"use node";

import { internalAction } from "../_generated/server";
import { v } from "convex/values";
import { internal } from "../_generated/api";
import type { Id } from "../_generated/dataModel";
import type { ActionCtx } from "../_generated/server";
import {
  FinTSClient,
  Mt940Parser,
  type BankAccount,
  type ClientResponse,
  type StatementResponse,
} from "lib-fints";
import {
  createFinTsClient,
  continueWithTan,
  encodePhotoTan,
  pickDecoupledTanMethod,
  resolveFintsEnv,
  buildSessionSnapshot,
  sleep,
  type FintsEnvConfig,
  type SerializedFintsSession,
} from "./fintsSession";
import { mapFinTsTransaction } from "./fintsMap";
import {
  fetchComdirectData,
  hasComdirectCredentials,
  isRestFallbackError,
} from "./comdirectProvider";
import type { ImportRow, NormalizedAccount, NormalizedTransaction } from "./types";

export const TAN_POLL_INTERVAL_MS = 4000;
export const TAN_TIMEOUT_MS = 5 * 60 * 1000;
export const TAN_MAX_POLL_ATTEMPTS = Math.ceil(TAN_TIMEOUT_MS / TAN_POLL_INTERVAL_MS);

// comdirect (and other banks) split large MT940 statement results across
// multiple responses using continuation marks (return code 3040). lib-fints
// sends every continuation request correctly but mis-merges the binary MT940
// pages (it string-concats the `@len@` framed payloads, so only the first page
// survives the decode). We capture the raw MT940 booked payload of every HIKAZ
// response here and reassemble all pages ourselves in fetchStatementsAllPages.
let mt940Pages: string[] = [];

// Extracts the booked MT940 content from every HIKAZ segment in a raw FinTS
// response. HIKAZ encodes its booked transactions as a Binary element
// `@<len>@<mt940text>` directly after the segment header `HIKAZ:n:7+`.
function extractHikazMt940Pages(text: string): string[] {
  const pages: string[] = [];
  let idx = 0;
  for (;;) {
    const h = text.indexOf("HIKAZ:", idx);
    if (h === -1) break;
    const at1 = text.indexOf("@", h);
    if (at1 === -1) break;
    const at2 = text.indexOf("@", at1 + 1);
    if (at2 === -1) break;
    const len = Number.parseInt(text.slice(at1 + 1, at2), 10);
    if (!Number.isFinite(len) || len <= 0) {
      idx = at2 + 1;
      continue;
    }
    const content = text.slice(at2 + 1, at2 + 1 + len);
    pages.push(content);
    idx = at2 + 1 + len;
  }
  return pages;
}

const origFetch: typeof fetch = globalThis.fetch.bind(globalThis);
globalThis.fetch = (async (...args: Parameters<typeof fetch>) => {
  const res = await origFetch(...args);
  try {
    const text = Buffer.from(await res.clone().text(), "base64").toString(
      "latin1",
    );
    if (text.includes("HIKAZ:")) {
      for (const page of extractHikazMt940Pages(text)) {
        mt940Pages.push(page);
      }
    }
  } catch {
    /* ignore non-FinTS responses */
  }
  return res;
}) as typeof fetch;

type PendingSyncJob = {
  from: string;
  to: string;
  accountId?: Id<"accounts">;
  provider: "fints" | "comdirect";
  phase: "fetch" | "persist";
  partialAccounts?: NormalizedAccount[];
  partialTransactions?: Record<string, NormalizedTransaction[]>;
};

async function waitForDecoupledTan(
  ctx: ActionCtx,
  userId: Id<"users">,
  client: FinTSClient,
  session: SerializedFintsSession,
  initialResponse: ClientResponse,
  syncJob: PendingSyncJob,
): Promise<ClientResponse> {
  let response = initialResponse;
  let sessionState = session;
  const isDecoupled = client.config.selectedTanMethod?.isDecoupled ?? false;

  if (!response.requiresTan || !response.tanReference) {
    return response;
  }

  const photo = encodePhotoTan(response);
  await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
    userId,
    status: "awaiting",
    challengeRef: response.tanReference,
    challengeMessage: response.tanChallenge ?? "Bitte TAN in der Banking-App freigeben",
    photoTanMimeType: photo.mimeType ?? null,
    photoTanBase64: photo.base64 ?? null,
    pollAttempt: 0,
    syncJobJson: JSON.stringify({ syncJob }),
    isDecoupled,
    submittedTan: null,
  });

