#!/usr/bin/env python
"""06 -- gr.State: per-session state, isolated between browser tabs.

gr.State lives for one browser session. A module-level variable would instead
be shared by every concurrent user -- a real bug in multi-user deployments.
"""
import gradio as gr
from _common import launch


def add(item, history):
    history = list(history or [])
    if item:
        history.append(item)
    return history, "\n".join(f"{i+1}. {h}" for i, h in enumerate(history)), ""


def reset():
    return [], "", ""


with gr.Blocks(title="Session state") as demo:
    gr.Markdown("## Per-session list\nOpen a second browser tab: the lists "
                "are independent.")
    state = gr.State([])              # not shared across sessions
    entry = gr.Textbox(label="Add an item")
    view = gr.Textbox(label="Your items", lines=6)
    with gr.Row():
        gr.Button("Add", variant="primary").click(
            add, [entry, state], [state, view, entry], api_name="add")
        gr.Button("Reset").click(reset, None, [state, view, entry])
    entry.submit(add, [entry, state], [state, view, entry])

if __name__ == "__main__":
    launch(demo)