# vim: set et nosta sw=4 ts=4 :

#

# Copyright (c) 2018-2020, Mahlon E. Smith <mahlon@martini.nu>

# All rights reserved.

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions are met:

#

#     * Redistributions of source code must retain the above copyright

#       notice, this list of conditions and the following disclaimer.

#

#     * Redistributions in binary form must reproduce the above copyright

#       notice, this list of conditions and the following disclaimer in the

#       documentation and/or other materials provided with the distribution.

#

#     * Neither the name of Mahlon E. Smith nor the names of his

#       contributors may be used to endorse or promote products derived

#       from this software without specific prior written permission.

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# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY

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# DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY

# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

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import

    db_postgres,

    json,

    math,

    nativesockets,

    net,

    parseopt,

    posix,

    strutils,

    strformat,

    tables,

    terminal,

    times

const

    VERSION = "v0.3.0"

    USAGE = """

./netdata_tsrelay [-adDhopqtTv]

  -a --listen-addr:

    The outbound IP address to listen for netdata streams.

  -d --debug:

    Debug: Show incoming and parsed data.

  -D --dropconn:

    Drop the persistent socket to netdata between samples to conserve

    local resources.  This may be helpful with a large number of clients.

    Defaults to false.

  -h --help:

    Help.  You're lookin' at it.

  -o --dbopts:

    The PostgreSQL connection string parameters.

    The default connection string is:

      "host=localhost dbname=netdata application_name=netdata-tsrelay"

  -p --listen-port:

    Change the listening port from the default (14866).

  -P --persistent:

    Don't disconnect from the database between samples.  This may be

    more efficient with a small number of clients, when not using a

    pooler, or with a very high sample size/rate.  Defaults to false.

  -q --quiet:

    Quiet mode.  No output at all.  Ignored if -d is supplied.

  -T --dbtable:

    Change the destination table name from the default (netdata).

  -t --timeout:

    Alter the maximum time (in ms) an open socket waits for data

    before processing the sample.  Default: 500ms.

  -v --version:

    Display version number.

    """

    INSERT_SQL = """

    INSERT INTO $1

        ( time, host, metrics )

    VALUES

        ( 'epoch'::timestamptz + ? * '1 second'::interval, ?, ? )

    """

type

    Config = object of RootObj

        dbopts:      string  # The postgresql connection parameters.  (See https://www.postgresql.org/docs/current/static/libpq-connect.html)

        dbtable:     string  # The name of the table to write to.

        dropconn:    bool    # Close the TCP connection between samples.

        persistent:  bool    # Don't close the database handle between samples.

        listen_port: int     # The port to listen for incoming connections.

        listen_addr: string  # The IP address listen for incoming connections.  Defaults to inaddr_any.

        verbose:     bool    # Be informative

        debug:       bool    # Spew out raw data

        insertsql:   string  # The SQL insert string after interpolating the table name.

        timeout:     int     # How long to block, waiting on connection data.

type

    NetdataClient = ref object

        sock: Socket    # The raw socket fd

        address: string # The remote IP address

        db: DbConn      # An optionally persistent database handle

# Global configuration

var conf: Config

proc hl( msg: string, fg: ForegroundColor, bright=false ): string =

    ## Quick wrapper for color formatting a string, since the 'terminal'

    ## module only deals with stdout directly.

    if not isatty(stdout): return msg

    var color: BiggestInt = ord( fg )

    if bright: inc( color, 60 )

    result = "\e[" & $color & 'm' & msg & "\e[0m"

proc fetch_data( client: NetdataClient ): string =

    ## Netdata JSON backend doesn't send a length nor a separator

    ## between samples, so we read line by line and wait for stream

    ## timeout to determine what constitutes a sample.

    var buf = ""

    while true:

        try:

            client.sock.readline( buf, timeout=conf.timeout )

            if buf == "":

                if conf.debug: echo "Client {client.address} closed socket.".fmt.hl( fgRed, bright=true )

                quit( 1 )

            result = result & buf & "\n"

        except OSError:

            quit( 1 )

        except TimeoutError:

            if result == "": continue 

            return

proc parse_data( data: string ): seq[ JsonNode ] =

    ## Given a raw +data+ string, parse JSON and return a sequence

    ## of JSON samples. Netdata can buffer multiple samples in one batch.

    result = @[]

    if data == "": return

    # Hash of sample timeperiods to pivoted json data

    var pivoted_data = init_table[ BiggestInt, JsonNode ]()

    for sample in split_lines( data ):

        if sample == "": continue

        if conf.debug: echo sample.hl( fgBlack, bright=true )

        var parsed: JsonNode

        try:

            parsed = sample.parse_json

        except JsonParsingError:

            if conf.debug: echo hl( "Unable to parse sample line: " & sample.hl(fgRed, bright=true), fgRed )

            continue

        if parsed.kind != JObject: return

        # Create or use existing Json object for modded data.

        #

        var pivot: JsonNode

        try:

            let key = parsed[ "timestamp" ].get_int

            if pivoted_data.has_key( key ):

                pivot = pivoted_data[ key ]

            else:

                pivot = newJObject()

                pivoted_data[ key ] = pivot

            var name = parsed[ "chart_id" ].get_str & "." & parsed[ "id" ].get_str

            pivot[ "hostname" ] = parsed[ "hostname" ]

            pivot[ "timestamp" ] = parsed[ "timestamp" ]

            pivot[ name ] = parsed[ "value" ]

        except:

            continue

    for timestamp, sample in pivoted_data:

        result.add( sample )

proc write_to_database( client: NetdataClient, samples: seq[ JsonNode ] ): void =

