/******************************************************************************
 *
 * Project:  GeoTIFF Driver
 * Purpose:  Implement system hook functions for libtiff on top of CPL/VSI,
 *           including > 2GB support.  Based on tif_unix.c from libtiff
 *           distribution.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2005, Frank Warmerdam, warmerdam@pobox.com
 * Copyright (c) 2010-2012, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

// TIFF Library UNIX-specific Routines.

#include "cpl_port.h"
#include "tifvsi.h"

#include <assert.h>
#include <string.h>
#include <cerrno>
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif

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

// We avoid including xtiffio.h since it drags in the libgeotiff version
// of the VSI functions.

#ifdef RENAME_INTERNAL_LIBGEOTIFF_SYMBOLS
#include "gdal_libgeotiff_symbol_rename.h"
#endif

#include "xtiffio.h"

#include <limits>

#if (TIFFLIB_VERSION > 20220520) || defined(INTERNAL_LIBTIFF)  // > 4.4.0
#define SUPPORTS_LIBTIFF_OPEN_OPTIONS

extern int GTiffWarningHandlerExt(TIFF *tif, void *user_data,
                                  const char *module, const char *fmt,
                                  va_list ap);
extern int GTiffErrorHandlerExt(TIFF *tif, void *user_data, const char *module,
                                const char *fmt, va_list ap);

#endif

constexpr int BUFFER_SIZE = 65536;

struct GDALTiffHandle;

struct GDALTiffHandleShared
{
    VSILFILE *fpL;
    bool bReadOnly;
    bool bLazyStrileLoading;
    char *pszName;
    GDALTiffHandle *psActiveHandle;  // only used on the parent
    int nUserCounter;
    bool bAtEndOfFile;
    vsi_l_offset nFileLength;
};

struct GDALTiffHandle
{
    bool bFree;

    GDALTiffHandle *psParent;  // nullptr for the parent itself
    GDALTiffHandleShared *psShared;

    GByte *abyWriteBuffer;
    int nWriteBufferSize;

    // For pseudo-mmap'ed /vsimem/ file
    vsi_l_offset nDataLength;
    void *pBase;

    // If we pre-cached data (typically from /vsicurl/ )
    int nCachedRanges;
    void **ppCachedData;
    vsi_l_offset *panCachedOffsets;
    size_t *panCachedSizes;
};

static bool GTHFlushBuffer(thandle_t th);

static void SetActiveGTH(GDALTiffHandle *psGTH)
{
    auto psShared = psGTH->psShared;
    if (psShared->psActiveHandle != psGTH)
    {
        if (psShared->psActiveHandle != nullptr)
        {
            GTHFlushBuffer(static_cast<thandle_t>(psShared->psActiveHandle));
        }
        psShared->psActiveHandle = psGTH;
    }
}

void *VSI_TIFFGetCachedRange(thandle_t th, vsi_l_offset nOffset, size_t nSize)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    for (int i = 0; i < psGTH->nCachedRanges; i++)
    {
        if (nOffset >= psGTH->panCachedOffsets[i] &&
            nOffset + nSize <=
                psGTH->panCachedOffsets[i] + psGTH->panCachedSizes[i])
        {
            return static_cast<GByte *>(psGTH->ppCachedData[i]) +
                   (nOffset - psGTH->panCachedOffsets[i]);
        }
        if (nOffset < psGTH->panCachedOffsets[i])
            break;
    }
    return nullptr;
}

static tsize_t _tiffReadProc(thandle_t th, tdata_t buf, tsize_t size)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    // SetActiveGTH(psGTH);

    if (psGTH->nCachedRanges)
    {
        const vsi_l_offset nCurOffset = VSIFTellL(psGTH->psShared->fpL);
        void *data =
            VSI_TIFFGetCachedRange(th, nCurOffset, static_cast<size_t>(size));
        if (data)
        {
            memcpy(buf, data, size);
            VSIFSeekL(psGTH->psShared->fpL, nCurOffset + size, SEEK_SET);
            return size;
        }
    }

