function OutboundGroupSession() {
    var size = Module['_olm_outbound_group_session_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_outbound_group_session'](this.buf);
}

function outbound_group_session_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = UTF8ToString(
                Module['_olm_outbound_group_session_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

OutboundGroupSession.prototype['free'] = function() {
    Module['_olm_clear_outbound_group_session'](this.ptr);
    free(this.ptr);
}

OutboundGroupSession.prototype['pickle'] = restore_stack(function(key) {
    var key_array = array_from_string(key);
    var pickle_length = outbound_group_session_method(
        Module['_olm_pickle_outbound_group_session_length']
    )(this.ptr);
    var key_buffer = stack(key_array);
    var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
    try {
        outbound_group_session_method(Module['_olm_pickle_outbound_group_session'])(
            this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
        );
    } finally {
        // clear out copies of the pickle key
        bzero(key_buffer, key_array.length)
        for (var i = 0; i < key_array.length; i++) {
            key_array[i] = 0;
        }
    }
    return UTF8ToString(pickle_buffer, pickle_length);
});

OutboundGroupSession.prototype['unpickle'] = restore_stack(function(key, pickle) {
    var key_array = array_from_string(key);
    var key_buffer = stack(key_array);
    var pickle_array = array_from_string(pickle);
    var pickle_buffer = stack(pickle_array);
    try {
        outbound_group_session_method(Module['_olm_unpickle_outbound_group_session'])(
            this.ptr, key_buffer, key_array.length, pickle_buffer,
            pickle_array.length
        );
    } finally {
        // clear out copies of the pickle key
        bzero(key_buffer, key_array.length)
        for (var i = 0; i < key_array.length; i++) {
            key_array[i] = 0;
        }
    }
});

OutboundGroupSession.prototype['create'] = restore_stack(function() {
    var random_length = outbound_group_session_method(
        Module['_olm_init_outbound_group_session_random_length']
    )(this.ptr);
    var random = random_stack(random_length);
    try {
        outbound_group_session_method(Module['_olm_init_outbound_group_session'])(
            this.ptr, random, random_length
        );
    } finally {
        // clear the random buffer
        bzero(random, random_length);
    }
});

OutboundGroupSession.prototype['encrypt'] = function(plaintext) {
    var plaintext_buffer, message_buffer, plaintext_length;
    try {
        plaintext_length = lengthBytesUTF8(plaintext);

        var message_length = outbound_group_session_method(
            Module['_olm_group_encrypt_message_length']
        )(this.ptr, plaintext_length);

        // need to allow space for the terminator (which stringToUTF8 always
        // writes), hence + 1.
        plaintext_buffer = malloc(plaintext_length + 1);
        stringToUTF8(plaintext, plaintext_buffer, plaintext_length + 1);

        message_buffer = malloc(message_length + NULL_BYTE_PADDING_LENGTH);
        outbound_group_session_method(Module['_olm_group_encrypt'])(
            this.ptr,
            plaintext_buffer, plaintext_length,
            message_buffer, message_length
        );

        // UTF8ToString requires a null-terminated argument, so add the
        // null terminator.
        setValue(
            message_buffer+message_length,
            0, "i8"
        );

        return UTF8ToString(message_buffer, message_length);
    } finally {
        if (plaintext_buffer !== undefined) {
            // don't leave a copy of the plaintext in the heap.
            bzero(plaintext_buffer, plaintext_length + 1);
            free(plaintext_buffer);
        }
        if (message_buffer !== undefined) {
            free(message_buffer);
        }
    }
};

OutboundGroupSession.prototype['session_id'] = restore_stack(function() {
    var length = outbound_group_session_method(
        Module['_olm_outbound_group_session_id_length']
    )(this.ptr);
    var session_id = stack(length + NULL_BYTE_PADDING_LENGTH);
    outbound_group_session_method(Module['_olm_outbound_group_session_id'])(
        this.ptr, session_id, length
    );
    return UTF8ToString(session_id, length);
});

OutboundGroupSession.prototype['session_key'] = restore_stack(function() {
    var key_length = outbound_group_session_method(
        Module['_olm_outbound_group_session_key_length']
    )(this.ptr);
    var key = stack(key_length + NULL_BYTE_PADDING_LENGTH);
    outbound_group_session_method(Module['_olm_outbound_group_session_key'])(
        this.ptr, key, key_length
    );
    var key_str = UTF8ToString(key, key_length);
    bzero(key, key_length); // clear out our copy of the key
    return key_str;
});

OutboundGroupSession.prototype['message_index'] = function() {
    var idx = outbound_group_session_method(
        Module['_olm_outbound_group_session_message_index']
    )(this.ptr);
    return idx;
};

olm_exports['OutboundGroupSession'] = OutboundGroupSession;
