/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Contains emulated camera service implementation.
 */

#include "qemu-common.h"
#include "android/globals.h"  /* for android_hw */
#include "android/hw-qemud.h"
#include "android/utils/misc.h"
#include "android/utils/system.h"
#include "android/utils/debug.h"
#include "android/camera/camera-capture.h"
#include "android/camera/camera-format-converters.h"
#include "android/camera/camera-service.h"

#define  E(...)    derror(__VA_ARGS__)
#define  W(...)    dwarning(__VA_ARGS__)
#define  D(...)    VERBOSE_PRINT(camera,__VA_ARGS__)
#define  D_ACTIVE  VERBOSE_CHECK(camera)

/* the T(...) macro is used to dump traffic */
#define  T_ACTIVE   0

#if T_ACTIVE
#define  T(...)    VERBOSE_PRINT(camera,__VA_ARGS__)
#else
#define  T(...)    ((void)0)
#endif

/* Defines name of the camera service. */
#define SERVICE_NAME    "camera"

/* Maximum number of supported emulated cameras. */
#define MAX_CAMERA      8

/* Camera sevice descriptor. */
typedef struct CameraServiceDesc CameraServiceDesc;
struct CameraServiceDesc {
    /* Information about camera devices connected to the host.
     * Note that once initialized, entries in this array are considered to be
     * constant. */
    CameraInfo  camera_info[MAX_CAMERA];
    /* Number of camera devices connected to the host. */
    int         camera_count;
};

/* One and only one camera service. */
static CameraServiceDesc    _camera_service_desc;

/********************************************************************************
 * Helper routines
 *******************************************************************************/

/* A strict 'int' version of the 'strtol'.
 * This routine is implemented on top of the standard 'strtol' for 32/64 bit
 * portability.
 */
static int
strtoi(const char *nptr, char **endptr, int base)
{
    long val;

    errno = 0;
    val = strtol(nptr, endptr, base);
    if (errno) {
        return (val == LONG_MAX) ? INT_MAX : INT_MIN;
    } else {
        if (val == (int)val) {
            return (int)val;
        } else {
            errno = ERANGE;
            return val > 0 ? INT_MAX : INT_MIN;
        }
    }
}

/* Gets a parameter value out of the parameter string.
 * All parameters that are passed to the camera service are formatted as such:
 *      "<name1>=<value1> <name2>=<value2> ... <nameN>=<valueN>"
 * I.e.:
 *  - Every parameter must have a name, and a value.
 *  - Name and value must be separated with '='.
 *  - No spaces are allowed around '=' separating name and value.
 *  - Parameters must be separated with a single ' ' character.
 *  - No '=' character is allowed in name and in value.
 * Param:
 *  params - String, containing the parameters.
 *  name - Parameter name.
 *  value - Upon success contains value for the given parameter.
 *  val_size - Size of the 'value' string buffer.
 * Return:
 *  0 on success, -1 if requested parameter is not found, or (a positive) number
 *  of bytes, required to make a copy of the parameter's value if 'value' string
 *  was too small to contain it.
 */
static int
_get_param_value(const char* params, const char* name, char* value, int val_size)
{
    const char* val_end;
    int len = strlen(name);
    const char* par_end = params + strlen(params);
    const char* par_start = strstr(params, name);

    /* Search for 'name=' */
    while (par_start != NULL) {
        /* Make sure that we're within the parameters buffer. */
        if ((par_end - par_start) < len) {
            par_start = NULL;
            break;
        }
        /* Make sure that par_start starts at the beginning of <name>, and only
         * then check for '=' value separator. */
        if ((par_start == params || (*(par_start - 1) == ' ')) &&
                par_start[len] == '=') {
            break;
        }
        /* False positive. Move on... */
        par_start = strstr(par_start + 1, name);
    }
    if (par_start == NULL) {
        return -1;
    }

    /* Advance past 'name=', and calculate value's string length. */
    par_start += len + 1;
    val_end = strchr(par_start, ' ');
    if (val_end == NULL) {
        val_end = par_start + strlen(par_start);
    }
    len = val_end - par_start;

    /* Check if fits... */
    if ((len + 1) <= val_size) {
        memcpy(value, par_start, len);
        value[len] = '\0';
        return 0;
    } else {
        return len + 1;
    }
}

/* Gets a parameter value out of the parameter string.
 * This routine is similar to _get_param_value, except it will always allocate
 * a string buffer for the value.
 * Param:
 *  params - String, containing the parameters.
 *  name - Parameter name.
 *  value - Upon success contains an allocated string containint the value for
 *      the given parameter. The caller is responsible for freeing the buffer
 *      returned in this parameter on success.
 * Return:
 *  0 on success, -1 if requested parameter is not found, or -2 on
 *  memory failure.
 */
static int
_get_param_value_alloc(const char* params, const char* name, char** value)
{
    char tmp;
    int res;

    /* Calculate size of string buffer required for the value. */
    const int val_size = _get_param_value(params, name, &tmp, 0);
    if (val_size < 0) {
        *value = NULL;
        return val_size;
    }

    /* Allocate string buffer, and retrieve the value. */
    *value = (char*)malloc(val_size);
    if (*value == NULL) {
        E("%s: Unable to allocated %d bytes for string buffer.",
          __FUNCTION__, val_size);
        return -2;
    }
    res = _get_param_value(params, name, *value, val_size);
    if (res) {
        E("%s: Unable to retrieve value into allocated buffer.", __FUNCTION__);
        free(*value);
        *value = NULL;
    }

    return res;
}

/* Gets an integer parameter value out of the parameter string.
 * Param:
 *  params - String, containing the parameters. See comments to _get_param_value
 *      routine on the parameters format.
 *  name - Parameter name. Parameter value must be a decimal number.
 *  value - Upon success contains integer value for the given parameter.
 * Return:
 *  0 on success, or -1 if requested parameter is not found, or -2 if parameter's
 *  format was bad (i.e. value was not a decimal number).
 */
static int
_get_param_value_int(const char* params, const char* name, int* value)
{
    char val_str[64];   // Should be enough for all numeric values.
    if (!_get_param_value(params, name, val_str, sizeof(val_str))) {
        errno = 0;
        *value = strtoi(val_str, (char**)NULL, 10);
        if (errno) {
            E("%s: Value '%s' of the parameter '%s' in '%s' is not a decimal number.",
              __FUNCTION__, val_str, name, params);
            return -2;
        } else {
            return 0;
        }
    } else {
        return -1;
    }
}