  await ctx.scheduler.runAfter(TAN_POLL_INTERVAL_MS, internal.bank.orchestrator.pollTan, {
    userId,
    attempt: 1,
  });

  for (let attempt = 1; attempt <= TAN_MAX_POLL_ATTEMPTS; attempt += 1) {
    await sleep(TAN_POLL_INTERVAL_MS);

    const pending = await ctx.runQuery(internal.bank.internal.getPendingTan, { userId });
    const submittedTan = pending?.submittedTan?.trim() || undefined;

    if (!isDecoupled && !submittedTan) {
      continue;
    }

    response = await continueWithTan(
      client,
      {
        ...sessionState,
        tanReference: response.tanReference ?? sessionState.tanReference,
      },
      submittedTan,
    );

    if (submittedTan) {
      await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
        userId,
        status: "awaiting",
        submittedTan: null,
        pollAttempt: attempt,
      });
    }

    if (!response.requiresTan) {
      await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
        userId,
        status: "done",
        challengeRef: null,
        challengeMessage: null,
        photoTanMimeType: null,
        photoTanBase64: null,
        syncJobJson: null,
        submittedTan: null,
        pollAttempt: attempt,
      });
      return response;
    }

    sessionState = buildSessionSnapshot(
      client,
      response.tanReference ?? sessionState.tanReference,
      sessionState.tanContinuation,
    );

    const nextPhoto = encodePhotoTan(response);
    await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
      userId,
      status: "awaiting",
      challengeRef: response.tanReference ?? sessionState.tanReference,
      challengeMessage: response.tanChallenge ?? "Bitte TAN in der Banking-App freigeben",
      photoTanMimeType: nextPhoto.mimeType ?? null,
      photoTanBase64: nextPhoto.base64 ?? null,
      pollAttempt: attempt,
      syncJobJson: JSON.stringify({ syncJob }),
      isDecoupled,
    });
  }

  await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
    userId,
    status: "error",
    errorMessage: "TAN-Freigabe Timeout (5 Minuten)",
  });
  throw new Error("TAN-Freigabe Timeout (5 Minuten)");
}

async function resolveTanResponse(
  ctx: ActionCtx,
  userId: Id<"users">,
  client: FinTSClient,
  response: ClientResponse,
  continuation: SerializedFintsSession["tanContinuation"],
  syncJob: PendingSyncJob,
): Promise<ClientResponse> {
  if (!response.requiresTan || !response.tanReference) {
    return response;
  }
  const session = buildSessionSnapshot(client, response.tanReference, continuation);
  return await waitForDecoupledTan(ctx, userId, client, session, response, syncJob);
}

async function logProvider(
  ctx: ActionCtx,
  userId: Id<"users">,
  provider: "comdirect" | "fints",
  reason: string,
) {
  console.info("[bank-sync]", { userId, provider, reason });
  await ctx.runMutation(internal.bank.internal.updateSyncState, {
    userId,
    lastProviderUsed: provider,
  });
}

async function ensureFinTsReady(
  client: FinTSClient,
  env: FintsEnvConfig,
  ctx: ActionCtx,
  userId: Id<"users">,
  syncJob: PendingSyncJob,
): Promise<FinTSClient> {
  let syncResponse = await client.synchronize();
  syncResponse = await resolveTanResponse(ctx, userId, client, syncResponse, "sync", syncJob);
  if (!syncResponse.success) {
    throw new Error(
      syncResponse.bankAnswers.map((a) => a.text).join("; ") || "FinTS-Synchronisation fehlgeschlagen",
    );
  }

  const tanMethodId = pickDecoupledTanMethod(client);
  if (tanMethodId && !client.config.selectedTanMethod) {
    const method = client.selectTanMethod(tanMethodId);
    if (method.tanMediaRequirement === 2 && method.activeTanMedia[0]) {
      client.selectTanMedia(method.activeTanMedia[0]);
    }
  }

