/**
 * 採購單相關工具函式
 */

import type { PurchaseOrderItem } from "@/types/purchase-order";
import { PRICE_ALERT_THRESHOLD } from "@/constants/purchase-order";

/**
 * 格式化金額
 */
export function formatCurrency(amount: number): string {
    return `$${amount.toLocaleString()}`;
}

/**
 * 計算項目小計
 */
export function calculateSubtotal(quantity: number, unitPrice: number): number {
    return quantity * unitPrice;
}

/**
 * 計算總金額
 */
export function calculateTotalAmount(items: PurchaseOrderItem[]): number {
    return items.reduce((sum, item) => sum + Number(item.subtotal || 0), 0);
}

/**
 * 檢查價格是否警示（超過閾值）
 */
export function isPriceAlert(currentPrice: number, previousPrice?: number): boolean {
    if (!previousPrice || previousPrice === 0) return false;
    const increase = ((currentPrice - previousPrice) / previousPrice) * 100;
    return increase > PRICE_ALERT_THRESHOLD;
}

/**
 * 計算價格漲幅百分比
 */
export function calculatePriceIncrease(currentPrice: number, previousPrice?: number): number {
    if (!previousPrice || previousPrice === 0) return 0;
    return ((currentPrice - previousPrice) / previousPrice) * 100;
}

/**
 * 生成採購單編號
 */
export function generatePONumber(): string {
    const year = new Date().getFullYear();
    const sequence = (Date.now() % 100000).toString().padStart(5, "0");
    return `PO${year}${sequence}`;
}

/**
 * 取得今天日期（YYYY-MM-DD 格式）
 */
export function getTodayDate(): string {
    return new Date().toISOString().split("T")[0];
}

/**
 * 驗證採購單表單
 */
export function validatePurchaseOrder(
    supplierId: string,
    expectedDate: string,
    items: PurchaseOrderItem[]
): boolean {
    return !!(
        supplierId &&
        expectedDate &&
        items.length > 0 &&
        items.some((item) => item.quantity > 0)
    );
}

/**
 * 過濾有效項目（數量和單價都必須大於 0）
 */
export function filterValidItems(items: PurchaseOrderItem[]): PurchaseOrderItem[] {
    return items.filter((item) => item.quantity > 0 && item.unitPrice > 0);
}