// gcc tgs2gif.c -o tgs2gif -lrlottie -O3 -lz `MagickWand-config --cppflags --cxxflags --ldflags --libs`
#include <rlottie_capi.h>
#include <MagickWand/MagickWand.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zlib.h>

// Size of the block of memory to use for reading
#define LENGTH 0x1000

char* readTGS(char* path)
{
    size_t cur_size = LENGTH * 2;
    size_t cursor = 0;
    char* result = (char*)calloc(cur_size, 1);
    if (!result)
        return NULL;
    gzFile file = gzopen(path, "r");
    if (!file)
        goto err;
    while (1)
    {
        char buffer[LENGTH];
        int bytes_read = gzread(file, buffer, LENGTH - 1);
        buffer[bytes_read] = '\0';
        strncpy(result + cursor, buffer, bytes_read);
        if (bytes_read < LENGTH - 1)
        {
            if (gzeof (file))
                break;
            else
                goto err;
        }
        char* new_result = (char*)calloc(cur_size + LENGTH, 1);
        memcpy(new_result, result, cur_size);
        free(result);
        result = new_result;
        cur_size += LENGTH;
        cursor += bytes_read;
    }
    gzclose(file);
    return result;
err:
    if (file)
        gzclose(file);
    free(result);
    return NULL;
}

void lottie_configure_model_cache_size(size_t cache_size);

int main(int argc, char* argv[])
{
    if (argc != 2)
    {
        printf("Usage: tgs2gif path_to_tgs_file\n");
        return 1;
    }
    lottie_configure_model_cache_size(0);
    char* tgs = readTGS(argv[1]);
    Lottie_Animation* animation = lottie_animation_from_data(tgs, "", "");
    if (!animation)
    {
        printf("Usage: Failed to import tgs\n");
        return 2;
    }
    free(tgs);

    size_t w = 0;
    size_t h = 0;
    lottie_animation_get_size(animation, &w, &h);

    void* buffer = malloc(w * h * 4);
    if (!buffer)
    {
        printf("Usage: Not enough memory\n");
        return 3;
    }

    size_t frame_count = lottie_animation_get_totalframe(animation);
    double frame_rate = lottie_animation_get_framerate(animation);
    MagickWandGenesis();
    MagickWand* wand = NewMagickWand();
    if (!wand)
    {
        printf("Usage: Not enough memory\n");
        lottie_animation_destroy(animation);
        return 3;
    }

    for (size_t i = 0; i < frame_count ; i++)
    {
        lottie_animation_render(animation, i, buffer, w, h, w * 4);
        MagickConstituteImage(wand, w, h, "BGRA", CharPixel, buffer);
        MagickSetImageDispose(wand, BackgroundDispose);
        MagickSetImageDelay(wand, (unsigned long)(1000. / frame_rate / 10.));
    }
    free(buffer);
    lottie_animation_destroy(animation);

    MagickWand* optimized = MagickOptimizeImageLayers(wand);
    DestroyMagickWand(wand);
    MagickOptimizeImageTransparency(optimized);
    MagickWriteImages(optimized, "output.gif", MagickTrue);
    DestroyMagickWand(optimized);
    MagickWandTerminus();
    return 0;
}