import streamlit as st
from datetime import datetime

# =============================
# Initialize session state
# =============================
if "tasks" not in st.session_state:
    st.session_state.tasks = []

if "habits" not in st.session_state:
    st.session_state.habits = []

# =============================
# App Title and Navigation
# =============================
st.set_page_config(page_title="To-Do & Habit Tracker", layout="centered")
st.title("📝 To-Do List & Habit Tracker")

page = st.sidebar.radio("Navigation", ["To-Do List", "Habit Tracker"])

# =============================
# TO-DO LIST SECTION
# =============================
if page == "To-Do List":
    st.header("📌 Your Tasks")

    # Use temporary variable for input
    new_task = st.text_input("Add a new task")

    if st.button("Add Task"):
        if new_task.strip():
            st.session_state.tasks.append({"task": new_task.strip(), "completed": False})
            new_task = ""  # just clear local variable (widget keeps its value until next rerun)

    st.subheader("Pending Tasks")
    for i, task in enumerate(st.session_state.tasks):
        if not task["completed"]:
            col1, col2 = st.columns([0.8, 0.2])
            with col1:
                checked = st.checkbox(task["task"], key=f"task_{i}")
                if checked:
                    st.session_state.tasks[i]["completed"] = True
            with col2:
                if st.button("Delete", key=f"delete_{i}"):
                    st.session_state.tasks.pop(i)
                    break  # break to avoid index issues

    st.subheader("Completed Tasks")
    for task in st.session_state.tasks:
        if task["completed"]:
            st.write("✅", task["task"])

# =============================
# HABIT TRACKER SECTION
# =============================
if page == "Habit Tracker":
    st.header("🔥 Daily Habit Tracker")

    new_habit = st.text_input("Add a new habit")

    if st.button("Add Habit"):
        if new_habit.strip():
            st.session_state.habits.append({"habit": new_habit.strip(), "dates": []})
            new_habit = ""  # clear local variable

    today = datetime.now().strftime("%Y-%m-%d")
    completed_today = 0

    for i, habit in enumerate(st.session_state.habits):
        checked = today in habit["dates"]

        new_checked = st.checkbox(habit["habit"], value=checked, key=f"habit_{i}")
        if new_checked and today not in habit["dates"]:
            st.session_state.habits[i]["dates"].append(today)
        elif not new_checked and today in habit["dates"]:
            st.session_state.habits[i]["dates"].remove(today)

        if today in st.session_state.habits[i]["dates"]:
            completed_today += 1

    if st.session_state.habits:
        progress = completed_today / len(st.session_state.habits)
        st.subheader("📊 Today's Progress")
        st.progress(progress)
        st.write(f"{int(progress * 100)}% habits completed today")