  if (!client.config.bankingInformation.upd?.bankAccounts?.length) {
    syncResponse = await client.synchronize();
    syncResponse = await resolveTanResponse(ctx, userId, client, syncResponse, "sync", syncJob);
    if (!syncResponse.success) {
      throw new Error(
        syncResponse.bankAnswers.map((a) => a.text).join("; ") ||
          "FinTS-Synchronisation fehlgeschlagen",
      );
    }
  }

  await ctx.runMutation(internal.bank.internal.upsertBankConfig, {
    userId,
    fints: {
      blz: env.blz,
      url: env.url,
      login: env.login,
      productId: env.productId,
      productVersion: env.productVersion,
      tanMethodId: client.config.selectedTanMethod?.id,
      tanMediaName: methodMediaName(client),
      bankingInformationJson: JSON.stringify(client.config.bankingInformation),
    },
  });

  return client;
}

function methodMediaName(client: FinTSClient): string | undefined {
  const method = client.config.selectedTanMethod;
  if (!method?.activeTanMedia?.length) return undefined;
  return method.activeTanMedia[0];
}

function mapBankAccount(account: BankAccount): NormalizedAccount {
  return {
    externalId: account.accountNumber,
    name: account.product ?? account.holder1 ?? "Bankkonto",
    iban: account.iban,
    balance: 0,
    currency: account.currency || "EUR",
  };
}

/**
 * Fetches account statements and reassembles multi-part (3040) MT940 results.
 *
 * comdirect ignores the `to` date and returns the full range `[from, now]`,
 * paginated across multiple responses via continuation marks (return code 3040
 * "Weitere Informationen liegen vor"). lib-fints sends every continuation
 * request correctly, but mis-merges the binary MT940 pages (it string-concats
 * the `@len@` framed payloads, so only the first page survives the decode).
 *
 * We capture the raw MT940 booked content of every HIKAZ response via the fetch
 * interceptor (`mt940Pages`) and parse the concatenated pages ourselves with
 * lib-fints' own Mt940Parser, which yields the complete, non-overlapping set.
 */
async function fetchStatementsAllPages(
  ctx: ActionCtx,
  userId: Id<"users">,
  client: FinTSClient,
  account: NormalizedAccount,
  fromDate: Date,
  toDate: Date,
  preferCamt: boolean,
  syncJob: PendingSyncJob,
): Promise<StatementResponse | null> {
  // Reset the per-fetch MT940 page collector; the fetch interceptor fills it
  // while getAccountStatements walks through all 3040 continuation responses.
  mt940Pages = [];
  let resp = await client.getAccountStatements(
    account.externalId,
    fromDate,
    toDate,
    preferCamt,
  );
  resp = (await resolveTanResponse(
    ctx,
    userId,
    client,
    resp,
    "statements",
    syncJob,
  )) as StatementResponse;

  if (!resp.success) {
    return resp;
  }

  // Reassemble all captured MT940 pages ourselves to bypass lib-fints' broken
  // multi-part merge. Only override when we actually captured MT940 content
  // (i.e. MT940/HKKAZ path; CAMT accounts produce no HIKAZ pages) and our
  // reassembly is at least as complete as lib-fints' own result.
  if (mt940Pages.length > 0) {
    const libFintsCount = countStatementTransactions(resp);
    try {
      const statements = new Mt940Parser(mt940Pages.join("\r\n")).parse();
      const reassembled = statements.reduce(
        (sum, s) => sum + (s.transactions?.length ?? 0),
        0,
      );
      if (reassembled >= libFintsCount) {
        resp = { ...resp, statements };
      }
    } catch (error) {
      console.warn("[fints] Eigenes MT940-Reassembly fehlgeschlagen", {
        account: account.externalId,
        error: error instanceof Error ? error.message : String(error),
      });
    }
  }

