archiveFilename);
        return nullptr;
    }

    // Allow natural chaining of VSI drivers without requiring double slash.

    CPLString osDoubleVsi(GetPrefix());
    osDoubleVsi += "/vsi";

    if (strncmp(pszFilename, osDoubleVsi.c_str(), osDoubleVsi.size()) == 0)
        pszFilename += strlen(GetPrefix());
    else
        pszFilename += strlen(GetPrefix()) + 1;

    // Parsing strings like
    // /vsitar//vsitar//vsitar//vsitar//vsitar//vsitar//vsitar//vsitar/a.tgzb.tgzc.tgzd.tgze.tgzf.tgz.h.tgz.i.tgz
    // takes a huge amount of time, so limit the number of nesting of such
    // file systems.
    int *pnCounter = static_cast<int *>(CPLGetTLS(CTLS_ABSTRACTARCHIVE_SPLIT));
    if (pnCounter == nullptr)
    {
        pnCounter = static_cast<int *>(CPLMalloc(sizeof(int)));
        *pnCounter = 0;
        CPLSetTLS(CTLS_ABSTRACTARCHIVE_SPLIT, pnCounter, TRUE);
    }
    if (*pnCounter == 3)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too deep recursion level in "
                 "VSIArchiveFilesystemHandler::SplitFilename()");
        return nullptr;
    }

    const std::vector<CPLString> oExtensions = GetExtensions();
    int nAttempts = 0;
    while (pszFilename[i])
    {
        int nToSkip = 0;

        for (std::vector<CPLString>::const_iterator iter = oExtensions.begin();
             iter != oExtensions.end(); ++iter)
        {
            const CPLString &osExtension = *iter;
            if (EQUALN(pszFilename + i, osExtension.c_str(),
                       osExtension.size()))
            {
                nToSkip = static_cast<int>(osExtension.size());
                break;
            }
        }

#ifdef DEBUG
        // For AFL, so that .cur_input is detected as the archive filename.
        if (EQUALN(pszFilename + i, ".cur_input", strlen(".cur_input")))
        {
            nToSkip = static_cast<int>(strlen(".cur_input"));
        }
#endif

        if (nToSkip != 0)
        {
            nAttempts++;
            // Arbitrary threshold to avoid DoS with things like
            // /vsitar/my.tar/my.tar/my.tar/my.tar/my.tar/my.tar/my.tar
            if (nAttempts == 5)
            {
                break;
            }
            VSIStatBufL statBuf;
            char *archiveFilename = CPLStrdup(pszFilename);
            bool bArchiveFileExists = false;

            if (IsEitherSlash(archiveFilename[i + nToSkip]))
            {
                archiveFilename[i + nToSkip] = 0;
            }

            if (!bCheckMainFileExists)
            {
                bArchiveFileExists = true;
            }
            else
            {
                CPLMutexHolder oHolder(&hMutex);

                if (oFileList.find(archiveFilename) != oFileList.end())
                {
                    bArchiveFileExists = true;
                }
            }

            if (!bArchiveFileExists)
            {
                (*pnCounter)++;

                VSIFilesystemHandler *poFSHandler =
                    VSIFileManager::GetHandler(archiveFilename);
                if (poFSHandler->Stat(archiveFilename, &statBuf,
                                      VSI_STAT_EXISTS_FLAG |
                                          VSI_STAT_NATURE_FLAG) == 0 &&
                    !VSI_ISDIR(statBuf.st_mode))
                {
                    bArchiveFileExists = true;
                }

                (*pnCounter)--;
            }

            if (bArchiveFileExists)
            {
                if (IsEitherSlash(pszFilename[i + nToSkip]))
                {
                    osFileInArchive =
                        CompactFilename(pszFilename + i + nToSkip + 1);
                }
                else
                {
                    osFileInArchive = "";
                }

                // Remove trailing slash.
                if (!osFileInArchive.empty())
                {
                    const char lastC = osFileInArchive.back();
                    if (IsEitherSlash(lastC))
                        osFileInArchive.resize(osFileInArchive.size() - 1);
                }

                return archiveFilename;
            }
            CPLFree(archiveFilename);
        }
        i++;
    }
    return nullptr;
}

/************************************************************************/
/*                           OpenArchiveFile()                          */
/************************************************************************/

