import gradio as gr
from datetime import datetime
import pytz

# In-session reminder list
reminders = []  # Format: {'time': datetime, 'message': str, 'tz': str}

# Add a reminder
def add_reminder(time_str, message, timezone):
    try:
        user_tz = pytz.timezone(timezone)
        naive_dt = datetime.strptime(time_str, "%Y-%m-%d %H:%M")
        aware_dt = user_tz.localize(naive_dt)

        now_utc = datetime.now(pytz.utc)
        if aware_dt.astimezone(pytz.utc) < now_utc:
            return "⛔ Time is in the past. Please enter a future time."

        reminders.append({'time': aware_dt, 'message': message, 'tz': timezone})
        reminders.sort(key=lambda x: x['time'].astimezone(pytz.utc))
        return f"✅ Reminder added for {aware_dt.strftime('%Y-%m-%d %H:%M %Z')}"
    except Exception as e:
        return f"❌ Error: {str(e)}"

# List reminders
def list_reminders():
    if not reminders:
        return "📭 No reminders yet."
    now = datetime.now(pytz.utc)
    result = []
    for r in reminders:
        local_time = r['time'].astimezone(pytz.timezone(r['tz']))
        time_left = r['time'].astimezone(pytz.utc) - now
        mins = int(time_left.total_seconds() / 60)
        result.append(f"🕒 {local_time.strftime('%Y-%m-%d %H:%M %Z')} → {r['message']} ({mins} min left)")
    return "\n".join(result)

# Check next due reminder
def check_next():
    now = datetime.now(pytz.utc)
    for r in reminders:
        if (r['time'].astimezone(pytz.utc) - now).total_seconds() < 60:
            local_time = r['time'].astimezone(pytz.timezone(r['tz']))
            return f"🔔 Due now: {r['message']} ({local_time.strftime('%H:%M %Z')})"
    return "✅ Nothing due right now."

# Delete reminder
def delete_reminder(time_str, timezone):
    try:
        user_tz = pytz.timezone(timezone)
        target_time = user_tz.localize(datetime.strptime(time_str, "%Y-%m-%d %H:%M"))
        global reminders
        original_len = len(reminders)
        reminders = [r for r in reminders if not (
            r['time'].astimezone(pytz.utc) == target_time.astimezone(pytz.utc)
        )]
        if len(reminders) < original_len:
            return f"🗑️ Reminder at {time_str} ({timezone}) deleted."
        return "⚠️ No matching reminder found."
    except Exception as e:
        return f"❌ Error: {str(e)}"

# Common timezone choices
timezone_choices = ["UTC", "Asia/Kolkata", "America/New_York", "Europe/London", "Asia/Tokyo"]

# Gradio UI
with gr.Blocks() as demo:
    gr.Markdown("## ⏰ Stateful Reminder Agent with Timezone Support")

    with gr.Tab("➕ Add Reminder"):
        time_in = gr.Textbox(label="Time (YYYY-MM-DD HH:MM)", placeholder="2025-06-07 09:00")
        msg_in = gr.Textbox(label="Reminder Message", placeholder="Doctor appointment")
        tz_in = gr.Dropdown(label="Timezone", choices=timezone_choices, value="UTC")
        out_add = gr.Textbox(label="Status")
        gr.Button("Add Reminder").click(fn=add_reminder, inputs=[time_in, msg_in, tz_in], outputs=out_add)

    with gr.Tab("📋 View All Reminders"):
        out_list = gr.Textbox(label="Reminders", lines=10)
        gr.Button("List Reminders").click(fn=list_reminders, outputs=out_list)

    with gr.Tab("🔔 Check What’s Due"):
        out_next = gr.Textbox(label="Next Reminder")
        gr.Button("What's Next?").click(fn=check_next, outputs=out_next)

    with gr.Tab("🗑️ Delete Reminder"):
        del_time = gr.Textbox(label="Time to Delete (YYYY-MM-DD HH:MM)")
        del_tz = gr.Dropdown(label="Timezone of Reminder", choices=timezone_choices, value="UTC")
        out_del = gr.Textbox(label="Status")
        gr.Button("Delete").click(fn=delete_reminder, inputs=[del_time, del_tz], outputs=out_del)

demo.launch()