import streamlit as st
import pandas as pd
import logging
from database import get_db, initialize_database, Product
from inventory import (add_product, get_all_products, get_product_by_id, add_product_memory, 
                      update_product_memory, delete_product_memory, add_stock_memory, 
                      remove_stock_memory)
from prediction import predict_stockout

logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")
logger = logging.getLogger(__name__)

st.set_page_config(page_title="Inventory Dashboard", layout="wide")
try:
    with open("styles.css") as f:
        st.markdown(f"<style>{f.read()}</style>", unsafe_allow_html=True)
except FileNotFoundError:
    logger.warning("styles.css not found")

# Initialize session state
if "user_products" not in st.session_state:
    st.session_state.user_products = []
if "user_transactions" not in st.session_state:
    st.session_state.user_transactions = []

# Initialize example products
def initialize_example_products(db):
    """Add electronics example products if database is empty."""
    try:
        if db.query(Product).count() == 0:
            examples = [
                ("Smartphone", 50.0, 20.0, 7.0, 200.0, "A"),  # Electronics
                ("Laptop", 30.0, 10.0, 5.0, 150.0, "A"),      # Electronics
                ("Headphones", 100.0, 30.0, 3.0, 120.0, "B"),  # Electronics
                ("Smartwatch", 80.0, 25.0, 4.0, 90.0, "C")     # Electronics
            ]
            for name, stock, safety, lead, demand, cls in examples:
                add_product(db, name, stock, safety, lead, demand, cls)
            logger.info("Added example electronics products")
    except Exception as e:
        logger.error(f"Error adding example products: {str(e)}")
        raise

# Initialize database and example products
try:
    initialize_database()  # Ensure tables are created
    with next(get_db()) as db:
        initialize_example_products(db)
        cached_products = get_all_products(db)  # Cache for efficiency
except Exception as e:
    logger.error(f"Error initializing database or example products: {str(e)}")
    st.error(f"Error: {str(e)}")
    st.stop()

# Navigation
st.sidebar.title("Navigation")
page = st.sidebar.radio("Go to", ["Dashboard", "Product Management", "User Guide"])
st.sidebar.markdown("**Note**: Changes are local to your session and reset on page refresh.")

# Footer
def display_footer():
    st.markdown("""
        <div class="footer">
            <p style="font-size: small; color: grey; text-align: center;">
                Developed By: Krishna Prakash
                <a href="https://www.linkedin.com/in/krishnaprakash-profile/" target="_blank">
                    <img src="https://img.icons8.com/ios-filled/30/0077b5/linkedin.png" alt="LinkedIn" style="vertical-align: middle; margin: 0 10px;"/>
                </a>
            </p>
        </div>
    """, unsafe_allow_html=True)

# Validate inputs
def validate_product_inputs(name, current_stock, safety_stock, lead_time, monthly_demand, product_class):
    if not name:
        return "Name is required."
    if any(x < 0 for x in [current_stock, safety_stock, lead_time, monthly_demand]):
        return "Negative values not allowed."
    if product_class not in ["A", "B", "C"]:
        return "Product class must be A, B, or C."
    return None

# Dashboard
if page == "Dashboard":
    st.title("Inventory Dashboard")
    try:
        session_products = st.session_state.user_products
        # Cache all_products to avoid repeated computation
        all_products = cached_products + [p for p in session_products]
        
        if not all_products:
            st.warning("No products found.")
        else:
            product_data = [{
                "ID": p.id if hasattr(p, "id") else p.get("id", "N/A"),
                "Name": p.name if hasattr(p, "name") else p.get("name", "Unknown"),
                "Stock": p.current_stock if hasattr(p, "current_stock") else p.get("current_stock", 0.0),
                "Safety Stock": p.safety_stock if hasattr(p, "safety_stock") else p.get("safety_stock", 0.0),
                "Lead Time (days)": p.lead_time if hasattr(p, "lead_time") else p.get("lead_time", 0.0),
                "Demand": p.monthly_demand if hasattr(p, "monthly_demand") else p.get("monthly_demand", 0.0),
                "Class": p.product_class if hasattr(p, "product_class") else p.get("product_class", "C"),
                "Source": "Example" if hasattr(p, "id") else "User"
            } for p in all_products]
            # Reset index to remove Sl. No. and keep ID
            df = pd.DataFrame(product_data).reset_index(drop=True)
            st.subheader("Inventory")
            st.dataframe(df, use_container_width=True)

