"""
Order aggregation script.

Reads all submitted orders for a given week and produces:
1. Order summary — total quantity of each meal (for submitting to Redefine Meals)
2. Payroll deduction report — CSV with employee name, email, itemized meals, total amount
"""

import csv
import json
import sys
from collections import defaultdict
from datetime import datetime
from pathlib import Path

PROJECT_ROOT = Path(__file__).resolve().parents[2]
CONFIG_PATH = PROJECT_ROOT / "config.json"
ORDERS_DIR = PROJECT_ROOT / "orders"
OUTPUT_DIR = PROJECT_ROOT / "output"


def load_config():
    with open(CONFIG_PATH) as f:
        return json.load(f)


def current_week() -> str:
    return datetime.now().strftime("%Y-W%U")


def load_orders(week: str) -> list[dict]:
    week_dir = ORDERS_DIR / week
    if not week_dir.exists():
        return []
    orders = []
    for f in sorted(week_dir.glob("*.json")):
        with open(f) as fh:
            orders.append(json.load(fh))
    return orders


def generate_order_summary(orders: list[dict]) -> dict:
    """Aggregate all meals across employees into a single order for Redefine."""
    meal_totals = defaultdict(
        lambda: {"quantity": 0, "bulk_price": 0, "employee_price": 0}
    )
    for order in orders:
        for item in order.get("items", []):
            name = item["name"]
            meal_totals[name]["quantity"] += item.get("quantity", 0)
            meal_totals[name]["bulk_price"] = item.get(
                "bulk_price", item.get("price", 0)
            )
            meal_totals[name]["employee_price"] = item.get("price", 0)

    summary = []
    for name, data in sorted(meal_totals.items()):
        summary.append(
            {
                "meal": name,
                "quantity": data["quantity"],
                "unit_price": data["bulk_price"],
                "employee_unit_price": data["employee_price"],
                "line_total": round(data["bulk_price"] * data["quantity"], 2),
                "employee_line_total": round(
                    data["employee_price"] * data["quantity"], 2
                ),
            }
        )

    grand_total = sum(s["line_total"] for s in summary)
    employee_total = sum(s["employee_line_total"] for s in summary)
    total_meals = sum(s["quantity"] for s in summary)

    return {
        "week": orders[0]["week"] if orders else "",
        "generated_at": datetime.now().isoformat(),
        "total_employees": len(orders),
        "total_meals": total_meals,
        "grand_total": round(grand_total, 2),
        "employee_total": round(employee_total, 2),
        "meals": summary,
    }


def generate_payroll_csv(orders: list[dict], output_path: Path):
    """Write a CSV for payroll with one row per employee."""
    with open(output_path, "w", newline="") as f:
        writer = csv.writer(f)
        writer.writerow(
            ["Employee Name", "Employee Email", "Items Ordered", "Total Deduction"]
        )
        for order in sorted(orders, key=lambda o: o["employee_name"]):
            items_str = "; ".join(
                f"{item['name']} x{item['quantity']} (${item['subtotal']:.2f})"
                for item in order.get("items", [])
            )
            writer.writerow(
                [
                    order["employee_name"],
                    order["employee_email"],
                    items_str,
                    f"${order['total']:.2f}",
                ]
            )


def generate_order_summary_csv(summary: dict, output_path: Path):
    """Write a CSV of the aggregated order for submitting to Redefine."""
    with open(output_path, "w", newline="") as f:
        writer = csv.writer(f)
        writer.writerow(["Meal", "Quantity", "Unit Price", "Line Total"])
        for meal in summary["meals"]:
            writer.writerow(
                [
                    meal["meal"],
                    meal["quantity"],
                    f"${meal['unit_price']:.2f}",
                    f"${meal['line_total']:.2f}",
                ]
            )
        writer.writerow([])
        writer.writerow(
            ["TOTAL", summary["total_meals"], "", f"${summary['grand_total']:.2f}"]
        )


def main():
    week = sys.argv[1] if len(sys.argv) > 1 else current_week()
    orders = load_orders(week)

    if not orders:
        print(f"No orders found for week {week}")
        print(f"  Expected directory: {ORDERS_DIR / week}")
        sys.exit(1)

    print(f"Processing {len(orders)} orders for week {week}")

    summary = generate_order_summary(orders)
    OUTPUT_DIR.mkdir(exist_ok=True)

    # Save order summary
    summary_json = OUTPUT_DIR / f"order-summary-{week}.json"
    with open(summary_json, "w") as f:
        json.dump(summary, f, indent=2)

    summary_csv = OUTPUT_DIR / f"order-summary-{week}.csv"
    generate_order_summary_csv(summary, summary_csv)

    # Save payroll report
    payroll_csv = OUTPUT_DIR / f"payroll-deductions-{week}.csv"
    generate_payroll_csv(orders, payroll_csv)

    # Print summary
    print(f"\n{'=' * 60}")
    print(f"ORDER SUMMARY — Week {week}")
    print(f"{'=' * 60}")
    print(f"{'Meal':<45} {'Qty':>4} {'Total':>8}")
    print("-" * 60)
    for meal in summary["meals"]:
        print(f"{meal['meal']:<45} {meal['quantity']:>4} ${meal['line_total']:>7.2f}")
    print("-" * 60)
    print(f"{'TOTAL':<45} {summary['total_meals']:>4} ${summary['grand_total']:>7.2f}")
    if (
        summary.get("employee_total") is not None
        and summary["employee_total"] != summary["grand_total"]
    ):
        print(f"{'PAYROLL DEDUCTIONS':<45}      ${summary['employee_total']:>7.2f}")
        subsidy = round(summary["grand_total"] - summary["employee_total"], 2)
        print(f"{'COMPANY SUBSIDY':<45}      ${subsidy:>7.2f}")
    print(f"\n{summary['total_employees']} employees ordered")

    print("\nFiles generated:")
    print(f"  Order summary: {summary_csv}")
    print(f"  Payroll report: {payroll_csv}")
    print(f"  Raw JSON:       {summary_json}")


if __name__ == "__main__":
    main()