/*
 * accelerometer - exports device orientation through property
 *
 * When an "change" event is received on an accelerometer,
 * open its device node, and from the value, as well as the previous
 * value of the property, calculate the device's new orientation,
 * and export it as ID_INPUT_ACCELEROMETER_ORIENTATION.
 *
 * Possible values are:
 * undefined
 * * normal
 * * bottom-up
 * * left-up
 * * right-up
 *
 * The property will be persistent across sessions, and the new
 * orientations can be deducted from the previous one (it allows
 * for a threshold for switching between opposite ends of the
 * orientation).
 *
 * Copyright (C) 2011 Red Hat, Inc.
 * Author:
 *   Bastien Nocera <hadess@hadess.net>
 *
 * orientation_calc() from the sensorfw package
 * Copyright (C) 2009-2010 Nokia Corporation
 * Authors:
 *   Üstün Ergenoglu <ext-ustun.ergenoglu@nokia.com>
 *   Timo Rongas <ext-timo.2.rongas@nokia.com>
 *   Lihan Guo <lihan.guo@digia.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <limits.h>
#include <linux/limits.h>
#include <linux/input.h>

#include "libudev.h"
#include "libudev-private.h"

/* we must use this kernel-compatible implementation */
#define BITS_PER_LONG (sizeof(unsigned long) * 8)
#define NBITS(x) ((((x)-1)/BITS_PER_LONG)+1)
#define OFF(x)  ((x)%BITS_PER_LONG)
#define BIT(x)  (1UL<<OFF(x))
#define LONG(x) ((x)/BITS_PER_LONG)
#define test_bit(bit, array)    ((array[LONG(bit)] >> OFF(bit)) & 1)

static int debug = 0;

static void log_fn(struct udev *udev, int priority,
                   const char *file, int line, const char *fn,
                   const char *format, va_list args)
{
        if (debug) {
                fprintf(stderr, "%s: ", fn);
                vfprintf(stderr, format, args);
        } else {
                vsyslog(priority, format, args);
        }
}

typedef enum {
        ORIENTATION_UNDEFINED,
        ORIENTATION_NORMAL,
        ORIENTATION_BOTTOM_UP,
        ORIENTATION_LEFT_UP,
        ORIENTATION_RIGHT_UP
} OrientationUp;

static const char *orientations[] = {
        "undefined",
        "normal",
        "bottom-up",
        "left-up",
        "right-up",
        NULL
};

#define ORIENTATION_UP_UP ORIENTATION_NORMAL

#define DEFAULT_THRESHOLD 250
#define RADIANS_TO_DEGREES 180.0/M_PI
#define SAME_AXIS_LIMIT 5

#define THRESHOLD_LANDSCAPE  25
#define THRESHOLD_PORTRAIT  20

static const char *
orientation_to_string (OrientationUp o)
{
        return orientations[o];
}

static OrientationUp
string_to_orientation (const char *orientation)
{
        int i;

        if (orientation == NULL)
                return ORIENTATION_UNDEFINED;
        for (i = 0; orientations[i] != NULL; i++) {
                if (strcmp (orientation, orientations[i]) == 0)
                        return i;
        }
        return ORIENTATION_UNDEFINED;
}

static OrientationUp
orientation_calc (OrientationUp prev,
                  int x, int y, int z)
{
        int rotation;
        OrientationUp ret = prev;

        /* Portrait check */
        rotation = round(atan((double) x / sqrt(y * y + z * z)) * RADIANS_TO_DEGREES);

        if (abs(rotation) > THRESHOLD_PORTRAIT) {
                ret = (rotation < 0) ? ORIENTATION_LEFT_UP : ORIENTATION_RIGHT_UP;

                /* Some threshold to switching between portrait modes */
                if (prev == ORIENTATION_LEFT_UP || prev == ORIENTATION_RIGHT_UP) {
                        if (abs(rotation) < SAME_AXIS_LIMIT) {
                                ret = prev;
                        }
                }

        } else {
                /* Landscape check */
                rotation = round(atan((double) y / sqrt(x * x + z * z)) * RADIANS_TO_DEGREES);

                if (abs(rotation) > THRESHOLD_LANDSCAPE) {
                        ret = (rotation < 0) ? ORIENTATION_BOTTOM_UP : ORIENTATION_NORMAL;

                        /* Some threshold to switching between landscape modes */
                        if (prev == ORIENTATION_BOTTOM_UP || prev == ORIENTATION_NORMAL) {
                                if (abs(rotation) < SAME_AXIS_LIMIT) {
                                        ret = prev;
                                }
                        }
                }
        }

        return ret;
}

static OrientationUp
get_prev_orientation(struct udev_device *dev)
{
        const char *value;

        value = udev_device_get_property_value(dev, "ID_INPUT_ACCELEROMETER_ORIENTATION");
        if (value == NULL)
                return ORIENTATION_UNDEFINED;
        return string_to_orientation(value);
}