/* Extracts query name, and (optionally) query parameters from the query string.
 * Param:
 *  query - Query string. Query string in the camera service are formatted as such:
 *          "<query name>[ <parameters>]",
 *      where parameters are optional, and if present, must be separated from the
 *      query name with a single ' '. See comments to _get_param_value routine
 *      for the format of the parameters string.
 *  query_name - Upon success contains query name extracted from the query
 *      string.
 *  query_name_size - Buffer size for 'query_name' string.
 *  query_param - Upon success contains a pointer to the beginning of the query
 *      parameters. If query has no parameters, NULL will be passed back with
 *      this parameter. This parameter is optional and can be NULL.
 * Return:
 *  0 on success, or number of bytes required for query name if 'query_name'
 *  string buffer was too small to contain it.
 */
static int
_parse_query(const char* query,
             char* query_name,
             int query_name_size,
             const char** query_param)
{
    /* Extract query name. */
    const char* qend = strchr(query, ' ');
    if (qend == NULL) {
        qend = query + strlen(query);
    }
    if ((qend - query) >= query_name_size) {
        return qend - query + 1;
    }
    memcpy(query_name, query, qend - query);
    query_name[qend - query] = '\0';

    /* Calculate query parameters pointer (if needed) */
    if (query_param != NULL) {
        if (*qend == ' ') {
            qend++;
        }
        *query_param = (*qend == '\0') ? NULL : qend;
    }

    return 0;
}

/* Appends one string to another, growing the destination string buffer if
 * needed.
 * Param:
 *  str_buffer - Contains pointer to the destination string buffer. Content of
 *      this parameter can be NULL. Note that content of this parameter will
 *      change if string buffer has been reallocated.
 *  str_buf_size - Contains current buffer size of the string, addressed by
 *      'str_buffer' parameter. Note that content of this parameter will change
 *      if string buffer has been reallocated.
 *  str - String to append.
 * Return:
 *  0 on success, or -1 on failure (memory allocation).
 */
static int
_append_string(char** str_buf, size_t* str_buf_size, const char* str)
{
    const size_t offset = (*str_buf != NULL) ? strlen(*str_buf) : 0;
    const size_t append_bytes = strlen(str) + 1;

    /* Make sure these two match. */
    if (*str_buf == NULL) {
        *str_buf_size = 0;
    }

    if ((offset + append_bytes) > *str_buf_size) {
        /* Reallocate string, so it can fit what's being append to it. Note that
         * we reallocate a bit bigger buffer than is needed in order to minimize
         * number of memory allocation calls in case there are more "appends"
         * coming. */
        const size_t required_mem = offset + append_bytes + 256;
        char* new_buf = (char*)realloc(*str_buf, required_mem);
        if (new_buf == NULL) {
            E("%s: Unable to allocate %d bytes for a string",
              __FUNCTION__, required_mem);
            return -1;
        }
        *str_buf = new_buf;
        *str_buf_size = required_mem;
    }
    memcpy(*str_buf + offset, str, append_bytes);

    return 0;
}

/* Represents camera information as a string formatted as follows:
 *  'name=<devname> channel=<num> pix=<format> facing=<direction> framedims=<widh1xheight1,...>\n'
 * Param:
 *  ci - Camera information descriptor to convert into a string.
 *  str - Pointer to the string buffer where to save the converted camera
 *      information descriptor. On entry, content of this parameter can be NULL.
 *      Note that string buffer addressed with this parameter may be reallocated
 *      in this routine, so (if not NULL) it must contain a buffer allocated with
 *      malloc.  The caller is responsible for freeing string buffer returned in
 *      this parameter.
 *  str_size - Contains byte size of the buffer addressed by 'str' parameter.
 * Return:
 *  0 on success, or != 0 on failure.
 */
static int
_camera_info_to_string(const CameraInfo* ci, char** str, size_t* str_size) {
    int res;
    int n;
    char tmp[128];

    /* Append device name. */
    snprintf(tmp, sizeof(tmp), "name=%s ", ci->device_name);
    res = _append_string(str, str_size, tmp);
    if (res) {
        return res;
    }
    /* Append input channel. */
    snprintf(tmp, sizeof(tmp), "channel=%d ", ci->inp_channel);
    res = _append_string(str, str_size, tmp);
    if (res) {
        return res;
    }
    /* Append pixel format. */
    snprintf(tmp, sizeof(tmp), "pix=%d ", ci->pixel_format);
    res = _append_string(str, str_size, tmp);
    if (res) {
        return res;
    }
    /* Append direction. */
    snprintf(tmp, sizeof(tmp), "dir=%s ", ci->direction);
    res = _append_string(str, str_size, tmp);
    if (res) {
        return res;
    }
    /* Append supported frame sizes. */
    snprintf(tmp, sizeof(tmp), "framedims=%dx%d",
             ci->frame_sizes[0].width, ci->frame_sizes[0].height);
    res = _append_string(str, str_size, tmp);
    if (res) {
        return res;
    }
    for (n = 1; n < ci->frame_sizes_num; n++) {
        snprintf(tmp, sizeof(tmp), ",%dx%d",
                 ci->frame_sizes[n].width, ci->frame_sizes[n].height);
        res = _append_string(str, str_size, tmp);
        if (res) {
            return res;
        }
    }

    /* Stringified camera properties should end with EOL. */
    return _append_string(str, str_size, "\n");
}

/* Gets camera information matching a display name.
 * Param:
 *  disp_name - Display name to match.
 *  arr - Array of camera informations.
 *  num - Number of elements in the array.
 * Return:
 *  Matching camera information, or NULL if matching camera information for the
 *  given display name has not been found in the array.
 */
static CameraInfo*
_camera_info_get_by_display_name(const char* disp_name, CameraInfo* arr, int num)
{
    int n;
    for (n = 0; n < num; n++) {
        if (arr[n].display_name != NULL && !strcmp(arr[n].display_name, disp_name)) {
            return &arr[n];
        }
    }
    return NULL;
}

/* Gets camera information matching a device name.
 * Param:
 *  device_name - Device name to match.
 *  arr - Array of camera informations.
 *  num - Number of elements in the array.
 * Return:
 *  Matching camera information, or NULL if matching camera information for the
 *  given device name has not been found in the array.
 */
static CameraInfo*
_camera_info_get_by_device_name(const char* device_name, CameraInfo* arr, int num)
{
    int n;
    for (n = 0; n < num; n++) {
        if (arr[n].device_name != NULL && !strcmp(arr[n].device_name, device_name)) {
            return &arr[n];
        }
    }
    return NULL;
}

