/**
 * Defines a simple interface to perform IO with USB devices using libusb.
 *
 * @file USBCom.c
 * @author
 * @author
 */

#include <stdio.h>
#include <libusb-1.0/libusb.h>
#include "USBCom.h"

/**
 * NOTE: Used internally. Not likely used by client programmer.
 *
 * Searches for a USB device with a matching vendorID.  If found, the corresponding
 * libusb device is returned.  If not, null is returned.
 *
 * @param vendorID The vendor ID of the device
 * @return The device handle of a device if a device matching the provided vendor ID is found.  Null otherwise.
 */
libusb_device_handle * USBCom_findDevice(int vendorID)
{

    libusb_device ** list;
    libusb_device * found = NULL;
    libusb_device * device;
    libusb_device_handle * handle;
    struct libusb_device_descriptor descriptor;

    ssize_t count = libusb_get_device_list(NULL, &list);
    ssize_t i = 0;
    int err = 0;

    if(count < 0)
        return -1;

    for(i = 0; i < count; i++) {
        device = list[i];

        libusb_get_device_descriptor(device, &descriptor);
        if(descriptor.idVendor == vendorID) {
            printf("Found!\n");
            found = device;

            break;
        }

    }

    if(found) {
        err = libusb_open(found, &handle);

        if(err)
            return -1;
    }

    libusb_free_device_list(list, 1);

    return handle;
}

/**
 * Initializes libusb and claims the device from the Operating system.  This function
 * MUST be called before any subsequent actions are performed on the USB device.
 *
 * @todo Implement contexts (allows IO with multiple USB devices)
 * @param dev USBDevice struct that describes the connected device.  Used throughout library.
 * @return 0 on Success
 */
int USBCom_setup(USBCom_USBDevice * dev)
{
    int error;

    libusb_init(NULL);

    dev->device = USBCom_findDevice(dev->vendorID);

    if(libusb_kernel_driver_active(dev->device, 0) == 1)
        error = libusb_detach_kernel_driver(dev->device, 0);

    //printf("Error code: %d\n", error);
    libusb_claim_interface(dev->device, 0);
    //printf("Error code: %d\n", error);

    return error;

}

/**
 * Clean up and exit libusb.  Call this function after all IO tasks have finished.
 *
 * @todo Implement contexts
 * @param dev The device descriptor
 * @ return 0 on Success
 */
int USBCom_cleanup(USBCom_USBDevice * dev)
{
    int error;

    error = libusb_attach_kernel_driver(dev->device, 0);
    libusb_exit(NULL);

    return error;
}

/**
 * Perform a bulk transfer on a USB device.  On success, the buffer is filled
 * and the number of bytes transferred is returned.  A call to USBCom_setup must precede
 * this function.
 *
 * @param buffer The buffer to which data is transfered.
 * @param bufferLength The length of the data buffer (number supplied to malloc())
 * @param dev The usb device descriptor
 * @retuen The number of bytes transfered.
 */
int USBCom_bulkGet(char * buffer, int bufferLength, USBCom_USBDevice * dev)
{
    int numBytes, error = 0;

    error = libusb_bulk_transfer(dev->device, (dev->inEndpoint | LIBUSB_ENDPOINT_IN), buffer, bufferLength, &numBytes, 0);

    return numBytes;
}


int USBCom_bulkSend(char * buffer, int bufferLength, USBCom_USBDevice * dev)
{
    int numBytes, error = 0;

    error = libusb_bulk_transfer(dev->device, (dev->outEndpoint | LIBUSB_ENDPOINT_OUT), buffer, bufferLength, &numBytes, 0);

    return numBytes;
}