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

// Default patterns (backward compatible with existing numbers)
const DEFAULT_OFFER_PATTERN = "{YYYY}/{PREFIX}/{NNN}";
const DEFAULT_ORDER_PATTERN = "{YY}{CODE}{NNNN}";
const DEFAULT_INVOICE_PATTERN = "{YY}{CODE}{NNNN}";

/**
 * Apply a numbering pattern template.
 * Placeholders: {YYYY}, {YY}, {PREFIX}, {CODE}, {N+} (padding = count of N's)
 */
function applyPattern(
  pattern: string,
  vars: { year: number; prefix: string; code: string; seq: number },
): string {
  const yyyy = String(vars.year);
  const yy = yyyy.slice(-2);

  return pattern.replace(/\{(\w+)\}/g, (match, key: string) => {
    if (key === "YYYY") return yyyy;
    if (key === "YY") return yy;
    if (key === "PREFIX") return vars.prefix;
    if (key === "CODE") return vars.code;
    if (/^N+$/.test(key)) return String(vars.seq).padStart(key.length, "0");
    return match;
  });
}

/**
 * Extract the static prefix and sequence position from a pattern.
 * Used to build SQL LIKE patterns for MAX(seq) queries.
 */
function buildLikePattern(
  pattern: string,
  vars: { year: number; prefix: string; code: string },
): { likePattern: string; prefixLen: number } {
  const yyyy = String(vars.year);
  const yy = yyyy.slice(-2);

  let staticPrefix = "";
  let foundSeq = false;
  const parts = pattern.split(/(\{[^}]+\})/);

  for (const part of parts) {
    const m = part.match(/^\{(\w+)\}$/);
    if (!m) {
      staticPrefix += part;
      continue;
    }
    const key = m[1];
    if (/^N+$/.test(key)) {
      foundSeq = true;
      break;
    }
    if (key === "YYYY") staticPrefix += yyyy;
    else if (key === "YY") staticPrefix += yy;
    else if (key === "PREFIX") staticPrefix += vars.prefix;
    else if (key === "CODE") staticPrefix += vars.code;
  }

  if (!foundSeq) {
    return { likePattern: staticPrefix + "%", prefixLen: staticPrefix.length };
  }

  return { likePattern: staticPrefix + "%", prefixLen: staticPrefix.length };
}

async function getSettings() {
  return prisma.company_settings.findFirst({
    select: {
      quotation_prefix: true,
      order_type_code: true,
      invoice_type_code: true,
      offer_number_pattern: true,
      order_number_pattern: true,
      invoice_number_pattern: true,
    },
  });
}

/**
 * Next offer/quotation number.
 */
export async function generateOfferNumber(): Promise<string> {
  const settings = await getSettings();
  const pattern = settings?.offer_number_pattern || DEFAULT_OFFER_PATTERN;
  const prefix = settings?.quotation_prefix || "NA";
  const year = new Date().getFullYear();

  const { likePattern, prefixLen } = buildLikePattern(pattern, {
    year,
    prefix,
    code: "",
  });

  const result = await prisma.$queryRaw<[{ max_seq: bigint | null }]>`
    SELECT COALESCE(MAX(CAST(SUBSTRING(quotation_number, ${prefixLen} + 1) AS UNSIGNED)), 0) as max_seq
    FROM quotations
    WHERE quotation_number LIKE ${likePattern}
  `;
  const nextNum = Number(result[0]?.max_seq ?? 0) + 1;

  return applyPattern(pattern, { year, prefix, code: "", seq: nextNum });
}

/**
 * Shared number for orders and projects.
 */
export async function generateSharedNumber(): Promise<string> {
  const settings = await getSettings();
  const pattern = settings?.order_number_pattern || DEFAULT_ORDER_PATTERN;
  const code = settings?.order_type_code || "71";
  const year = new Date().getFullYear();

  const { likePattern, prefixLen } = buildLikePattern(pattern, {
    year,
    prefix: "",
    code,
  });

  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 applyPattern(pattern, { year, prefix: "", code, seq: nextNum });
}

/**
 * Next invoice number.
 */
export async function generateInvoiceNumber(
  _year?: number,
): Promise<{ number: string; next_number: string }> {
  const settings = await getSettings();
  const pattern = settings?.invoice_number_pattern || DEFAULT_INVOICE_PATTERN;
  const code = settings?.invoice_type_code || "81";
  const year = _year || new Date().getFullYear();

  const { likePattern, prefixLen } = buildLikePattern(pattern, {
    year,
    prefix: "",
    code,
  });

  const result = await prisma.$queryRaw<[{ max_seq: bigint | null }]>`
    SELECT COALESCE(MAX(CAST(SUBSTRING(invoice_number, ${prefixLen} + 1) AS UNSIGNED)), 0) as max_seq
    FROM invoices
    WHERE invoice_number LIKE ${likePattern}
  `;
  const nextNum = Number(result[0]?.max_seq ?? 0) + 1;

  const number = applyPattern(pattern, {
    year,
    prefix: "",
    code,
    seq: nextNum,
  });
  return { number, next_number: number };
}

/** Preview what a pattern would produce (for settings UI) */
export function previewPattern(
  pattern: string,
  prefix: string,
  code: string,
): string {
  return applyPattern(pattern, {
    year: new Date().getFullYear(),
    prefix,
    code,
    seq: 1,
  });
}