import { registerAs } from "@nestjs/config";

/**
 * Ethiopian MoR EIMS e-invoicing gateway.
 *
 * Disabled by default: with `EIMS_ENABLED=false` the config resolves to a stub and every EIMS
 * service throws a clear error on use, so a deployment without credentials still boots.
 *
 * Secrets (client secret, API key) and the credential file paths live only here and are never
 * logged — validation reports missing variable *names*, never their values.
 */
export interface EimsConfig {
  enabled: boolean;
  baseUrl: string;
  clientId: string;
  clientSecret: string;
  apiKey: string;
  tin: string;
  /**
   * Optional *expectations* for the source-system identity, not inputs.
   *
   * The access token MoR issues carries `systemNumber` and `systemType` claims for the credentials
   * that authenticated, and those are what registration uses. When these are set they are compared
   * against the token and a mismatch fails fast — neither side silently wins. Leave them empty to
   * take whatever the gateway says.
   */
  systemNumber: string;
  systemType: string;
  /** Filesystem path to the INSA-issued RSA private key (PEM). Never leaves the server. */
  privateKeyPath: string;
  /** Filesystem path to the INSA-issued certificate bundle; sent as base64 of its exact bytes. */
  certificatePath: string;
  httpTimeoutMs: number;
  /** Re-authenticate this many ms before the access token actually expires. */
  tokenSkewMs: number;
  /**
   * Automatic submission of issued invoices, off by default.
   *
   * Invoices are produced by the workflow, so the production path is a sweep rather than a human
   * action — but enabling it starts filing real documents with the tax authority, which is
   * irreversible from our side. It therefore needs its own deliberate switch, separate from
   * `EIMS_ENABLED`, so that authentication can be live long before filing is.
   */
  autoSubmit: boolean;
  autoSubmitCron: string;
  /** MoR rejects a document whose date is more than 3 days old; the sweep will not attempt those. */
  autoSubmitMaxAgeDays: number;
  /**
   * Seller identity and tax/business treatment for the invoice document.
   *
   * None of this is derivable from the database: EDR's own legal identity exists nowhere in the
   * codebase, and the app models no tax at all. Values are required at registration time and are
   * validated there rather than at boot, so a deployment can run with EIMS enabled for
   * authentication before finance has signed off on the tax treatment.
   */
  invoice: EimsInvoiceConfig;
}

export interface EimsInvoiceConfig {
  sellerLegalName: string;
  sellerVatNumber: string;
  sellerPhone: string;
  sellerEmail: string;
  /** MoR *codes*, not names (e.g. "13" for Addis Ababa, "574"). */
  sellerRegion: string;
  sellerWereda: string;
  sellerCity: string | null;
  sellerSubCity: string | null;
  sellerHouseNumber: string | null;
  sellerLocality: string | null;
  /** REQUIRES_BUSINESS_CONFIRMATION — no tax model exists in this application. */
  taxCode: string;
  taxRatePercent: number | null;
  exciseTaxValue: number | null;
  incomeWithholdValue: number | null;
  transactionWithholdValue: number | null;
  /** B2B / B2C — a tax classification, so it is configured, not inferred. */
  transactionType: string;
  natureOfSupplies: string;
  paymentMode: string;
  paymentTerm: string;
  unitDefault: string;
  buyerCountryCode: string | null;
  cashierName: string | null;
  salesPersonName: string | null;
}

const REQUIRED_VARS = [
  "EIMS_CLIENT_ID",
  "EIMS_CLIENT_SECRET",
  "EIMS_API_KEY",
  "EIMS_TIN",
  "EIMS_PRIVATE_KEY_PATH",
  "EIMS_CERTIFICATE_PATH",
] as const;

const positiveInt = (raw: string | undefined, fallback: number, name: string): number => {
  if (raw === undefined || raw === "") return fallback;
  const value = Number.parseInt(raw, 10);
  if (Number.isNaN(value) || value <= 0) {
    throw new Error(`${name} must be a positive integer`);
  }
  return value;
};

