import streamlit as st
      import pandas as pd
      from pathlib import Path
      from datetime import date, time
      DATA_DIR = Path("data")
      TODO_FILE = DATA_DIR / "todo.csv"
      CALENDAR_FILE = DATA_DIR / "calendar.csv"
      DATA_DIR.mkdir(parents=True, exist_ok=True)
      TODO_COLUMNS = [
          "id","titel","beschreibung","kategorie","prioritaet","status",
          "faellig_am","wiederholen","notiz"
      ]
      CALENDAR_COLUMNS = [
          "id","titel","datum","uhrzeit","dauer_min","kalender","kategorie",
          "erinnerung_min","wiederholen","notiz"
      ]
      def load_csv(path: Path, columns: list[str]) -> pd.DataFrame:
          if path.exists():
              df = pd.read_csv(path)
              for col in columns:
                  if col not in df.columns:
                      df[col] = ""
              return df[columns]
          return pd.DataFrame(columns=columns)
      def save_csv(df: pd.DataFrame, path: Path) -> None:
          df.to_csv(path, index=False)
      def next_id(df: pd.DataFrame) -> int:
          if df.empty or "id" not in df.columns:
              return 1
          try:
              return int(df["id"].max()) + 1
          except Exception:
              return 1
      st.set_page_config(page_title="Bitcoin-Programm", layout="wide")
      st.title("Bitcoin-Programm – To-do & Kalender")
      tab1, tab2, tab3 = st.tabs(["To-do anlegen", "Kalendertermin anlegen", "Daten ansehen"])
      with tab1:
          st.subheader("Neues To-do")
          todo_df = load_csv(TODO_FILE, TODO_COLUMNS)
          new_todo_id = next_id(todo_df)
          with st.form("todo_form", clear_on_submit=True):
              titel = st.text_input("Titel")
              beschreibung = st.text_area("Beschreibung")
              kategorie = st.selectbox("Kategorie", ["Allgemein", "Bitcoin", "Dokumentation", "Kalender", "Admin", "Sonstiges"])
              prioritaet = st.selectbox("Priorität", ["Niedrig", "Mittel", "Hoch"])
              status = st.selectbox("Status", ["Offen", "In Arbeit", "Wartet", "Erledigt"])
              faellig_am = st.date_input("Fällig am", value=date.today())
              wiederholen = st.selectbox("Wiederholen", ["Nein", "Täglich", "Wöchentlich", "Monatlich"])
              notiz = st.text_area("Notiz")
              submitted = st.form_submit_button("To-do speichern")
          if submitted:
              if not titel.strip():
                  st.error("Bitte mindestens einen Titel eingeben.")
              else:
                  new_row = pd.DataFrame([{
                      "id": new_todo_id,
                      "titel": titel,
                      "beschreibung": beschreibung,
                      "kategorie": kategorie,
                      "prioritaet": prioritaet,
                      "status": status,
                      "faellig_am": faellig_am.isoformat(),
                      "wiederholen": wiederholen,
                      "notiz": notiz,
                  }])
                  todo_df = pd.concat([todo_df, new_row], ignore_index=True)
                  save_csv(todo_df, TODO_FILE)
                  st.success("To-do gespeichert.")
      with tab2:
          st.subheader("Neuen Kalendereintrag")
          cal_df = load_csv(CALENDAR_FILE, CALENDAR_COLUMNS)
          new_cal_id = next_id(cal_df)
          with st.form("calendar_form", clear_on_submit=True):
              titel = st.text_input("Titel")
              datum = st.date_input("Datum", value=date.today())
              uhrzeit = st.time_input("Uhrzeit", value=time(9, 0))
              dauer_min = st.number_input("Dauer in Minuten", min_value=5, max_value=1440, value=60, step=5)
              kalender = st.selectbox("Kalender", ["Arbeit", "Privat", "Bitcoin", "Todo"])
              kategorie = st.selectbox("Kategorie", ["Meeting", "Aufgabe", "Erinnerung", "Termin", "Sonstiges"])
              erinnerung_min = st.number_input("Erinnerung vorab in Minuten", min_value=0, max_value=10080, value=30, step=5)
              wiederholen = st.selectbox("Wiederholen", ["Nein", "Täglich", "Wöchentlich", "Monatlich"])
              notiz = st.text_area("Notiz")
              submitted = st.form_submit_button("Kalendertermin speichern")
          if submitted:
              if not titel.strip():
                  st.error("Bitte mindestens einen Titel eingeben.")
              else:
                  new_row = pd.DataFrame([{
                      "id": new_cal_id,
                      "titel": titel,
                      "datum": datum.isoformat(),
                      "uhrzeit": uhrzeit.strftime("%H:%M"),
                      "dauer_min": int(dauer_min),
                      "kalender": kalender,
                      "kategorie": kategorie,
                      "erinnerung_min": int(erinnerung_min),
                      "wiederholen": wiederholen,
                      "notiz": notiz,
                  }])
                  cal_df = pd.concat([cal_df, new_row], ignore_index=True)
                  save_csv(cal_df, CALENDAR_FILE)
                  st.success("Kalendertermin gespeichert.")
      with tab3:
          st.subheader("Gespeicherte Daten")
          col1, col2 = st.columns(2)
          with col1:
              st.markdown("### To-dos")
              todo_df = load_csv(TODO_FILE, TODO_COLUMNS)
              st.dataframe(todo_df, use_container_width=True)
              st.download_button("To-do CSV herunterladen", data=todo_df.to_csv(index=False).encode("utf-8"), file_name="todo.csv", mime="text/csv")
          with col2:
              st.markdown("### Kalender")
              cal_df = load_csv(CALENDAR_FILE, CALENDAR_COLUMNS)
              st.dataframe(cal_df, use_container_width=True)
              st.download_button("Kalender CSV herunterladen", data=cal_df.to_csv(index=False).encode("utf-8"), file_name="calendar.csv", mime="text/csv")