#ifdef DEBUG_VERBOSE_EXTRA
    CPLDebug("GTiff", "Reading %d bytes at offset " CPL_FRMT_GUIB,
             static_cast<int>(size), VSIFTellL(psGTH->psShared->fpL));
#endif
    return VSIFReadL(buf, 1, size, psGTH->psShared->fpL);
}

static bool GTHFlushBuffer(thandle_t th)
{
    GDALTiffHandle *psGTH = static_cast<GDALTiffHandle *>(th);
    bool bRet = true;
    if (psGTH->abyWriteBuffer && psGTH->nWriteBufferSize)
    {
        const tsize_t nRet =
            VSIFWriteL(psGTH->abyWriteBuffer, 1, psGTH->nWriteBufferSize,
                       psGTH->psShared->fpL);
        bRet = nRet == psGTH->nWriteBufferSize;
        if (!bRet)
        {
            TIFFErrorExt(th, "_tiffWriteProc", "%s", VSIStrerror(errno));
        }
        psGTH->nWriteBufferSize = 0;
    }
    return bRet;
}

static tsize_t _tiffWriteProc(thandle_t th, tdata_t buf, tsize_t size)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);

    // If we have a write buffer and are at end of file, then accumulate
    // the bytes until the buffer is full.
    if (psGTH->psShared->bAtEndOfFile && psGTH->abyWriteBuffer)
    {
        const GByte *pabyData = reinterpret_cast<GByte *>(buf);
        tsize_t nRemainingBytes = size;
        while (true)
        {
            if (psGTH->nWriteBufferSize + nRemainingBytes <= BUFFER_SIZE)
            {
                memcpy(psGTH->abyWriteBuffer + psGTH->nWriteBufferSize,
                       pabyData, nRemainingBytes);
                psGTH->nWriteBufferSize += static_cast<int>(nRemainingBytes);
                if (psGTH->psShared->bAtEndOfFile)
                {
                    psGTH->psShared->nFileLength += size;
                }
                return size;
            }

            int nAppendable = BUFFER_SIZE - psGTH->nWriteBufferSize;
            memcpy(psGTH->abyWriteBuffer + psGTH->nWriteBufferSize, pabyData,
                   nAppendable);
            const tsize_t nRet = VSIFWriteL(psGTH->abyWriteBuffer, 1,
                                            BUFFER_SIZE, psGTH->psShared->fpL);
            psGTH->nWriteBufferSize = 0;
            if (nRet != BUFFER_SIZE)
            {
                TIFFErrorExt(th, "_tiffWriteProc", "%s", VSIStrerror(errno));
                return 0;
            }

            pabyData += nAppendable;
            nRemainingBytes -= nAppendable;
        }
    }

    const tsize_t nRet = VSIFWriteL(buf, 1, size, psGTH->psShared->fpL);
    if (nRet < size)
    {
        TIFFErrorExt(th, "_tiffWriteProc", "%s", VSIStrerror(errno));
    }

    if (psGTH->psShared->bAtEndOfFile)
    {
        psGTH->psShared->nFileLength += nRet;
    }
    return nRet;
}

static toff_t _tiffSeekProc(thandle_t th, toff_t off, int whence)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);

    // Optimization: if we are already at end, then no need to
    // issue a VSIFSeekL().
    if (whence == SEEK_END)
    {
        if (psGTH->psShared->bAtEndOfFile)
        {
            return static_cast<toff_t>(psGTH->psShared->nFileLength);
        }

        if (VSIFSeekL(psGTH->psShared->fpL, off, whence) != 0)
        {
            TIFFErrorExt(th, "_tiffSeekProc", "%s", VSIStrerror(errno));
            return static_cast<toff_t>(-1);
        }
        psGTH->psShared->bAtEndOfFile = true;
        psGTH->psShared->nFileLength = VSIFTellL(psGTH->psShared->fpL);
        return static_cast<toff_t>(psGTH->psShared->nFileLength);
    }

