# -*- coding: utf-8 -*- 
import calendar
import tkinter as tk
import tkinter.font as tkFont
from tkinter import ttk

datetime = calendar.datetime.datetime
timedelta = calendar.datetime.timedelta

class Calendar:

  def __init__(s, point = None, position = None):
    # point  提供一个基点，来确定窗口位置
    # position 窗口在点的位置 'ur'-右上, 'ul'-左上, 'll'-左下, 'lr'-右下
    #s.master = tk.Tk()
    s.master = tk.Toplevel()
    s.master.withdraw()
    fwday = calendar.SUNDAY

    year = datetime.now().year
    month = datetime.now().month
    locale = None
    sel_bg = '#ecffc4'
    sel_fg = '#05640e'

    s._date = datetime(year, month, 1)
    s._selection = None # 设置为未选中日期

    s.G_Frame = ttk.Frame(s.master)

    s._cal = s.__get_calendar(locale, fwday)

    s.__setup_styles()    # 创建自定义样式
    s.__place_widgets()   # pack/grid 小部件
    s.__config_calendar()  # 调整日历列和安装标记
    # 配置画布和正确的绑定，以选择日期。
    s.__setup_selection(sel_bg, sel_fg)

    # 存储项ID，用于稍后插入。
    s._items = [s._calendar.insert('', 'end', values='') for _ in range(6)]

    # 在当前空日历中插入日期
    s._update()

    s.G_Frame.pack(expand = 1, fill = 'both')
    s.master.overrideredirect(1)
    s.master.update_idletasks()
    width, height = s.master.winfo_reqwidth(), s.master.winfo_reqheight()
    if point and position:
      if  position == 'ur': x, y = point[0], point[1] - height
      elif position == 'lr': x, y = point[0], point[1]
      elif position == 'ul': x, y = point[0] - width, point[1] - height
      elif position == 'll': x, y = point[0] - width, point[1]
    else: x, y = (s.master.winfo_screenwidth() - width)/2, (s.master.winfo_screenheight() - height)/2
    s.master.geometry('%dx%d+%d+%d' % (width, height, x, y)) #窗口位置居中
    s.master.after(300, s._main_judge)
    s.master.deiconify()
    s.master.focus_set()
    s.master.wait_window() #这里应该使用wait_window挂起窗口，如果使用mainloop,可能会导致主程序很多错误

  def __get_calendar(s, locale, fwday):
    # 实例化适当的日历类
    if locale is None:
      return calendar.TextCalendar(fwday)
    else:
      return calendar.LocaleTextCalendar(fwday, locale)

  def __setitem__(s, item, value):
    if item in ('year', 'month'):
      raise AttributeError("attribute '%s' is not writeable" % item)
    elif item == 'selectbackground':
      s._canvas['background'] = value
    elif item == 'selectforeground':
      s._canvas.itemconfigure(s._canvas.text, item=value)
    else:
      s.G_Frame.__setitem__(s, item, value)

  def __getitem__(s, item):
    if item in ('year', 'month'):
      return getattr(s._date, item)
    elif item == 'selectbackground':
      return s._canvas['background']
    elif item == 'selectforeground':
      return s._canvas.itemcget(s._canvas.text, 'fill')
    else:
      r = ttk.tclobjs_to_py({item: ttk.Frame.__getitem__(s, item)})
      return r[item]

  def __setup_styles(s):
    # 自定义TTK风格
    style = ttk.Style(s.master)
    arrow_layout = lambda dir: (
      [('Button.focus', {'children': [('Button.%sarrow' % dir, None)]})]
    )
    style.layout('L.TButton', arrow_layout('left'))
    style.layout('R.TButton', arrow_layout('right'))

  def __place_widgets(s):
    # 标头框架及其小部件
    Input_judgment_num = s.master.register(s.Input_judgment) # 需要将函数包装一下，必要的
    hframe = ttk.Frame(s.G_Frame)
    gframe = ttk.Frame(s.G_Frame)
    bframe = ttk.Frame(s.G_Frame)
    hframe.pack(in_=s.G_Frame, side='top', pady=5, anchor='center')
    gframe.pack(in_=s.G_Frame, fill=tk.X, pady=5)
    bframe.pack(in_=s.G_Frame, side='bottom', pady=5)

