import streamlit as st
import pandas as pd
import numpy as np
import requests
import logging
from datetime import datetime
import io

# ------------------------------------------------
# CONSTANTS (API endpoints)
# ------------------------------------------------
API_SINGLE = "https://Lokiiparihar-backendlokii.hf.space/v1/sales/predict"
API_BATCH = "https://Lokiiparihar-backendlokii.hf.space/v1/sales/predict/batch"
#Lokiiparihar/backendlokii

# ------------------------------------------------
# LOGGING
# ------------------------------------------------
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    handlers=[logging.StreamHandler()]
)
logger = logging.getLogger(__name__)

# ------------------------------------------------
# DIRECT PICKLIST VALUES (raw strings — no encoding)
# ------------------------------------------------

STORE_IDS = ["OUT001", "OUT002", "OUT003", "OUT004"]

STORE_TYPES = [
    "Departmental Store",
    "Food Mart",
    "Supermarket Type1",
    "Supermarket Type2"
]

STORE_SIZES = ["High", "Medium", "Small"]

STORE_CITY_TYPES = ["Tier 1", "Tier 2", "Tier 3"]

PRODUCT_TYPES = [
    "Baking Goods", "Breads", "Breakfast", "Canned", "Dairy",
    "Frozen Foods", "Fruits and Vegetables", "Hard Drinks",
    "Health and Hygiene", "Household", "Meat", "Others",
    "Seafood", "Snack Foods", "Soft Drinks", "Starchy Foods"
]

PRODUCT_SUGAR_CONTENT = ["Low Sugar", "No Sugar", "Regular"]

# Allowed prefixes
PRODUCT_PREFIXES = ["DR", "FD", "NC"]


# ------------------------------------------------
# API HELPERS
# ------------------------------------------------

def predict_single(input_data):
    """Send raw (non-encoded) data directly to the API."""
    response = requests.post(API_SINGLE, json=input_data)
    if response.status_code != 200:
        raise ValueError(f"API Error: {response.text}")

    result = response.json()
    return float(result["Prediction"])


def predict_batch(df):
  # Convert DataFrame to CSV buffer
  csv_buffer = io.StringIO()
  df.to_csv(csv_buffer, index=False)
  csv_buffer.seek(0)

  # Send file as multipart/form-data
  files = {'file': ('data.csv', csv_buffer.getvalue())}
  response = requests.post(API_BATCH, files=files)

  if response.status_code != 200:
      raise ValueError(f"API Error: {response.text}")

  # Server returns dict {Product_Id: prediction}
  predictions_dict = response.json()

  # Map predictions back to DataFrame
  df_out = df.copy()
  df_out["Predicted_Sales"] = df_out["Product_Id"].map(
      lambda x: round(predictions_dict.get(x, 0), 2)
  )

  return df_out


# ------------------------------------------------
# STREAMLIT UI
# ------------------------------------------------
st.title("Superkart Product Sales Prediction")

# ---------------------
# BATCH PREDICTION
# ---------------------
st.header("Batch Prediction")
uploaded = st.file_uploader("Upload CSV", type=["csv"])

if uploaded is not None:
  df = pd.read_csv(uploaded)
  st.write(df.head())

  # Show Predict button only after upload
  if st.button("Predict Batch"):
    try:
      # --- Add derived columns required by the model ---
      df['Product_Id_Prefix'] = df['Product_Id'].str[:2]
      current_year = datetime.now().year
      df['Store_Age'] = current_year - df['Store_Establishment_Year']

      df_pred = predict_batch(df)
      st.success("Batch Prediction Completed!")
      st.dataframe(df_pred)

      # ---- DOWNLOAD MERGED FILE ----
      csv = df_pred.to_csv(index=False)
      st.download_button("Download CSV", csv, "predictions.csv")

    except Exception as e:
      st.error(str(e))

# ---------------------
# SINGLE PREDICTION
# ---------------------
st.header("Single Prediction")
st.write("Store and Product datatils:")
with st.form("single_form"):
    col1, col2 = st.columns(2)

    with col1:
        product_id_input = st.text_input("Product ID (e.g., DR123, FD889A)")
        sugar = st.selectbox("Product Sugar Content", PRODUCT_SUGAR_CONTENT)
        product_type = st.selectbox("Product Type", PRODUCT_TYPES)

        store_id = st.selectbox("Store ID", STORE_IDS)
        store_size = st.selectbox("Store Size", STORE_SIZES)
        store_type = st.selectbox("Store Type", STORE_TYPES)
    with col2:
        weight = st.number_input("Product Weight", min_value=0.0, step=1.0)
        area = st.number_input("Product Allocated Area", min_value=0.0, max_value=1.0, step=0.010, format="%.3f")
        mrp = st.number_input("Product MRP", min_value=0.0, step=20.0)

        est_year = st.number_input(
            "Store Establishment Year",
            1900, datetime.now().year,
            2015
        )
        store_city = st.selectbox("Store Location City Type", STORE_CITY_TYPES)

    submit = st.form_submit_button("Predict")

    if submit:
        try:
            # ---- Extract and validate prefix ----
            product_id = product_id_input.strip().upper()

            if len(product_id) < 2:
                st.error("Product ID must contain at least 2 characters (prefix) followed by few digits.")
                st.stop()

            prefix = product_id[:2]

            if prefix not in PRODUCT_PREFIXES:
                st.error(f"Invalid Product Prefix '{prefix}'. Valid prefixes: {PRODUCT_PREFIXES}")
                st.stop()

            # Compute store age
            current_year = datetime.now().year
            store_age = current_year - est_year

            # Build payload
            payload = {
                "Store_Id": store_id,
                "Store_Type": store_type,
                "Store_Size": store_size,
                "Store_Location_City_Type": store_city,

                "Product_ID": product_id,
                "Product_Id_Prefix": prefix,
                "Product_Type": product_type,
                "Product_Sugar_Content": sugar,

                "Store_Age": store_age,
                "Product_Weight": weight,
                "Product_Allocated_Area": area,
                "Product_MRP": mrp
            }

            pred = predict_single(payload)

            final_pred = round(pred, 2)

            st.success(f"Predicted Sales: {final_pred} units")

        except Exception as e:
            st.error(e)