  return resp;
}

async function fetchFinTsAccountData(
  client: FinTSClient,
  account: NormalizedAccount,
  from: string,
  to: string,
  ctx: ActionCtx,
  userId: Id<"users">,
  syncJob: PendingSyncJob,
  ownNames: string[],
  salaryShift: {
    enabled: boolean;
    categoryNames: string[];
    dayThreshold: number;
  },
): Promise<{ balance: number; transactions: NormalizedTransaction[] }> {
  const fromDate = new Date(from);
  const toDate = new Date(to);
  const canFetchBalance = client.canGetAccountBalance(account.externalId);
  const canFetchStatements = client.canGetAccountStatements(account.externalId);
  const canFetchCamtStatements = client.config.isAccountTransactionSupported(
    account.externalId,
    "HKCAZ",
  );
  const canFetchMt940Statements = client.config.isAccountTransactionSupported(
    account.externalId,
    "HKKAZ",
  );

  console.info("[fints] Konto-Capabilities", {
    account: account.externalId,
    iban: account.iban,
    name: account.name,
    canFetchBalance,
    canFetchStatements,
    canFetchCamtStatements,
    canFetchMt940Statements,
  });

  let balance = account.balance;
  if (canFetchBalance) {
    let balanceResponse = await client.getAccountBalance(account.externalId);
    balanceResponse = await resolveTanResponse(
      ctx,
      userId,
      client,
      balanceResponse,
      "balance",
      syncJob,
    );
    balance = balanceResponse.balance?.balance ?? account.balance;
  } else {
    console.warn("[fints] Konto unterstützt keinen HKSAL-Kontostandabruf", {
      account: account.externalId,
    });
  }

  if (!canFetchStatements) {
    console.warn("[fints] Konto unterstützt keinen Umsatzabruf", {
      account: account.externalId,
    });
    return { balance, transactions: [] };
  }

  // Prefer MT940 (HKKAZ) when available: comdirect's CAMT (HKCAZ) responds with
  // "Kontonummer ist ungültig" and MT940 is the reliable path. Large windows are
  // split adaptively to avoid lib-fints' broken multi-part (3040) reassembly.
  const preferCamtForFetch = !canFetchMt940Statements;
  let statementResponse = await fetchStatementsAllPages(
    ctx,
    userId,
    client,
    account,
    fromDate,
    toDate,
    preferCamtForFetch,
    syncJob,
  );

  if (
    canFetchCamtStatements &&
    canFetchMt940Statements &&
    (!statementResponse ||
      (statementResponse.success &&
        countStatementTransactions(statementResponse) === 0))
  ) {
    console.info("[fints] Bevorzugtes Format ohne Umsätze, versuche Alternative", {
      account: account.externalId,
      preferCamtForFetch,
    });
    const altResponse = await fetchStatementsAllPages(
      ctx,
      userId,
      client,
      account,
      fromDate,
      toDate,
      !preferCamtForFetch,
      syncJob,
    );
    if (
      altResponse &&
      altResponse.success &&
      countStatementTransactions(altResponse) > 0
    ) {
      statementResponse = altResponse;
    }
  }

  if (!statementResponse || !statementResponse.success) {
    console.warn("[fints] Umsatzabruf nicht erfolgreich", {
      account: account.externalId,
      bankAnswers: statementResponse?.bankAnswers.map((answer) => answer.text) ?? [],
    });
    return { balance, transactions: [] };
  }

  let transactions = mapStatements(statementResponse, ownNames, salaryShift);
  transactions = transactions.filter(
    (tx) =>
      (!tx.bookingDate || tx.bookingDate >= from) &&
      (!tx.bookingDate || tx.bookingDate <= to),
  );
  const statementCount = statementResponse.statements?.length ?? 0;
  const rawTransactionCount = countStatementTransactions(statementResponse);
  console.info("[fints] Umsatzabruf Ergebnis", {
    account: account.externalId,
    statementCount,
    rawTransactionCount,
    mappedTransactionCount: transactions.length,
  });

  return { balance, transactions };
}

function countStatementTransactions(response: StatementResponse): number {
  return (
    response.statements?.reduce(
      (sum, statement) => sum + (statement.transactions?.length ?? 0),
      0,
    ) ?? 0
  );
}