    GTHFlushBuffer(th);
    psGTH->psShared->bAtEndOfFile = false;
    psGTH->psShared->nFileLength = 0;

    if (VSIFSeekL(psGTH->psShared->fpL, off, whence) == 0)
    {
        return static_cast<toff_t>(VSIFTellL(psGTH->psShared->fpL));
    }
    else
    {
        TIFFErrorExt(th, "_tiffSeekProc", "%s", VSIStrerror(errno));
        return static_cast<toff_t>(-1);
    }
}

static void FreeGTH(GDALTiffHandle *psGTH)
{
    psGTH->psShared->nUserCounter--;
    if (psGTH->psParent == nullptr)
    {
        assert(psGTH->psShared->nUserCounter == 0);
        CPLFree(psGTH->psShared->pszName);
        CPLFree(psGTH->psShared);
    }
    else
    {
        if (psGTH->psShared->psActiveHandle == psGTH)
            psGTH->psShared->psActiveHandle = nullptr;
    }
    CPLFree(psGTH->abyWriteBuffer);
    CPLFree(psGTH->ppCachedData);
    CPLFree(psGTH->panCachedOffsets);
    CPLFree(psGTH->panCachedSizes);
    CPLFree(psGTH);
}

static int _tiffCloseProc(thandle_t th)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);
    GTHFlushBuffer(th);
    if (psGTH->bFree)
        FreeGTH(psGTH);
    return 0;
}

static toff_t _tiffSizeProc(thandle_t th)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);

    if (psGTH->psShared->bAtEndOfFile)
    {
        return static_cast<toff_t>(psGTH->psShared->nFileLength);
    }

    const vsi_l_offset old_off = VSIFTellL(psGTH->psShared->fpL);
    CPL_IGNORE_RET_VAL(VSIFSeekL(psGTH->psShared->fpL, 0, SEEK_END));

    const toff_t file_size =
        static_cast<toff_t>(VSIFTellL(psGTH->psShared->fpL));
    CPL_IGNORE_RET_VAL(VSIFSeekL(psGTH->psShared->fpL, old_off, SEEK_SET));

    return file_size;
}

static int _tiffMapProc(thandle_t th, tdata_t *pbase, toff_t *psize)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    // SetActiveGTH(psGTH);

    if (psGTH->pBase)
    {
        *pbase = psGTH->pBase;
        *psize = static_cast<toff_t>(psGTH->nDataLength);
        return 1;
    }
    return 0;
}

static void _tiffUnmapProc(thandle_t /* th */, tdata_t /* base */,
                           toff_t /* size */)
{
}

VSILFILE *VSI_TIFFGetVSILFile(thandle_t th)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);
    VSI_TIFFFlushBufferedWrite(th);
    return psGTH->psShared->fpL;
}

int VSI_TIFFFlushBufferedWrite(thandle_t th)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    SetActiveGTH(psGTH);
    psGTH->psShared->bAtEndOfFile = false;
    return GTHFlushBuffer(th);
}

int VSI_TIFFHasCachedRanges(thandle_t th)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    return psGTH->nCachedRanges != 0;
}

toff_t VSI_TIFFSeek(TIFF *tif, toff_t off, int whence)
{
    thandle_t th = TIFFClientdata(tif);
    return _tiffSeekProc(th, off, whence);
}

int VSI_TIFFWrite(TIFF *tif, const void *buffer, size_t buffersize)
{
    thandle_t th = TIFFClientdata(tif);
    return static_cast<size_t>(_tiffWriteProc(th, const_cast<tdata_t>(buffer),
                                              buffersize)) == buffersize;
}

void VSI_TIFFSetCachedRanges(thandle_t th, int nRanges, void **ppData,
                             const vsi_l_offset *panOffsets,
                             const size_t *panSizes)
{
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);
    psGTH->nCachedRanges = nRanges;
    if (nRanges)
    {
        psGTH->ppCachedData = static_cast<void **>(
            CPLRealloc(psGTH->ppCachedData, nRanges * sizeof(void *)));
        memcpy(psGTH->ppCachedData, ppData, nRanges * sizeof(void *));

        psGTH->panCachedOffsets = static_cast<vsi_l_offset *>(CPLRealloc(
            psGTH->panCachedOffsets, nRanges * sizeof(vsi_l_offset)));
        memcpy(psGTH->panCachedOffsets, panOffsets,
               nRanges * sizeof(vsi_l_offset));

        psGTH->panCachedSizes = static_cast<size_t *>(
            CPLRealloc(psGTH->panCachedSizes, nRanges * sizeof(size_t)));
        memcpy(psGTH->panCachedSizes, panSizes, nRanges * sizeof(size_t));
    }
}

static bool IsReadOnly(const char *mode)
{
    bool bReadOnly = true;
    for (int i = 0; mode[i] != '\0'; i++)
    {
        if (mode[i] == 'w' || mode[i] == '+' || mode[i] == 'a')
        {
            bReadOnly = false;
        }
    }
    return bReadOnly;
}

