import os
import gradio as gr
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_core.messages import SystemMessage, HumanMessage, AIMessage


# ── FAQ Knowledge Base ────────────────────────────────────────────────────────

FAQ_KNOWLEDGE_BASE = """
**Shipping & Delivery**

Q: What are your shipping options?
A: We offer standard shipping (5-7 business days, free over $50) and express shipping (2-3 business days, $15 flat rate). International shipping is available to select countries.

Q: Do you ship internationally?
A: Yes, we ship to over 30 countries. International shipping costs vary by destination and are calculated at checkout. Delivery typically takes 10-15 business days.

**Returns & Refunds**

Q: What is your return policy?
A: We accept returns within 30 days of delivery for unworn, unwashed items with original tags. Refunds are processed within 5-7 business days after we receive your return.

Q: How do I initiate a return?
A: Log into your account, go to Order History, select the item you want to return, and follow the return instructions. You'll receive a prepaid return label via email.

**Payment & Orders**

Q: What payment methods do you accept?
A: We accept all major credit cards (Visa, Mastercard, American Express, Discover), PayPal, Apple Pay, and Google Pay.

Q: How can I track my order?
A: Once your order ships, you'll receive a tracking number via email. You can also track your order by logging into your account and visiting the Order History page.

Q: How do I place an order?
A: You can place an order directly from the product page by selecting the product, choosing quantity, and clicking 'Add to Cart' then 'Checkout'. Follow the prompts to complete your order.

Q: Can I change my order after placing it?
A: Once your order is submitted, you cannot change it via the chatbot. Please contact support if you need to modify it.

**Product Availability**

Q: What if an item is out of stock?
A: You can sign up for back-in-stock notifications on the product page. We'll email you when the item is available again. Most items are restocked within 2-4 weeks.

Q: How can I know if a product is in stock?
A: You can check the product page for availability. If it's out of stock, you can sign up for back-in-stock notifications and we'll email you when it's available.

Q: Do you offer gift cards?
A: Yes, we offer digital gift cards in denominations of $25, $50, $100, and $200. They're delivered via email and never expire.

**Products**

Q: What products do you offer?
A: We currently offer Product A, Product B, and Product C. Each product has its own details listed on the product page.

Q: Can I get details about a product before ordering?
A: Yes! Each product page includes full details, specifications, and pricing. You can also contact support for more information.
"""

SYSTEM_PROMPT = f"""You are ShopAssist, a helpful and friendly customer support chatbot for an e-commerce store.

Answer questions using ONLY the FAQ knowledge base below. Be concise and clear (2-4 sentences).
If a question is not covered by the FAQ, politely say you don't have that specific information and suggest contacting support@shopstore.com.
Never make up information that is not in the FAQ. You may use previous messages in the conversation for context.

{FAQ_KNOWLEDGE_BASE}"""

SAMPLE_QUESTIONS = [
    "📦 How long does shipping take?",
    "↩️ What is your return policy?",
    "💳 What payment methods do you accept?",
    "🔍 How do I track my order?",
    "🎁 Do you offer gift cards?",
    "🛒 How do I place an order?",
    "📵 What if an item is out of stock?",
    "🌍 Do you ship internationally?",
]

# ── LLM ───────────────────────────────────────────────────────────────────────

def get_llm():
    return ChatGoogleGenerativeAI(
        model="gemini-2.5-flash",
        google_api_key=os.environ["GOOGLE_API_KEY"],
        temperature=0.3,
    )

# ── Chat — history is list of {"role": ..., "content": ...} dicts ─────────────

def chat(user_message: str, history: list):
    if not user_message.strip():
        return "", history

    lc_messages = [SystemMessage(content=SYSTEM_PROMPT)]
    for msg in history:
        if msg["role"] == "user":
            lc_messages.append(HumanMessage(content=msg["content"]))
        elif msg["role"] == "assistant":
            lc_messages.append(AIMessage(content=msg["content"]))
    lc_messages.append(HumanMessage(content=user_message))

    response = get_llm().invoke(lc_messages)
    return "", history + [
        {"role": "user", "content": user_message},
        {"role": "assistant", "content": response.content},
    ]


def use_sample(question: str, history: list):
    clean = question.split(" ", 1)[-1]
    return chat(clean, history)


def clear_chat():
    return [], ""

# ── UI ────────────────────────────────────────────────────────────────────────

with gr.Blocks(title="ShopAssist FAQ") as demo:

    gr.Markdown(
        """
        # 🛍️ ShopAssist — FAQ Assistant
        Ask me anything about shipping, returns, orders, or products.
        """
    )

    chatbot = gr.Chatbot(
        label="Conversation",
        height=440,
    )

    with gr.Row():
        txt = gr.Textbox(
            placeholder="Type your question and press Enter…",
            show_label=False,
            scale=9,
            container=False,
        )
        send = gr.Button("Send", variant="primary", scale=1, min_width=70)

    gr.Markdown("**💡 Try one of these:**")
    for i in range(0, len(SAMPLE_QUESTIONS), 4):
        with gr.Row():
            for q in SAMPLE_QUESTIONS[i : i + 4]:
                btn = gr.Button(q, size="sm")
                btn.click(use_sample, inputs=[btn, chatbot], outputs=[txt, chatbot])

    clear = gr.Button("🗑️ Clear conversation", size="sm")

    txt.submit(chat, [txt, chatbot], [txt, chatbot])
    send.click(chat, [txt, chatbot], [txt, chatbot])
    clear.click(clear_chat, outputs=[chatbot, txt])

if __name__ == "__main__":
    demo.launch(theme=gr.themes.Soft())