import java.util.List;

public class ProgressMonitor implements Runnable {

    private final String fileName;
    private final int totalSizeMB;
    private final List<ChunkStatus> chunks;
    private final long monitorDelayMs;

    public ProgressMonitor(DownloadConfig config, List<ChunkStatus> chunks) {
        this.fileName = config.getFileName();
        this.totalSizeMB = config.getTotalSizeMB();
        this.chunks = chunks;
        this.monitorDelayMs = 500;
    }

    @Override
    public void run() {
        double previousProgress = 0.0;

        while (true) {
            double totalDownloadedMB = 0.0;
            int completedChunks = 0;

            for (ChunkStatus chunk : chunks) {
                totalDownloadedMB += chunk.getDownloadedMB();

                if (chunk.isCompleted()) {
                    completedChunks++;
                }
            }

            double percent = 0.0;
            if (totalSizeMB > 0) {
                percent = (totalDownloadedMB * 100.0) / totalSizeMB;
            }


            double deltaMB = totalDownloadedMB - previousProgress;
            double speedMBps = deltaMB / (monitorDelayMs / 1000.0);
            previousProgress = totalDownloadedMB;


            double remainingMB = totalSizeMB - totalDownloadedMB;
            long etaSeconds = (speedMBps > 0) ? (long)(remainingMB / speedMBps) : 0;


            int barWidth = 30;
            int filled = (int)(percent / 100.0 * barWidth);
            filled = Math.min(filled, barWidth);
            String bar = "=".repeat(filled) + (filled < barWidth ? ">" : "") + " ".repeat(Math.max(0, barWidth - filled - 1));


            System.out.printf("\r[%-30s] %5.1f%% | %5.1f/%d MB | Speed: %.2f MB/s | ETA: %ds | Chunks: %d/%d   ",
                    bar, percent, totalDownloadedMB, totalSizeMB,
                    speedMBps, etaSeconds,
                    completedChunks, chunks.size());

//            System.out.printf(
//                    "Progress for %s: %.1f/%.1f MB (%.2f%%), completed chunks: %d/%d%n",
//                    fileName,
//                    totalDownloadedMB,
//                    (double) totalSizeMB,
//                    percent,
//                    completedChunks,
//                    chunks.size()
//            );


            if (completedChunks == chunks.size()) {
                System.out.println("download completed!");
                break;
            } else {

                try {
                    Thread.sleep(monitorDelayMs);
                } catch (InterruptedException e) {
                    System.out.println("Progress monitor interrupted.");
                    return;
                }
            }
        }
    }
}