            st.subheader("Stockout Predictions")
            for p in all_products:
                with st.expander(f"{p.name if hasattr(p, 'name') else p.get('name', 'Unknown')} (ID: {p.id if hasattr(p, 'id') else p.get('id', 'N/A')})"):
                    result = predict_stockout(
                        p.monthly_demand if hasattr(p, "monthly_demand") else p.get("monthly_demand", 0.0),
                        p.lead_time if hasattr(p, "lead_time") else p.get("lead_time", 0.0),
                        p.current_stock if hasattr(p, "current_stock") else p.get("current_stock", 0.0),
                        p.product_class if hasattr(p, "product_class") else p.get("product_class", "C")
                    )
                    st.markdown(result, unsafe_allow_html=True)

            st.subheader("Alerts")
            alerts = []
            for p in all_products:
                stock = p.current_stock if hasattr(p, "current_stock") else p.get("current_stock", 0.0)
                safety = p.safety_stock if hasattr(p, "safety_stock") else p.get("safety_stock", 0.0)
                name = p.name if hasattr(p, "name") else p.get("name", "Unknown")
                # Use prediction to determine alert
                result = predict_stockout(
                    p.monthly_demand if hasattr(p, "monthly_demand") else p.get("monthly_demand", 0.0),
                    p.lead_time if hasattr(p, "lead_time") else p.get("lead_time", 0.0),
                    stock,
                    p.product_class if hasattr(p, "product_class") else p.get("product_class", "C")
                )
                risk_level = "Low Risk" if "Low Risk" in result else "Medium Risk" if "Medium Risk" in result else "High Risk"
                if "High Risk" in risk_level:
                    alerts.append(f"High Risk Alert: {name} has {stock} units. Replenish inventory immediately.")
                elif "Medium Risk" in risk_level:
                    alerts.append(f"Medium Risk Alert: {name} has {stock} units. Monitor closely.")
                elif "Low Risk" in risk_level and stock < safety:
                    alerts.append(f"Low Risk Alert: {name} has {stock} units, below {safety}. No action needed yet.")
            if alerts:
                for alert in alerts:
                    alert_class = "alert-high" if "High Risk" in alert else "alert-medium" if "Medium Risk" in alert else "alert"
                    st.markdown(f"<div class='{alert_class}'>{alert}</div>", unsafe_allow_html=True)
            else:
                st.success("All products are above predicted safety thresholds.")
    except Exception as e:
        logger.error(f"Dashboard error: {str(e)}")
        st.error(f"Error: {str(e)}")

# Product Management
elif page == "Product Management":
    st.title("Product Management")
    st.markdown("**Note**: Products and changes are local to your session and reset on page refresh.")
    try:
        st.subheader("Add Product")
        with st.form("add_form"):
            name = st.text_input("Name")
            current_stock = st.number_input("Stock", min_value=0.0, step=1.0)
            safety_stock = st.number_input("Safety Stock", min_value=0.0, step=1.0)
            lead_time = st.number_input("Lead Time (days)", min_value=0.0, max_value=90.0, step=1.0)
            monthly_demand = st.number_input("Monthly Demand", min_value=0.0, step=1.0)
            product_class = st.selectbox("Class", ["A", "B", "C"])
            if st.form_submit_button("Add"):
                error = validate_product_inputs(name, current_stock, safety_stock, lead_time, monthly_demand, product_class)
                if error:
                    st.error(error)
                else:
                    add_product_memory(st.session_state.user_products, name, current_stock, safety_stock, lead_time, monthly_demand, product_class)
                    st.success(f"Added {name} (local to your session)")

