/**
 * 採購單表單管理 Hook
 */

import { useState, useEffect } from "react";
import type { PurchaseOrder, PurchaseOrderItem, Supplier, PurchaseOrderStatus } from "@/types/purchase-order";
import { calculateSubtotal } from "@/utils/purchase-order";

interface UsePurchaseOrderFormProps {
    order?: PurchaseOrder;
    suppliers: Supplier[];
}

export function usePurchaseOrderForm({ order, suppliers }: UsePurchaseOrderFormProps) {
    const [supplierId, setSupplierId] = useState("");
    const [expectedDate, setExpectedDate] = useState("");
    const [items, setItems] = useState<PurchaseOrderItem[]>([]);
    const [notes, setNotes] = useState("");
    const [status, setStatus] = useState<PurchaseOrderStatus>("draft");
    const [warehouseId, setWarehouseId] = useState<string | number>("");

    // 載入編輯訂單資料
    useEffect(() => {
        if (order) {
            setSupplierId(order.supplierId);
            setExpectedDate(order.expectedDate);
            setItems(order.items);
            setNotes(order.remark || "");
            setStatus(order.status);
            setWarehouseId(order.warehouse_id || "");
        }
    }, [order]);

    const resetForm = () => {
        setSupplierId("");
        setExpectedDate("");
        setItems([]);
        setNotes("");
        setStatus("draft");
        setWarehouseId("");
    };

    const selectedSupplier = suppliers.find((s) => String(s.id) === String(supplierId));
    const isOrderSent = order && order.status !== "draft";

    // 新增商品項目
    const addItem = () => {
        if (!selectedSupplier) return;

        setItems([
            ...items,
            {
                productId: "",
                productName: "",
                quantity: 0,
                unit: "",
                unitPrice: 0,
                subtotal: 0,
            },
        ]);
    };

    // 移除商品項目
    const removeItem = (index: number) => {
        setItems(items.filter((_, i) => i !== index));
    };

    // 更新商品項目
    const updateItem = (index: number, field: keyof PurchaseOrderItem, value: string | number) => {
        const newItems = [...items];
        newItems[index] = { ...newItems[index], [field]: value };

        // 當選擇商品時，自動填入商品資訊
        if (field === "productId" && selectedSupplier) {
            const product = selectedSupplier.commonProducts.find((p) => p.productId === value);
            if (product) {
                newItems[index].productName = product.productName;
                newItems[index].unit = product.unit;
                newItems[index].base_unit = product.base_unit;
                newItems[index].purchase_unit = product.purchase_unit;
                newItems[index].conversion_rate = product.conversion_rate;
                newItems[index].unitPrice = product.lastPrice;
                newItems[index].previousPrice = product.lastPrice;
            }
        }

        // 計算小計
        if (field === "quantity" || field === "unitPrice") {
            newItems[index].subtotal = calculateSubtotal(
                Number(newItems[index].quantity),
                Number(newItems[index].unitPrice)
            );
        }

        setItems(newItems);
    };

    return {
        // State
        supplierId,
        expectedDate,
        items,
        notes,
        status,
        selectedSupplier,
        isOrderSent,
        warehouseId,

        // Setters
        setSupplierId,
        setExpectedDate,
        setNotes,
        setStatus,
        setWarehouseId,

        // Methods
        addItem,
        removeItem,
        updateItem,
        resetForm,
    };
}