/********************************************************************************
 * CameraServiceDesc API
 *******************************************************************************/

/* Initializes camera service descriptor.
 */
static void
_camera_service_init(CameraServiceDesc* csd)
{
    CameraInfo ci[MAX_CAMERA];
    int connected_cnt;
    int i;

    /* Enumerate camera devices connected to the host. */
    memset(ci, 0, sizeof(CameraInfo) * MAX_CAMERA);
    memset(csd->camera_info, 0, sizeof(CameraInfo) * MAX_CAMERA);
    csd->camera_count = 0;
    connected_cnt = enumerate_camera_devices(ci, MAX_CAMERA);
    if (connected_cnt <= 0) {
        /* Nothing is connected - nothing to emulate. */
        return;
    }

    /* For each webcam declared in hw.ini find an actual camera information
     * descriptor, and save it into the service descriptor for the emulation.
     * Stop the loop when all the connected cameras have been added to the
     * service. */
    for (i = 0; i < android_hw->hw_webcam_count &&
                csd->camera_count < connected_cnt; i++) {
        const char* disp_name;
        const char* dir;
        CameraInfo* found;

        switch (i) {
            case 0:
                disp_name = android_hw->hw_webcam_0_name;
                dir = android_hw->hw_webcam_0_direction;
                break;
            case 1:
                disp_name = android_hw->hw_webcam_1_name;
                dir = android_hw->hw_webcam_1_direction;
                break;
            case 2:
                disp_name = android_hw->hw_webcam_2_name;
                dir = android_hw->hw_webcam_2_direction;
                break;
            case 3:
                disp_name = android_hw->hw_webcam_3_name;
                dir = android_hw->hw_webcam_3_direction;
                break;
            case 4:
                disp_name = android_hw->hw_webcam_4_name;
                dir = android_hw->hw_webcam_4_direction;
                break;
            case 5:
            default:
                disp_name = android_hw->hw_webcam_5_name;
                dir = android_hw->hw_webcam_5_direction;
                break;
        }
        found = _camera_info_get_by_display_name(disp_name, ci, connected_cnt);
        if (found != NULL) {
            /* Save to the camera info array that will be used by the service.
             * Note that we just copy everything over, and NULL the source
             * record. */
            memcpy(csd->camera_info + csd->camera_count, found, sizeof(CameraInfo));
            /* Update direction parameter. */
            if (csd->camera_info[csd->camera_count].direction != NULL) {
                free(csd->camera_info[csd->camera_count].direction);
            }
            csd->camera_info[csd->camera_count].direction = ASTRDUP(dir);
            D("Camera %d '%s' connected to '%s' facing %s using %.4s pixel format",
              csd->camera_count, csd->camera_info[csd->camera_count].display_name,
              csd->camera_info[csd->camera_count].device_name,
              csd->camera_info[csd->camera_count].direction,
              (const char*)(&csd->camera_info[csd->camera_count].pixel_format));
            csd->camera_count++;
            memset(found, 0, sizeof(CameraInfo));
        } else {
            W("Camera name '%s' is not found in the list of connected cameras.\n"
              "Use '-webcam list' emulator option to obtain the list of connected camera names.\n",
              disp_name);
        }
    }

    /* Make sure that camera 0 and camera 1 are facing in opposite directions.
     * If they don't the camera application will crash on an attempt to switch
     * cameras. */
    if (csd->camera_count > 0) {
        const char* cam2_dir = NULL;
        const char* cam2_name = NULL;
        if (csd->camera_count >= 2) {
            cam2_dir = csd->camera_info[1].direction;
            cam2_name = csd->camera_info[1].display_name;
        } else if (strcmp(android_hw->hw_fakeCamera, "off")) {
            cam2_dir = android_hw->hw_fakeCamera;
            cam2_name = "fake camera";
        }
        if (cam2_dir != NULL && !strcmp(csd->camera_info[0].direction, cam2_dir)) {
            W("Cameras '%s' and '%s' are both facing %s.\n"
              "It is required by the camera application that first two emulated cameras\n"
              "are facing in opposite directions. If they both are facing in the same direction,\n"
              "the camera application will crash on an attempt to switch the camera.\n",
              csd->camera_info[0].display_name, cam2_name, cam2_dir);

        }
    }
}

/* Gets camera information for the given camera device name.
 * Param:
 *  cs - Initialized camera service descriptor.
 *  device_name - Camera's device name to look up the information for.
 * Return:
 *  Camera information pointer on success, or NULL if no camera information has
 *  been found for the given device name.
 */
static CameraInfo*
_camera_service_get_camera_info_by_device_name(CameraServiceDesc* cs,
                                               const char* device_name)
{
    return _camera_info_get_by_device_name(device_name, cs->camera_info,
                                           cs->camera_count);
}

/********************************************************************************
 * Helpers for handling camera client queries
 *******************************************************************************/

/* Formats paload size according to the protocol, and sends it to the client.
 * To simplify endianess handling we convert payload size to an eight characters
 * string, representing payload size value in hexadecimal format.
 * Param:
 *  qc - Qemu client to send the payload size to.
 *  payload_size - Payload size to report to the client.
 */
static void
_qemu_client_reply_payload(QemudClient* qc, size_t payload_size)
{
    char payload_size_str[9];
    snprintf(payload_size_str, sizeof(payload_size_str), "%08x", payload_size);
    qemud_client_send(qc, (const uint8_t*)payload_size_str, 8);
}

/*
 * Prefixes for replies to camera client queries.
 */

/* Success, no data to send in reply. */
#define OK_REPLY        "ok"
/* Failure, no data to send in reply. */
#define KO_REPLY        "ko"
/* Success, there are data to send in reply. */
#define OK_REPLY_DATA   OK_REPLY ":"
/* Failure, there are data to send in reply. */
#define KO_REPLY_DATA   KO_REPLY ":"

