#include <effectlab/transition_c.h>
#include <QGuiApplication>
#include <QFile>
#include <QImage>
#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>
#include <fstream>
#include <iostream>
#include <vector>

// Render lossless RGBA frames through the public SDK C ABI. The asset builder
// supplies each cover's native frame schedule and encodes its original type.
int main(int argc,char** argv) {
    QGuiApplication app(argc,argv);
    if(argc!=8){std::cerr<<"usage: preview_card package input0 input1 spec.json frames.rgba report.json ffmpeg\n";return 64;}
    QFile specFile(QString::fromLocal8Bit(argv[4]));if(!specFile.open(QIODevice::ReadOnly))return 65;
    auto spec=QJsonDocument::fromJson(specFile.readAll()).object();
    const int w=spec["render_width"].toInt(),h=spec["render_height"].toInt();
    const auto durations=spec["durations_ms"].toArray();
    if(w<1||h<1||w>4096||h>4096||durations.size()<2||durations.size()>10000)return 65;
    std::vector<QImage> inputs;
    for(int i=2;i<4;++i){QImage image(QString::fromLocal8Bit(argv[i]));if(image.isNull())return 65;
        image=image.scaled(w,h,Qt::KeepAspectRatioByExpanding,Qt::SmoothTransformation);
        inputs.push_back(image.copy((image.width()-w)/2,(image.height()-h)/2,w,h).convertToFormat(QImage::Format_RGBA8888));}
    el_transition* handle=nullptr;int status=el_transition_create(argv[1],&handle);
    auto finish=[&](bool passed,int frames,const QString& error){
        QJsonArray warnings;const char* data=handle?el_transition_diagnostics(handle):nullptr;
        if(data)warnings=QJsonDocument::fromJson(data).array();
        QJsonObject report{{"passed",passed},{"frames_rendered",frames},{"frames_requested",durations.size()},
            {"error",error},{"warnings",warnings},{"route",handle?el_transition_route(handle):"unsupported"}};
        QFile f(QString::fromLocal8Bit(argv[6]));if(f.open(QIODevice::WriteOnly))f.write(QJsonDocument(report).toJson());
        el_transition_destroy(handle);return passed?0:3;
    };
    if(status!=EL_OK)return finish(false,0,el_transition_last_error());
    if(el_transition_set_media_decoder(handle,argv[7])!=EL_OK)return finish(false,0,el_transition_last_error());
    el_rgba_view left{inputs[0].constBits(),uint32_t(w),uint32_t(h),size_t(inputs[0].bytesPerLine()),size_t(inputs[0].sizeInBytes())};
    el_rgba_view right{inputs[1].constBits(),uint32_t(w),uint32_t(h),size_t(inputs[1].bytesPerLine()),size_t(inputs[1].sizeInBytes())};
    std::vector<uint8_t> pixels(size_t(w)*h*4);el_rgba_output output{pixels.data(),uint32_t(w),uint32_t(h),size_t(w)*4,pixels.size()};
    std::ofstream raw(argv[5],std::ios::binary|std::ios::trunc);if(!raw)return finish(false,0,"cannot create RGBA output");
    double total=0;for(const auto& value:durations){if(value.toInt()<1)return finish(false,0,"invalid frame duration");total+=value.toInt();}
    double elapsed=0;
    for(int frame=0;frame<durations.size();++frame){
        // Capture at the start of each original cover frame. The final frame
        // occupies its original remaining interval; the encoded loop ends at total.
        const double timestamp=elapsed/total;
        status=el_transition_render(handle,timestamp,durations[frame].toInt()/1000.,&left,&right,&output);
        if(status!=EL_OK)return finish(false,frame,QString("frame %1: %2").arg(frame).arg(el_transition_last_error()));
        raw.write(reinterpret_cast<const char*>(pixels.data()),pixels.size());
        if(!raw)return finish(false,frame,"cannot write RGBA output");
        elapsed+=durations[frame].toInt();
    }
    raw.close();return finish(true,durations.size(),{});
}