/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*  Fluent Bit

 *  ==========

 *  Copyright (C) 2015-2022 The Fluent Bit Authors

 *

 *  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.

 */

#include <fluent-bit/flb_info.h>

#include <fluent-bit/flb_output.h>

#include <fluent-bit/flb_utils.h>

#include <fluent-bit/flb_network.h>

#include <fluent-bit/flb_time.h>

#include <fluent-bit/flb_upstream.h>

#include <fluent-bit/flb_crypto.h>

#include <fluent-bit/flb_pack.h>

#include <fluent-bit/flb_sds.h>

#include <fluent-bit/flb_http_client.h>

#include <fluent-bit/flb_config_map.h>

#include <msgpack.h>

#include "websocket.h"

#include "websocket_conf.h"

struct flb_output_plugin out_websocket_plugin;

#define SECURED_BY "Fluent Bit"

static int flb_ws_handshake(struct flb_connection *u_conn,

                                    struct flb_out_ws *ctx)

{

    int ret;

    size_t bytes_sent;

    struct flb_http_client *c;

    if (!u_conn) {

        flb_error("[output_ws] upstream connection error");

        return -1;

    }

    /* Compose HTTP Client request */

    c = flb_http_client(u_conn, FLB_HTTP_GET, ctx->uri,

                        NULL, 0, NULL, 0, NULL, 0);

    if (!c) {

       flb_upstream_conn_release(u_conn);

       return -1;

    }

    flb_http_buffer_size(c, ctx->buffer_size);

    flb_http_add_header(c, "Upgrade", 7, "websocket", 9);

    flb_http_add_header(c, "Connection", 10, "Upgrade", 7);

    flb_http_add_header(c, "Sec-WebSocket-Key", 17, "dGhlIHNhbXBsZSBub25jZQ==", 24);

    flb_http_add_header(c, "Sec-WebSocket-Version", 21, "13", 2);

    /* Perform request*/

    ret = flb_http_do(c, &bytes_sent);

    if (ret != 0 || c->resp.status != 101) {

        if (c->resp.payload_size > 0) {

            flb_debug("[output_ws] Websocket Server Response\n%s",

                c->resp.payload);

        }

        flb_http_client_destroy(c);

        flb_upstream_conn_release(u_conn);

        flb_debug("[out_ws] Http Get Operation ret = %i, http resp = %i", ret, c->resp.status);

        return -1;

    }

    flb_http_client_destroy(c);

    return 0;

}

static void flb_ws_mask(char *data, int len, char *mask)

{

    int i;

    for (i=0;i<len;++i) {

        *(data+i) ^= *(mask+(i%4));

    }

}

static int flb_ws_sendDataFrameHeader(struct flb_connection *u_conn,

                                      struct flb_out_ws *ctx, const void *data, size_t bytes)

{

    int ret = -1;

    char* data_frame_head;

    size_t bytes_sent;

    int data_frame_head_len = 0;

    //TODO use random function to generate masking_key

    char masking_key[4] = {0x12, 0x34, 0x56, 0x78};

    unsigned long long payloadSize = bytes;

    flb_ws_mask((char *)data, payloadSize, masking_key);

    if (payloadSize < 126) {

        data_frame_head = (char *)flb_malloc(6);

        if (!data_frame_head) {

            flb_errno();

            return -1;

        }

        data_frame_head[0] = 0x81;

        data_frame_head[1] = (payloadSize & 0xff) | 0x80;

        data_frame_head[2] = masking_key[0];

        data_frame_head[3] = masking_key[1];

        data_frame_head[4] = masking_key[2];

        data_frame_head[5] = masking_key[3];

        data_frame_head_len = 6;

    }

    else if (payloadSize < 65536) {

        data_frame_head = (char *)flb_malloc(8);

        if (!data_frame_head) {

            flb_errno();

            return -1;

        }

        data_frame_head[0] = 0x81;

        data_frame_head[1] = 126 | 0x80;

        data_frame_head[2] = (payloadSize >> 8) & 0xff;

        data_frame_head[3] = (payloadSize >> 0) & 0xff;

        data_frame_head[4] = masking_key[0];

        data_frame_head[5] = masking_key[1];

        data_frame_head[6] = masking_key[2];

        data_frame_head[7] = masking_key[3];

        data_frame_head_len = 8;

    }

    else {

        data_frame_head = (char *)flb_malloc(14);

        if (!data_frame_head) {

            flb_errno();

            return -1;

        }

        data_frame_head[0] = 0x81;

        data_frame_head[1] = 127 | 0x80;

        data_frame_head[2] = (payloadSize >> 56) & 0xff;

        data_frame_head[3] = (payloadSize >> 48) & 0xff;

        data_frame_head[4] = (payloadSize >> 40) & 0xff;

        data_frame_head[5] = (payloadSize >> 32) & 0xff;

        data_frame_head[6] = (payloadSize >> 24) & 0xff;

        data_frame_head[7] = (payloadSize >> 16) & 0xff;

        data_frame_head[8] = (payloadSize >>  8) & 0xff;

        data_frame_head[9] = (payloadSize >>  0) & 0xff;

        data_frame_head[10] = masking_key[0];

        data_frame_head[11] = masking_key[1];

        data_frame_head[12] = masking_key[2];

        data_frame_head[13] = masking_key[3];

        data_frame_head_len = 14;

    }

    ret = flb_io_net_write(u_conn, data_frame_head, data_frame_head_len, &bytes_sent);

    if (ret == -1) {

        flb_error("[out_ws] could not write dataframe header");

        goto error;

    }

    flb_free(data_frame_head);

    return 0;

error:

    flb_free(data_frame_head);

    return -1;