/* Builds and sends a reply to a query.
 * All replies to a query in camera service have a prefix indicating whether the
 * query has succeeded ("ok"), or failed ("ko"). The prefix can be followed by
 * extra data, containing response to the query. In case there are extra data,
 * they are separated from the prefix with a ':' character.
 * Param:
 *  qc - Qemu client to send the reply to.
 *  ok_ko - An "ok", or "ko" selector, where 0 is for "ko", and !0 is for "ok".
 *  extra - Optional extra query data. Can be NULL.
 *  extra_size - Extra data size.
 */
static void
_qemu_client_query_reply(QemudClient* qc,
                         int ok_ko,
                         const void* extra,
                         size_t extra_size)
{
    const char* ok_ko_str;
    size_t payload_size;

    /* Make sure extra_size is 0 if extra is NULL. */
    if (extra == NULL && extra_size != 0) {
        W("%s: 'extra' = NULL, while 'extra_size' = %d",
          __FUNCTION__, (int)extra_size);
        extra_size = 0;
    }

    /* Calculate total payload size, and select appropriate 'ok'/'ko' prefix */
    if (extra_size) {
        /* 'extra' size + 2 'ok'/'ko' bytes + 1 ':' separator byte. */
        payload_size = extra_size + 3;
        ok_ko_str = ok_ko ? OK_REPLY_DATA : KO_REPLY_DATA;
    } else {
        /* No extra data: just zero-terminated 'ok'/'ko'. */
        payload_size = 3;
        ok_ko_str = ok_ko ? OK_REPLY : KO_REPLY;
    }

    /* Send payload size first. */
    _qemu_client_reply_payload(qc, payload_size);
    /* Send 'ok[:]'/'ko[:]' next. Note that if there is no extra data, we still
     * need to send a zero-terminator for 'ok'/'ko' string instead of the ':'
     * separator. So, one way or another, the prefix is always 3 bytes. */
    qemud_client_send(qc, (const uint8_t*)ok_ko_str, 3);
    /* Send extra data (if present). */
    if (extra != NULL) {
        qemud_client_send(qc, (const uint8_t*)extra, extra_size);
    }
}

/* Replies query success ("OK") back to the client.
 * Param:
 *  qc - Qemu client to send the reply to.
 *  ok_str - An optional string containing query results. Can be NULL.
 */
static void
_qemu_client_reply_ok(QemudClient* qc, const char* ok_str)
{
    _qemu_client_query_reply(qc, 1, ok_str,
                             (ok_str != NULL) ? (strlen(ok_str) + 1) : 0);
}

/* Replies query failure ("KO") back to the client.
 * Param:
 *  qc - Qemu client to send the reply to.
 *  ko_str - An optional string containing reason for failure. Can be NULL.
 */
static void
_qemu_client_reply_ko(QemudClient* qc, const char* ko_str)
{
    _qemu_client_query_reply(qc, 0, ko_str,
                             (ko_str != NULL) ? (strlen(ko_str) + 1) : 0);
}

/********************************************************************************
 * Camera Factory API
 *******************************************************************************/

/* Handles 'list' query received from the Factory client.
 * Response to this query is a string that represents each connected camera in
 * this format: 'name=devname framedims=widh1xheight1,widh2xheight2,widhNxheightN\n'
 * Strings, representing each camera are separated with EOL symbol.
 * Param:
 *  csd, client - Factory serivice, and client.
 * Return:
 *  0 on success, or != 0 on failure.
 */
static int
_factory_client_list_cameras(CameraServiceDesc* csd, QemudClient* client)
{
    int n;
    size_t reply_size = 0;
    char* reply = NULL;

    /* Lets see if there was anything found... */
    if (csd->camera_count == 0) {
        /* No cameras connected to the host. Reply with "\n" */
        _qemu_client_reply_ok(client, "\n");
        return 0;
    }

    /* "Stringify" each camera information into the reply string. */
    for (n = 0; n < csd->camera_count; n++) {
        const int res =
            _camera_info_to_string(csd->camera_info + n, &reply, &reply_size);
        if (res) {
            if (reply != NULL) {
                free(reply);
            }
            _qemu_client_reply_ko(client, "Memory allocation error");
            return res;
        }
    }

    D("%s Replied: %s", __FUNCTION__, reply);
    _qemu_client_reply_ok(client, reply);
    free(reply);

    return 0;
}

/* Handles a message received from the emulated camera factory client.
 * Queries received here are represented as strings:
 *  'list' - Queries list of cameras connected to the host.
 * Param:
 *  opaque - Camera service descriptor.
 *  msg, msglen - Message received from the camera factory client.
 *  client - Camera factory client pipe.
 */
static void
_factory_client_recv(void*         opaque,
                     uint8_t*      msg,
                     int           msglen,
                     QemudClient*  client)
{
    /*
     * Emulated camera factory client queries.
     */

    /* List cameras connected to the host. */
    static const char _query_list[]     = "list";

    CameraServiceDesc* csd = (CameraServiceDesc*)opaque;
    char query_name[64];
    const char* query_param = NULL;

    /* Parse the query, extracting query name and parameters. */
    if (_parse_query((const char*)msg, query_name, sizeof(query_name),
                     &query_param)) {
        E("%s: Invalid format in query '%s'", __FUNCTION__, (const char*)msg);
        _qemu_client_reply_ko(client, "Invalid query format");
        return;
    }

    D("%s Camera factory query '%s'", __FUNCTION__, query_name);

    /* Dispatch the query to an appropriate handler. */
    if (!strcmp(query_name, _query_list)) {
        /* This is a "list" query. */
        _factory_client_list_cameras(csd, client);
    } else {
        E("%s: Unknown camera factory query name in '%s'",
          __FUNCTION__, (const char*)msg);
        _qemu_client_reply_ko(client, "Unknown query name");
    }
}

/* Emulated camera factory client has been disconnected from the service. */
static void
_factory_client_close(void*  opaque)
{
    /* There is nothing to clean up here: factory service is just an alias for
     * the "root" camera service, that doesn't require anything more, than camera
     * dervice descriptor already provides. */
}

/********************************************************************************
 * Camera client API
 *******************************************************************************/

/* Describes an emulated camera client.
 */
typedef struct CameraClient CameraClient;
struct CameraClient
{
    /* Client name.
     *  On Linux this is the name of the camera device.
     *  On Windows this is the name of capturing window.
     */
    char*               device_name;
    /* Input channel to use to connect to the camera. */
    int                 inp_channel;
    /* Camera information. */
    const CameraInfo*   camera_info;
    /* Emulated camera device descriptor. */
    CameraDevice*       camera;
    /* Buffer allocated for video frames.
     * Note that memory allocated for this buffer
     * also contains preview framebuffer. */
    uint8_t*            video_frame;
    /* Preview frame buffer.
     * This address points inside the 'video_frame' buffer. */
    uint16_t*           preview_frame;
    /* Byte size of the videoframe buffer. */
    size_t              video_frame_size;
    /* Byte size of the preview frame buffer. */
    size_t              preview_frame_size;
    /* Pixel format required by the guest. */
    uint32_t            pixel_format;
    /* Frame width. */
    int                 width;
    /* Frame height. */
    int                 height;
    /* Number of pixels in a frame buffer. */
    int                 pixel_num;
    /* Status of video and preview frame cache. */
    int                 frames_cached;
};

