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+__pycache__/
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+# README for agenda
+This small python project uses [python3-caldav](https://github.com/python-caldav/caldav) to connect to my calendar, and then generates a summary agenda for my day. It is very basic, but it gets my job done. I use this in a cron job to send an email to myself before the day starts. I always check email, but I apparently forget to check my calendar.
+
+## Upstream
+This project's upstream is at <https://bgstack15.ddns.net/cgit/agenda>.
+
+## Alternatives
+None researched. There's a million ways to get a summary of your day in any calendaring program.
+
+## Reason for existence
+For myself.
+
+## Using
+Only a basic library exists; no frontend exists. In an interactive python3 shell, you would run:
+
+    import importlib, agenda
+    print(agenda.summarize("2023-05-17",url="https://example.com/radicale/",username="bgstack15",password="plaintext"))
+
+You can also pass a datetime.datetime or datetime.date object instead of a `YYYY-MM-DD` string.
+
+## Dependencies
+
+* python3-caldav
+
+## Building
+None
+
+## References
+See references heading in the [file](agenda.py).
diff --git a/agenda.py b/agenda.py
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+#!/usr/bin/env python3
+# File: agenda.py
+# Location: https://bgstack15.ddns.net/cgit/agenda
+# Author: bgstack15
+# Startdate: 2023-05-16-3 14:09
+# Title: Generate daily agenda html message
+# Purpose: remind myself of what is happening today
+# History:
+# Usage: See function summarize()
+# Reference:
+#    1. basic_usage_examples.py from caldav
+#    2. https://stackoverflow.com/questions/29643352/converting-hex-to-rgb-value-in-python
+#    3. https://stackoverflow.com/questions/3942878/how-to-decide-font-color-in-white-or-black-depending-on-background-color
+# Improve:
+# Dependencies:
+#    python3-caldav
+
+import sys, caldav
+from datetime import date, datetime, timedelta
+
+def get_calendar_color(calendar):
+   """
+   Author: bgstack15
+   Purpose: return the hexadecimal color (and alpha channel if present) for the given caldav calendar.
+   """
+   color = prop = None
+   try:
+      colorprop = caldav.elements.ical.CalendarColor()
+      prop = calendar.get_properties(props=[colorprop])
+      if prop:
+         for j in prop:
+            # only the one
+            color = prop[j]
+   except Exception as e:
+      print(f"Debug: no color info available for calendar {calendar}, e: {e}")
+   return color
+
+def print_calendars_demo(calendars):
+   """
+   This example prints the name and URL for every calendar on the list
+   """
+   if calendars:
+      ## Some calendar servers will include all calendars you have
+      ## access to in this list, and not only the calendars owned by
+      ## this principal.
+      print("your principal has %i calendars:" % len(calendars))
+      for c in calendars:
+         color = get_calendar_color(c)
+         print("Name: %-36s Color: %-9s URL: %s" % (c.name, color, c.url))
+   else:
+      print("your principal has no calendars")
+
+def show_event(event):
+   response = ""
+   all_dtstart_dt = []
+   all_dtstart_str_dt = []
+   #print(event.data)
+   #for i in event.icalendar_component:
+   #   print(f"{i} IS {event.icalendar_component[i]}")
+   dtstart = event.icalendar_component["DTSTART"]
+   dtstart_dt = dtstart and dtstart.dt
+   if str(dtstart_dt) not in all_dtstart_str_dt:
+      all_dtstart_dt.append(dtstart_dt)
+      all_dtstart_str_dt.append(str(dtstart_dt))
+   if all_dtstart_dt:
+      for i in all_dtstart_dt:
+         summary = event.icalendar_component["SUMMARY"].strip()
+         thishour = int(i.strftime("%I"))
+         thistime = str(thishour) + i.strftime(":%M%P")
+         if type(event.icalendar_component["DTEND"].dt) == date:
+            thistime = "All day"
+         response += f"{thistime}: {summary}<br/>\n"
+   return response
+
+# From reference 2
+def hex_to_rgb(value):
+   value = value.lstrip('#').rstrip(";")
+   lv = len(value)
+   return tuple(int(value[i:i + lv // 3], 16) for i in range(0, lv, lv // 3))
+def rgb_to_hex(rgb):
+   return '#%02x%02x%02x' % rgb
+
+# bgstack15
+def get_faded_color(hexcolor):
+   """ Given hexcolor as string of '#ffccaa', return a faded color """
+   outcolor = ""
+   try:
+      r, g, b = hex_to_rgb(hexcolor)
+   except:
+      try:
+         r, g, b, a = hex_to_rgb(hexcolor)
+      except:
+         print(f"Warning! Cannot understand color {hexcolor} for getting a faded value.")
+         return hexcolor
+   # so now we have r, g, b. We do not know yet how to use alpha.