}

static int cb_ws_init(struct flb_output_instance *ins,

                      struct flb_config *config, void *data)

{

    struct flb_out_ws *ctx = NULL;

    ctx = flb_ws_conf_create(ins, config);

    if (!ctx) {

        return -1;

    }

    ctx->handshake = 1;

    ctx->last_input_timestamp = time(NULL);

    flb_output_set_context(ins, ctx);

    return 0;

}

static int cb_ws_exit(void *data, struct flb_config *config)

{

    struct flb_out_ws *ctx = data;

    flb_ws_conf_destroy(ctx);

    return 0;

}

static void cb_ws_flush(struct flb_event_chunk *event_chunk,

                        struct flb_output_flush *out_flush,

                        struct flb_input_instance *i_ins,

                        void *out_context,

                        struct flb_config *config)

{

    int ret = -1;

    size_t bytes_sent;

    flb_sds_t json = NULL;

    struct flb_upstream *u;

    struct flb_connection *u_conn;

    struct flb_out_ws *ctx = out_context;

    time_t now;

    /* Get upstream context and connection */

    u = ctx->u;

    u_conn = flb_upstream_conn_get(u);

    if (!u_conn) {

        flb_error("[out_ws] no upstream connections available to %s:%i", u->tcp_host, u->tcp_port);

        ctx->handshake = 1;

        FLB_OUTPUT_RETURN(FLB_RETRY);

    }

    now = time(NULL);

    //TODO how to determine the interval? conn disconnet is about 30 sec, so we set 20 ssecnds here.

    flb_debug("[out_ws] interval is  %ld and handshake is %d", now - ctx->last_input_timestamp, ctx->handshake);

    if ((now - ctx->last_input_timestamp > ctx->idle_interval) && (ctx->handshake == 0)) {

        ctx->handshake = 1;

        flb_upstream_conn_release(u_conn);

        FLB_OUTPUT_RETURN(FLB_RETRY);

    }

    ctx->last_input_timestamp = now;

    if (ctx->handshake == 1) {

        /* Handshake with websocket server*/

        flb_info("[out_ws] handshake for ws");

        ret = flb_ws_handshake(u_conn, ctx);

        if (ret == -1) {

            flb_upstream_conn_release(u_conn);

            FLB_OUTPUT_RETURN(FLB_RETRY);

        }

        ctx->handshake = 0;

    }

    /* Data format process*/

    if (ctx->out_format != FLB_PACK_JSON_FORMAT_NONE) {

        json = flb_pack_msgpack_to_json_format(event_chunk->data,

                                               event_chunk->size,

                                               ctx->out_format,

                                               ctx->json_date_format,

                                               ctx->json_date_key);

        if (!json) {

            flb_error("[out_ws] error formatting JSON payload");

            flb_upstream_conn_release(u_conn);

            FLB_OUTPUT_RETURN(FLB_ERROR);

        }

    }

    /* Write message header */

    if (ctx->out_format == FLB_PACK_JSON_FORMAT_NONE) {

        ret = flb_ws_sendDataFrameHeader(u_conn, ctx,

                                         event_chunk->data,

                                         event_chunk->size);

    }

    else {

        ret = flb_ws_sendDataFrameHeader(u_conn, ctx, json, flb_sds_len(json));

    }

    if (ret == -1) {

        flb_error("[out_ws] dataFrameHeader sent failed");

        ctx->handshake = 1;

        if (json) {

            flb_sds_destroy(json);

        }

        flb_upstream_conn_release(u_conn);

        FLB_OUTPUT_RETURN(FLB_RETRY);

    }

    /* Write message body*/

    if (ctx->out_format == FLB_PACK_JSON_FORMAT_NONE) {

        ret = flb_io_net_write(u_conn,

                               event_chunk->data,

                               event_chunk->size,

                               &bytes_sent);

    }

    else {

        ret = flb_io_net_write(u_conn, json, flb_sds_len(json), &bytes_sent);

        flb_sds_destroy(json);

    }

    //flb_info("[out_ws] sendDataFrame number of bytes sent = %i", ret);

    if (ret == -1) {

        ctx->handshake = 1;

        flb_upstream_conn_release(u_conn);

        FLB_OUTPUT_RETURN(FLB_RETRY);

    }

    /* Release the connection */

    flb_upstream_conn_release(u_conn);

    FLB_OUTPUT_RETURN(FLB_OK);

}

/* Configuration properties map */

static struct flb_config_map config_map[] = {

    {

     FLB_CONFIG_MAP_STR, "uri", NULL,

     0, FLB_TRUE, offsetof(struct flb_out_ws, uri),

     "Specify an optional URI for the target web socket server, e.g: /something"

    },

    {

     FLB_CONFIG_MAP_STR, "format", NULL,

     0, FLB_FALSE, 0,

     "Set desired payload format: json, json_stream, json_lines, gelf or msgpack"

    },

    {

     FLB_CONFIG_MAP_STR, "json_date_format", "double",

     0, FLB_FALSE, 0,

     "Specify the format of the date"

    },

    {

     FLB_CONFIG_MAP_STR, "json_date_key", "date",

     0, FLB_TRUE, offsetof(struct flb_out_ws, json_date_key),

     "Specify the name of the date field in output"

    },

    /* EOF */

    {0}

};

/* Plugin reference */

struct flb_output_plugin out_websocket_plugin = {

    .name         = "websocket",

    .description  = "Websocket",

    .cb_init      = cb_ws_init,

    .cb_flush     = cb_ws_flush,

    .cb_exit      = cb_ws_exit,

    .config_map   = config_map,

    .flags        = FLB_OUTPUT_NET | FLB_IO_OPT_TLS,

};