const { runTencentVatOcr } = require("./tencent");
const { runMockOcr } = require("./mock");

const REQUIRED_OCR_FIELDS_BY_TYPE = {
  vat: ["invoiceCode", "invoiceNumber", "invoiceDate", "totalAmount", "sellerName"],
};

function isOcrEnabledForType(config, ocrType) {
  if (config.ocrProvider === "mock") {
    return ocrType === "vat";
  }

  return config.ocrProvider === "tencent" && ocrType === "vat";
}

function getMissingRequiredOcrFields(ocrType, normalized) {
  const requiredFields = REQUIRED_OCR_FIELDS_BY_TYPE[ocrType] ?? [];
  if (!requiredFields.length) {
    return [];
  }

  return requiredFields.filter((field) => {
    const value = normalized?.[field];
    return value == null || value === "";
  });
}

function buildMissingRequiredOcrError(ocrType, normalized) {
  const missingFields = getMissingRequiredOcrFields(ocrType, normalized);
  if (!missingFields.length) {
    return null;
  }

  return `missing_required_fields:${missingFields.join(",")}`;
}

async function runOcrForInvoice({ config, ocrType, imageBase64 }) {
  if (config.ocrProvider === "mock") {
    return runMockOcr({ ocrType, imageBase64 });
  }

  if (config.ocrProvider !== "tencent") {
    throw new Error(`Unsupported OCR provider: ${config.ocrProvider}`);
  }

  if (ocrType !== "vat") {
    throw new Error(`Unsupported OCR type: ${ocrType}`);
  }

  return runTencentVatOcr(config, imageBase64);
}

module.exports = {
  buildMissingRequiredOcrError,
  getMissingRequiredOcrFields,
  isOcrEnabledForType,
  runOcrForInvoice,
};