Multi-Part Processing

/**
 * Namespace class for multi-part content support
 */
class MultiPart {
    /** Extract boundary parameter from Content-Type header */
    static String extractBoundary(String contentType);
    
    /** Generate multipart boundary with prefix and random characters */
    static String generateBoundary(String prefix, int randomLength);
    
    /**
     * Individual part within multi-part content
     */
    abstract static class Part implements Content.Source.Factory, Closeable {
        /** Get part name from Content-Disposition header */
        String getName();
        
        /** Get filename from Content-Disposition header */
        String getFileName();
        
        /** Get part headers */
        HttpFields getHeaders();
        
        /** Get part content as source */
        Content.Source getContentSource();
        
        /** Get part content length */
        long getLength();
        
        /** Get part content type */
        String getContentType();
        
        /** Check if part represents a file upload */
        boolean isFile();
        
        /** Close part and release resources */
        void close();
    }
    
    /**
     * Multi-part content parser
     */
    static class Parser {
        /** Create parser with boundary and buffer pool */
        Parser(String boundary, ByteBufferPool bufferPool);
        
        /** Parse content source into parts */
        void parse(Content.Source source, PartHandler handler);
        
        /** Interface for handling parsed parts */
        interface PartHandler {
            /** Handle parsed part */
            void handle(Part part);
        }
    }
}

/**
 * Multi-part form data processing with async support
 */
class MultiPartFormData {
    /** Create form data processor with default configuration */
    MultiPartFormData();
    
    /** Create with custom configuration */
    MultiPartFormData(MultiPartConfig config);
    
    /** Parse multi-part content asynchronously */
    CompletableFuture<Parts> parse(Content.Source source);
    
    /** Parse multi-part content synchronously (blocking) */
    Parts from(Content.Source source);
    
    /** Parse with content type header */
    CompletableFuture<Parts> parse(Content.Source source, String contentType);
    
    /** Get maximum part size */
    long getMaxPartSize();
    
    /** Set maximum part size */
    void setMaxPartSize(long maxPartSize);
    
    /** Get maximum file size for uploads */
    long getMaxFileSize();
    
    /** Set maximum file size for uploads */
    void setMaxFileSize(long maxFileSize);
    
    /** Get maximum request size */
    long getMaxRequestSize();
    
    /** Set maximum request size */
    void setMaxRequestSize(long maxRequestSize);
    
    /**
     * Collection of parsed multi-part form parts
     */
    interface Parts extends Iterable<MultiPart.Part> {
        /** Get part by name */
        MultiPart.Part get(String name);
        
        /** Get all parts with given name */
        List<MultiPart.Part> getAll(String name);
        
        /** Get part names */
        Set<String> getNames();
        
        /** Get all parts as list */
        List<MultiPart.Part> asList();
        
        /** Get number of parts */
        int size();
        
        /** Check if empty */
        boolean isEmpty();
        
        /** Release all parts */
        void release();
    }
}

/**
 * Multi-part byte ranges for HTTP Range responses
 */
class MultiPartByteRanges {
    /** Create byte ranges with content type */
    MultiPartByteRanges(String contentType);
    
    /** Add byte range part */
    void addPart(ByteRange range, Content.Source content);
    
    /** Get boundary string */
    String getBoundary();
    
    /** Get content type with boundary */
    String getContentType();
    
    /** Get parts as content source */
    Content.Source getContentSource();
    
    /** Get total content length */
    long getContentLength();
}

/**
 * Configuration for multi-part processing
 */
class MultiPartConfig {
    /** Create configuration with default settings */
    MultiPartConfig();
    
    /** Create with size limits */
    MultiPartConfig(long maxFileSize, long maxRequestSize, int fileSizeThreshold);
    
    /** Create with full configuration */
    MultiPartConfig(long maxFileSize, long maxRequestSize, 
                   int fileSizeThreshold, String location);
    
    /** Get maximum file size for individual uploads */
    long getMaxFileSize();
    
    /** Get maximum total request size */
    long getMaxRequestSize();
    
    /** Get file size threshold for writing to disk */
    int getFileSizeThreshold();
    
    /** Get temporary file location */
    String getLocation();
}

/**
 * Multi-part compliance modes and validation
 */
class MultiPartCompliance {
    /** RFC 7578 compliant parsing */
    static final MultiPartCompliance RFC7578;
    
    /** Legacy compatibility mode */
    static final MultiPartCompliance LEGACY;
    
    /** Check if violation is allowed */
    boolean allows(Violation violation);
    
    /** Get allowed violations */
    Set<Violation> getAllowed();
    
    /** Get compliance mode name */
    String getName();
    
    /**
     * Multi-part compliance violations
     */
    enum Violation {
        /** No boundary specified */
        NO_BOUNDARY,
        
        /** Invalid boundary characters */
        INVALID_BOUNDARY,
        
        /** Missing final boundary */
        NO_FINAL_BOUNDARY,
        
        /** Invalid Content-Disposition header */
        INVALID_CONTENT_DISPOSITION,
        
        /** Duplicate part names */
        DUPLICATE_NAMES;
    }
}

/**
 * HTTP Range request processing
 */
class ByteRange {
    /** Create byte range */
    ByteRange(long first, long last);
    
