#include <cstdio>
#include <exiv2/exiv2.hpp>
#include <cassert>
#include <exiv2/image.hpp>
#include <memory>
#include <string>

#include <unistd.h>

const char* ORIENTATION_KEY = "Exif.Image.Orientation";


extern "C" unsigned int getExifOrientation(uint8_t* imgBytes, unsigned int size) {
    try {
        Exiv2::XmpParser::initialize();
        ::atexit(Exiv2::XmpParser::terminate);
        Exiv2::enableBMFF();

        Exiv2::Image::AutoPtr image = Exiv2::ImageFactory::open(imgBytes, size);
        assert(image.get() != 0);
        image->readMetadata();

        Exiv2::ExifData &exifData = image->exifData();
        if (exifData.empty()) {
            return 9;
        }

        return (unsigned int) exifData[ORIENTATION_KEY].toLong();
    }
    //catch (std::exception& e) {
    //catch (Exiv2::AnyError& e) {
    catch (Exiv2::Error& e) {
        std::cout << "Caught Exiv2 exception '" << e.what() << "'\n";
        return 9;
    }
}


extern "C" void setExifOrientation(char* fileName, unsigned int orientation) {
    try {
   // Exiv init
        Exiv2::XmpParser::initialize();
        ::atexit(Exiv2::XmpParser::terminate);
        Exiv2::enableBMFF();

        // using blob works, except that exiv2 won't write back to the blob :(
        //  std::unique_ptr<Exiv2::Image> image = Exiv2::ImageFactory::open(imgBytes, size);
        // So instead we load from the temp file
        std::unique_ptr<Exiv2::Image> image = Exiv2::ImageFactory::open(fileName);
        assert(image.get() != 0);
        image->readMetadata();
        Exiv2::ExifData &exifData = image->exifData();

        exifData[ORIENTATION_KEY] = orientation;

        // Save exif to image object & save image back to file
        image->setExifData(exifData);
        image->writeMetadata();
    }
    catch (Exiv2::Error& e) {
        std::cout << "Caught Exiv2 exception '" << e.what() << "'\n";
    }
}
/*
extern "C" void setExifOrientation(uint8_t* imgBytes, unsigned int size, unsigned int orientation) {
    try {
        // Hack to work around Exiv2 seeming to refuse to write back to blob, but will write
        // back to a file. Create temp file -> operate on it -> copy back to blob, unlink file.
        // tmpFileName gets overwritten with the actual filename by mkstemp
        char tmpFileName[] = "/tmp/image-temp.XXXXXX";
        int fd = mkstemp(tmpFileName);
        assert(fd != -1);
        write(fd, imgBytes, size);
        close(fd);

        // Exiv init
        Exiv2::XmpParser::initialize();
        ::atexit(Exiv2::XmpParser::terminate);
        Exiv2::enableBMFF();


        // using blob works, except that exiv2 won't write back to the blob :(
        //  std::unique_ptr<Exiv2::Image> image = Exiv2::ImageFactory::open(imgBytes, size);
        // So instead we load from the temp file
        std::unique_ptr<Exiv2::Image> image = Exiv2::ImageFactory::open(tmpFileName);
        assert(image.get() != 0);
        image->readMetadata();
        Exiv2::ExifData &exifData = image->exifData();

        exifData[ORIENTATION_KEY] = orientation;

        // Save exif to image object & save image back to file
        image->setExifData(exifData);
        image->writeMetadata();


        //TODO: fix problem of img file corruption caused by output being a different size
        //      to the input buffer

        FILE *fileptr;
        char *buffer;
        long filelen;

        fileptr = fopen(tmpFileName, "rb");
        fseek(fileptr, 0, SEEK_END);
        filelen = ftell(fileptr);
        rewind(fileptr);

        buffer = (char *)malloc(filelen * sizeof(char));
        fread(buffer, filelen, 1, fileptr);
        fclose(fileptr);

        printf("new len: %ld old len: %d", filelen, size);


        // reopen temp file, copy result back into byte array
        fileptr = fopen(tmpFileName, "rb");
        fread(imgBytes, size, 1, fileptr);
        fclose(fileptr);
//        unlink(tmpFileName);
    }
    catch (Exiv2::Error& e) {
        std::cout << "Caught Exiv2 exception '" << e.what() << "'\n";
    }
}*/