function mapStatements(
  response: StatementResponse,
  ownNames: string[],
  salaryShift: {
    enabled: boolean;
    categoryNames: string[];
    dayThreshold: number;
  },
): NormalizedTransaction[] {
  const rows: NormalizedTransaction[] = [];
  for (const statement of response.statements ?? []) {
    for (const tx of statement.transactions ?? []) {
      const mapped = mapFinTsTransaction(
        {
          valueDate: tx.valueDate,
          entryDate: tx.entryDate,
          amount: tx.amount,
          transactionType: tx.transactionType,
          bankReference: tx.bankReference,
          bookingText: tx.bookingText,
          purpose: tx.purpose,
          remoteName: tx.remoteName,
          customerReference: tx.customerReference,
        },
        ownNames,
        salaryShift,
      );
      rows.push({
        bookingDate: mapped.bookingDate,
        valueDate: mapped.valueDate,
        description: mapped.description,
        counterparty: mapped.counterparty,
        amount: mapped.amount,
        vorgang: mapped.vorgang,
        isPending: mapped.isPending,
        rawText: mapped.rawText,
        externalRef: mapped.externalRef,
        categoryName: mapped.categoryName,
        assignedMonth: mapped.assignedMonth,
        effectiveMonth: mapped.effectiveMonth,
      });
    }
  }
  return rows;
}

async function fetchFinTsData(
  ctx: ActionCtx,
  userId: Id<"users">,
  from: string,
  to: string,
  filterAccountId: Id<"accounts"> | undefined,
  pin: string | undefined,
  ownNames: string[],
  salaryShift: {
    enabled: boolean;
    categoryNames: string[];
    dayThreshold: number;
  },
): Promise<{
  accounts: NormalizedAccount[];
  transactionsByAccount: Map<string, NormalizedTransaction[]>;
}> {
  const bankConfig = await ctx.runQuery(internal.bank.internal.getBankConfig, { userId });
  const env = resolveFintsEnv({
    blz: bankConfig?.fints.blz,
    url: bankConfig?.fints.url,
    login: bankConfig?.fints.login,
    productId: bankConfig?.fints.productId,
    productVersion: bankConfig?.fints.productVersion,
    tanMethodId: bankConfig?.fints.tanMethodId,
    tanMediaName: bankConfig?.fints.tanMediaName,
    bankingInformationJson: bankConfig?.fints.bankingInformationJson,
    pin,
  });

  const syncJob: PendingSyncJob = { from, to, accountId: filterAccountId, provider: "fints", phase: "fetch" };
  let client = createFinTsClient(env);
  client = await ensureFinTsReady(client, env, ctx, userId, syncJob);

  const bankAccounts = client.config.bankingInformation.upd?.bankAccounts ?? [];
  const accounts = bankAccounts.map(mapBankAccount);
  const transactionsByAccount = new Map<string, NormalizedTransaction[]>();

  for (const account of accounts) {
    if (filterAccountId) {
      const convexId = await ctx.runMutation(internal.bank.internal.upsertAccountFromProvider, {
        userId,
        externalId: account.externalId,
        name: account.name,
        iban: account.iban,
        balance: account.balance,
        currency: account.currency,
      });
      if (convexId !== filterAccountId) continue;
    }

    const { balance, transactions } = await fetchFinTsAccountData(
      client,
      account,
      from,
      to,
      ctx,
      userId,
      syncJob,
      ownNames,
      salaryShift,
    );
    account.balance = balance;
    transactionsByAccount.set(account.externalId, transactions);
  }

  await ctx.runMutation(internal.bank.internal.upsertBankConfig, {
    userId,
    fints: {
      blz: env.blz,
      url: env.url,
      login: env.login,
      productId: env.productId,
      bankingInformationJson: JSON.stringify(client.config.bankingInformation),
      tanMethodId: client.config.selectedTanMethod?.id,
      tanMediaName: methodMediaName(client),
    },
  });

  return { accounts, transactionsByAccount };
}

async function persistSyncResults(
  ctx: ActionCtx,
  userId: Id<"users">,
  provider: "comdirect" | "fints",
  from: string,
  to: string,
  filterAccountId: Id<"accounts"> | undefined,
  accounts: NormalizedAccount[],
  transactionsByAccount: Map<string, NormalizedTransaction[]>,
): Promise<{ importedCount: number; skippedCount: number }> {
  const accountIdMap = new Map<string, Id<"accounts">>();
  for (const account of accounts) {
    const convexAccountId = await ctx.runMutation(internal.bank.internal.upsertAccountFromProvider, {
      userId,
      externalId: account.externalId,
      name: account.name,
      iban: account.iban,
      balance: account.balance,
      currency: account.currency,
    });
    accountIdMap.set(account.externalId, convexAccountId);
  }