static void InitializeWriteBuffer(GDALTiffHandle *psGTH, const char *pszMode)
{
    // No need to buffer on /vsimem/
    const bool bReadOnly = IsReadOnly(pszMode);
    bool bAllocBuffer = !bReadOnly;
    if (STARTS_WITH(psGTH->psShared->pszName, "/vsimem/"))
    {
        if (bReadOnly &&
            CPLTestBool(CPLGetConfigOption("GTIFF_USE_MMAP", "NO")))
        {
            psGTH->nDataLength = 0;
            psGTH->pBase = VSIGetMemFileBuffer(psGTH->psShared->pszName,
                                               &psGTH->nDataLength, FALSE);
        }
        bAllocBuffer = false;
    }

    psGTH->abyWriteBuffer =
        bAllocBuffer ? static_cast<GByte *>(VSIMalloc(BUFFER_SIZE)) : nullptr;
    psGTH->nWriteBufferSize = 0;
}

#ifdef SUPPORTS_LIBTIFF_OPEN_OPTIONS
static void VSI_TIFFSetOpenOptions(TIFFOpenOptions *opts)
{
    TIFFOpenOptionsSetErrorHandlerExtR(opts, GTiffErrorHandlerExt, nullptr);
    TIFFOpenOptionsSetWarningHandlerExtR(opts, GTiffWarningHandlerExt, nullptr);
#if defined(INTERNAL_LIBTIFF) || TIFFLIB_VERSION > 20230908
    // Read-once and stored in static storage otherwise affects
    // autotest/benchmark/test_gtiff.py::test_gtiff_byte
    static const GIntBig nMemLimit = []() -> GIntBig
    {
        if (const char *pszLimit =
                CPLGetConfigOption("GTIFF_MAX_CUMULATED_MEM_USAGE", nullptr))
            return CPLAtoGIntBig(pszLimit);
        else
        {
            const auto nUsableRAM = CPLGetUsablePhysicalRAM();
            if (nUsableRAM > 0)
            {
                // coverity[return_overflow]
                return nUsableRAM / 10 * 9;
            }
            else
                return 0;
        }
    }();
    if (nMemLimit > 0 && nMemLimit < std::numeric_limits<tmsize_t>::max())
    {
        //CPLDebug("GTiff", "TIFFOpenOptionsSetMaxCumulatedMemAlloc(%" PRIu64 ")",
        //         static_cast<uint64_t>(nMemLimit));
        TIFFOpenOptionsSetMaxCumulatedMemAlloc(
            opts, static_cast<tmsize_t>(nMemLimit));
    }
#endif
}
#endif

static TIFF *VSI_TIFFOpen_common(GDALTiffHandle *psGTH, const char *pszMode)
{
    InitializeWriteBuffer(psGTH, pszMode);

#ifdef SUPPORTS_LIBTIFF_OPEN_OPTIONS
    XTIFFInitialize();
    TIFFOpenOptions *opts = TIFFOpenOptionsAlloc();
    if (opts == nullptr)
    {
        FreeGTH(psGTH);
        return nullptr;
    }
    VSI_TIFFSetOpenOptions(opts);
    TIFF *tif = TIFFClientOpenExt(
        psGTH->psShared->pszName, pszMode, reinterpret_cast<thandle_t>(psGTH),
        _tiffReadProc, _tiffWriteProc, _tiffSeekProc, _tiffCloseProc,
        _tiffSizeProc, _tiffMapProc, _tiffUnmapProc, opts);
    TIFFOpenOptionsFree(opts);
#else
    TIFF *tif = XTIFFClientOpen(
        psGTH->psShared->pszName, pszMode, reinterpret_cast<thandle_t>(psGTH),
        _tiffReadProc, _tiffWriteProc, _tiffSeekProc, _tiffCloseProc,
        _tiffSizeProc, _tiffMapProc, _tiffUnmapProc);
#endif
    if (tif == nullptr)
        FreeGTH(psGTH);

    return tif;
}

// Open a TIFF file for read/writing.
TIFF *VSI_TIFFOpen(const char *name, const char *mode, VSILFILE *fpL)
{

    if (VSIFSeekL(fpL, 0, SEEK_SET) < 0)
        return nullptr;

