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

/**
 * Utility methods related to chunk creation.
 */
public class ChunkUtils {

    private ChunkUtils() {
        // Utility class
    }

    /**
     * Splits the total file size into a list of chunks.
     * Chunk sizes are as even as possible.
     * If the size is not exactly divisible, the last chunk gets the remainder.
     *
     * @param totalSizeMB total file size in MB
     * @param chunkCount number of chunks
     * @return list of ChunkStatus objects
     */
    public static List<ChunkStatus> createChunks(int totalSizeMB, int chunkCount) {
        List<ChunkStatus> chunks = new ArrayList<>();

        if (totalSizeMB <= 0 || chunkCount <= 0) {
            return chunks;
        }

        int baseChunkSize = totalSizeMB / chunkCount;
        int remainder = totalSizeMB % chunkCount;

        for (int i = 0; i < chunkCount; i++) {
            int chunkSize = baseChunkSize;

            if (i == chunkCount - 1) {
                chunkSize += remainder;
            }

            // Create one ChunkStatus object for each chunk.
            // chunkId is the chunk number, and chunkSize is this chunk's total size.
            chunks.add(new ChunkStatus(i + 1, chunkSize));
        }

        return chunks;
    }
}