        st.subheader("Manage Products")
        session_products = st.session_state.user_products
        if session_products:
            product_id = st.selectbox("Select Product", [p["id"] for p in session_products], format_func=lambda x: next(p["name"] for p in session_products if p["id"] == x))
            product = next(p for p in session_products if p["id"] == product_id)
            with st.form("edit_form"):
                edit_name = st.text_input("Name", value=product["name"])
                edit_current_stock = st.number_input("Stock", min_value=0.0, step=1.0, value=float(product["current_stock"]))
                edit_safety_stock = st.number_input("Safety Stock", min_value=0.0, step=1.0, value=float(product["safety_stock"]))
                edit_lead_time = st.number_input("Lead Time (days)", min_value=0.0, max_value=90.0, step=1.0, value=float(product["lead_time"]))
                edit_monthly_demand = st.number_input("Monthly Demand", min_value=0.0, step=1.0, value=float(product["monthly_demand"]))
                edit_product_class = st.selectbox("Class", ["A", "B", "C"], index=["A", "B", "C"].index(product["product_class"]))
                col1, col2, col3, col4 = st.columns(4)
                with col1:
                    if st.form_submit_button("Update"):
                        error = validate_product_inputs(edit_name, edit_current_stock, edit_safety_stock, edit_lead_time, edit_monthly_demand, edit_product_class)
                        if error:
                            st.error(error)
                        else:
                            update_product_memory(st.session_state.user_products, product_id, edit_name, edit_current_stock, edit_safety_stock, edit_lead_time, edit_monthly_demand, edit_product_class)
                            st.success(f"Updated {edit_name} (local)")
                with col2:
                    if st.form_submit_button("Delete"):
                        delete_product_memory(st.session_state.user_products, product_id)
                        st.success(f"Deleted {product['name']} (local)")
                with col3:
                    add_qty = st.number_input("Add Stock", min_value=0.0, step=1.0, key="add_qty")
                    if st.form_submit_button("Add Stock"):
                        if add_qty <= 0:
                            st.error("Quantity must be positive.")
                        else:
                            add_stock_memory(st.session_state.user_products, st.session_state.user_transactions, product_id, add_qty)
                            st.success(f"Added {add_qty} to {product['name']} (local)")
                with col4:
                    remove_qty = st.number_input("Remove Stock", min_value=0.0, step=1.0, key="remove_qty")
                    if st.form_submit_button("Remove Stock"):
                        if remove_qty <= 0:
                            st.error("Quantity must be positive.")
                        else:
                            remove_stock_memory(st.session_state.user_products, st.session_state.user_transactions, product_id, remove_qty)
                            st.success(f"Removed {remove_qty} from {product['name']} (local)")
        else:
            st.warning("No user-added products in your session.")
    except Exception as e:
        logger.error(f"Product management error: {str(e)}")
        st.error(f"Error: {str(e)}")

# User Guide
elif page == "User Guide":
    st.title("User Guide")
    st.markdown("""
        Welcome to the **Inventory Dashboard**! This guide explains how to use the system, the meaning of risk levels, and inventory management concepts.
    """)

    with st.expander("What is the Inventory Dashboard?"):
        st.markdown("""
            The Inventory Dashboard helps you track and manage stock levels for electronics products. It predicts stockout risks and provides alerts to ensure availability.
        """)

    with st.expander("ABC Classification"):
        st.markdown("""
            <b>ABC Classification</b> categorizes inventory based on value and quantity to prioritize management efforts:<br>
            - <b>Class A</b>: High-value, low-quantity items (e.g., Smartphones, Laptops) requiring tight control.<br>
            - <b>Class B</b>: Medium-value, medium-quantity items (e.g., Headphones) needing balanced oversight.<br>
            - <b>Class C</b>: Low-value, high-quantity items (e.g., Smartwatches) requiring minimal attention.<br>
            <b>Example</b>: A store might prioritize restocking Smartphones (Class A) over Smartwatches (Class C) due to higher value and demand variability.
        """, unsafe_allow_html=True)

    with st.expander("Risk Levels"):
        st.markdown("""
            - <b>Low Risk</b>: Risk below 15%. Indicates the current stock is sufficient with no immediate action needed.<br>
            - <b>Medium Risk</b>: Risk between 15% and 40%. Suggests monitoring the product closely to avoid potential stockouts.<br>
            - <b>High Risk</b>: Risk above 40%. Indicates a need to replenish inventory immediately to prevent stockouts.
        """, unsafe_allow_html=True)

    with st.expander("Inventory Levels"):
        st.markdown("""
            - <b>Optimal Inventory Level</b>: Stock is well above safety stock, ensuring availability without excess.<br>
            - <b>Monitor Closely</b>: Stock is nearing safety stock; keep an eye on demand and supply.<br>
            - <b>Replenish Inventory</b>: Stock is below safety stock; urgent action is required to restock.
        """, unsafe_allow_html=True)


    with st.expander("Benefits and Use Cases"):
        st.markdown("""
            <b>Benefits include:</b><br>
            - Cost Savings: Reduces excess inventory and storage costs.<br>
            - Efficiency: Automates tracking, saving time.<br>
            - Customer Satisfaction: Prevents stockouts, ensuring product availability.<br>
            <b>Use Cases:</b><br>
            - Retail: Manage stock in electronics stores or e-commerce.<br>
            - Manufacturing: Track electronic components and finished goods.<br>
            - Healthcare: Ensure availability of medical electronics.
        """, unsafe_allow_html=True)

display_footer()