/* Frees emulated camera client descriptor. */
static void
_camera_client_free(CameraClient* cc)
{
    /* The only exception to the "read only" rule: we have to mark the camera
     * as being not used when we destroy a service for it. */
    if (cc->camera_info != NULL) {
        ((CameraInfo*)cc->camera_info)->in_use = 0;
    }
    if (cc->camera != NULL) {
        camera_device_close(cc->camera);
    }
    if (cc->video_frame != NULL) {
        free(cc->video_frame);
    }
    if (cc->device_name != NULL) {
        free(cc->device_name);
    }

    AFREE(cc);
}

/* Creates descriptor for a connecting emulated camera client.
 * Param:
 *  csd - Camera service descriptor.
 *  param - Client parameters. Must be formatted as described in comments to
 *      _get_param_value routine, and must contain at least 'name' parameter,
 *      identifiying the camera device to create the service for. Also parameters
 *      may contain a decimal 'inp_channel' parameter, selecting the input
 *      channel to use when communicating with the camera device.
 * Return:
 *  Emulated camera client descriptor on success, or NULL on failure.
 */
static CameraClient*
_camera_client_create(CameraServiceDesc* csd, const char* param)
{
    CameraClient* cc;
    CameraInfo* ci;
    int res;
    ANEW0(cc);

    /*
     * Parse parameter string, containing camera client properties.
     */

    /* Pull required device name. */
    if (_get_param_value_alloc(param, "name", &cc->device_name)) {
        E("%s: Allocation failure, or required 'name' parameter is missing, or misformed in '%s'",
          __FUNCTION__, param);
        return NULL;
    }

    /* Pull optional input channel. */
    res = _get_param_value_int(param, "inp_channel", &cc->inp_channel);
    if (res != 0) {
        if (res == -1) {
            /* 'inp_channel' parameter has been ommited. Use default input
             * channel, which is zero. */
            cc->inp_channel = 0;
        } else {
            E("%s: 'inp_channel' parameter is misformed in '%s'",
              __FUNCTION__, param);
            return NULL;
        }
    }

    /* Get camera info for the emulated camera represented with this service.
     * Array of camera information records has been created when the camera
     * service was enumerating camera devices during the service initialization.
     * By the camera service protocol, camera service clients must first obtain
     * list of enumerated cameras via the 'list' query to the camera service, and
     * then use device name reported in the list to connect to an emulated camera
     * service. So, if camera information for the given device name is not found
     * in the array, we fail this connection due to protocol violation. */
    ci = _camera_service_get_camera_info_by_device_name(csd, cc->device_name);
    if (ci == NULL) {
        E("%s: Cannot find camera info for device '%s'",
          __FUNCTION__, cc->device_name);
        _camera_client_free(cc);
        return NULL;
    }

    /* We can't allow multiple camera services for a single camera device, Lets
     * make sure that there is no client created for this camera. */
    if (ci->in_use) {
        E("%s: Camera device '%s' is in use", __FUNCTION__, cc->device_name);
        _camera_client_free(cc);
        return NULL;
    }

    /* We're done. Set camera in use, and succeed the connection. */
    ci->in_use = 1;
    cc->camera_info = ci;

    D("%s: Camera service is created for device '%s' using input channel %d",
      __FUNCTION__, cc->device_name, cc->inp_channel);

    return cc;
}

/********************************************************************************
 * Camera client queries
 *******************************************************************************/

/* Client has queried conection to the camera.
 * Param:
 *  cc - Queried camera client descriptor.
 *  qc - Qemu client for the emulated camera.
 *  param - Query parameters. There are no parameters expected for this query.
 */
static void
_camera_client_query_connect(CameraClient* cc, QemudClient* qc, const char* param)
{
    if (cc->camera != NULL) {
        /* Already connected. */
        W("%s: Camera '%s' is already connected", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ok(qc, "Camera is already connected");
        return;
    }

    /* Open camera device. */
    cc->camera = camera_device_open(cc->device_name, cc->inp_channel);
    if (cc->camera == NULL) {
        E("%s: Unable to open camera device '%s'", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ko(qc, "Unable to open camera device.");
        return;
    }

    D("%s: Camera device '%s' is now connected", __FUNCTION__, cc->device_name);

    _qemu_client_reply_ok(qc, NULL);
}

/* Client has queried disconection from the camera.
 * Param:
 *  cc - Queried camera client descriptor.
 *  qc - Qemu client for the emulated camera.
 *  param - Query parameters. There are no parameters expected for this query.
 */
static void
_camera_client_query_disconnect(CameraClient* cc,
                                QemudClient* qc,
                                const char* param)
{
    if (cc->camera == NULL) {
        /* Already disconnected. */
        W("%s: Camera '%s' is already disconnected", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ok(qc, "Camera is not connected");
        return;
    }

    /* Before we can go ahead and disconnect, we must make sure that camera is
     * not capturing frames. */
    if (cc->video_frame != NULL) {
        E("%s: Cannot disconnect camera '%s' while it is not stopped",
          __FUNCTION__, cc->device_name);
        _qemu_client_reply_ko(qc, "Camera is not stopped");
        return;
    }

    /* Close camera device. */
    camera_device_close(cc->camera);
    cc->camera = NULL;

    D("Camera device '%s' is now disconnected", cc->device_name);

    _qemu_client_reply_ok(qc, NULL);
}

/* Client has queried the client to start capturing video.
 * Param:
 *  cc - Queried camera client descriptor.
 *  qc - Qemu client for the emulated camera.
 *  param - Query parameters. Parameters for this query must contain a 'dim', and
 *      a 'pix' parameters, where 'dim' must be "dim=<width>x<height>", and 'pix'
 *      must be "pix=<format>", where 'width' and 'height' must be numerical
 *      values for the capturing video frame width, and height, and 'format' must
 *      be a numerical value for the pixel format of the video frames expected by
 *      the client. 'format' must be one of the V4L2_PIX_FMT_XXX values.
 */
static void
_camera_client_query_start(CameraClient* cc, QemudClient* qc, const char* param)
{
    char* w;
    char dim[64];
    int width, height, pix_format;

