/**
 * 格式化相關工具函式
 */

/**
 * 格式化數字為千分位格式
 */
export const formatNumber = (num: number | null | undefined): string => {
  if (num === null || num === undefined) return "0";
  return num.toLocaleString();
};

/**
 * 格式化貨幣（NT$）
 */
export const formatCurrency = (num: number | null | undefined): string => {
  if (num === null || num === undefined) return "NT$ 0";
  return `NT$ ${num.toLocaleString()}`;
};

/**
 * 格式化日期
 */
export const formatDate = (date: string): string => {
  if (!date) return "-";
  // Assume date format is YYYY-MM-DD or YYYY-MM-DD HH:mm:ss
  const datePart = date.split("T")[0].split(" ")[0];
  // Directly return the parsed string components to guarantee no timezone shift
  const parts = datePart.split("-");
  if (parts.length === 3) {
    return `${parts[0]}/${parts[1]}/${parts[2]}`;
  }
  // Fallback for unexpected formats
  return datePart.replace(/-/g, "/");
};

/**
 * 格式化日期並包含星期
 */
export const formatDateWithDayOfWeek = (date: string): string => {
  if (!date) return "-";
  const datePart = date.split("T")[0].split(" ")[0];
  const parts = datePart.split("-");

  if (parts.length === 3) {
    const [y, m, d] = parts.map(Number);
    // Use noon to safely calculate the day of week
    const dt = new Date(y, m - 1, d, 12, 0, 0);
    const weekDay = dt.toLocaleDateString("zh-TW", { weekday: "short" });

    // Return original string parts + calculated weekday
    return `${parts[0]}/${parts[1]}/${parts[2]} (${weekDay})`;
  }

  return datePart.replace(/-/g, "/");
};

/**
 * 格式化發票號碼
 * 例如：AB12345678 -> AB-12345678
 */
export const formatInvoiceNumber = (invoice: string | null | undefined): string => {
  if (!invoice) return "-";
  const cleanInvoice = invoice.replace(/-/g, "");
  if (/^[a-zA-Z]{2}\d+$/.test(cleanInvoice)) {
    return `${cleanInvoice.slice(0, 2).toUpperCase()}-${cleanInvoice.slice(2)}`;
  }
  return invoice;
};

/**
 * 獲取當前日期（YYYY-MM-DD 格式）
 */
export const getCurrentDate = (): string => {
  const now = new Date();
  const year = now.getFullYear();
  const month = String(now.getMonth() + 1).padStart(2, "0");
  const day = String(now.getDate()).padStart(2, "0");
  return `${year}-${month}-${day}`;
};

/**
 * 生成唯一 ID
 */
export const generateId = (): string => {
  return `${Date.now()}-${Math.random().toString(36).substring(2, 9)}`;
};

/**
 * 生成撥補單號
 */
export const generateOrderNumber = (): string => {
  return `TO${Date.now().toString().slice(-8)}`;
};

/**
 * 生成批號
 * 格式：{倉庫代碼}-{日期YYYYMMDD}-{流水號}
 * 例如：WH1-20251128-001
 */
export const generateBatchNumber = (
  warehouseId: string,
  date?: string,
  sequence?: number
): string => {
  const targetDate = date || getCurrentDate();
  const dateStr = targetDate.replace(/-/g, "");
  const seq = sequence || Math.floor(Math.random() * 1000);
  const seqStr = seq.toString().padStart(3, "0");
  return `WH${warehouseId}-${dateStr}-${seqStr}`;
};

/**
 * 獲取當前日期時間（YYYY-MM-DDTHH:mm 格式，用於 datetime-local input）
 */
export const getCurrentDateTime = (): string => {
  const now = new Date();
  const year = now.getFullYear();
  const month = String(now.getMonth() + 1).padStart(2, "0");
  const day = String(now.getDate()).padStart(2, "0");
  const hours = String(now.getHours()).padStart(2, "0");
  const minutes = String(now.getMinutes()).padStart(2, "0");
  return `${year}-${month}-${day}T${hours}:${minutes}`;
};

/**
 * 格式化日期時間顯示
 */
export const formatDateTime = (datetime: string): string => {
  if (!datetime) return "-";
  return new Date(datetime).toLocaleString("zh-TW", {
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    hour: "2-digit",
    minute: "2-digit",
    hour12: false,
  });
};

/**
 * 獲取日期區間（YYYY-MM-DD 格式）
 * 支援: today, yesterday, this_week, this_month, last_month
 */
export const getDateRange = (type: string): { start: string, end: string } => {
  const now = new Date();
  // Reset time to avoid timezone issues when calculating dates
  now.setHours(12, 0, 0, 0);

  let start = new Date(now);
  let end = new Date(now);

  const format = (d: Date) => {
    const year = d.getFullYear();
    const month = String(d.getMonth() + 1).padStart(2, "0");
    const day = String(d.getDate()).padStart(2, "0");
    return `${year}-${month}-${day}`;
  };

  switch (type) {
    case "today":
      break;
    case "yesterday":
      start.setDate(now.getDate() - 1);
      end.setDate(now.getDate() - 1);
      break;
    case "this_week":
      // 週一為一週的第一天
      const dayOfWeek = now.getDay() || 7;
      start.setDate(now.getDate() - dayOfWeek + 1);
      end.setDate(now.getDate() + (7 - dayOfWeek));
      break;
    case "this_month":
      start = new Date(now.getFullYear(), now.getMonth(), 1);
      end = new Date(now.getFullYear(), now.getMonth() + 1, 0);
      break;
    case "last_month":
      start = new Date(now.getFullYear(), now.getMonth() - 1, 1);
      end = new Date(now.getFullYear(), now.getMonth(), 0);
      break;
  }

  return {
    start: format(start),
    end: format(end)
  };
};