import gradio as gr

MAX_QUEUE = 10

def _normalize_name(name: str) -> str:
    return (name or "").strip()

def _parse_age(age_text: str):
    age_text = (age_text or "").strip()
    if not age_text:
        return None, "Please enter an age."
    try:
        age = int(age_text)
    except ValueError:
        return None, "Age must be a whole number."
    if age < 0 or age > 130:
        return None, "Please enter a realistic age (0–130)."
    return age, None

def _sorted_queue(queue):
    # Oldest first; ties broken by entry order (seq)
    return sorted(queue, key=lambda x: (-x["age"], x["seq"]))

def _render(queue):
    if not queue:
        return "Queue is empty."
    q_sorted = _sorted_queue(queue)

    lines = ["### Smart Queue (Oldest First)"]
    for idx, item in enumerate(q_sorted, start=1):
        lines.append(f"**#{idx}** — {item['name']} (Age {item['age']})")
    lines.append("")
    lines.append(f"Slots used: **{len(queue)}/{MAX_QUEUE}**")
    lines.append("Rule: **Oldest first**; if ages tie, **earlier signup first**.")
    return "\n\n".join(lines)

def add_to_queue(name, age_text, queue_state, seq_state):
    queue_state = queue_state or []
    seq_state = int(seq_state or 1)

    if len(queue_state) >= MAX_QUEUE:
        return queue_state, seq_state, _render(queue_state), f"❌ Queue is full (max {MAX_QUEUE}). Please reset or serve next.", gr.update(), gr.update()

    name = _normalize_name(name)
    if not name:
        return queue_state, seq_state, _render(queue_state), "❌ Please enter a name.", gr.update(), gr.update()

    age, err = _parse_age(age_text)
    if err:
        return queue_state, seq_state, _render(queue_state), f"❌ {err}", gr.update(), gr.update()

    queue_state.append({"name": name, "age": age, "seq": seq_state})
    seq_state += 1

    # After adding, show their *current* position in the sorted queue
    q_sorted = _sorted_queue(queue_state)
    position = next(i for i, p in enumerate(q_sorted, start=1) if p["name"] == name and p["age"] == age and p["seq"] == seq_state - 1)

    msg = f"✅ Added **{name}** (Age {age}). Current queue position: **#{position}** (oldest-first ordering)."
    return queue_state, seq_state, _render(queue_state), msg, gr.update(value=""), gr.update(value="")

def serve_next(queue_state):
    queue_state = queue_state or []
    if not queue_state:
        return queue_state, _render(queue_state), "Queue is empty. Nothing to serve."

    q_sorted = _sorted_queue(queue_state)
    next_person = q_sorted[0]

    # Remove by unique seq
    queue_state = [p for p in queue_state if p["seq"] != next_person["seq"]]
    msg = f"➡️ Served: **{next_person['name']}** (Age {next_person['age']})."
    return queue_state, _render(queue_state), msg

def reset_queue():
    queue_state = []
    seq_state = 1
    return queue_state, seq_state, _render(queue_state), "🔄 Queue reset. You can add up to 10 people.", gr.update(value=""), gr.update(value="")

with gr.Blocks(title="Smart Queue (Oldest First)") as demo:
    gr.Markdown(
        "# 👥 Smart Queue (Oldest First)\n"
        "Enter **name** and **age**. The queue is ordered by **oldest first**.\n"
        "If ages are the same, the earlier signup comes first.\n"
        "**Maximum 10 people**."
    )

    queue_state = gr.State([])
    seq_state = gr.State(1)  # internal counter to preserve signup order

    with gr.Row():
        name_in = gr.Textbox(label="Name", placeholder="e.g., Anna")
        age_in = gr.Textbox(label="Age", placeholder="e.g., 29")

    with gr.Row():
        add_btn = gr.Button("Join Queue", variant="primary")
        serve_btn = gr.Button("Serve Next")
        reset_btn = gr.Button("Reset Queue")

    status = gr.Markdown("Ready.")
    queue_view = gr.Markdown(_render([]))

    add_btn.click(
        add_to_queue,
        inputs=[name_in, age_in, queue_state, seq_state],
        outputs=[queue_state, seq_state, queue_view, status, name_in, age_in],
    )

    # Enter key on either field submits
    name_in.submit(
        add_to_queue,
        inputs=[name_in, age_in, queue_state, seq_state],
        outputs=[queue_state, seq_state, queue_view, status, name_in, age_in],
    )
    age_in.submit(
        add_to_queue,
        inputs=[name_in, age_in, queue_state, seq_state],
        outputs=[queue_state, seq_state, queue_view, status, name_in, age_in],
    )

    serve_btn.click(
        serve_next,
        inputs=[queue_state],
        outputs=[queue_state, queue_view, status],
    )

    reset_btn.click(
        reset_queue,
        inputs=[],
        outputs=[queue_state, seq_state, queue_view, status, name_in, age_in],
    )

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