#include <qpdf/Pl_Flate.hh>

#include <climits>

#include <cstring>

#include <zlib.h>

#include <qpdf/QIntC.hh>

#include <qpdf/QUtil.hh>

#include <qpdf/qpdf-config.h>

#ifdef ZOPFLI

# include <zopfli.h>

#endif

namespace

{

    unsigned long long memory_limit_{0};

} // namespace

int Pl_Flate::compression_level = Z_DEFAULT_COMPRESSION;

Pl_Flate::Members::Members(size_t out_bufsize, action_e action) :

    out_bufsize(out_bufsize),

    action(action),

    initialized(false),

    zdata(nullptr)

{

    this->outbuf = QUtil::make_shared_array<unsigned char>(out_bufsize);

    // Indirect through zdata to reach the z_stream so we don't have to include zlib.h in

    // Pl_Flate.hh.  This means people using shared library versions of qpdf don't have to have zlib

    // development files available, which particularly helps in a Windows environment.

    zdata = new z_stream;

    if (out_bufsize > UINT_MAX) {

        throw std::runtime_error(

            "Pl_Flate: zlib doesn't support buffer sizes larger than unsigned int");

    }

    z_stream& zstream = *(static_cast<z_stream*>(this->zdata));

    zstream.zalloc = nullptr;

    zstream.zfree = nullptr;

    zstream.opaque = nullptr;

    zstream.next_in = nullptr;

    zstream.avail_in = 0;

    zstream.next_out = this->outbuf.get();

    zstream.avail_out = QIntC::to_uint(out_bufsize);

    if (action == a_deflate && Pl_Flate::zopfli_enabled()) {

        zopfli_buf = std::make_unique<std::string>();

    }

}

Pl_Flate::Members::~Members()

{

    if (initialized) {

        z_stream& zstream = *(static_cast<z_stream*>(zdata));

        if (action == a_deflate) {

            deflateEnd(&zstream);

        } else {

            inflateEnd(&zstream);

        }

    }

    delete static_cast<z_stream*>(this->zdata);

    zdata = nullptr;

}

Pl_Flate::Pl_Flate(

    char const* identifier, Pipeline* next, action_e action, unsigned int out_bufsize_int) :

    Pipeline(identifier, next),

    m(std::make_unique<Members>(QIntC::to_size(out_bufsize_int), action))

{

    if (!next) {

        throw std::logic_error("Attempt to create Pl_Flate with nullptr as next");

    }

}

// Must be explicit and not inline -- see QPDF_DLL_CLASS in README-maintainer

Pl_Flate::~Pl_Flate() = default;

unsigned long long

Pl_Flate::memory_limit()

{

    return memory_limit_;

}

void

Pl_Flate::memory_limit(unsigned long long limit)

{

    memory_limit_ = limit;

}

void

Pl_Flate::setWarnCallback(std::function<void(char const*, int)> callback)

{

    m->callback = callback;

}

void

Pl_Flate::warn(char const* msg, int code)

{

    if (m->callback) {

        m->callback(msg, code);

    }

}

void

Pl_Flate::write(unsigned char const* data, size_t len)

{

    if (!m->outbuf) {

        throw std::logic_error(

            this->identifier + ": Pl_Flate: write() called after finish() called");

    }

    if (m->zopfli_buf) {

        m->zopfli_buf->append(reinterpret_cast<char const*>(data), len);

        return;

    }

    // Write in chunks in case len is too big to fit in an int. Assume int is at least 32 bits.

    static size_t const max_bytes = 1 << 30;

    size_t bytes_left = len;

    unsigned char const* buf = data;

    while (bytes_left > 0) {

        size_t bytes = (bytes_left >= max_bytes ? max_bytes : bytes_left);

        handleData(buf, bytes, (m->action == a_inflate ? Z_SYNC_FLUSH : Z_NO_FLUSH));

        bytes_left -= bytes;

        buf += bytes;

    }

}

void

Pl_Flate::handleData(unsigned char const* data, size_t len, int flush)

{

    if (len > UINT_MAX) {

        throw std::runtime_error("Pl_Flate: zlib doesn't support data blocks larger than int");

    }

    z_stream& zstream = *(static_cast<z_stream*>(m->zdata));

    // zlib is known not to modify the data pointed to by next_in but doesn't declare the field

    // value const unless compiled to do so.

    zstream.next_in = const_cast<unsigned char*>(data);

    zstream.avail_in = QIntC::to_uint(len);

    if (!m->initialized) {

        int err = Z_OK;

        // deflateInit and inflateInit are macros that use old-style casts.

#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || defined(__clang__))

# pragma GCC diagnostic push

# pragma GCC diagnostic ignored "-Wold-style-cast"

#endif

        if (m->action == a_deflate) {

            err = deflateInit(&zstream, compression_level);

        } else {

            err = inflateInit(&zstream);

        }

#if ((defined(__GNUC__) && ((__GNUC__ * 100) + __GNUC_MINOR__) >= 406) || defined(__clang__))

# pragma GCC diagnostic pop

#endif

        checkError("Init", err);

        m->initialized = true;

    }

    int err = Z_OK;

    bool done = false;

    while (!done) {

        if (m->action == a_deflate) {

            err = deflate(&zstream, flush);

        } else {

            err = inflate(&zstream, flush);

        }

        if ((m->action == a_inflate) && (err != Z_OK) && zstream.msg &&

            (strcmp(zstream.msg, "incorrect data check") == 0)) {

            // Other PDF readers ignore this specific error. Combining this with Z_SYNC_FLUSH

            // enables qpdf to handle some broken zlib streams without losing data.

            err = Z_STREAM_END;

