decrypt-freddie.py

# https://www.youtube.com/watch?v=3L-rrkyvApU :)

text = """
Ysq xaxrvl! W zsix yfi dmdxd kvaw obdvcl! A'q oxrp jwvr loifq xatt pcm wixnk mgyk mids uvtvkzby xabs, sil xabs yok rhmhzby xh wo nwll tgy ldusfbnx Jspox picvyvms. Zh'k nnlt fz'Xvxwdzs Osgz bvwfk t mokod ntvkrgkl!

Xbfe zg ksfxtywfk rhu nwdp gxvvf yim uaty, ks ahpvtmper yfi zew t lriyl hk tncl!

Tym aep rmhx, bf pcm'vx mhv tavlm tf qjevd tywk, wxgd ds s ChnTlpw qxlsruw abmh kvw takajs: "Xvxwdzs qsn trv o bikd aer A atgt dm lmfx brqc" egw I'cz zshd yfi mt pbty ggqxmhzby. Em lods hsbgt.

Sm llx pap, Gsq'l poiyarz hn fij rxqt gfgnxvt kvwvx hn ywk ghfplhwv, bgsgwjiw uy Rqlmobszcf'w kxcvbl evmimwlc. Dxeg of irx olh

Kmgveisdc, Ykeurai, Ukaergr, tgd Dolxaxw, kvw ghhlvgl hnwej cf xax iehwvgxt. 
"""

alphabet = "abcdefghijklmnopqrstuvwxyz"
double = alphabet * 2

def shift_by(char, idx):
        return double[alphabet.index(char) + idx]

shifts = (9, 12, 8, 22, 7, 7, 0)

if __name__ == "__main__":
        i = 0
        decrypted = []
        for x, c in enumerate(text):
                if len(text) > x+1 and text[x+1] == "!": # pull a char every exclam
                        continue
                char = c.lower()
                if char not in alphabet:
                        decrypted.append(c)
                        continue

                if i == len(shifts):
                        i = 0
                shift = shifts[i]
                i += 1
                if shift == -1:
                        continue
                decrypted.append(shift_by(char, shift))
        print "".join(decrypted)