    lbtn = ttk.Button(hframe, style='L.TButton', command=s._prev_month)
    lbtn.grid(in_=hframe, column=0, row=0, padx=12)
    rbtn = ttk.Button(hframe, style='R.TButton', command=s._next_month)
    rbtn.grid(in_=hframe, column=5, row=0, padx=12)
    
    s.CB_year = ttk.Combobox(hframe, width = 5, values = [str(year) for year in range(datetime.now().year, datetime.now().year-11,-1)], validate = 'key', validatecommand = (Input_judgment_num, '%P'))
    s.CB_year.current(0)
    s.CB_year.grid(in_=hframe, column=1, row=0)
    s.CB_year.bind('<KeyPress>', lambda event:s._update(event, True))
    s.CB_year.bind("<<ComboboxSelected", s._update)
    tk.Label(hframe, text = '年', justify = 'left').grid(in_=hframe, column=2, row=0, padx=(0,5))

    s.CB_month = ttk.Combobox(hframe, width = 3, values = ['%02d' % month for month in range(1,13)], state = 'readonly')
    s.CB_month.current(datetime.now().month - 1)
    s.CB_month.grid(in_=hframe, column=3, row=0)
    s.CB_month.bind("<<ComboboxSelected", s._update)
    tk.Label(hframe, text = '月', justify = 'left').grid(in_=hframe, column=4, row=0)

    # 日历部件
    s._calendar = ttk.Treeview(gframe, show='', selectmode='none', height=7)
    s._calendar.pack(expand=1, fill='both', side='bottom', padx=5)

    ttk.Button(bframe, text = "确 定", width = 6, command = lambda: s._exit(True)).grid(row = 0, column = 0, sticky = 'ns', padx = 20)
    ttk.Button(bframe, text = "取 消", width = 6, command = s._exit).grid(row = 0, column = 1, sticky = 'ne', padx = 20)
    
    
    tk.Frame(s.G_Frame, bg = '#565656').place(x = 0, y = 0, relx = 0, rely = 0, relwidth = 1, relheigh = 2/200)
    tk.Frame(s.G_Frame, bg = '#565656').place(x = 0, y = 0, relx = 0, rely = 198/200, relwidth = 1, relheigh = 2/200)
    tk.Frame(s.G_Frame, bg = '#565656').place(x = 0, y = 0, relx = 0, rely = 0, relwidth = 2/200, relheigh = 1)
    tk.Frame(s.G_Frame, bg = '#565656').place(x = 0, y = 0, relx = 198/200, rely = 0, relwidth = 2/200, relheigh = 1)

  def __config_calendar(s):
    # cols = s._cal.formatweekheader(3).split()
    cols = ['日','一','二','三','四','五','六']
    s._calendar['columns'] = cols
    s._calendar.tag_configure('header', background='grey90')
    s._calendar.insert('', 'end', values=cols, tag='header')
    # 调整其列宽
    font = tkFont.Font()
    maxwidth = max(font.measure(col) for col in cols)
    for col in cols:
      s._calendar.column(col, width=maxwidth, minwidth=maxwidth,
        anchor='center')

  def __setup_selection(s, sel_bg, sel_fg):
    def __canvas_forget(evt):
      canvas.place_forget()
      s._selection = None

    s._font = tkFont.Font()
    s._canvas = canvas = tk.Canvas(s._calendar, background=sel_bg, borderwidth=0, highlightthickness=0)
    canvas.text = canvas.create_text(0, 0, fill=sel_fg, anchor='w')

    canvas.bind('<Button-1>', __canvas_forget)
    s._calendar.bind('<Configure>', __canvas_forget)
    s._calendar.bind('<Button-1>', s._pressed)

  def _build_calendar(s):
    year, month = s._date.year, s._date.month

    # update header text (Month, YEAR)
    header = s._cal.formatmonthname(year, month, 0)

    # 更新日历显示的日期
    cal = s._cal.monthdayscalendar(year, month)
    for indx, item in enumerate(s._items):
      week = cal[indx] if indx < len(cal) else []
      fmt_week = [('%02d' % day) if day else '' for day in week]
      s._calendar.item(item, values=fmt_week)

  def _show_select(s, text, bbox):
    """为新的选择配置画布。"""
    x, y, width, height = bbox

    textw = s._font.measure(text)

    canvas = s._canvas
    canvas.configure(width = width, height = height)
    canvas.coords(canvas.text, (width - textw)/2, height / 2 - 1)
    canvas.itemconfigure(canvas.text, text=text)
    canvas.place(in_=s._calendar, x=x, y=y)

