#-*- coding: UTF-8 -*-
#
# From: http://svn.python.org/projects/sandbox/trunk/decimal/telco/telco.py
# Committed by rhettinger.
#
# Background:
# ===========
#
#   http://speleotrove.com/decimal/telco.html
#
# Sanity check:
# =============
#
# Download:
#
#   http://svn.python.org/projects/sandbox/trunk/decimal/telco/telco.testb
#
# In the same directory:
#
#   python telco.py
#
# Benchmark:
# ==========
#
# Download and unzip:
#
#   http://speleotrove.com/decimal/expon180-1e6b.zip
#
# In the same directory:
#
#   python telco.py full
#

""" Telco Benchmark for measuring the performance of decimal calculations

A call type indicator, c, is set from the bottom (least significant) bit of
the duration (hence c is 0 or 1).

A r, r, is determined from the call type. Those calls with c=0 have a low r:
0.0013; the remainder (‘distance calls’) have a ‘premium’ r: 0.00894. (The
rates are, very roughly, in Euros or dollar rates per second.)

A price, p, for the call is then calculated (p=r*n). This is rounded to
exactly 2 fractional digits using round-half-even (Banker’s round to nearest).

A basic tax, b, is calculated: b=p*0.0675 (6.75%). This is truncated to
exactly 2 fractional digits (round-down), and the total basic tax variable is
then incremented (sumB=sumB+b).

For distance calls: a distance tax, d, is calculated: d=p*0.0341 (3.41%).
This is truncated to exactly 2 fractional digits (round-down), and then
the total distance tax variable is incremented (sumD=sumD+d).

The total price, t, is calculated (t=p+b, and, if a distance call, t=t+d).
The total prices variable is incremented (sumT=sumT+t).
The total price, t, is converted to a string, s.

"""

from struct import unpack
from time import perf_counter as time
from decimal import *
import sys, os, io

def benchmark(data):
    getcontext().rounding = ROUND_DOWN
    rates = list(map(Decimal, ('0.0013', '0.00894')))
    twodig = Decimal('0.01')
    Banker = Context(rounding=ROUND_HALF_EVEN)
    basictax = Decimal("0.0675")
    disttax = Decimal("0.0341")

    data_index = 0
    #infil = io.BytesIO(data)
    #outfil = io.StringIO()
    start = time()

    sumT = Decimal("0")   # sum of total prices
    sumB = Decimal("0")   # sum of basic tax
    sumD = Decimal("0")   # sum of 'distance' tax

    while 1:
        #datum = infil.read(8)
        datum = data[data_index: data_index + 8]
        data_index += 8
        if len(datum) < 8: break
        n, =  unpack('>Q', datum)

        calltype = n & 1
        r = rates[calltype]

        p = Banker.quantize(r * n, twodig)

        b = p * basictax
        b = b.quantize(twodig)
        sumB += b

        t = p + b

        if calltype:
            d = p * disttax
            d = d.quantize(twodig)
            sumD += d
            t += d

        sumT += t
        #outfil.write("%s\n" % t)

        #if test:
        #    print('%6d   %1s  |%6s %6s %6s  |%6s' % (n, 'LD'[calltype], p, b, (not calltype and " " or d), t))

    #infil.close()
    #outfil.close()
    end = time()

    #print('\nControl totals:')
    #print('Actual  ', list(map(str, (sumT, sumB, sumD))))
    #print('Expected', list(map(str, expected)))
    print('Elapsed time:', end-start)

def main():
    # To run the full test with 1,000,000 entries:  python telco.py full
    test = 'full' not in ' '.join(sys.argv[1:]).lower()

    if test:
        filename = "telco.testb"
        expected = list(map(Decimal, "8.91 0.50 0.22".split()))
        print("  Time Rate | Price   Btax   Dtax  | Output")
        print("------------+----------------------+--------")
    else:
        filename = "expon180.1e6b"
        if not os.access(filename, os.F_OK):
            print("You must download and unzip the test file from: "
                  "http://speleotrove.com/decimal/expon180-1e6b.zip")
            sys.exit(-1)
        expected = list(map(Decimal, "1004737.58 57628.30 25042.17".split()))

    with open(filename, "rb") as fp:
        data = fp.read()


    for run in range(5):
        benchmark(data)
    print("")
    os.system("grep -E -i 'cpu|ctx' /proc/%s/status" % os.getpid())

if __name__ == "__main__":
    main()