VSIArchiveReader *
VSIArchiveFilesystemHandler::OpenArchiveFile(const char *archiveFilename,
                                             const char *fileInArchiveName)
{
    VSIArchiveReader *poReader = CreateReader(archiveFilename);

    if (poReader == nullptr)
    {
        return nullptr;
    }

    if (fileInArchiveName == nullptr || strlen(fileInArchiveName) == 0)
    {
        if (poReader->GotoFirstFile() == FALSE)
        {
            delete (poReader);
            return nullptr;
        }

        // Skip optional leading subdir.
        const CPLString osFileName = poReader->GetFileName();
        if (osFileName.empty() || IsEitherSlash(osFileName.back()))
        {
            if (poReader->GotoNextFile() == FALSE)
            {
                delete (poReader);
                return nullptr;
            }
        }

        if (poReader->GotoNextFile())
        {
            CPLString msg;
            msg.Printf("Support only 1 file in archive file %s when "
                       "no explicit in-archive filename is specified",
                       archiveFilename);
            const VSIArchiveContent *content =
                GetContentOfArchive(archiveFilename, poReader);
            if (content)
            {
                msg += "\nYou could try one of the following :\n";
                for (int i = 0; i < content->nEntries; i++)
                {
                    msg += CPLString().Printf("  %s/{%s}/%s\n", GetPrefix(),
                                              archiveFilename,
                                              content->entries[i].fileName);
                }
            }

            CPLError(CE_Failure, CPLE_NotSupported, "%s", msg.c_str());

            delete (poReader);
            return nullptr;
        }
    }
    else
    {
        // Optimization: instead of iterating over all files which can be
        // slow on .tar.gz files, try reading the first one first.
        // This can help if it is really huge.
        {
            CPLMutexHolder oHolder(&hMutex);

            if (oFileList.find(archiveFilename) == oFileList.end())
            {
                if (poReader->GotoFirstFile() == FALSE)
                {
                    delete (poReader);
                    return nullptr;
                }

                const CPLString osFileName = poReader->GetFileName();
                bool bIsDir = false;
                const CPLString osStrippedFilename =
                    GetStrippedFilename(osFileName, bIsDir);
                if (!osStrippedFilename.empty())
                {
                    const bool bMatch =
                        strcmp(osStrippedFilename, fileInArchiveName) == 0;
                    if (bMatch)
                    {
                        if (bIsDir)
                        {
                            delete (poReader);
                            return nullptr;
                        }
                        return poReader;
                    }
                }
            }
        }

        const VSIArchiveEntry *archiveEntry = nullptr;
        if (FindFileInArchive(archiveFilename, fileInArchiveName,
                              &archiveEntry) == FALSE ||
            archiveEntry->bIsDir)
        {
            delete (poReader);
            return nullptr;
        }
        if (!poReader->GotoFileOffset(archiveEntry->file_pos))
        {
            delete poReader;
            return nullptr;
        }
    }
    return poReader;
}

/************************************************************************/
/*                                 Stat()                               */
/************************************************************************/

int VSIArchiveFilesystemHandler::Stat(const char *pszFilename,
                                      VSIStatBufL *pStatBuf, int /* nFlags */)
{
    memset(pStatBuf, 0, sizeof(VSIStatBufL));

    CPLString osFileInArchive;
    char *archiveFilename = SplitFilename(pszFilename, osFileInArchive, TRUE);
    if (archiveFilename == nullptr)
        return -1;

    int ret = -1;
    if (!osFileInArchive.empty())
    {
#ifdef DEBUG_VERBOSE
        CPLDebug("VSIArchive", "Looking for %s %s", archiveFilename,
                 osFileInArchive.c_str());
#endif

        const VSIArchiveEntry *archiveEntry = nullptr;
        if (FindFileInArchive(archiveFilename, osFileInArchive, &archiveEntry))
        {
            // Patching st_size with uncompressed file size.
            pStatBuf->st_size = archiveEntry->uncompressed_size;
            pStatBuf->st_mtime =
                static_cast<time_t>(archiveEntry->nModifiedTime);
            if (archiveEntry->bIsDir)
                pStatBuf->st_mode = S_IFDIR;
            else
                pStatBuf->st_mode = S_IFREG;
            ret = 0;
        }
    }
    else
    {
        VSIArchiveReader *poReader = CreateReader(archiveFilename);
        CPLFree(archiveFilename);
        archiveFilename = nullptr;

