"""
Inventory Management Module
Handles reading and querying product metadata from stock.csv.
"""

import os
import sys
import csv
from typing import Dict, Optional, Any, List

if sys.platform.startswith('win'):
    try:
        sys.stdout.reconfigure(encoding='utf-8')
    except Exception:
        pass


class InventoryManager:
    def __init__(self, stock_dir: str = "stock", csv_filename: str = "stock.csv"):
        self.stock_dir = stock_dir
        self.csv_path = os.path.join(stock_dir, csv_filename)
        self.products: Dict[str, Dict[str, Any]] = {}
        self.load_inventory()

    def load_inventory(self) -> None:
        """Loads inventory data from the CSV file."""
        if not os.path.exists(self.csv_path):
            print(f"[Warning] Inventory CSV not found at: {self.csv_path}")
            return

        with open(self.csv_path, mode="r", encoding="utf-8") as f:
            reader = csv.DictReader(f)
            for row in reader:
                sku_id = row.get("SKU_ID", "").strip()
                if not sku_id:
                    continue

                # Locate the corresponding template image in stock_dir
                local_image = self._find_template_image(sku_id)

                self.products[sku_id] = {
                    "sku_id": sku_id,
                    "product_name": row.get("product_name", "").strip(),
                    "receipt_date": row.get("receipt_date", "").strip(),
                    "expiration_date": row.get("expiration_date", "").strip(),
                    "number_in": int(row.get("number_in", 0) or 0),
                    "number_out": int(row.get("number_out", 0) or 0),
                    "number_on": int(row.get("number_on", 0) or 0),
                    "price": float(row.get("price", 0) or 0),
                    "raw_image_link": row.get("image_link", "").strip(),
                    "local_image_path": local_image
                }

    def _find_template_image(self, sku_id: str) -> Optional[str]:
        """Finds the local image file for the given SKU_ID."""
        extensions = [".jpeg", ".jpg", ".png"]
        for ext in extensions:
            candidate = os.path.join(self.stock_dir, f"{sku_id}{ext}")
            if os.path.exists(candidate):
                return candidate
        return None

    def get_product(self, sku_id: str) -> Optional[Dict[str, Any]]:
        """Retrieves product information for a given SKU_ID."""
        return self.products.get(sku_id)

    def list_all_skus(self) -> List[str]:
        """Returns all available SKU IDs."""
        return list(self.products.keys())

    def update_stock(self, sku_id: str, quantity_delta: int) -> bool:
        """Updates the on-shelf quantity (e.g., when purchased or restocked)."""
        if sku_id in self.products:
            current = self.products[sku_id]["number_on"]
            new_val = max(0, current + quantity_delta)
            self.products[sku_id]["number_on"] = new_val
            if quantity_delta < 0:
                self.products[sku_id]["number_out"] += abs(quantity_delta)
            else:
                self.products[sku_id]["number_in"] += quantity_delta
            return True
        return False


if __name__ == "__main__":
    inv = InventoryManager("stock")
    print(f"Loaded {len(inv.products)} products.")
    for sku in inv.list_all_skus():
        p = inv.get_product(sku)
        print(f"[{sku}] {p['product_name']} | Price: {p['price']} | In-Stock: {p['number_on']} | Image: {p['local_image_path']}")