import tkinter as tk
import math


class CrashGui:
    MINS = 4**5
    MAXS = 4**21
    
    def __init__(self, parms=None):
        self.root = tk.Tk()
        self.root.title("Crash")
        vcmd = (self.root.register(self.validate_spin), '%W', '%P')

        self.frame = tk.Frame(self.root, borderwidth=0, relief=tk.RIDGE, bg="white")
        self.frame.pack(fill=tk.BOTH, expand=1)
        
        self.c1 = tk.Frame(self.frame, bg="white")
        self.c1.pack(fill=tk.X, expand=1)
        
        self.vara = tk.StringVar()
        self.vara.set(2)
        self.spina = tk.Spinbox(self.c1, justify="right", width=4, bd=2,
                                      from_=0, to=21, textvariable=self.vara)
        self.spina.config(validate="key", validatecommand=vcmd)
        self.spina.grid(row=0, column=0, sticky="w")

        self.varb = tk.StringVar()
        self.varb.set(6)
        self.spinb = tk.Spinbox(self.c1, justify="right", width=4, bd=2,
                                      from_=0, to=21, textvariable=self.varb)
        self.spinb.config(validate="key", validatecommand=vcmd)
        self.spinb.grid(row=1, column=0, sticky="w")


        
    def validate_spin(self, name, new_val):
        widget = self.root.nametowidget(name)
        try:
            vda = int(self.spina.get() if widget==self.spinb else new_val)
            vdb = int(self.spinb.get() if widget==self.spina else new_val)
            valid = vdb <= 21 and vda <= 21
            if valid:
                if widget == self.spina:
                    f = max(0, math.ceil(math.log2(self.MINS/(4**vda))))
                    t = min(21, math.floor(math.log2(self.MAXS/(4**vda))))
                    self.spinb.config(validate=None)
                    self.varb.set(min(max(vdb,f),t))
                    self.spinb.config(validate="key")
                else:
                    f = max(0, math.ceil(math.log2(self.MINS/(2**vdb))/2))
                    t = min(21, math.floor(math.log2(self.MAXS/(2**vdb))/2))
                    self.spina.config(validate=None)
                    self.vara.set(min(max(vda,f),t))
                    self.spina.config(validate="key")

        except ValueError:
            valid = False

        return valid

if __name__ == "__main__":
    CrashGui()
    tk.mainloop()