        if (poReader != nullptr && poReader->GotoFirstFile())
        {
            // Skip optional leading subdir.
            const CPLString osFileName = poReader->GetFileName();
            if (IsEitherSlash(osFileName.back()))
            {
                if (poReader->GotoNextFile() == FALSE)
                {
                    delete (poReader);
                    return -1;
                }
            }

            if (poReader->GotoNextFile())
            {
                // Several files in archive --> treat as dir.
                pStatBuf->st_size = 0;
                pStatBuf->st_mode = S_IFDIR;
            }
            else
            {
                // Patching st_size with uncompressed file size.
                pStatBuf->st_size = poReader->GetFileSize();
                pStatBuf->st_mtime =
                    static_cast<time_t>(poReader->GetModifiedTime());
                pStatBuf->st_mode = S_IFREG;
            }

            ret = 0;
        }

        delete (poReader);
    }

    CPLFree(archiveFilename);
    return ret;
}

/************************************************************************/
/*                             ReadDirEx()                              */
/************************************************************************/

char **VSIArchiveFilesystemHandler::ReadDirEx(const char *pszDirname,
                                              int nMaxFiles)
{
    CPLString osInArchiveSubDir;
    char *archiveFilename = SplitFilename(pszDirname, osInArchiveSubDir, TRUE);
    if (archiveFilename == nullptr)
        return nullptr;

    const int lenInArchiveSubDir = static_cast<int>(osInArchiveSubDir.size());

    CPLStringList oDir;

    const VSIArchiveContent *content = GetContentOfArchive(archiveFilename);
    if (!content)
    {
        CPLFree(archiveFilename);
        return nullptr;
    }

#ifdef DEBUG_VERBOSE
    CPLDebug("VSIArchive", "Read dir %s", pszDirname);
#endif
    for (int i = 0; i < content->nEntries; i++)
    {
        const char *fileName = content->entries[i].fileName;
        /* Only list entries at the same level of inArchiveSubDir */
        if (lenInArchiveSubDir != 0 &&
            strncmp(fileName, osInArchiveSubDir, lenInArchiveSubDir) == 0 &&
            IsEitherSlash(fileName[lenInArchiveSubDir]) &&
            fileName[lenInArchiveSubDir + 1] != 0)
        {
            const char *slash = strchr(fileName + lenInArchiveSubDir + 1, '/');
            if (slash == nullptr)
                slash = strchr(fileName + lenInArchiveSubDir + 1, '\\');
            if (slash == nullptr || slash[1] == 0)
            {
                char *tmpFileName = CPLStrdup(fileName);
                if (slash != nullptr)
                {
                    tmpFileName[strlen(tmpFileName) - 1] = 0;
                }
#ifdef DEBUG_VERBOSE
                CPLDebug("VSIArchive", "Add %s as in directory %s",
                         tmpFileName + lenInArchiveSubDir + 1, pszDirname);
#endif
                oDir.AddString(tmpFileName + lenInArchiveSubDir + 1);
                CPLFree(tmpFileName);
            }
        }
        else if (lenInArchiveSubDir == 0 && strchr(fileName, '/') == nullptr &&
                 strchr(fileName, '\\') == nullptr)
        {
            // Only list toplevel files and directories.
#ifdef DEBUG_VERBOSE
            CPLDebug("VSIArchive", "Add %s as in directory %s", fileName,
                     pszDirname);
#endif
            oDir.AddString(fileName);
        }

        if (nMaxFiles > 0 && oDir.Count() > nMaxFiles)
            break;
    }

    CPLFree(archiveFilename);
    return oDir.StealList();
}

/************************************************************************/
/*                               IsLocal()                              */
/************************************************************************/

bool VSIArchiveFilesystemHandler::IsLocal(const char *pszPath)
{
    if (!STARTS_WITH(pszPath, GetPrefix()))
        return false;
    const char *pszBaseFileName = pszPath + strlen(GetPrefix());
    VSIFilesystemHandler *poFSHandler =
        VSIFileManager::GetHandler(pszBaseFileName);
    return poFSHandler->IsLocal(pszPath);
}

//! @endcond