#include <libusb-1.0/libusb.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <signal.h>
  #include <unistd.h>
  
  // arduino ID vendor and product
  #define ID_VENDOR 0x2341
  #define ID_PRODUCT 0x01
  #define ENDPOINTS_NUMBER 4
  #define TIMEOUT 50
  #define MAX_DATA 50
  
  void init(libusb_context **context, libusb_device ***devices, ssize_t *devices_count){
  	int status = libusb_init(context);
  	if(status != 0){perror("libusb_init"); exit(-1);}
  
  	*devices_count = libusb_get_device_list(*context, devices);
  	if(*devices_count < 0){perror("libusb_get_device_list"); exit(-1);}
  }
  
  libusb_device* searchArduino(libusb_device **devices, ssize_t devices_count){
  	for(int i=0; i<devices_count; i++){
  		libusb_device *device = devices[i];
  
  		// device description
  		struct libusb_device_descriptor desc;
  		int status = libusb_get_device_descriptor(device, &desc);
  		if(status != 0) continue;
  		
  		// search for device
  		if(desc.idVendor == ID_VENDOR
  				&& desc.idProduct == ID_PRODUCT)
  			return device;
  	}
  	return NULL;
  }
  
  void openConnection(libusb_device *arduino, libusb_device_handle **handle, struct libusb_config_descriptor **config_desc){
  	// open connection
  	int status = libusb_open(arduino, handle);
  	if(status != 0){ perror("libusb_open"); exit(-1); }
  	
  	// prepare config
  	status = libusb_get_config_descriptor(arduino, 0, config_desc);
  	if(status != 0){ perror("libusb_get_config_descriptor"); exit(-1); }
  	int configuration = (*config_desc)->bConfigurationValue;
  
  	// detach kernel
  	for(int j=0; j<(*config_desc)->bNumInterfaces; j++){
  		int interface = (*config_desc)->interface[j].altsetting[0].bInterfaceNumber;
  		if(libusb_kernel_driver_active(*handle, interface)){
  			status = libusb_detach_kernel_driver(*handle, interface);
  			if(status != 0){ perror("libusb_detach_kernel_driver"); exit(-1); }
  		}
  	}
  	
  	// use config
  	status = libusb_set_configuration(*handle, configuration);
  	if(status != 0){ perror("libusb_set_configuration"); exit(-1); }
  	
  	// claim interfaces
  	for(int j=0; j<(*config_desc)->bNumInterfaces; j++){
  		struct libusb_interface_descriptor interface_desc = (*config_desc)->interface[j].altsetting[0];
  		int interface = interface_desc.bInterfaceNumber;
  
  		status = libusb_claim_interface(*handle, interface);
  		if(status != 0){ perror("libusb_claim_interface"); exit(-1); }
  	}
  }
  
  void getEndpoints(struct libusb_config_descriptor *config_desc, struct libusb_endpoint_descriptor *endpoint_desc_list){
  	int count = 0;
  	// in interfaces
  	for(int j=0; j<config_desc->bNumInterfaces; j++){
  		// find endpoints
  		for(int k=0; k<config_desc->interface[j].altsetting[0].bNumEndpoints; k++){
  			if(count > ENDPOINTS_NUMBER){ printf("getEndpoints: Array out of bound :%d:", count); exit(-1); }
  			*(endpoint_desc_list + count) = config_desc->interface[j].altsetting[0].endpoint[k];
  			count++;
  		}
  	}
  	//if(count != ENDPOINTS_NUMBER){ printf("Wrong number of endpoints.\nIs this the good device ?\n"); exit(-1); }
  }
  
  void start(libusb_context **context, libusb_device ***devices, libusb_device_handle **handle, struct libusb_config_descriptor **config_desc, struct libusb_endpoint_descriptor *endpoint_desc_list){
  	// init
  	ssize_t devices_count;
  	init(context, devices, &devices_count);
  
  	// get arduino device
  	libusb_device *arduino = searchArduino(*devices, devices_count);
  	if(arduino == NULL){ printf("Arduino device not found\n"); exit(-1); }
  
  	// open connection, use config, detach kernel and claim interfaces
  	openConnection(arduino, handle, config_desc);
  
  	// get enpoints
  	getEndpoints(*config_desc, endpoint_desc_list);
  }
  
  void stop(struct libusb_config_descriptor *config_desc, libusb_device_handle *handle, libusb_device **devices, libusb_context *context){
  	// release interfaces
  	for(int j=0; j<config_desc->bNumInterfaces; j++){
  		struct libusb_interface_descriptor interface_desc = config_desc->interface[j].altsetting[0];
  		int interface = interface_desc.bInterfaceNumber;
  
  		int status = libusb_release_interface(handle, interface);
  		if(status != 0){ perror("libusb_release_interface"); exit(-1); }
  	}
  	
  	// free config
  	libusb_free_config_descriptor(config_desc);
  
  	// close connection
  	libusb_close(handle);
  
  	// free device list
  	libusb_free_device_list(devices, 1);
  
  	// libusb exit
  	libusb_exit(context);
  }
  
  void sendData(int endpoint_id, uint8_t data, libusb_device_handle *handle, struct libusb_endpoint_descriptor *endpoint_desc_list){
  	if(endpoint_id < 0 || endpoint_id > 1){ printf("(sendData) Wrong endpoint !\nMust be 0 or 1\n"); return; }
  	int status = libusb_interrupt_transfer(handle, endpoint_desc_list[endpoint_id].bEndpointAddress, (unsigned char *) &data, 1, NULL, TIMEOUT);
  	if(status!=0 && status!=LIBUSB_ERROR_TIMEOUT){ perror("libusb_interrupt_transfer"); exit(-1); }
  }
  
  int receiveData(int endpoint_id, uint8_t *data, libusb_device_handle *handle, struct libusb_endpoint_descriptor *endpoint_desc_list){
  	if(endpoint_id < 2 || endpoint_id > 3){ printf("(sendData) Wrong endpoint !\nMust be 2 or 3\n"); return -1; }
  	int status = libusb_interrupt_transfer(handle, endpoint_desc_list[endpoint_id].bEndpointAddress, (unsigned char *) data, 1, NULL, TIMEOUT);
  	if(status!=0 && status!=LIBUSB_ERROR_TIMEOUT){ perror("libusb_interrupt_transfer"); exit(-1); }
  	return status;
  }
  
  int go = 1;
  void signalINT(int sig){
  	if(sig == SIGINT){
  		go = 0;
  	}
  }
  int main(){
  	libusb_context *context;
  	libusb_device **devices;
  	libusb_device_handle *handle;
  	struct libusb_config_descriptor *config_desc;
  	struct libusb_endpoint_descriptor endpoint_desc_list[ENDPOINTS_NUMBER];
  
  	// start
  	printf("Starting...\n");
  	start(&context, &devices, &handle, &config_desc, endpoint_desc_list);
  	printf("Start complete\n");
  
  	// singals
  	struct sigaction action;
  	action.sa_handler = signalINT;
  	sigaction(SIGINT, &action, NULL);
  
  	uint8_t data;
  	while(go){
  		int status = receiveData(2, &data, handle, endpoint_desc_list);
  		if(status == 0)
  			sendData(0, data, handle, endpoint_desc_list);
  	}
  
  	// stop
  	printf("\nStopping...\n");
  	stop(config_desc, handle, devices, context);
  	printf("Stop complete...\n");
  }