    /** Get first byte position */
    long getFirst();
    
    /** Get last byte position */
    long getLast();
    
    /** Get range length */
    long getLength();
    
    /** Check if range is suffix range */
    boolean isSuffix();
    
    /** Get range as Content-Range header value */
    String toHeaderValue(long contentLength);
    
    /** Parse Range header value */
    static List<ByteRange> parse(String rangeHeader, long contentLength);
    
    /** Parse single range specification */
    static ByteRange parseRange(String range, long contentLength);
    
    /** Check if ranges are satisfiable */
    static boolean satisfiable(List<ByteRange> ranges, long contentLength);
}

import org.eclipse.jetty.http.*;
import java.util.concurrent.CompletableFuture;

// Parse multi-part form data asynchronously
MultiPartConfig config = new MultiPartConfig(
    10 * 1024 * 1024,  // maxFileSize: 10MB
    50 * 1024 * 1024,  // maxRequestSize: 50MB  
    8192,              // fileSizeThreshold: 8KB
    "/tmp"             // temp directory
);

MultiPartFormData formData = new MultiPartFormData(config);

// Async parsing
Content.Source requestBody = getRequestBodySource();
CompletableFuture<MultiPartFormData.Parts> future = 
    formData.parse(requestBody, "multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW");

future.thenAccept(parts -> {
    // Process form fields
    MultiPart.Part textField = parts.get("username");
    if (textField != null) {
        String username = readPartContent(textField);
    }
    
    // Process file uploads
    MultiPart.Part fileUpload = parts.get("avatar");
    if (fileUpload != null && fileUpload.isFile()) {
        String filename = fileUpload.getFileName();
        String contentType = fileUpload.getContentType();
        long size = fileUpload.getLength();
        
        // Save uploaded file
        saveFile(fileUpload.getContentSource(), filename);
    }
    
    // Release resources
    parts.release();
});

// Synchronous parsing  
MultiPartFormData.Parts parts = formData.from(requestBody);

// Iterate through all parts
for (MultiPart.Part part : parts) {
    String name = part.getName();
    String filename = part.getFileName();
    HttpFields headers = part.getHeaders();
    
    if (part.isFile()) {
        // Handle file upload
        processFileUpload(part);
    } else {
        // Handle form field
        String value = readPartContent(part);
    }
}

// Get multiple parts with same name (e.g., checkboxes)
List<MultiPart.Part> selectedItems = parts.getAll("items");
for (MultiPart.Part item : selectedItems) {
    String value = readPartContent(item);
}

// Create multi-part content programmatically
MultiPart multiPart = new MultiPart("----WebKitFormBoundary7MA4YWxkTrZu0gW");

// Add text part
MultiPart.Part textPart = createTextPart("username", "john.doe");
multiPart.addPart(textPart);

// Add file part
MultiPart.Part filePart = createFilePart("document", "report.pdf", 
    "application/pdf", fileContent);
multiPart.addPart(filePart);

// Multi-part byte ranges for HTTP Range responses
MultiPartByteRanges byteRanges = new MultiPartByteRanges("text/plain");

// Add range parts
ByteRange range1 = new ByteRange(0, 499);      // bytes 0-499
ByteRange range2 = new ByteRange(1000, 1499);  // bytes 1000-1499

byteRanges.addPart(range1, getContentSource(0, 500));
byteRanges.addPart(range2, getContentSource(1000, 500));

String contentType = byteRanges.getContentType(); 
// "multipart/byteranges; boundary=..."

// Parse HTTP Range header
String rangeHeader = "bytes=0-499,1000-1499";
long contentLength = 2000;
List<ByteRange> ranges = ByteRange.parse(rangeHeader, contentLength);

for (ByteRange range : ranges) {
    long first = range.getFirst();
    long last = range.getLast();
    long length = range.getLength();
    
    String contentRange = range.toHeaderValue(contentLength);
    // "bytes 0-499/2000" or "bytes 1000-1499/2000"
}

// Check if ranges are satisfiable
boolean satisfiable = ByteRange.satisfiable(ranges, contentLength);

// Multi-part compliance handling
MultiPartCompliance compliance = MultiPartCompliance.RFC7578;
ComplianceViolation.Listener listener = 
    (mode, violation, details) -> {
        System.err.println("Multi-part violation: " + violation + " - " + details);
    };

// Helper methods (implementation dependent)
private String readPartContent(MultiPart.Part part) {
    // Read part content as string
    return null; // Implementation specific
}

private void saveFile(Content.Source source, String filename) {
    // Save file to disk
}

private void processFileUpload(MultiPart.Part part) {
    // Process uploaded file
}

private MultiPart.Part createTextPart(String name, String value) {
    // Create text form field part
    return null; // Implementation specific
}

private MultiPart.Part createFilePart(String name, String filename, 
                                     String contentType, byte[] content) {
    // Create file upload part
    return null; // Implementation specific
}

private Content.Source getRequestBodySource() {
    // Get request body content source
    return null; // Implementation specific
}

private Content.Source getContentSource(long offset, long length) {
    // Get content source for byte range
    return null; // Implementation specific
}