from math import sin, cos, pi
from colorama import Fore,Back,Style
from time import sleep
from random import randint
import argparse

#command line arg stuff
desc="Displays an ASCII art strand of DNA, because why not?"
epi="""Protip: to watch an animated strand of ASCII DNA scroll across the screen,
set length to a really large number and pause to a reasonable number like 50 
or 100 milliseconds. Enjoy!"""
parser=argparse.ArgumentParser(description=desc, epilog=epi)
parser.add_argument("-l", "--length", type=int, help="Changes the length of the ASCII DNA. Default = 40")
parser.add_argument("-p", "--pause", type=int, help="Number of milliseconds to pause after plotting each line. Default=0")
parser.add_argument("-b", "--block", action="store_true", help="Display using block characters instead of letters. Default=False")
args=parser.parse_args()

if args.length: length=args.length
else: length=40

if args.pause: pause=args.pause
else: pause=0

if args.block:
    chars={"x":"█","a":"█","t":"█","g":"█","c":"█"}
else:
    chars={"x":"X","a":"A","t":"T","g":"G","c":"C"}

#define and initialize stuff
class DnaStrand:
    def __init__(self, char, func):
        self.char=char
        self.func=func
    def pos(self,x):
        return int(self.func(x))
    def getchar(self): return self.char

width = 20
blank=[]
lin=[]
theta=0
basecount=2
step=pi/12

bluchar=Fore.BLUE+chars["x"]+Fore.WHITE
blustrand=DnaStrand(bluchar, lambda x: (width/2-1)*(sin(x)+1))
redchar=Fore.RED+chars["x"]+Fore.WHITE
redstrand=DnaStrand(redchar, lambda x: (width/2-1)*(cos(x)+1))

a=Fore.YELLOW+chars["a"]+Fore.WHITE
t=Fore.WHITE+chars["t"]+Fore.WHITE
g=Fore.GREEN+chars["g"]+Fore.WHITE
c=Fore.CYAN+chars["c"]+Fore.WHITE
msg="tilde.club"
for i in range (width):
    blank.append(" ")
  

#Draw
for i in range(length):
    lin=blank.copy()
    blupos=blustrand.pos(theta)
    redpos=redstrand.pos(theta)
    lin[blupos]=blustrand.getchar()
    lin[redpos]=redstrand.getchar()

    if basecount%3==0 and abs(blupos-redpos) > 3:
        bp=randint(1,4)
        if bp==1:bp1,bp2=a,t
        elif bp==2:bp1,bp2=t,a
        elif bp==3:bp1,bp2=g,c
        else:bp1,bp2=c,g
        halfway=int(abs(blupos+redpos)/2)
        start=min(redpos,blupos)+1
        end=max(redpos,blupos)
        lin[start:halfway]=[bp1]*abs(halfway-start)
        lin[halfway:end]=[bp2]*abs(end-halfway)
        tc=randint(1,5)
        if tc==5 and end-start > len (msg):
            lin[start:start+len(msg)]=list(msg)

    print("".join(lin))
    theta += step
    basecount+=1
    sleep(pause/1000)