import prisma from "../config/database";

/**
 * Shared number generator for orders and projects.
 * Format: YYtypeCode + 4-digit sequence (e.g., 26710003)
 * Queries MAX from both orders and projects tables.
 */
export async function generateSharedNumber(): Promise<string> {
  const settings = await prisma.company_settings.findFirst({
    select: { order_type_code: true },
  });
  const typeCode = settings?.order_type_code || "71";
  const yy = String(new Date().getFullYear()).slice(-2);
  const prefix = `${yy}${typeCode}`;
  const prefixLen = prefix.length;
  const likePattern = `${prefix}%`;

  const result = await prisma.$queryRaw<[{ max_seq: bigint | null }]>`
    SELECT COALESCE(MAX(seq), 0) as max_seq FROM (
      SELECT CAST(SUBSTRING(order_number, ${prefixLen} + 1) AS UNSIGNED) AS seq
      FROM orders WHERE order_number LIKE ${likePattern}
      UNION ALL
      SELECT CAST(SUBSTRING(project_number, ${prefixLen} + 1) AS UNSIGNED) AS seq
      FROM projects WHERE project_number LIKE ${likePattern}
    ) combined
  `;
  const nextNum = Number(result[0]?.max_seq ?? 0) + 1;
  return `${prefix}${String(nextNum).padStart(4, "0")}`;
}

/**
 * Next offer number. Queries MAX from quotations table.
 * Format: YEAR/PREFIX/NNN (e.g., 2026/NA/008)
 */
export async function generateOfferNumber(): Promise<string> {
  const settings = await prisma.company_settings.findFirst({
    select: { quotation_prefix: true },
  });
  const prefix = settings?.quotation_prefix || "NA";
  const year = new Date().getFullYear();
  const likePattern = `${year}/${prefix}/%`;

  const result = await prisma.$queryRaw<[{ max_num: bigint | null }]>`
    SELECT COALESCE(MAX(CAST(SUBSTRING_INDEX(quotation_number, '/', -1) AS UNSIGNED)), 0) as max_num
    FROM quotations
    WHERE quotation_number LIKE ${likePattern}
  `;
  const nextNum = Number(result[0]?.max_num ?? 0) + 1;
  return `${year}/${prefix}/${String(nextNum).padStart(3, "0")}`;
}

/**
 * Next invoice number via atomic sequence table.
 */
export async function generateInvoiceNumber(year: number): Promise<number> {
  return prisma.$transaction(async (tx) => {
    const existing = await tx.number_sequences.findFirst({
      where: { type: "invoice", year },
    });

    if (existing) {
      const nextNum = (existing.last_number ?? 0) + 1;
      await tx.number_sequences.update({
        where: { id: existing.id },
        data: { last_number: nextNum },
      });
      return nextNum;
    }

    await tx.number_sequences.create({
      data: { type: "invoice", year, last_number: 1 },
    });
    return 1;
  });
}