+   if len(hexcolor) == 4:
+      # that is, if hexcolor is "#fff" or similar
+      r = r * 16
+      g = g * 16
+      b = b * 16
+   r1 = int((255 + r)/2)
+   g1 = int((255 + g)/2)
+   b1 = int((255 + b)/2)
+   outcolor = rgb_to_hex((r1,g1,b1))
+   return outcolor
+
+# Adapted from reference 3
+def get_text_color_based_on_background_color(bgColor, lightColor, darkColor):
+   color = bgColor.lstrip("#").rstrip(";")
+   r, g, b = hex_to_rgb(color)
+   uicolors = [r/255, g/255, b/255]
+   adjusted = []
+   for col in uicolors:
+      col2 = col
+      if col <= 0.03928:
+         col2 = col/12.92
+      col2 = pow((col2 + 0.055)/1.055,2.4)
+      adjusted.append(col2)
+   L = (0.2126 * adjusted[0] + 0.7152 * adjusted[1] + (0.072 * adjusted[2]))
+   return darkColor if L > 0.179 else lightColor
+
+#function pickTextColorBasedOnBgColorAdvanced(bgColor, lightColor, darkColor) {
+#  var color = (bgColor.charAt(0) === '#') ? bgColor.substring(1, 7) : bgColor;
+#  var r = parseInt(color.substring(0, 2), 16); // hexToR
+#  var g = parseInt(color.substring(2, 4), 16); // hexToG
+#  var b = parseInt(color.substring(4, 6), 16); // hexToB
+#  var uicolors = [r / 255, g / 255, b / 255];
+#  var c = uicolors.map((col) => {
+#    if (col <= 0.03928) {
+#      return col / 12.92;
+#    }
+#    return Math.pow((col + 0.055) / 1.055, 2.4);
+#  });
+#  var L = (0.2126 * c[0]) + (0.7152 * c[1]) + (0.0722 * c[2]);
+#  return (L > 0.179) ? darkColor : lightColor;
+#}
+
+def event_key(i):
+   return i.icalendar_component["DTSTART"].dt
+
+def summarize_calendar(calendar, thisdate = None, count = 0):
+   """
+   Examine calendar for given thisdate (of type datetime.date)
+   """
+   response = ""
+   #d = date.today()+timedelta(days=-1)
+   if type(thisdate) == datetime:
+      thisdate = thisdate.date()
+   if type(thisdate) != date:
+      thisdate = datetime.today()
+   # so now, thisdate should be of type datetime.date
+   d = thisdate
+   d2 = d + timedelta(days=1)
+   year, month, day = d2.year, d2.month, d2.day
+   events_fetched = calendar.search(
+      start=d,
+      end=datetime(year,month,day),
+      event=True,
+      expand=True,
+   )
+   x = 0
+   events_wholeday = [i for i in events_fetched if type(i.icalendar_component["DTSTART"].dt) == date]
+   events_regular = [i for i in events_fetched if type(i.icalendar_component["DTSTART"].dt) != date]
+   events_sorted = sorted(events_regular, key=event_key)
+   for i in events_wholeday + events_sorted:
+      x = x + 1
+      if 1 == x:
+         if 1 == count:
+            datestring = thisdate.strftime("%B %d")
+            response += f"<h1>Summary for {datestring}</h1>\n"
+         color = get_calendar_color(calendar)
+         color2 = get_faded_color(color)
+         h2_text_color = get_text_color_based_on_background_color(color,"#ffffff","#000000")
+         text_color = get_text_color_based_on_background_color(color2,"#ffffff","#000000")
+         response += f"<div style='background-color: {color2}; color: {text_color}'><h2 style='background-color: {color}; color: {h2_text_color}'>{calendar.name}</h2>\n"
+      response += show_event(i)
+   if x > 0:
+      response += "</div>\n"
+   return response
+
+def summarize(thisdate = None, url = "http://example.com/radicale/", username = "username", password = "insecure"):
+   """
+   Given a date ("YYYY-MM-DD" or datetime.date object), produce a string of html suitable for an agenda email.
+   Example:
+      with open("agenda.html","w") as w:
+         w.write(summarize("2023-05-14",url="https://server3.ipa.example.com/radicale/",username="username",password="password"))
+   """
+   response = ""
+   if type(thisdate) == str:
+      try:
+         thisdate = datetime.strptime(thisdate,"%Y-%m-%d")
+      except:
+         print("Warning! Expected YYYY-MM-DD or a datetime.date or datetime.datetime object. Using today's date.")
+         thisdate = datetime.today()
+   if type(thisdate) == datetime:
+      thisdate = thisdate.date()
+   elif thisdate is None:
+      thisdate = date.today()
+   if type(thisdate) != date:
+      print(f"Warning! Unknown date: \"{thisdate}\". Using today.")
+      thisdate = date.today()
+   with caldav.DAVClient(url=url, username=username, password=password) as client:
+      my_principal = client.principal()
+      calendars = my_principal.calendars()
+      #print_calendars_demo(calendars)
+      x = 0
+      for cal in calendars:
+         x = x + 1
+         response += summarize_calendar(cal, thisdate, x)
+   return response