/** Unset stays null so the registration-time check can name it; a set-but-bogus value throws. */
const optionalNumber = (raw: string | undefined, name: string): number | null => {
  if (raw === undefined || raw === "") return null;
  const value = Number(raw);
  if (!Number.isFinite(value)) throw new Error(`${name} must be a number`);
  return value;
};

export default registerAs("eims", (): EimsConfig => {
  const enabled = (process.env.EIMS_ENABLED ?? "false").toLowerCase() === "true";
  const baseUrl = (process.env.EIMS_BASE_URL ?? "https://core.mor.gov.et").replace(/\/+$/, "");
  const httpTimeoutMs = positiveInt(process.env.EIMS_HTTP_TIMEOUT_MS, 30_000, "EIMS_HTTP_TIMEOUT_MS");
  const tokenSkewMs =
    positiveInt(process.env.EIMS_TOKEN_SKEW_SECONDS, 45, "EIMS_TOKEN_SKEW_SECONDS") * 1000;

  const base: EimsConfig = {
    enabled,
    baseUrl,
    clientId: process.env.EIMS_CLIENT_ID ?? "",
    clientSecret: process.env.EIMS_CLIENT_SECRET ?? "",
    apiKey: process.env.EIMS_API_KEY ?? "",
    tin: process.env.EIMS_TIN ?? "",
    systemNumber: process.env.EIMS_SYSTEM_NUMBER ?? "",
    systemType: process.env.EIMS_SYSTEM_TYPE ?? "",
    privateKeyPath: process.env.EIMS_PRIVATE_KEY_PATH ?? "",
    certificatePath: process.env.EIMS_CERTIFICATE_PATH ?? "",
    httpTimeoutMs,
    tokenSkewMs,
    autoSubmit: (process.env.EIMS_AUTO_SUBMIT ?? "false").toLowerCase() === "true",
    // Every 5 minutes by default: filing is not latency-sensitive, and a slow cadence keeps a
    // misconfiguration from filing a burst of bad documents before anyone notices.
    autoSubmitCron: process.env.EIMS_AUTO_SUBMIT_CRON || "0 */5 * * * *",
    autoSubmitMaxAgeDays: positiveInt(
      process.env.EIMS_AUTO_SUBMIT_MAX_AGE_DAYS,
      3,
      "EIMS_AUTO_SUBMIT_MAX_AGE_DAYS",
    ),
    invoice: {
      sellerLegalName: process.env.EIMS_SELLER_LEGAL_NAME ?? "",
      sellerVatNumber: process.env.EIMS_SELLER_VAT_NUMBER ?? "",
      sellerPhone: process.env.EIMS_SELLER_PHONE ?? "",
      sellerEmail: process.env.EIMS_SELLER_EMAIL ?? "",
      sellerRegion: process.env.EIMS_SELLER_REGION ?? "",
      sellerWereda: process.env.EIMS_SELLER_WEREDA ?? "",
      sellerCity: process.env.EIMS_SELLER_CITY || null,
      sellerSubCity: process.env.EIMS_SELLER_SUBCITY || null,
      sellerHouseNumber: process.env.EIMS_SELLER_HOUSE_NUMBER || null,
      sellerLocality: process.env.EIMS_SELLER_LOCALITY || null,
      taxCode: process.env.EIMS_TAX_CODE ?? "",
      taxRatePercent: optionalNumber(process.env.EIMS_TAX_RATE_PERCENT, "EIMS_TAX_RATE_PERCENT"),
      exciseTaxValue: optionalNumber(process.env.EIMS_EXCISE_TAX_VALUE, "EIMS_EXCISE_TAX_VALUE"),
      incomeWithholdValue: optionalNumber(
        process.env.EIMS_INCOME_WITHHOLD_VALUE,
        "EIMS_INCOME_WITHHOLD_VALUE",
      ),
      transactionWithholdValue: optionalNumber(
        process.env.EIMS_TRANSACTION_WITHHOLD_VALUE,
        "EIMS_TRANSACTION_WITHHOLD_VALUE",
      ),
      transactionType: process.env.EIMS_TRANSACTION_TYPE ?? "",
      natureOfSupplies: process.env.EIMS_NATURE_OF_SUPPLIES ?? "",
      paymentMode: process.env.EIMS_PAYMENT_MODE ?? "",
      paymentTerm: process.env.EIMS_PAYMENT_TERM ?? "",
      unitDefault: process.env.EIMS_UNIT_DEFAULT ?? "",
      buyerCountryCode: process.env.EIMS_BUYER_COUNTRY_CODE || null,
      cashierName: process.env.EIMS_CASHIER_NAME || null,
      salesPersonName: process.env.EIMS_SALESPERSON_NAME || null,
    },
  };

  if (!enabled) return base;

  const missing = REQUIRED_VARS.filter((name) => !process.env[name]);
  if (missing.length > 0) {
    throw new Error(
      `EIMS integration is enabled (EIMS_ENABLED=true) but the following env vars are missing: ${missing.join(", ")}`,
    );
  }
  return base;
});