  def _pressed(s, evt = None, item = None, column = None, widget = None):
    """在日历的某个地方点击。"""
    if not item:
      x, y, widget = evt.x, evt.y, evt.widget
      item = widget.identify_row(y)
      column = widget.identify_column(x)

    if not column or not item in s._items:
      # 在工作日行中单击或仅在列外单击。
      return

    item_values = widget.item(item)['values']
    if not len(item_values): # 这个月的行是空的。
      return

    text = item_values[int(column[1]) - 1]
    if not text: # 日期为空
      return

    bbox = widget.bbox(item, column)
    if not bbox: # 日历尚不可见
      s.master.after(20, lambda : s._pressed(item = item, column = column, widget = widget))
      return

    # 更新，然后显示选择
    text = '%02d' % text
    s._selection = (text, item, column)
    s._show_select(text, bbox)

  def _prev_month(s):
    """更新日历以显示前一个月。"""
    s._canvas.place_forget()
    s._selection = None

    s._date = s._date - timedelta(days=1)
    s._date = datetime(s._date.year, s._date.month, 1)
    s.CB_year.set(s._date.year)
    s.CB_month.set(s._date.month)
    s._update()

  def _next_month(s):
    """更新日历以显示下一个月。"""
    s._canvas.place_forget()
    s._selection = None

    year, month = s._date.year, s._date.month
    s._date = s._date + timedelta(
      days=calendar.monthrange(year, month)[1] + 1)
    s._date = datetime(s._date.year, s._date.month, 1)
    s.CB_year.set(s._date.year)
    s.CB_month.set(s._date.month)
    s._update()

  def _update(s, event = None, key = None):
    """刷新界面"""
    if key and event.keysym != 'Return': return
    year = int(s.CB_year.get())
    month = int(s.CB_month.get())
    if year == 0 or year > 9999: return
    s._canvas.place_forget()
    s._date = datetime(year, month, 1)
    s._build_calendar() # 重建日历

    if year == datetime.now().year and month == datetime.now().month:
      day = datetime.now().day
      for _item, day_list in enumerate(s._cal.monthdayscalendar(year, month)):
        if day in day_list:
          item = 'I00' + str(_item + 2)
          column = '#' + str(day_list.index(day)+1)
          s.master.after(100, lambda :s._pressed(item = item, column = column, widget = s._calendar))

  def _exit(s, confirm = False):
    """退出窗口"""
    if not confirm: s._selection = None
    s.master.destroy()

  def _main_judge(s):
    """判断窗口是否在最顶层"""
    try:
      #s.master 为 TK 窗口
      #if not s.master.focus_displayof(): s._exit()
      #else: s.master.after(10, s._main_judge)

      #s.master 为 toplevel 窗口
      if s.master.focus_displayof() == None or 'toplevel' not in str(s.master.focus_displayof()): s._exit()
      else: s.master.after(10, s._main_judge)
    except:
      s.master.after(10, s._main_judge)

    #s.master.tk_focusFollowsMouse() # 焦点跟随鼠标

  def selection(s):
    """返回表示当前选定日期的日期时间。"""
    if not s._selection: return None

    year, month = s._date.year, s._date.month
    return str(datetime(year, month, int(s._selection[0])))[:10]

  def Input_judgment(s, content):
    """输入判断"""
    # 如果不加上==""的话，就会发现删不完。总会剩下一个数字
    if content.isdigit() or content == "":
      return True
    else:
      return False

if __name__ == '__main__':
  root = tk.Tk()

  width, height = root.winfo_reqwidth() + 50, 50 #窗口大小
  x, y = (root.winfo_screenwidth() - width )/2, (root.winfo_screenheight() - height)/2
  root.geometry('%dx%d+%d+%d' % (width, height, x, y )) #窗口位置居中

  date_str = tk.StringVar()
  date = ttk.Entry(root, textvariable = date_str)
  date.place(x = 0, y = 0, relx = 5/20, rely = 1/6, relwidth = 14/20, relheigh = 2/3)

  #Calendar((x, y), 'ur').selection() 获取日期，x,y为点坐标
  date_str_gain = lambda: [
    date_str.set(date)
    for date in [Calendar((x, y), 'ur').selection()] 
    if date]
  tk.Button(root, text = '日期:', command = date_str_gain).place(x = 0, y = 0, relx = 1/20, rely = 1/6, relwidth = 4/20, relheigh = 2/3)
  root.mainloop()