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;
  /**
   * Inline alternative to `privateKeyPath` — the key file's own bytes, base64-encoded, so a
   * container that can't be given a host bind mount can still receive it as a plain env var.
   * Takes precedence over the path when set. Either one must be present when EIMS is enabled.
   */
  privateKeyBase64: string;
  /** Inline alternative to `certificatePath`, same precedence rule. */
  certificateBase64: 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;
  /**
   * Domestic fallback only — used when the buyer's `Company.country` is empty or "Ethiopia" (the
   * column's own default) and not already listed in `buyerCountryCodes`. A genuinely foreign
   * buyer must be in `buyerCountryCodes` by name or the mapping fails locally; this value is never
   * applied to them, so an unconfigured foreign country can't silently be filed as Ethiopia.
   */
  buyerCountryCode: string | null;
  /**
   * Country name → MoR code, from `EIMS_BUYER_COUNTRY_CODES` ("Ethiopia=231,Djibouti=071"). Format
   * unconfirmed (unlike Region/Wereda, MoR has never named a Country regex), so — unlike them —
   * this is not validated against a fixed digit pattern, only looked up by name.
   */
  buyerCountryCodes: Record<string, string>;
  /**
   * Buyer region name → MoR numeric code, from `EIMS_BUYER_REGION_CODES`
   * ("Addis Ababa=13,Oromia=4"). A buyer whose region is neither a code nor in this map fails
   * locally rather than being filed with a guessed one.
   */
  buyerRegionCodes: Record<string, string>;
  /** Same mechanism as `buyerRegionCodes`, for `EIMS_BUYER_WEREDA_CODES` ("Yeka=574"). */
  buyerWeredaCodes: Record<string, string>;
  /**
   * Buyer *zone* name → MoR City code, from `EIMS_BUYER_CITY_CODES` ("Kirkos=101"). `Company` has
   * no dedicated city column — Zone is the closest match in EDR's own data. Optional, unlike
   * Region/Wereda: MoR has never required City on a live buyer (confirmed — filing already
   * succeeds with it null), so an unmapped zone falls back to null rather than failing the
   * mapping.
   */
  buyerCityCodes: Record<string, string>;
  /**
   * Per-`chargeType` tax treatment, e.g. `EIMS_TAX_CODE_BY_CHARGE_TYPE=RAIL_FREIGHT=VAT0` +
   * `EIMS_TAX_RATE_BY_CHARGE_TYPE=RAIL_FREIGHT=0`. A charge type not listed here falls back to
   * `taxCode`/`taxRatePercent`. Needed for an invoice whose lines carry different MoR tax
   * treatment (e.g. zero-rated freight next to a taxed accessorial) — the flat `taxCode` above
   * cannot express that. Values are raw strings; the context builder parses/validates them.
   */
  taxCodeByChargeType: Record<string, string>;
  taxRateByChargeType: Record<string, string>;
  /** Same mechanism, for `EIMS_EXCISE_BY_CHARGE_TYPE` / `EIMS_DISCOUNT_BY_CHARGE_TYPE`. Charge
   *  types not listed fall back to `exciseTaxValue` / 0 respectively. */
  exciseByChargeType: Record<string, string>;
  discountByChargeType: Record<string, string>;
  cashierName: string | null;
  salesPersonName: string | null;
  /**
   * TEMPORARY / experimental — `EIMS_BUYER_ID_TYPE` + `EIMS_BUYER_ID_NUMBER`, applied to every
   * buyer regardless of who they are. Only exists to test whether rule 7004 ("Id types should be
   * one of NID, KID, SID, WID, PST, DLS, MRS") is satisfied by *any* IdType/IdNumber pair, ahead
   * of MoR's answer on whether it's required for a TIN-only corporate buyer and which value fits.
   * Wrong for a real, non-self buyer — remove once MoR answers and a real per-buyer field exists.
   */
  buyerIdType: string | null;
  buyerIdNumber: string | null;
}

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

// Key/cert each have two ways in (file path or inline base64) — checked separately from
// REQUIRED_VARS since it's "at least one of", not "this exact var".
const REQUIRED_EITHER_OR: Array<[string, string]> = [
  ["EIMS_PRIVATE_KEY_PATH", "EIMS_PRIVATE_KEY_BASE64"],
  ["EIMS_CERTIFICATE_PATH", "EIMS_CERTIFICATE_BASE64"],
];

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;
};

/** "Addis Ababa=13,Oromia=4" → { "Addis Ababa": "13", Oromia: "4" }. */
const parseCodeMap = (raw: string | undefined): Record<string, string> => {
  const map: Record<string, string> = {};
  for (const pair of (raw ?? "").split(",")) {
    const [name, code] = pair.split("=");
    if (name?.trim() && code?.trim()) map[name.trim()] = code.trim();
  }
  return map;
};

/** 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 ?? "",
    privateKeyBase64: process.env.EIMS_PRIVATE_KEY_BASE64 ?? "",
    certificateBase64: process.env.EIMS_CERTIFICATE_BASE64 ?? "",
    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,
      buyerCountryCodes: parseCodeMap(process.env.EIMS_BUYER_COUNTRY_CODES),
      buyerRegionCodes: parseCodeMap(process.env.EIMS_BUYER_REGION_CODES),
      buyerWeredaCodes: parseCodeMap(process.env.EIMS_BUYER_WEREDA_CODES),
      buyerCityCodes: parseCodeMap(process.env.EIMS_BUYER_CITY_CODES),
      taxCodeByChargeType: parseCodeMap(process.env.EIMS_TAX_CODE_BY_CHARGE_TYPE),
      taxRateByChargeType: parseCodeMap(process.env.EIMS_TAX_RATE_BY_CHARGE_TYPE),
      exciseByChargeType: parseCodeMap(process.env.EIMS_EXCISE_BY_CHARGE_TYPE),
      discountByChargeType: parseCodeMap(process.env.EIMS_DISCOUNT_BY_CHARGE_TYPE),
      cashierName: process.env.EIMS_CASHIER_NAME || null,
      salesPersonName: process.env.EIMS_SALESPERSON_NAME || null,
      buyerIdType: process.env.EIMS_BUYER_ID_TYPE || null,
      buyerIdNumber: process.env.EIMS_BUYER_ID_NUMBER || null,
    },
  };

  if (!enabled) return base;

  const missing: string[] = REQUIRED_VARS.filter((name) => !process.env[name]);
  for (const [pathVar, base64Var] of REQUIRED_EITHER_OR) {
    if (!process.env[pathVar] && !process.env[base64Var]) missing.push(`${pathVar} or ${base64Var}`);
  }
  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;
});