#define SET_AXIS(axis, code_) if (ev[i].code == code_) { if (got_##axis == 0) { axis = ev[i].value; got_##axis = true; } }

/* accelerometers */
static void test_orientation(struct udev *udev,
                             struct udev_device *dev,
                             const char *devpath)
{
        OrientationUp old, new;
        int _cleanup_close_ fd = -1;
        struct input_event ev[64];
        bool got_syn = false;
        bool got_x = false, got_y = false, got_z = false;
        int x = 0, y = 0, z = 0;
        char text[64];

        old = get_prev_orientation(dev);

        fd = open(devpath, O_RDONLY);
        if (fd < 0)
                return;

        while (1) {
                int i, r;

                r = read(fd, ev, sizeof(struct input_event) * 64);

                if (r < (int) sizeof(struct input_event))
                        return;

                for (i = 0; i < r / (int) sizeof(struct input_event); i++) {
                        if (got_syn) {
                                if (ev[i].type == EV_ABS) {
                                        SET_AXIS(x, ABS_X);
                                        SET_AXIS(y, ABS_Y);
                                        SET_AXIS(z, ABS_Z);
                                }
                        }
                        if (ev[i].type == EV_SYN && ev[i].code == SYN_REPORT)
                                got_syn = true;
                        if (got_x && got_y && got_z)
                                goto read_dev;
                }
        }

read_dev:
        new = orientation_calc(old, x, y, z);
        snprintf(text, sizeof(text),
                 "ID_INPUT_ACCELEROMETER_ORIENTATION=%s", orientation_to_string(new));
        puts(text);
}

static void help(void)
{
        printf("Usage: accelerometer [options] <device path>\n"
               "  --debug         debug to stderr\n"
               "  --help          print this help text\n\n");
}

int main (int argc, char** argv)
{
        struct udev *udev;
        struct udev_device *dev;

        static const struct option options[] = {
                { "debug", no_argument, NULL, 'd' },
                { "help", no_argument, NULL, 'h' },
                {}
        };

        char devpath[PATH_MAX];
        char *devnode;
        struct udev_enumerate *enumerate;
        struct udev_list_entry *list_entry;

        udev = udev_new();
        if (udev == NULL)
                return 1;

        log_open();
        udev_set_log_fn(udev, log_fn);

        /* CLI argument parsing */
        while (1) {
                int option;

                option = getopt_long(argc, argv, "dxh", options, NULL);
                if (option == -1)
                        break;

                switch (option) {
                case 'd':
                        debug = 1;
                        log_set_max_level(LOG_DEBUG);
                        udev_set_log_priority(udev, LOG_DEBUG);
                        break;
                case 'h':
                        help();
                        exit(0);
                default:
                        exit(1);
                }
        }

        if (argv[optind] == NULL) {
                help();
                exit(1);
        }

        /* get the device */
        snprintf(devpath, sizeof(devpath), "/sys/%s", argv[optind]);
        dev = udev_device_new_from_syspath(udev, devpath);
        if (dev == NULL) {
                fprintf(stderr, "unable to access '%s'\n", devpath);
                return 1;
        }

        /* Get the children devices and find the devnode */
        devnode = NULL;
        enumerate = udev_enumerate_new(udev);
        udev_enumerate_add_match_parent(enumerate, dev);
        udev_enumerate_scan_devices(enumerate);
        udev_list_entry_foreach(list_entry, udev_enumerate_get_list_entry(enumerate)) {
                struct udev_device *device;
                const char *node;

                device = udev_device_new_from_syspath(udev_enumerate_get_udev(enumerate),
                                                      udev_list_entry_get_name(list_entry));
                if (device == NULL)
                        continue;
                /* Already found it */
                if (devnode != NULL) {
                        udev_device_unref(device);
                        continue;
                }

                node = udev_device_get_devnode(device);
                if (node == NULL) {
                        udev_device_unref(device);
                        continue;
                }
                /* Use the event sub-device */
                if (strstr(node, "/event") == NULL) {
                        udev_device_unref(device);
                        continue;
                }

                devnode = strdup(node);
                udev_device_unref(device);
        }

        if (devnode == NULL) {
                fprintf(stderr, "unable to get device node for '%s'\n", devpath);
                return 0;
        }

        log_debug("opening accelerometer device %s\n", devnode);
        test_orientation(udev, dev, devnode);
        free(devnode);
        log_close();
        return 0;
}