#include <avr/io.h>
#include <avr/wdt.h>
#include <avr/power.h>
#include <avr/interrupt.h>
#include <string.h>

#include "Descriptors.h"

#include <LUFA/Drivers/USB/USB.h>
#include <LUFA/Platform/Platform.h>

void SetupHardware(void);
void CDC_Task(void);

void EVENT_USB_Device_Connect(void);
void EVENT_USB_Device_Disconnect(void);
void EVENT_USB_Device_ConfigurationChanged(void);
void EVENT_USB_Device_ControlRequest(void);


/** Contains the current baud rate and other settings of the virtual serial port. While this demo does not use
 *  the physical USART and thus does not use these settings, they must still be retained and returned to the host
 *  upon request or the host will assume the device is non-functional.
 *
 *  These values are set by the host via a class-specific request, however they are not required to be used accurately.
 *  It is possible to completely ignore these value or use other settings as the host is completely unaware of the physical
 *  serial link characteristics and instead sends and receives data in endpoint streams.
 */
static CDC_LineEncoding_t LineEncoding = { .BaudRateBPS = 0,
                                           .CharFormat  = CDC_LINEENCODING_OneStopBit,
                                           .ParityType  = CDC_PARITY_None,
                                           .DataBits    = 8                            };


/** Main program entry point. This routine contains the overall program flow, including initial
 *  setup of all components and the main program loop.
 */
int main(void)
{
    SetupHardware();

    GlobalInterruptEnable();

    for (;;)
    {
        CDC_Task();
        USB_USBTask();
    }
}

/** Configures the board hardware and chip peripherals for the demo's functionality. */
void SetupHardware(void)
{
    /* Disable watchdog if enabled by bootloader/fuses */
    MCUSR &= ~(1 << WDRF);
    wdt_disable();

    /* Disable clock division */
    clock_prescale_set(clock_div_1);

    USB_Init();
}

/** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs and
 *  starts the library USB task to begin the enumeration and USB management process.
 */
void EVENT_USB_Device_Connect(void)
{
}

/** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 *  the status LEDs and stops the USB management and CDC management tasks.
 */
void EVENT_USB_Device_Disconnect(void)
{
}

/** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 *  of the USB device after enumeration - the device endpoints are configured and the CDC management task started.
 */
void EVENT_USB_Device_ConfigurationChanged(void)
{
    /* Setup CDC Data Endpoints */
    Endpoint_ConfigureEndpoint(CDC_NOTIFICATION_EPADDR, EP_TYPE_INTERRUPT, CDC_NOTIFICATION_EPSIZE, 1);
    Endpoint_ConfigureEndpoint(CDC_TX_EPADDR, EP_TYPE_BULK, CDC_TXRX_EPSIZE, 1);
    Endpoint_ConfigureEndpoint(CDC_RX_EPADDR, EP_TYPE_BULK,  CDC_TXRX_EPSIZE, 1);

    /* Reset line encoding baud rate so that the host knows to send new values */
    LineEncoding.BaudRateBPS = 0;
}

/** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
 *  the device from the USB host before passing along unhandled control requests to the library for processing
 *  internally.
 */
void EVENT_USB_Device_ControlRequest(void)
{
    /* Process CDC specific control requests */
    switch (USB_ControlRequest.bRequest)
    {
        case CDC_REQ_GetLineEncoding:
            if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_INTERFACE))
            {
                Endpoint_ClearSETUP();

                /* Write the line coding data to the control endpoint */
                Endpoint_Write_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));
                Endpoint_ClearOUT();
            }
            break;

        case CDC_REQ_SetLineEncoding:
            if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
            {
                Endpoint_ClearSETUP();

                /* Read the line coding data in from the host into the global struct */
                Endpoint_Read_Control_Stream_LE(&LineEncoding, sizeof(CDC_LineEncoding_t));
                Endpoint_ClearIN();
            }
            break;

        case CDC_REQ_SetControlLineState:
            if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
            {
                Endpoint_ClearSETUP();
                Endpoint_ClearStatusStage();
            }
            break;
    }
}

/** Function to manage CDC data transmission and reception to and from the host. */
void CDC_Task(void)
{
    char*       ReportString    = NULL;
    static bool ActionSent      = false;

    /* Device must be connected and configured for the task to run */
    if (USB_DeviceState != DEVICE_STATE_Configured)
        return;

    ActionSent = false;

    /* Flag management - Only allow one string to be sent per action */
    if ((ReportString != NULL) && (ActionSent == false) && LineEncoding.BaudRateBPS)
    {
        ActionSent = true;

        /* Select the Serial Tx Endpoint */
        Endpoint_SelectEndpoint(CDC_TX_EPADDR);

        /* Write the String to the Endpoint */
        Endpoint_Write_Stream_LE(ReportString, strlen(ReportString), NULL);

        /* Remember if the packet to send completely fills the endpoint */
        bool IsFull = (Endpoint_BytesInEndpoint() == CDC_TXRX_EPSIZE);

        /* Finalize the stream transfer to send the last packet */
        Endpoint_ClearIN();

        /* If the last packet filled the endpoint, send an empty packet to release the buffer on
            * the receiver (otherwise all data will be cached until a non-full packet is received) */
        if (IsFull)
        {
            /* Wait until the endpoint is ready for another packet */
            Endpoint_WaitUntilReady();

            /* Send an empty packet to ensure that the host does not buffer data sent to it */
            Endpoint_ClearIN();
        }
    }

    /* Select the Serial Rx Endpoint */
    Endpoint_SelectEndpoint(CDC_RX_EPADDR);

    /* Throw away any received data from the host */
    if (Endpoint_IsOUTReceived())
        Endpoint_ClearOUT();
}