    ## Given a sequence of json samples, write them to database.

    if samples.len == 0: return

    if client.db.isNil:

        client.db = open( "", "", "", conf.dbopts )

    try:

        client.db.exec sql( "BEGIN" )

        for sample in samples:

            var

                timestamp = sample[ "timestamp" ].get_int

                host = sample[ "hostname" ].get_str.to_lowerascii

            sample.delete( "timestamp" )

            sample.delete( "hostname" )

            client.db.exec sql( conf.insertsql ), timestamp, host, sample

        client.db.exec sql( "COMMIT" )

    except:

        let

            e = getCurrentException()

            msg = getCurrentExceptionMsg()

        echo "Got exception ", repr(e), " while writing to DB: ", msg

        discard

    if not conf.persistent:

        client.db.close

        client.db = nil

proc process( client: NetdataClient ): void =

    ## Do the work for a connected client within child process.

    let t0 = cpu_time()

    var raw_data = client.fetch_data

    # Done with the socket, netdata will automatically

    # reconnect.  Save local resources/file descriptors

    # by closing after the send is considered complete.

    #

    if conf.dropconn:

        try:

            client.sock.close

        except OSError:

            return

    # Pivot the parsed data to a single JSON blob per sample time.

    var samples = parse_data( raw_data )

    client.write_to_database( samples )

    if conf.verbose:

        let cputime = cpu_time() - t0

        echo(

            hl( $(epochTime().to_int), fgMagenta, bright=true ),

            " ",

            hl( $(samples.len), fgWhite, bright=true ),

            " sample(s) parsed from ",

            client.address.hl( fgYellow, bright=true ),

            " in ", hl( "{cputime:<2.3f}".fmt, fgWhite, bright=true), " seconds."

        )

proc serverloop( conf: Config ): void =

    ## Open a database connection, bind to the listening socket,

    ## and start serving incoming netdata streams.

    let db = open( "", "", "", conf.dbopts )

    db.close

    if conf.verbose: echo( "Successfully tested connection to the backend database.".hl( fgGreen ) )

    # Ensure children are properly reaped.

    #

    var sa: Sigaction

    sa.sa_handler = SIG_IGN

    discard sigaction( SIGCHLD, sa )

    # Setup listening socket.

    #

    var server = newSocket()

    server.set_sock_opt( OptReuseAddr, true )

    server.bind_addr( Port(conf.listen_port), conf.listen_addr )

    server.listen()

    if conf.verbose:

        echo(

            "Listening for incoming connections on ".hl( fgGreen, bright=true ),

            hl( (if conf.listen_addr == "0.0.0.0": "*" else: conf.listen_addr) , fgBlue, bright=true ),

            ":",

            hl( $conf.listen_port, fgBlue, bright=true ),

        )

        echo ""

    # Wait for incoming connections, fork for each client.

    #

    while true:

        let client = NetdataClient.new

        client.sock = Socket.new

        # Block, waiting for new connections.

        server.acceptAddr( client.sock, client.address )

        if fork() == 0:

            server.close

            if conf.dropconn:

                # "one shot" mode.

                client.process

                quit( 0 )

            else:

                # Keep the connection to netdata open.

                while true: client.process

        client.sock.close

        when defined( testing ): dumpNumberOfInstances()

proc parse_cmdline: Config =

    ## Populate the config object with the user's preferences.

    # Config object defaults.

    #

    result = Config(

        dbopts: "host=localhost dbname=netdata application_name=netdata-tsrelay",

        dbtable: "netdata",

        dropconn: false,

        listen_port: 14866,

        listen_addr: "0.0.0.0",

        verbose: true,

        debug: false,

        timeout: 500,

        persistent: false,

        insertsql: INSERT_SQL % [ "netdata" ]

    )

    # always set debug mode if development build.

    result.debug = defined( testing )

    for kind, key, val in getopt():

        case kind

        of cmdArgument:

            discard

        of cmdLongOption, cmdShortOption:

            case key

                of "debug", "d":

                    result.debug = true

                of "dropconn", "D":

                    if result.persistent:

                        echo "Dropping TCP sockets are incompatible with persistent database connections."

                        quit( 1 )

                    result.dropconn = true

                of "help", "h":

                    echo USAGE

                    quit( 0 )

                of "quiet", "q":

                    result.verbose = false

                of "version", "v":

                    echo hl( "netdata_tsrelay " & VERSION, fgWhite, bright=true )

                    quit( 0 )

                of "timeout", "t": result.timeout = val.parse_int

                of "dbtable", "T":

                    result.insertsql = INSERT_SQL % [ val ]

                of "dbopts", "o": result.dbopts = val

                of "listen-addr", "a": result.listen_addr = val

                of "listen-port", "p": result.listen_port = val.parse_int

                of "persistent", "P":

                    if result.dropconn:

                        echo "Persistent database connections are incompatible with dropping TCP sockets."

                        quit( 1 )

                    result.persistent = true

                else: discard

        of cmdEnd: assert( false ) # shouldn't reach here ever

when isMainModule:

    system.addQuitProc( resetAttributes )

    conf = parse_cmdline()

    if conf.debug: echo hl( $conf, fgYellow )

    serverloop( conf )