    /* Sanity check. */
    if (cc->camera == NULL) {
        /* Not connected. */
        E("%s: Camera '%s' is not connected", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ko(qc, "Camera is not connected");
        return;
    }

    /*
     * Parse parameters.
     */

    if (param == NULL) {
        E("%s: Missing parameters for the query", __FUNCTION__);
        _qemu_client_reply_ko(qc, "Missing parameters for the query");
        return;
    }

    /* Pull required 'dim' parameter. */
    if (_get_param_value(param, "dim", dim, sizeof(dim))) {
        E("%s: Invalid or missing 'dim' parameter in '%s'", __FUNCTION__, param);
        _qemu_client_reply_ko(qc, "Invalid or missing 'dim' parameter");
        return;
    }

    /* Pull required 'pix' parameter. */
    if (_get_param_value_int(param, "pix", &pix_format)) {
        E("%s: Invalid or missing 'pix' parameter in '%s'", __FUNCTION__, param);
        _qemu_client_reply_ko(qc, "Invalid or missing 'pix' parameter");
        return;
    }

    /* Parse 'dim' parameter, and get requested frame width and height. */
    w = strchr(dim, 'x');
    if (w == NULL || w[1] == '\0') {
        E("%s: Invalid 'dim' parameter in '%s'", __FUNCTION__, param);
        _qemu_client_reply_ko(qc, "Invalid 'dim' parameter");
        return;
    }
    *w = '\0'; w++;
    errno = 0;
    width = strtoi(dim, NULL, 10);
    height = strtoi(w, NULL, 10);
    if (errno) {
        E("%s: Invalid 'dim' parameter in '%s'", __FUNCTION__, param);
        _qemu_client_reply_ko(qc, "Invalid 'dim' parameter");
        return;
    }

    /* After collecting capture parameters lets see if camera has already
     * started, and if so, lets see if parameters match. */
    if (cc->video_frame != NULL) {
        /* Already started. Match capture parameters. */
        if (cc->pixel_format != pix_format ||cc->width != width ||
            cc->height != height) {
            /* Parameters match. Succeed the query. */
            W("%s: Camera '%s' is already started", __FUNCTION__, cc->device_name);
            _qemu_client_reply_ok(qc, "Camera is already started");
        } else {
            /* Parameters don't match. Fail the query. */
            E("%s: Camera '%s' is already started, and parameters don't match:\n"
              "Current %.4s[%dx%d] != requested %.4s[%dx%d]",
              __FUNCTION__, cc->device_name, (const char*)&cc->pixel_format,
              cc->width, cc->height, (const char*)&pix_format, width, height);
            _qemu_client_reply_ko(qc,
                "Camera is already started with different capturing parameters");
        }
        return;
    }

    /*
     * Start the camera.
     */

    /* Save capturing parameters. */
    cc->pixel_format = pix_format;
    cc->width = width;
    cc->height = height;
    cc->pixel_num = cc->width * cc->height;
    cc->frames_cached = 0;

    /* Make sure that pixel format is known, and calculate video framebuffer size
     * along the lines. */
    switch (cc->pixel_format) {
        case V4L2_PIX_FMT_YUV420:
        case V4L2_PIX_FMT_YVU420:
        case V4L2_PIX_FMT_NV12:
        case V4L2_PIX_FMT_NV21:
            cc->video_frame_size = (cc->pixel_num * 12) / 8;
            break;

        default:
            E("%s: Unknown pixel format %.4s",
              __FUNCTION__, (char*)&cc->pixel_format);
            _qemu_client_reply_ko(qc, "Pixel format is unknown");
            return;
    }

    /* Make sure that we have a converters between the original camera pixel
     * format and the one that the client expects. Also a converter must exist
     * for the preview window pixel format (RGB32) */
    if (!has_converter(cc->camera_info->pixel_format, cc->pixel_format) ||
        !has_converter(cc->camera_info->pixel_format, V4L2_PIX_FMT_RGB32)) {
        E("%s: No conversion exist between %.4s and %.4s (or RGB32) pixel formats",
          __FUNCTION__, (char*)&cc->camera_info->pixel_format, (char*)&cc->pixel_format);
        _qemu_client_reply_ko(qc, "No conversion exist for the requested pixel format");
        return;
    }

    /* TODO: At the moment camera framework in the emulator requires RGB32 pixel
     * format for preview window. So, we need to keep two framebuffers here: one
     * for the video, and another for the preview window. Watch out when this
     * changes (if changes). */
    cc->preview_frame_size = cc->pixel_num * 4;

    /* Allocate buffer large enough to contain both, video and preview
     * framebuffers. */
    cc->video_frame =
        (uint8_t*)malloc(cc->video_frame_size + cc->preview_frame_size);
    if (cc->video_frame == NULL) {
        E("%s: Not enough memory for framebuffers %d + %d",
          __FUNCTION__, cc->video_frame_size, cc->preview_frame_size);
        _qemu_client_reply_ko(qc, "Out of memory");
        return;
    }

    /* Set framebuffer pointers. */
    cc->preview_frame = (uint16_t*)(cc->video_frame + cc->video_frame_size);

    /* Start the camera. */
    if (camera_device_start_capturing(cc->camera, cc->camera_info->pixel_format,
                                      cc->width, cc->height)) {
        E("%s: Cannot start camera '%s' for %.4s[%dx%d]: %s",
          __FUNCTION__, cc->device_name, (const char*)&cc->pixel_format,
          cc->width, cc->height, strerror(errno));
        free(cc->video_frame);
        cc->video_frame = NULL;
        _qemu_client_reply_ko(qc, "Cannot start the camera");
        return;
    }

    D("%s: Camera '%s' is now started for %.4s[%dx%d]",
      __FUNCTION__, cc->device_name, (char*)&cc->pixel_format, cc->width,
      cc->height);

    _qemu_client_reply_ok(qc, NULL);
}

/* Client has queried the client to stop capturing video.
 * Param:
 *  cc - Queried camera client descriptor.
 *  qc - Qemu client for the emulated camera.
 *  param - Query parameters. There are no parameters expected for this query.
 */
static void
_camera_client_query_stop(CameraClient* cc, QemudClient* qc, const char* param)
{
    if (cc->video_frame == NULL) {
        /* Not started. */
        W("%s: Camera '%s' is not started", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ok(qc, "Camera is not started");
        return;
    }

