# This is the template file for Lab #4, Task #4
import numpy,random,sys
import lab4
from lab4_3 import ViterbiDecoder
# Note: Task 4 will only work if Task 3 does

class SoftViterbiDecoder(ViterbiDecoder):
    # Override the default branch metric with a soft decision metric:
    # the square of the Euclidian distance between the 
    # expected and received voltages.
    def branch_metric(self,expected,received):
        # your code here...
        pass

if __name__=='__main__':
    # Test whether branch metrics are as expected (needed for checkoff)
    if lab4.verify_task4(SoftViterbiDecoder):
        print "Branch metric test for soft decoder matches"
    else:
        print "Soft decision branch metric test failed"
        sys.exit(1)

    # This test for soft decoding produces a random message of
    # nbits=1000 in length, from a fixed random seed (so each time the
    # program is run, the same behavior will occur. We encode the
    # message and then use your soft decoder (code above) to test it.
    # If the decoded stream is the same as what we expect from our
    # encoder, we consider the test case to have passed.  Note, it is
    # possible (though not likely) that your soft decoder may not pass
    # this test case, but is in fact correct.  That's why we have not
    # made the test case part of the verification before checkoff.
    K, glist = 3, (7,6)
    soft = SoftViterbiDecoder(K, glist)
    nbits = 1000
    sigma = 0.5                # noise defined as 2*sigma^2 = 1/8
    numpy.random.seed(617617617)
    message = numpy.random.random_integers(0,1,nbits)
    expected = numpy.array([1,1,0,0,1,0,1,0,0,0,0,0,0,0,0,1,1,0,1,1,0,1,0,1,1,0,0,1,0,0,1,0,1,0,0,0,1,1,1,0,1,1,1,1,0,1,0,1,0,1,0,0,1,0,0,1,0,1,1,0,0,1,0,1,0,1,1,1,1,1,0,1,0,0,0,0,1,1,1,0,1,0,0,1,1,0,0,1,0,1,1,1,0,0,0,1,0,0,1,0,1,0,0,1,0,1,0,1,1,0,0,0,1,0,1,0,0,0,1,0,1,1,0,1,0,1,0,1,1,1,0,1,1,0,0,1,1,0,0,0,0,1,1,1,1,1,0,1,1,0,0,1,1,1,1,0,1,1,0,1,0,1,0,0,1,1,0,0,1,0,1,0,0,1,0,0,0,1,0,0,0,1,1,0,1,1,1,1,0,0,0,0,1,0,0,1,0,1,1,0,0,1,1,0,1,1,1,1,0,1,0,0,0,0,0,1,1,0,1,0,0,0,1,0,1,1,1,0,1,0,0,0,0,0,0,1,0,0,0,1,1,1,1,1,1,0,1,1,0,0,1,1,0,0,0,1,0,0,1,0,1,0,0,0,0,0,0,0,1,0,0,1,1,1,1,0,0,0,0,0,0,1,0,0,1,0,1,0,0,1,0,0,0,1,1,1,0,1,0,0,0,1,0,1,1,0,0,1,1,0,0,1,1,0,0,0,0,0,0,0,1,0,1,0,1,0,1,1,1,0,0,1,1,1,1,0,0,1,0,0,0,1,0,0,1,0,0,0,1,1,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,0,0,1,0,1,1,0,0,1,1,0,1,1,0,0,1,0,1,0,0,0,1,0,0,1,1,1,1,0,1,0,1,1,1,0,1,1,1,1,1,1,0,0,0,0,1,0,1,0,1,1,0,1,0,1,1,0,0,0,1,0,0,0,1,0,0,1,0,1,0,0,0,1,1,1,0,1,1,0,1,0,0,0,1,1,0,0,1,1,0,0,1,0,1,0,0,0,0,0,0,1,0,1,1,1,0,0,1,1,1,1,0,0,1,0,0,0,0,1,1,1,1,0,1,1,1,0,1,0,0,0,1,1,0,1,1,0,0,1,1,0,0,1,0,1,0,1,1,0,1,1,1,1,1,0,0,1,0,1,1,0,1,1,0,0,0,1,1,1,0,0,0,0,1,0,1,1,1,1,1,0,0,0,0,1,1,1,0,0,0,0,0,1,0,1,0,0,0,1,1,1,1,0,1,0,1,1,1,0,1,0,1,0,0,1,0,0,0,1,1,0,0,1,1,1,0,0,0,0,1,1,1,0,0,0,1,0,1,1,0,1,1,0,0,1,0,0,1,1,0,1,0,1,1,1,1,0,0,1,1,0,1,0,0,0,1,0,1,1,1,1,1,1,1,0,1,0,1,1,1,0,0,1,1,0,0,1,0,1,0,0,1,1,1,0,1,0,0,1,1,1,0,1,1,0,1,0,0,1,0,1,1,1,0,1,0,0,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,1,0,1,1,0,0,0,0,1,0,0,0,0,0,1,1,0,1,1,0,1,1,1,0,1,1,1,1,1,0,0,0,0,1,0,1,1,1,0,0,0,1,1,0,0,0,0,1,1,0,1,0,1,1,1,0,1,0,0,0,1,0,1,1,0,0,1,1,1,1,1,1,0,0,1,0,0,1,0,1,1,1,1,0,0,0,0,1,1,1,0,1,1,0,1,0,0,1,1,1,0,1,1,0,1,0,1,0,1,0,1,1,0,0,1,1,0,0,1,1,0,1,0,1,1,0,1,1,1,1,0,1,0,0,1,1,1,0,1,0,1,0,0,1,0,1,0,1,1,0,0,0,1,1,0,0,0,0,1,0,0,1,1,0,1,1,0,0,1,0,0,1,0,1,1,1,0,0,1,1,1,0,0,1,0,0,1,1,0,0,0,0,0,1,1,0,0,0,1,0,0,1,1,1,0,1,1,1,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,0,1,1,1,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,1,1,1,1,1,1,0,1,1,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,1,0,1,1,1,1,0,0,1,1,0,0,0,1,1])

    encoded = lab4.convolutional_encoder(message, K, glist)


    noisy = numpy.random.normal(0,sigma,len(encoded))
    received = encoded + noisy

    decoded = numpy.array(soft.decode(received))
    if (decoded == expected).all() == True:
        print 'Soft decoding succeeded on test case: congratulations!'
    else:
        print 'Oops... error in soft decoding'
        print 'Decoded as', decoded
        print 'Expected  ', expected
        sys.exit(1)

        
    # When ready for checkoff, enable the following line.
    #lab4.checkoff(SoftViterbiDecoder,task='L4_4',debug=False)