import sys
import csv
import numpy

numpak_r1_rtts_path = "../../data/rtt/numpak/r1.csv"
numpak_r1_estrtts_path = "../../data/rtt/numpak/r1est.csv"

def readsamepleRTTs(datapath):
    sampleRTT = []
    with open(datapath, mode='r') as csv_file:
        csv_reader = csv.DictReader(csv_file)
        for row in csv_reader:
            # apply a sane filter
            if (row['tcp.analysis.ack_rtt'] != ""):
                sampleRTT.append( (int(row['frame.number']), float(row['tcp.analysis.ack_rtt'])) )
    csv_file.close()
    return sampleRTT

def writeestRTTs(datapath, samples, estimates):
    with open(datapath, mode='w') as csv_file:
        csv_writer = csv.writer(csv_file, delimiter=",")
        for i, sample in enumerate(samples):
            csv_writer.writerow([ sample[0], sample[1], estimates[i] ])
    csv_file.close()
    return 0

def calcEST(samples):
    ests = []
    K = 4
    G = 0.1 # =100 msec
    alpha = 1/8.0
    beta = 1/4.0

    # (2.1) of rtc6298
    RTO = 1.0
    counter = 1
    for sample in samples:
        R = sample[1]
        # (2.2) of rtc6298
        if counter == 1:
            SRTT = R
            RTTVAR = R / 2.0
        # (2.3) of rtc6298
        else:
            RTTVAR = (1.0 - beta) * RTTVAR + beta * abs(SRTT - R)
            SRTT = (1.0 - alpha) * SRTT + alpha * R

        RTO = SRTT + max(G, K * RTTVAR)
        # (2.4) of rtc6298
        RTO = max(1.0, RTO)
        ests.append(SRTT)
        counter += 1
    return ests

# get the csv data into array
numpak_r1_rtts = readsamepleRTTs(numpak_r1_rtts_path)
# calcuate estimates
numpak_r1_ets  = calcEST(numpak_r1_rtts)
# write everything to csv
writeestRTTs(numpak_r1_estrtts_path, numpak_r1_rtts, numpak_r1_ets)
print("done")