typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint16_t bcdCDC;
} usb_vcp_header_descriptor_t;

typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bmCapabilities;
    uint8_t bDataInterface;
} usb_vcp_cm_descriptor_t;

typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bmCapabilities;
} usb_vcp_acm_descriptor_t;

typedef struct __attribute__((packed)) {
    uint8_t bFunctionLength;
    uint8_t bDescriptorType;
    uint8_t bDescriptorSubtype;
    uint8_t bControlInterface;
    uint8_t bSubordinateInterface0;
} usb_vcp_union_descriptor_t;

typedef struct __attribute__((packed)) {
    usb_interface_assoc_descriptor_t assoc;
    usb_interface_descriptor_t iface_cdc;
    usb_vcp_header_descriptor_t fheader; // Class-Specific Descriptor Header Format
    usb_vcp_cm_descriptor_t fcm;         // Call Management Functional Descriptor
    usb_vcp_acm_descriptor_t facm;       // Abstract Control Management Functional Descriptor
    usb_vcp_union_descriptor_t funion;   // Union Interface Functional Descriptor
    usb_endpoint_descriptor_t ep_cmd;
    usb_interface_descriptor_t iface_data;
    usb_endpoint_descriptor_t ep_in;
    usb_endpoint_descriptor_t ep_out;
} usb_vcp_descriptor_block_t;

typedef struct {
    uint8_t iface_num;           // Address of this VCP interface
    uint8_t data_iface_num;      // Address of data interface of the VCP interface association
    uint8_t ep_cmd;              // Address of IN CMD endpoint (with the highest bit set)
    uint8_t ep_in;               // Address of IN endpoint (with the highest bit set)
    uint8_t ep_out;              // Address of OUT endpoint
    uint8_t polling_interval;    // In units of 1ms
    uint8_t max_cmd_packet_len;
    uint8_t max_data_packet_len;
} usb_vcp_info_t;

// typedef struct {
//     uint32_t cap;
//     uint32_t read;
//     uint32_t write;
//     uint8_t *buf;
// } ring_buffer_t;

typedef struct {
    uint8_t is_connected;
    uint8_t in_idle;
    // uint8_t cmd_op_code;
    // uint8_t cmd_length;

    // Configuration (copied from usb_vcp_info_t on init)
    uint8_t data_iface_num;
    uint8_t ep_cmd;
    uint8_t ep_in;
    uint8_t ep_out;
    uint8_t polling_interval;
    uint8_t max_cmd_packet_len;
    uint8_t max_data_packet_len;

    const usb_vcp_descriptor_block_t *desc_block;
} usb_vcp_state_t;

int usb_vcp_add(const usb_vcp_info_t *vcp_info);
int usb_vcp_can_read(uint8_t iface_num);
int usb_vcp_can_write(uint8_t iface_num);
int usb_vcp_read(uint8_t iface_num, uint8_t *buf, uint32_t len);
int usb_vcp_write(uint8_t iface_num, const uint8_t *buf, uint32_t len);

int usb_vcp_read_blocking(uint8_t iface_num, uint8_t *buf, uint32_t len, uint32_t timeout);
int usb_vcp_write_blocking(uint8_t iface_num, const uint8_t *buf, uint32_t len, uint32_t timeout);