import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        System.out.println("=== Simulated Download Manager ===");

        // 1. Read config
        DownloadConfig config;
        try {
            config = ConfigReader.readConfig("download_config.txt");
        } catch (Exception e) {
            System.out.println("Failed to read configuration: " + e.getMessage());
            return;
        }

        System.out.println("File name: " + config.getFileName());
        System.out.println("Total size (MB): " + config.getTotalSizeMB());
        System.out.println("Chunk count: " + config.getChunkCount());
        System.out.println();

        // 2. Create chunks
        List<ChunkStatus> chunks = ChunkUtils.createChunks(
                config.getTotalSizeMB(),
                config.getChunkCount()
        );

        // 3. Create worker threads
        List<Thread> workerThreads = new ArrayList<>();

        for (ChunkStatus chunk : chunks) {
            DownloadWorker worker = new DownloadWorker(chunk, config);
            Thread workerThread = new Thread(worker, "Worker-" + chunk.getChunkId());

            workerThreads.add(workerThread);

            // TODO:
            // Students may print helpful debug information here,
            // for example which chunk is assigned to which worker thread.
        }

        // 4. Create and start monitor thread
        ProgressMonitor monitor = new ProgressMonitor(config, chunks);
        Thread monitorThread = new Thread(monitor, "Progress-Monitor");

        // TODO:
        // Start the monitor thread before starting the workers
        // so that progress can be displayed while downloading happens.
        //
        // Example idea:
        // monitorThread.start();

        // 5. Start worker threads
        // TODO:
        // Start each worker thread in workerThreads.
        // Use a loop and call start() on each thread.

        // 6. Wait for workers to finish
        // TODO:
        // Wait for all worker threads to complete by calling join().
        // This should be done inside a try-catch block for InterruptedException.
        //
        // Hint:
        // for (Thread thread : workerThreads) {
        //     thread.join();
        // }

        // TODO:
        // After all workers finish, the monitor thread may also need to stop.
        // Depending on how ProgressMonitor is implemented, students may:
        // - wait for it to finish on its own, or
        // - add a stopping mechanism in ProgressMonitor later.
        //
        // If your monitor finishes automatically, you may join it here.

        // NOTE:
        // this final report may show 0 progress because no worker has actually run yet.
        // Until students complete the thread start/join TODOs above,

        // 7. Print final report
        System.out.println();
        System.out.println("=== Final Report ===");

        int completedChunks = 0;
        double downloadedMB = 0.0;

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

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

            System.out.println(
                    "Chunk " + chunk.getChunkId()
                            + ": " + chunk.getDownloadedMB()
                            + "/" + chunk.getChunkSizeMB()
                            + " MB"
            );
        }

        System.out.println();
        System.out.println("Completed chunks: " + completedChunks + "/" + chunks.size());
        System.out.println("Downloaded total: " + downloadedMB + "/" + config.getTotalSizeMB() + " MB");
        System.out.println("Simulation finished.");
    }
}