    /* Stop the camera. */
    if (camera_device_stop_capturing(cc->camera)) {
        E("%s: Cannot stop camera device '%s': %s",
          __FUNCTION__, cc->device_name, strerror(errno));
        _qemu_client_reply_ko(qc, "Cannot stop camera device");
        return;
    }

    free(cc->video_frame);
    cc->video_frame = NULL;

    D("%s: Camera device '%s' is now stopped.", __FUNCTION__, cc->device_name);
    _qemu_client_reply_ok(qc, NULL);
}

/* Client has queried next frame.
 * Param:
 *  cc - Queried camera client descriptor.
 *  qc - Qemu client for the emulated camera.
 *  param - Query parameters. Parameters for this query are formatted as such:
 *          video=<size> preview=<size> whiteb=<red>,<green>,<blue> expcomp=<comp>
 *      where:
 *       - 'video', and 'preview' both must be decimal values, defining size of
 *         requested video, and preview frames respectively. Zero value for any
 *         of these parameters means that this particular frame is not requested.
 *       - whiteb contains float values required to calculate whilte balance.
 *       - expcomp contains a float value required to calculate exposure
 *         compensation.
 */
static void
_camera_client_query_frame(CameraClient* cc, QemudClient* qc, const char* param)
{
    int video_size = 0;
    int preview_size = 0;
    int repeat;
    ClientFrameBuffer fbs[2];
    int fbs_num = 0;
    size_t payload_size;
    uint64_t tick;
    float r_scale = 1.0f, g_scale = 1.0f, b_scale = 1.0f, exp_comp = 1.0f;
    char tmp[256];

    /* Sanity check. */
    if (cc->video_frame == NULL) {
        /* Not started. */
        E("%s: Camera '%s' is not started", __FUNCTION__, cc->device_name);
        _qemu_client_reply_ko(qc, "Camera is not started");
        return;
    }

    /* Pull required parameters. */
    if (_get_param_value_int(param, "video", &video_size) ||
        _get_param_value_int(param, "preview", &preview_size)) {
        E("%s: Invalid or missing 'video', or 'preview' parameter in '%s'",
          __FUNCTION__, param);
        _qemu_client_reply_ko(qc,
            "Invalid or missing 'video', or 'preview' parameter");
        return;
    }

    /* Pull white balance values. */
    if (!_get_param_value(param, "whiteb", tmp, sizeof(tmp))) {
        if (sscanf(tmp, "%g,%g,%g", &r_scale, &g_scale, &b_scale) != 3) {
            D("Invalid value '%s' for parameter 'whiteb'", tmp);
            r_scale = g_scale = b_scale = 1.0f;
        }
    }

    /* Pull exposure compensation. */
    if (!_get_param_value(param, "expcomp", tmp, sizeof(tmp))) {
        if (sscanf(tmp, "%g", &exp_comp) != 1) {
            D("Invalid value '%s' for parameter 'whiteb'", tmp);
            exp_comp = 1.0f;
        }
    }

    /* Verify that framebuffer sizes match the ones that the started camera
     * operates with. */
    if ((video_size != 0 && cc->video_frame_size != video_size) ||
        (preview_size != 0 && cc->preview_frame_size != preview_size)) {
        E("%s: Frame sizes don't match for camera '%s':\n"
          "Expected %d for video, and %d for preview. Requested %d, and %d",
          __FUNCTION__, cc->device_name, cc->video_frame_size,
          cc->preview_frame_size, video_size, preview_size);
        _qemu_client_reply_ko(qc, "Frame size mismatch");
        return;
    }

    /*
     * Initialize framebuffer array for frame read.
     */

    if (video_size) {
        fbs[fbs_num].pixel_format = cc->pixel_format;
        fbs[fbs_num].framebuffer = cc->video_frame;
        fbs_num++;
    }
    if (preview_size) {
        /* TODO: Watch out for preview format changes! */
        fbs[fbs_num].pixel_format = V4L2_PIX_FMT_RGB32;
        fbs[fbs_num].framebuffer = cc->preview_frame;
        fbs_num++;
    }

    /* Capture new frame. */
    tick = _get_timestamp();
    repeat = camera_device_read_frame(cc->camera, fbs, fbs_num,
                                      r_scale, g_scale, b_scale, exp_comp);

    /* Note that there is no (known) way how to wait on next frame being
     * available, so we could dequeue frame buffer from the device only when we
     * know it's available. Instead we're shooting in the dark, and quite often
     * device will response with EAGAIN, indicating that it doesn't have frame
     * ready. In turn, it means that the last frame we have obtained from the
     * device is still good, and we can reply with the cached frames. The only
     * case when we need to keep trying to obtain a new frame is when frame cache
     * is empty. To prevent ourselves from an indefinite loop in case device got
     * stuck on something (observed with some Microsoft devices) we will limit
     * the loop by 2 second time period (which is more than enough to obtain
     * something from the device) */
    while (repeat == 1 && !cc->frames_cached &&
           (_get_timestamp() - tick) < 2000000LL) {
        /* Sleep for 10 millisec before repeating the attempt. */
        _camera_sleep(10);
        repeat = camera_device_read_frame(cc->camera, fbs, fbs_num,
                                          r_scale, g_scale, b_scale, exp_comp);
    }
    if (repeat == 1 && !cc->frames_cached) {
        /* Waited too long for the first frame. */
        E("%s: Unable to obtain first video frame from the camera '%s' in %d milliseconds: %s.",
          __FUNCTION__, cc->device_name,
          (uint32_t)(_get_timestamp() - tick) / 1000, strerror(errno));
        _qemu_client_reply_ko(qc, "Unable to obtain video frame from the camera");
        return;
    } else if (repeat < 0) {
        /* An I/O error. */
        E("%s: Unable to obtain video frame from the camera '%s': %s.",
          __FUNCTION__, cc->device_name, strerror(errno));
        _qemu_client_reply_ko(qc, strerror(errno));
        return;
    }

    /* We have cached something... */
    cc->frames_cached = 1;

    /*
     * Build the reply.
     */

    /* Payload includes "ok:" + requested video and preview frames. */
    payload_size = 3 + video_size + preview_size;

    /* Send payload size first. */
    _qemu_client_reply_payload(qc, payload_size);