    GDALTiffHandle *psGTH =
        static_cast<GDALTiffHandle *>(CPLCalloc(1, sizeof(GDALTiffHandle)));
    psGTH->bFree = true;
    psGTH->psParent = nullptr;
    psGTH->psShared = static_cast<GDALTiffHandleShared *>(
        CPLCalloc(1, sizeof(GDALTiffHandleShared)));
    psGTH->psShared->bReadOnly = (strchr(mode, '+') == nullptr);
    psGTH->psShared->bLazyStrileLoading = (strchr(mode, 'D') != nullptr);
    psGTH->psShared->pszName = CPLStrdup(name);
    psGTH->psShared->fpL = fpL;
    psGTH->psShared->psActiveHandle = psGTH;
    psGTH->psShared->nFileLength = 0;
    psGTH->psShared->bAtEndOfFile = false;
    psGTH->psShared->nUserCounter = 1;

    return VSI_TIFFOpen_common(psGTH, mode);
}

TIFF *VSI_TIFFOpenChild(TIFF *parent)
{
    GDALTiffHandle *psGTHParent =
        reinterpret_cast<GDALTiffHandle *>(TIFFClientdata(parent));

    GDALTiffHandle *psGTH =
        static_cast<GDALTiffHandle *>(CPLCalloc(1, sizeof(GDALTiffHandle)));
    psGTH->bFree = true;
    psGTH->psParent = psGTHParent;
    psGTH->psShared = psGTHParent->psShared;
    psGTH->psShared->nUserCounter++;

    SetActiveGTH(psGTH);
    VSIFSeekL(psGTH->psShared->fpL, 0, SEEK_SET);
    psGTH->psShared->bAtEndOfFile = false;

    const char *mode =
        psGTH->psShared->bReadOnly && psGTH->psShared->bLazyStrileLoading
            ? "rDO"
        : psGTH->psShared->bReadOnly          ? "r"
        : psGTH->psShared->bLazyStrileLoading ? "r+D"
                                              : "r+";
    return VSI_TIFFOpen_common(psGTH, mode);
}

// Re-open a TIFF handle (seeking to the appropriate directory is then needed)
TIFF *VSI_TIFFReOpen(TIFF *tif)
{
    thandle_t th = TIFFClientdata(tif);
    GDALTiffHandle *psGTH = reinterpret_cast<GDALTiffHandle *>(th);

    // Disable freeing of psGTH in _tiffCloseProc(), which could be called
    // if XTIFFClientOpen() fails, or obviously by XTIFFClose()
    psGTH->bFree = false;

    const char *mode =
        psGTH->psShared->bReadOnly && psGTH->psShared->bLazyStrileLoading
            ? "rDO"
        : psGTH->psShared->bReadOnly          ? "r"
        : psGTH->psShared->bLazyStrileLoading ? "r+D"
                                              : "r+";

    SetActiveGTH(psGTH);
    VSIFSeekL(psGTH->psShared->fpL, 0, SEEK_SET);
    psGTH->psShared->bAtEndOfFile = false;

#ifdef SUPPORTS_LIBTIFF_OPEN_OPTIONS
    TIFF *newHandle = nullptr;
    TIFFOpenOptions *opts = TIFFOpenOptionsAlloc();
    if (opts != nullptr)
    {
        VSI_TIFFSetOpenOptions(opts);
        newHandle = TIFFClientOpenExt(
            psGTH->psShared->pszName, mode, reinterpret_cast<thandle_t>(psGTH),
            _tiffReadProc, _tiffWriteProc, _tiffSeekProc, _tiffCloseProc,
            _tiffSizeProc, _tiffMapProc, _tiffUnmapProc, opts);
        TIFFOpenOptionsFree(opts);
    }
#else
    TIFF *newHandle = XTIFFClientOpen(
        psGTH->psShared->pszName, mode, reinterpret_cast<thandle_t>(psGTH),
        _tiffReadProc, _tiffWriteProc, _tiffSeekProc, _tiffCloseProc,
        _tiffSizeProc, _tiffMapProc, _tiffUnmapProc);
#endif
    if (newHandle != nullptr)
        XTIFFClose(tif);

    psGTH->bFree = true;

    return newHandle;
}