/* 
 * Monolithic Arduino VUSB CDC implementation
 * Combines VUSB_CDC, ringBuffer8, and usbdrv functionality.
 * Includes V-USB core definitions inline.
 */

// Includes for Arduino compatibility
#include "Arduino.h"

/* VUSB Core Definitions - usbdrv.h */
/* Minimal USB driver header based on V-USB */

#define USB_PUBLIC static
#define usbMsgPtr_t unsigned char*

// Device request codes
#define USBRQ_TYPE_MASK     0x60
#define USBRQ_TYPE_STANDARD (0x00 << 5)
#define USBRQ_TYPE_CLASS    (0x01 << 5)
#define USBRQ_TYPE_VENDOR   (0x02 << 5)
#define USBRQ_TYPE_RESERVED (0x03 << 5)

#define USBRQ_DIR_MASK      0x80
#define USBRQ_DIR_HOST_TO_DEVICE 0x00
#define USBRQ_DIR_DEVICE_TO_HOST 0x80

// Declare USB functions (simulate usbdrv.h and usbdrv.c behavior)
void usbInit() {
    // Initialize USB hardware (stub for simplicity)
}

void usbPoll() {
    // Poll USB events (stub for simplicity)
}

// USB functions used in the CDC implementation
#define usbFunctionSetup(data)  0  // Stub
#define usbFunctionRead()       0  // Stub
#define usbFunctionWrite()      0  // Stub

/* CDC Implementation - VUSB_CDC.h */
#define HW_CDC_BUF_SIZE 24
#define HW_CDC_BULK_OUT_SIZE 8
#define HW_CDC_BULK_IN_SIZE 8

// Ring buffer implementation
class RingBuffer_t {
    uint8_t buffer[HW_CDC_BUF_SIZE];
    uint8_t head;
    uint8_t tail;
public:
    RingBuffer_t() : head(0), tail(0) {}
    void put(uint8_t data) {
        uint8_t next = (head + 1) % HW_CDC_BUF_SIZE;
        if (next != tail) {  // Prevent overwriting
            buffer[head] = data;
            head = next;
        }
    }
    int16_t get() {
        if (head == tail) return -1;  // Empty
        uint8_t value = buffer[tail];
        tail = (tail + 1) % HW_CDC_BUF_SIZE;
        return value;
    }
    bool isEmpty() {
        return head == tail;
    }
};

static RingBuffer_t rxBuf;
static RingBuffer_t txBuf;

// VUSB CDC class
class VUSB_CDCDevice : public Stream {
public:
    void begin() {
        usbInit();
        usbPoll();
    }
    void end() {}
    void refresh() {
        usbPoll();
    }
    virtual int available() {
        return !rxBuf.isEmpty();
    }
    virtual int peek() {
        // No direct support; user should implement this if needed
        return -1;
    }
    virtual int read() {
        return rxBuf.get();
    }
    virtual void flush() {}
    virtual size_t write(uint8_t c) {
        txBuf.put(c);
        return 1;
    }
    size_t write1(uint8_t c) {
        return write(c);
    }
    uint8_t WaitTxEmpty() {
        // Simulate waiting for TX buffer
        while (!txBuf.isEmpty()) {}
        return 0;
    }
    using Print::write;
};

VUSB_CDCDevice Serial_VUSB;

/* Main Arduino Sketch */

void setup() {
    Serial_VUSB.begin();
}

void loop() {
    Serial_VUSB.refresh();
    if (Serial_VUSB.available()) {
        int c = Serial_VUSB.read();
        Serial_VUSB.write(c);  // Echo back received data
    }
}