import datetime
from tkinter import *
from time import *

def show_time():
    strt.set(strftime('%H:%M:%S'))
    root.after(1000, show_time)

def WHATDAY(yy,mm,dd):
    #***********************************
    # Zeller's congruence
    #***********************************
    # int_day=1 to 7 => Mon to Sun
    cc=int(yy/100)
    pp=dd+int(26*(mm+1)/10)+int(yy%100)+int((yy%100)/4)+(5*cc+int(cc/4))+5
    int_day=int(pp%7)+1
    return int_day

def LEAP_YEAR(yy):
    LEAP_YEAR=0
    if yy%400==0 or (yy%4==0 and yy%100!=0): LEAP_YEAR=1
    return LEAP_YEAR

def CALC(yy,mm,dd,ddate):
    m_days=[31,28,31,30,31,30,31,31,30,31,30,31]
    cal=[[0]*7 for i in range(0,6)]
    yc=yy
    mc=mm
    if mm==1: yc=yy-1; mc=13
    if mm==2: yc=yy-1; mc=14
    int_day=WHATDAY(yc,mc,dd)
    ly=LEAP_YEAR(yy)
    if ly==1 and mm==2: m_days[1]=29
    if ly==0 and (mc==14 and dd==29):
        print('Date inputted is invalid!')
    ir=-1
    ic=-1
    k=0
    for i in range(1,m_days[mm-1]+1):
        int_day=WHATDAY(yc,mc,i)
        cal[k][int(int_day)-1]=i
        if ddate.year==yy and ddate.month==mm and ddate.day==i: ir=k; ic=int(int_day)-1
        if int_day==7: k=k+1
    nw=5
    if cal[5][0]!=0: nw=6
    return nw,cal,ir,ic

def CH_L():
    global yi,mi,yd,md,dm,t2,t3
    dm=dm-1
    md=int((mi+dm)%12)
    if md==0: md=12
    dy=(mi+dm)//12
    if int((mi+dm)%12)==0: dy=dy-1
    yd=yi+dy
    t2.destroy()
    t3.destroy()
    DRAW_T2()
    DRAW_T3()

def CH_R():
    global yi,mi,yd,md,dm,t2,t3
    dm=dm+1
    md=int((mi+dm)%12)
    if md==0: md=12
    dy=(mi+dm)//12
    if int((mi+dm)%12)==0: dy=dy-1
    yd=yi+dy
    t2.destroy()
    t3.destroy()
    DRAW_T2()
    DRAW_T3()

def CH_C():
    global yi,mi,yd,md,dm,t2
    d=datetime.datetime.today()
    yi=d.year
    mi=d.month
    dm=0
    yd=yi
    md=mi
    t2.destroy()
    t3.destroy()
    DRAW_T2()
    DRAW_T3()

def DRAW_T2():
    global yd,md,t2
    ddate=datetime.datetime.today()
    t2=Frame(root,bg='#ffffff')
    t2.pack(side=TOP,fill=BOTH)
    hh=yd-2000+12
    m_list=['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']
    w_list=['M','T','W','T','F','S','S']
    colbg1=['#ffffff','#ffffff','#ffffff','#ffffff','#ffffff','#0000ff','#ff0000']
    colfg1=['#000000','#000000','#000000','#000000','#000000','#ffffff','#ffffff']
    colbg2=['#ffffff','#ffffff','#ffffff','#ffffff','#ffffff','#ffffff','#ffffff']
    colfg2=['#000000','#000000','#000000','#000000','#000000','#0000ff','#ff0000']
    col1='#ffffdd'
    col2='#000088'
    str2=m_list[md-1]+' '+str(yd)+'  (H'+str(hh)+')'
    Label(t2,text=str2,bg=col1,fg=col2,font='consolas 12 bold',relief=FLAT).grid(row=1,column=0,columnspan=7,sticky=W+E)
    for c in range(7):
        col1=colbg1[c]
        col2=colfg1[c]
        str3=w_list[c]
        Label(t2, text=str3, bg=col1, fg=col2,font='consolas 10 bold',relief=FLAT,bd=0).grid(row=2,column=c,padx=0,pady=0)
    nw,cal,ir,ic=CALC(yd,md,1,ddate)
    for r in range(nw):
        for c in range(7):
            col1=colbg2[c]
            col2=colfg2[c]
            if cal[r][c]==0: str4='  '
            else: str4='{0:2d}'.format(cal[r][c])
            if 0<=ir and 0<=ic:
                if r==ir and c==ic: col1='#808000'; col2='#ffffff'
            Label(t2, text=str4, bg=col1, fg=col2,font='consolas 12 bold',relief=FLAT,bd=0).grid(row=r+3,column=c,padx=0,pady=0)
    del m_list,w_list,colbg1,colbg2,colfg1,colfg2,cal

def DRAW_T3():
    global t3
    t3=Frame(root,bg='#eeeeee')
    t3.pack(side=TOP,fill=BOTH)
    Label(t3,textvariable=strt,bg='#eeeeee',fg='#000000',font='consolas 14 bold').pack(side=BOTTOM,fill=BOTH)
    show_time()

#Main routine
d=datetime.datetime.today()
yi=d.year
mi=d.month
dm=0
yd=yi
md=mi

root=Tk()
t1=Frame(root,bg='#eeeeee')
t1.pack(side=TOP,fill=BOTH)
strt=StringVar()
strt.set('')
strd=StringVar()
strd.set(strftime('%d %b %Y'))
Button(t1,text = '<',bg='#eeeeee',fg='#000000',font='consolas 11 bold',command = CH_L).pack(side=LEFT)
Button(t1,textvariable=strd,bg='#eeeeee',fg='#000000',font='consolas 11 bold',width=12,command=CH_C).pack(side=LEFT,fill=X)
Button(t1,text = '>',bg='#eeeeee',fg='#000000',font='consolas 11 bold',command = CH_R).pack(side=RIGHT)
DRAW_T2()
DRAW_T3()

root.mainloop( )