class GPSD2JSON

# File lib/gpsd2json.rb, line 21
def initialize(host: 'localhost', port: 2947)
    @socket = nil
    @socket_ready = false
    @host = host
    @port = port
    @trackthread = nil
    @socket_init_thread = nil
    @min_speed = 0 # speed needs to be higher than this to make the gps info count
    @last = nil #last gps info
    @sats = nil # last satellites info
    @json_raw_callback = nil
    @json_pos_callback = nil
    @json_sat_callback = nil
end

# File lib/gpsd2json.rb, line 55
def change_min_speed(speed:)
    @min_speed = speed
end

# File lib/gpsd2json.rb, line 200
def close_socket
    begin
        if @socket
            @socket.puts '?WATCH={"enable":false}'
            @socket.close
        end
        @socket = nil
    rescue
        puts "#$!" if VERBOSE
    end
end

# File lib/gpsd2json.rb, line 108
def init_socket
    begin
        puts "init_socket" if VERBOSE
        close_socket if @socket
        @socket = TCPSocket.new(@host, @port)
        @socket.puts("w+")
        puts "reading socket..." if VERBOSE
        welkom = ::JSON.parse(@socket.gets)
        puts "welkom: #{welkom.inspect}" if VERBOSE
        @socket_ready = (welkom and welkom['class'] and welkom['class'] == 'VERSION')
        puts "@socket_ready: #{@socket_ready.inspect}" if VERBOSE
    rescue
        @socket_ready = false
        puts "#$!" if VERBOSE
    end
end

# File lib/gpsd2json.rb, line 191
def is_new_measurement(json:)
    if @last.nil? or (@last['lat'] != json['lat'] and @last['lon'] != json['lon'] and json['speed'] >= @min_speed)
        @last = json
        return true
    end
    return false
end

# File lib/gpsd2json.rb, line 44
def on_position_change(options:{}, &block)
    @json_pos_callback = block
end

# File lib/gpsd2json.rb, line 38
def on_raw_change(options:{}, &block)
    @json_raw_callback = block
end

# File lib/gpsd2json.rb, line 50
def on_satellites_change(options:{}, &block)
    @json_sat_callback = block
end

# File lib/gpsd2json.rb, line 145
def parse_socket_json(json:)
    case json['class']
    when 'DEVICE', 'DEVICES'
        # devices that are found, not needed
    when 'WATCH'
        # gps deamon is ready and will send other packets, not needed yet
    when 'TPV'
        # gps position
        #  "tag"=>"RMC", #  "device"=>"/dev/ttyS0", #  "mode"=>3,
        #  "time"=>"2017-11-28T12:54:54.000Z", #  "ept"=>0.005, #  "lat"=>52.368576667,
        #  "lon"=>4.901715, #  "alt"=>-6.2, #  "epx"=>2.738, #  "epy"=>3.5,
        #  "epv"=>5.06, #  "track"=>198.53, #  "speed"=>0.19, #  "climb"=>0.0,
        #  "eps"=>7.0, #  "epc"=>10.12
        if json['mode'] > 1
           #we have a 2d or 3d fix
            if is_new_measurement(json: json)
                json['time'] = DateTime.parse(json['time'])
                puts "lat: #{json['lat']}, lng: #{json['lon']}, alt: #{json['alt']}, speed: #{json['speed']} at #{json['time']}, which is #{(Time.now - json['time'].to_time) * 1000}ms old" if VERBOSE
                @json_pos_callback.call(json) if @json_pos_callback
            end
        end
    when 'SKY'
        # report on found satellites
        sats = json['satellites']
        if satellites_changed(sats: sats)
            puts "found #{sats.length} satellites, of which #{sats.count{|sat| sat['used']}} are used" if VERBOSE
            @json_sat_callback.call(sats) if @json_sat_callback
        end
    else
        puts "hey...found unknow tag: #{json.inspect}" if VERBOSE
    end
    @json_raw_callback.call(json) if @json_raw_callback
end

# File lib/gpsd2json.rb, line 126
def read_from_socket
    if @socket_ready
        begin
            if input = @socket.gets.chomp and not input.to_s.empty?
                parse_socket_json(json: JSON.parse(input))
            else
                sleep 0.1
            end
        rescue
            puts "error reading from socket: #{$!}" if VERBOSE
        end
    else
        sleep 0.1
    end
end

# File lib/gpsd2json.rb, line 181
def satellites_changed(sats:)
    if @sats.nil? or (@sats.length != sats.length or @sats.count{|sat| sat['used']} != sats.count{|sat| sat['used']})
        @sats = sats
        return true
    end
    return false
end

# File lib/gpsd2json.rb, line 60
def start
    # background thread that is used to open the socket and wait for it to be ready
    @socket_init_thread = Thread.start do
        #open the socket
        while not @socket_ready
            init_socket
            #wait for it to be ready
            sleep 0.1
        end
        # it's ready, tell it to start watching and passing
        puts "socket ready, start watching" if VERBOSE
        @socket.puts '?WATCH={"enable":true,"json":true}'
    end

    # background thead that is used to read info from the socket and use it
    @trackthread = Thread.start do
        while true do
            begin
                read_from_socket
            rescue
                "error while reading socket: #{$!}" if VERBOSE
            end
        end
    end
end

# File lib/gpsd2json.rb, line 96
def stop
    # last read(s)
    3.times { read_from_socket }
    # then close
    close_socket
    # then cleanup
    Thread.kill(@socket_init_thread) if @socket_init_thread
    Thread.kill(@trackthread) if @trackthread
    @socket_ready = false
end

# File lib/gpsd2json.rb, line 87
def to_status
    return "lat: #{last['lat']}, lng: #{last['lon']}, speed:#{last['speed']}, sats: #{@sats.length}(#{@sats.count{|sat| sat['used']}})" if @socket_ready and @last and @sats
    return "lat: #{last['lat']}, lng: #{last['lon']}, speed:#{last['speed']}" if @socket_ready and @last and @sats.nil?
    return "sats: #{@sats.length}(#{@sats.count{|sat| sat['used']}}), no fix yet" if @socket_ready and @last.nil? and @sats
    return "connected with gpsd, waiting for data" if @socket_ready
    return "waiting for connection with gpsd" if @socket_ready == false
end