/* package input is a thing Go wrapper around the Linux kernel input event 
 * system. */
package input

import "gitlab.com/beoran/galago/os/linux"
import "os"
import "unsafe"
import "syscall"
import "fmt"
import "path/filepath"


// Device models an input device
type Device struct { 
    *os.File
}

const Directory = "/dev/input"

func Open(name string) (*Device, error) {
    f, err := os.OpenFile(filepath.Join(Directory, name), os.O_RDWR, 0666)
    if err != nil {
        return nil, err
    }
    return &Device{File: f}, nil
} 

func List() ([]string, error) {
    dir, err := os.Open(Directory)
    if err != nil {
        return nil, err
    }
    return dir.Readdirnames(-1)
}


// Icotl performs an ioctl on the given de
func (d * Device) Ioctl(code uint32, pointer unsafe.Pointer) error {
    fmt.Printf("ioctl: %d %d %d\n", uintptr(d.Fd()), uintptr(code), uintptr(pointer))
    _, _, errno := syscall.Syscall(
        syscall.SYS_IOCTL,
        uintptr(d.Fd()),
        uintptr(code),
        uintptr(pointer))
    if (errno != 0) {
        return errno
    }
    return nil
}


func (d * Device) DriverVersion() (int32, error) {
    res := int32(0) 
    data := unsafe.Pointer(&res)
    err := d.Ioctl(linux.EVIOCGVERSION, data)
    return res, err
}

func (d * Device) Name() (string, error) {
    buffer := [256]byte{}
    err := d.Ioctl(linux.EVIOCGNAME(uintptr(len(buffer))), unsafe.Pointer(&buffer))
    return string(buffer[0:len(buffer)]), err
}


func (d * Device) Id() (linux.INPUT_id, error) {
    var result linux.INPUT_id 
    err := d.Ioctl(linux.EVIOCGID, unsafe.Pointer(&result))
    return result, err
}

// The Linux developers thought it was a great idea a to use an array of 
// unsigned longs for the bit flags of input devices. Of course, the length 
// of an unsigned long is platform dependent which then entails all sorts of
// gymnastics to extract the bits from the array...

const SIZEOF_LONG = uint(unsafe.Sizeof(*((*linux.UnsignedLong)(nil))))      
const BITS_PER_LONG = SIZEOF_LONG * 8

func BitsToLong(bits uint) uint {
    return ((bits) + (8 * SIZEOF_LONG) - 1) / (8 * SIZEOF_LONG)
}

func TestBit(bit uint, array []linux.UnsignedLong) bool {
    elem := array[ bit / ( 8 * SIZEOF_LONG)]
    flag := linux.UnsignedLong(1) << linux.UnsignedLong(bit % (8 * SIZEOF_LONG))
    return (elem & flag ) != 0
}

func (d * Device) Topology() (string, error) {
    buffer := [256]byte{}
    err := d.Ioctl(linux.EVIOCGPHYS(uintptr(len(buffer))), unsafe.Pointer(&buffer))
    return string(buffer[0:len(buffer)]), err
}

func (d * Device) SupportedEvents() ([]uint, error) {
	size := BitsToLong(linux.EV_MAX)
    bits := make([]linux.UnsignedLong, size)
    for i := uint(0); i < size; i ++ {
        bits[i] = 0
    }
	err := d.Ioctl(linux.EVIOCGBIT(0, uintptr(size)), unsafe.Pointer(&bits));
    if err != nil {
        return nil, err
    }
    fmt.Printf("size %d, bits: %v\n", size, bits)
    result := []uint{}
    for i := uint(0); i < uint(linux.EV_MAX); i++ {
        if (TestBit(i, bits)) {
            result = append(result, uint(i))
		}
    }
    
    return result, nil
} 

/*    
	printf("Supported events:\n");
	for (i = 0; i < EV_MAX; i++)
		if (TestBit(i, bit[0])) {
            
		}
		

	printf("Testing ... (interrupt to exit)\n");

	while (1) {
		rd = read(fd, ev, sizeof(struct input_event) * 64);

		if (rd < (int) sizeof(struct input_event)) {
			printf("yyy\n");
			perror("\nevtest: error reading");
			return 1;
		}

		for (i = 0; i < rd / sizeof(struct input_event); i++)

			if (ev[i].type == EV_SYN) {
				printf("Event: time %ld.%06ld, -------------- %s ------------\n",
					ev[i].time.tv_sec, ev[i].time.tv_usec, ev[i].code ? "Config Sync" : "Report Sync" );
			} else if (ev[i].type == EV_MSC && (ev[i].code == MSC_RAW || ev[i].code == MSC_SCAN)) {
				printf("Event: time %ld.%06ld, type %d (%s), code %d (%s), value %02x\n",
					ev[i].time.tv_sec, ev[i].time.tv_usec, ev[i].type,
					events[ev[i].type] ? events[ev[i].type] : "?",
					ev[i].code,
					names[ev[i].type] ? (names[ev[i].type][ev[i].code] ? names[ev[i].type][ev[i].code] : "?") : "?",
					ev[i].value);
			} else {
				printf("Event: time %ld.%06ld, type %d (%s), code %d (%s), value %d\n",
					ev[i].time.tv_sec, ev[i].time.tv_usec, ev[i].type,
					events[ev[i].type] ? events[ev[i].type] : "?",
					ev[i].code,
					names[ev[i].type] ? (names[ev[i].type][ev[i].code] ? names[ev[i].type][ev[i].code] : "?") : "?",
					ev[i].value);
			}	

	}
}
*/