        }

        switch (err) {

        case Z_BUF_ERROR:

            // Probably shouldn't be able to happen, but possible as a boundary condition: if the

            // last call to inflate exactly filled the output buffer, it's possible that the next

            // call to inflate could have nothing to do. There are PDF files in the wild that have

            // this error (including at least one in qpdf's test suite). In some cases, we want to

            // know about this, because it indicates incorrect compression, so call a callback if

            // provided.

            warn("input stream is complete but output may still be valid", err);

            done = true;

            break;

        case Z_STREAM_END:

            done = true;

            // fall through

        case Z_OK:

            {

                if ((zstream.avail_in == 0) && (zstream.avail_out > 0)) {

                    // There is nothing left to read, and there was sufficient buffer space to write

                    // everything we needed, so we're done for now.

                    done = true;

                }

                uLong ready = QIntC::to_ulong(m->out_bufsize - zstream.avail_out);

                if (ready > 0) {

                    if (memory_limit_ && m->action != a_deflate) {

                        m->written += ready;

                        if (m->written > memory_limit_) {

                            throw std::runtime_error("PL_Flate memory limit exceeded");

                        }

                    }

                    next()->write(m->outbuf.get(), ready);

                    zstream.next_out = m->outbuf.get();

                    zstream.avail_out = QIntC::to_uint(m->out_bufsize);

                }

            }

            break;

        default:

            checkError("data", err);

            break;

        }

    }

}

void

Pl_Flate::finish()

{

    if (m->written > memory_limit_) {

        throw std::runtime_error("PL_Flate memory limit exceeded");

    }

    try {

        if (m->zopfli_buf) {

            finish_zopfli();

        } else if (m->outbuf.get()) {

            if (m->initialized) {

                z_stream& zstream = *(static_cast<z_stream*>(m->zdata));

                unsigned char buf[1];

                buf[0] = '\0';

                handleData(buf, 0, Z_FINISH);

                int err = Z_OK;

                if (m->action == a_deflate) {

                    err = deflateEnd(&zstream);

                } else {

                    err = inflateEnd(&zstream);

                }

                m->initialized = false;

                checkError("End", err);

            }

            m->outbuf = nullptr;

        }

    } catch (std::exception& e) {

        try {

            next()->finish();

        } catch (...) {

            // ignore secondary exception

        }

        throw std::runtime_error(e.what());

    }

    next()->finish();

}

void

Pl_Flate::setCompressionLevel(int level)

{

    compression_level = level;

}

void

Pl_Flate::checkError(char const* prefix, int error_code)

{

    z_stream& zstream = *(static_cast<z_stream*>(m->zdata));

    if (error_code != Z_OK) {

        char const* action_str = (m->action == a_deflate ? "deflate" : "inflate");

        std::string msg = identifier + ": " + action_str + ": " + prefix + ": ";

        if (zstream.msg) {

            msg += zstream.msg;

        } else {

            switch (error_code) {

            case Z_ERRNO:

                msg += "zlib system error";

                break;

            case Z_STREAM_ERROR:

                msg += "zlib stream error";

                break;

            case Z_DATA_ERROR:

                msg += "zlib data error";

                break;

            case Z_MEM_ERROR:

                msg += "zlib memory error";

                break;

            case Z_BUF_ERROR:

                msg += "zlib buffer error";

                break;

            case Z_VERSION_ERROR:

                msg += "zlib version error";

                break;

            default:

                msg += std::string("zlib unknown error (") + std::to_string(error_code) + ")";

                break;

            }

        }

        throw std::runtime_error(msg);

    }

}

void

Pl_Flate::finish_zopfli()

{

#ifdef ZOPFLI

    if (!m->zopfli_buf) {

        return;

    }

    auto buf = std::move(*m->zopfli_buf.release());

    ZopfliOptions z_opt;

    ZopfliInitOptions(&z_opt);

    unsigned char* out{nullptr};

    size_t out_size{0};

    ZopfliCompress(

        &z_opt,

        ZOPFLI_FORMAT_ZLIB,

        reinterpret_cast<unsigned char const*>(buf.c_str()),

        buf.size(),

        &out,

        &out_size);

    std::unique_ptr<unsigned char, decltype(&free)> p(out, &free);

    next()->write(out, out_size);

    // next()->finish is called by finish()

#endif

}

bool

Pl_Flate::zopfli_supported()

{

#ifdef ZOPFLI

    return true;

#else

    return false;

#endif

}

bool

Pl_Flate::zopfli_enabled()

{

    if (zopfli_supported()) {

        std::string value;

        static bool enabled = QUtil::get_env("QPDF_ZOPFLI", &value) && value != "disabled";

        return enabled;

    } else {

        return false;

    }

}

bool

Pl_Flate::zopfli_check_env(QPDFLogger* logger)

{

    if (Pl_Flate::zopfli_supported()) {

        return true;

    }

    std::string value;

    auto is_set = QUtil::get_env("QPDF_ZOPFLI", &value);

    if (!is_set || value == "disabled" || value == "silent") {

        return true;

    }

    if (!logger) {

        logger = QPDFLogger::defaultLogger().get();

    }

    // This behavior is known in QPDFJob (for the --zopfli argument), Pl_Flate.hh, README.md,

    // and the manual. Do a case-insensitive search for zopfli if changing the behavior.

    if (value == "force") {

        throw std::runtime_error("QPDF_ZOPFLI=force, and zopfli support is not enabled");

    }

    logger->warn("QPDF_ZOPFLI is set, but libqpdf was not built with zopfli support\n");

    logger->warn(

        "Set QPDF_ZOPFLI=silent to suppress this warning and use zopfli when available.\n");

    return false;

}