    /* After that send the 'ok:'. Note that if there is no frames sent, we should
     * use prefix "ok" instead of "ok:" */
    if (video_size || preview_size) {
        qemud_client_send(qc, (const uint8_t*)"ok:", 3);
    } else {
        /* Still 3 bytes: zero terminator is required in this case. */
        qemud_client_send(qc, (const uint8_t*)"ok", 3);
    }

    /* After that send video frame (if requested). */
    if (video_size) {
        qemud_client_send(qc, cc->video_frame, video_size);
    }

    /* After that send preview frame (if requested). */
    if (preview_size) {
        qemud_client_send(qc, (const uint8_t*)cc->preview_frame, preview_size);
    }
}

/* Handles a message received from the emulated camera client.
 * Queries received here are represented as strings:
 * - 'connect' - Connects to the camera device (opens it).
 * - 'disconnect' - Disconnexts from the camera device (closes it).
 * - 'start' - Starts capturing video from the connected camera device.
 * - 'stop' - Stop capturing video from the connected camera device.
 * - 'frame' - Queries video and preview frames captured from the camera.
 * Param:
 *  opaque - Camera service descriptor.
 *  msg, msglen - Message received from the camera factory client.
 *  client - Camera factory client pipe.
 */
static void
_camera_client_recv(void*         opaque,
                    uint8_t*      msg,
                    int           msglen,
                    QemudClient*  client)
{
    /*
     * Emulated camera client queries.
     */

    /* Connect to the camera. */
    static const char _query_connect[]    = "connect";
    /* Disconnect from the camera. */
    static const char _query_disconnect[] = "disconnect";
    /* Start video capturing. */
    static const char _query_start[]      = "start";
    /* Stop video capturing. */
    static const char _query_stop[]       = "stop";
    /* Query frame(s). */
    static const char _query_frame[]      = "frame";

    char query_name[64];
    const char* query_param;
    CameraClient* cc = (CameraClient*)opaque;

    /*
     * Emulated camera queries are formatted as such:
     *  "<query name> [<parameters>]"
     */

    T("%s: Camera client query: '%s'", __FUNCTION__, (char*)msg);
    if (_parse_query((const char*)msg, query_name, sizeof(query_name),
        &query_param)) {
        E("%s: Invalid query '%s'", __FUNCTION__, (char*)msg);
        _qemu_client_reply_ko(client, "Invalid query");
        return;
    }

    /* Dispatch the query to an appropriate handler. */
    if (!strcmp(query_name, _query_frame)) {
        /* A frame is queried. */
        _camera_client_query_frame(cc, client, query_param);
    } else if (!strcmp(query_name, _query_connect)) {
        /* Camera connection is queried. */
        _camera_client_query_connect(cc, client, query_param);
    } else if (!strcmp(query_name, _query_disconnect)) {
        /* Camera disnection is queried. */
        _camera_client_query_disconnect(cc, client, query_param);
    } else if (!strcmp(query_name, _query_start)) {
        /* Start capturing is queried. */
        _camera_client_query_start(cc, client, query_param);
    } else if (!strcmp(query_name, _query_stop)) {
        /* Stop capturing is queried. */
        _camera_client_query_stop(cc, client, query_param);
    } else {
        E("%s: Unknown query '%s'", __FUNCTION__, (char*)msg);
        _qemu_client_reply_ko(client, "Unknown query");
    }
}

/* Emulated camera client has been disconnected from the service. */
static void
_camera_client_close(void* opaque)
{
    CameraClient* cc = (CameraClient*)opaque;

    D("%s: Camera client for device '%s' on input channel %d is now closed",
      __FUNCTION__, cc->device_name, cc->inp_channel);

    _camera_client_free(cc);
}

/********************************************************************************
 * Camera service API
 *******************************************************************************/

/* Connects a client to the camera service.
 * There are two classes of the client that can connect to the service:
 *  - Camera factory that is insterested only in listing camera devices attached
 *    to the host.
 *  - Camera device emulators that attach to the actual camera devices.
 * The distinction between these two classes is made by looking at extra
 * parameters passed in client_param variable. If it's NULL, or empty, the client
 * connects to a camera factory. Otherwise, parameters describe the camera device
 * the client wants to connect to.
 */
static QemudClient*
_camera_service_connect(void*          opaque,
                        QemudService*  serv,
                        int            channel,
                        const char*    client_param)
{
    QemudClient*  client = NULL;
    CameraServiceDesc* csd = (CameraServiceDesc*)opaque;

    D("%s: Connecting camera client '%s'",
      __FUNCTION__, client_param ? client_param : "Factory");
    if (client_param == NULL || *client_param == '\0') {
        /* This is an emulated camera factory client. */
        client = qemud_client_new(serv, channel, client_param, csd,
                                  _factory_client_recv, _factory_client_close,
                                  NULL, NULL);
    } else {
        /* This is an emulated camera client. */
        CameraClient* cc = _camera_client_create(csd, client_param);
        if (cc != NULL) {
            client = qemud_client_new(serv, channel, client_param, cc,
                                      _camera_client_recv, _camera_client_close,
                                      NULL, NULL);
        }
    }

    return client;
}

void
android_camera_service_init(void)
{
    static int _inited = 0;

    if (!_inited) {
        _camera_service_init(&_camera_service_desc);
        QemudService*  serv = qemud_service_register( SERVICE_NAME, 0,
                                                      &_camera_service_desc,
                                                      _camera_service_connect,
                                                      NULL, NULL);
        if (serv == NULL) {
            derror("%s: Could not register '%s' service",
                   __FUNCTION__, SERVICE_NAME);
            return;
        }
        D("%s: Registered '%s' qemud service", __FUNCTION__, SERVICE_NAME);
    }
}

void
android_list_web_cameras(void)
{
    CameraInfo ci[MAX_CAMERA];
    int connected_cnt;
    int i;

    /* Enumerate camera devices connected to the host. */
    connected_cnt = enumerate_camera_devices(ci, MAX_CAMERA);
    if (connected_cnt <= 0) {
        return;
    }

    printf("List of web cameras connected to the computer:\n");
    for (i = 0; i < connected_cnt; i++) {
        printf(" Camera '%s' is connected to device '%s' on channel %d using pixel format '%.4s'\n",
               ci[i].display_name, ci[i].device_name, ci[i].inp_channel,
               (const char*)&ci[i].pixel_format);
    }
    printf("\n");
}