import gradio as gr
from config import CHAT_SYSTEM_PROMPT_PLACEHOLDER, CHAT_MODEL_SPECS
from models import get_model_response
import logging
import copy

logger = logging.getLogger(__name__)

# --- Backend Logic ---

def handle_chat(message, history, system_prompt, temperature, model_id):
    """Core function to handle chat message submission"""
    logger.debug(f"handle_chat 输入: message={message}, history={history}, system_prompt={system_prompt}, temperature={temperature}, model_id={model_id}")
    if history is None:
        history = []
    history = copy.deepcopy(history)
    history.append((message, ""))
    
    # Get the display name from the spec
    model_display_name = CHAT_MODEL_SPECS.get(model_id, {}).get("display_name", model_id)
    
    is_first_chunk = True
    for chunk in get_model_response(model_id, history, system_prompt, temperature):
        if is_first_chunk:
            # Add model name before the first chunk
            history[-1] = (message, f"**{model_display_name}**\n\n" + chunk)
            is_first_chunk = False
        else:
            history[-1] = (message, history[-1][1] + chunk)
        yield copy.deepcopy(history), ""

# --- UI Event Handlers ---

def handle_model_change(model_id):
    """Update UI when user switches model"""
    spec = CHAT_MODEL_SPECS[model_id]
    scenarios = spec.get("prompt_scenarios", [])
    
    # Load the first scenario by default
    if scenarios:
        first_scenario = scenarios[0]
        scenario_titles = [[s["title"]] for s in scenarios]
        message_examples = [[m] for m in first_scenario["message_examples"]]
        system_prompt_value = first_scenario["system_prompt"]
    else: # Compatible with no scenarios
        scenario_titles = []
        message_examples = []
        system_prompt_value = ""

    return (
        gr.update(value=spec["description"]),
        gr.update(samples=scenario_titles),
        gr.update(value=system_prompt_value),
        gr.update(samples=message_examples)
    )

def handle_scenario_selection(model_id, evt: gr.SelectData):
    """Update UI when user selects a scenario from the dataset"""
    logger.debug(f"--- Scenario Selection Event ---")
    logger.debug(f"Selected event value: {evt.value}")
    logger.debug(f"Type of event value: {type(evt.value)}")
    
    # Correction: extract string from list
    selected_title = evt.value[0] if isinstance(evt.value, list) and evt.value else None
    if not selected_title:
        logger.error("Selected event value is not a valid list or is empty.")
        return gr.update(), gr.update()

    spec = CHAT_MODEL_SPECS[model_id]
    scenarios = spec.get("prompt_scenarios", [])
    
    available_titles = [s['title'] for s in scenarios]
    logger.debug(f"Available scenario titles for model '{model_id}': {available_titles}")

    selected_scenario = next((s for s in scenarios if s["title"] == selected_title), None)
    
    if selected_scenario:
        logger.debug(f"Found matching scenario: '{selected_title}'")
        system_prompt_value = selected_scenario["system_prompt"]
        message_examples = [[m] for m in selected_scenario["message_examples"]]
        return gr.update(value=system_prompt_value), gr.update(samples=message_examples)
    
    logger.warning(f"No matching scenario found for title: '{selected_title}'")
    # If no scenario is found, do not update
    return gr.update(), gr.update()

# --- UI Creation ---

def create_chat_tab():
    """Create and return all Gradio components for the chat tab"""
    
    # Extract model information from config for UI display
    # choices is a list of (display_name, model_id) tuples
    model_choices = [(spec["display_name"], model_id) for model_id, spec in CHAT_MODEL_SPECS.items()]
    default_model_id = list(CHAT_MODEL_SPECS.keys())[0]
    default_spec = CHAT_MODEL_SPECS[default_model_id]
    default_scenarios = default_spec.get("prompt_scenarios", [])

    with gr.Row():
        with gr.Column(scale=3):
            chatbot = gr.Chatbot(
                label="Chat Window",
                bubble_full_width=False,
                height=500,
                value=[(None, "Hello! I'm Ling. Try selecting a scenario and a message example below to get started.")]
            )
            with gr.Row():
                chat_input = gr.Textbox(placeholder="Ask me anything...", label="Input", show_label=False, scale=4)
                send_button = gr.Button("Send", variant="primary", scale=1)

            # 新的场景化示例区域
            with gr.Accordion("✨ Try these scenarios...", open=True):
                # 场景选择器
                scenario_selector = gr.Dataset(
                    components=[gr.Textbox(visible=False)],
                    samples=[[s["title"]] for s in default_scenarios],
                    label="System Prompt Examples",
                    headers=["Select a role or task to get started:"],
                )
                # 消息示例
                message_examples_display = gr.Dataset(
                    components=[chat_input],
                    samples=[[m] for m in default_scenarios[0]["message_examples"]] if default_scenarios else [],
                    label="Message Examples",
                    headers=["Then, try these specific questions:"],
                )

        with gr.Column(scale=1):
            model_selector = gr.Radio(
                choices=model_choices,
                label="Select Model",
                value=default_model_id
            )
            model_description = gr.Markdown(default_spec["description"])
            system_prompt = gr.Textbox(
                label="System Prompt",
                lines=8,
                placeholder=CHAT_SYSTEM_PROMPT_PLACEHOLDER,
                value=default_scenarios[0]["system_prompt"] if default_scenarios else ""
            )
            temperature_slider = gr.Slider(minimum=0.0, maximum=2.0, value=1.0, step=0.1, label="Temperature")

    # --- Event Listeners ---
    model_selector.change(
        fn=handle_model_change,
        inputs=[model_selector],
        outputs=[model_description, scenario_selector, system_prompt, message_examples_display]
    )
    
    scenario_selector.select(
        fn=handle_scenario_selection,
        inputs=[model_selector],
        outputs=[system_prompt, message_examples_display]
    )

    message_examples_display.click(
        fn=lambda value: value[0],
        inputs=[message_examples_display],
        outputs=[chat_input]
    )
    
    return {
        "chatbot": chatbot,
        "chat_input": chat_input,
        "send_button": send_button,
        "system_prompt": system_prompt,
        "temperature_slider": temperature_slider,
        "model_selector": model_selector,
    }