  const rows: ImportRow[] = [];
  const rowCountsByAccount: Record<string, number> = {};
  const targetAccounts = filterAccountId
    ? [...accountIdMap.entries()].filter(([, id]) => id === filterAccountId)
    : [...accountIdMap.entries()];

  for (const [externalAccountId, convexAccountId] of targetAccounts) {
    const txs = transactionsByAccount.get(externalAccountId) ?? [];
    rowCountsByAccount[externalAccountId] = txs.length;
    for (const tx of txs) {
      rows.push({
        accountId: convexAccountId,
        categoryName: tx.categoryName ?? "Sonstiges",
        bookingDate: tx.bookingDate,
        valueDate: tx.valueDate,
        description: tx.description,
        counterparty: tx.counterparty,
        amount: tx.amount,
        vorgang: tx.vorgang,
        isPending: tx.isPending,
        rawText: tx.rawText,
        assignedMonth: tx.assignedMonth,
        effectiveMonth: tx.effectiveMonth,
        externalRef:
          provider === "fints" && tx.externalRef
            ? `${externalAccountId}:${tx.externalRef}`
            : tx.externalRef,
      });
    }
  }

  console.info("[bank-sync] Persistiere Umsätze", {
    provider,
    accountCount: accounts.length,
    targetAccountCount: targetAccounts.length,
    rowCount: rows.length,
    rowCountsByAccount,
  });

  const commitResult = await ctx.runMutation(internal.imports.commitRowsInternal, {
    userId,
    filename: `${provider}-sync-${from}-${to}`,
    source: provider === "comdirect" ? "comdirect-api" : "fints",
    accountId: filterAccountId,
    rows,
  });
  console.info("[bank-sync] Import-Ergebnis", {
    provider,
    importedCount: commitResult.importedCount,
    skippedCount: commitResult.skippedCount,
  });

  if (provider === "comdirect") {
    await ctx.runMutation(internal.comdirect.internal.clearSession, { userId });
  }

  await ctx.runMutation(internal.bank.internal.updateSyncState, {
    userId,
    lastSync: Date.now(),
    lastProviderUsed: provider,
    lastError: null,
  });

  await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
    userId,
    status: "done",
    challengeRef: null,
    challengeMessage: null,
    photoTanMimeType: null,
    photoTanBase64: null,
    syncJobJson: null,
  });

  return {
    importedCount: commitResult.importedCount,
    skippedCount: commitResult.skippedCount,
  };
}

export const runSyncInternal = internalAction({
  args: {
    userId: v.id("users"),
    from: v.string(),
    to: v.string(),
    accountId: v.optional(v.id("accounts")),
    pin: v.optional(v.string()),
  },
  returns: v.object({
    importedCount: v.number(),
    skippedCount: v.number(),
    provider: v.union(v.literal("comdirect"), v.literal("fints")),
    awaitingTan: v.boolean(),
  }),
  handler: async (ctx, args) => {
    const comdirectReady = hasComdirectCredentials();
    await ctx.runMutation(internal.bank.internal.upsertBankConfig, {
      userId: args.userId,
      comdirectHasCredentials: comdirectReady,
    });

    const bankConfig = await ctx.runQuery(internal.bank.internal.getBankConfig, { userId: args.userId });
    const preference = bankConfig?.providerPreference ?? "auto";
    const settings = await ctx.runQuery(internal.settings.getInternal, { userId: args.userId });
    const ownNames = settings?.ownNames ?? [];
    const salaryShift = settings?.salaryShift ?? {
      enabled: true,
      categoryNames: ["Gehalt & Besoldung"],
      dayThreshold: 25,
    };

    const tryFinTs = async (reason: string) => {
      await logProvider(ctx, args.userId, "fints", reason);
      try {
        const { accounts, transactionsByAccount } = await fetchFinTsData(
          ctx,
          args.userId,
          args.from,
          args.to,
          args.accountId,
          args.pin,
          ownNames,
          salaryShift,
        );
        const result = await persistSyncResults(
          ctx,
          args.userId,
          "fints",
          args.from,
          args.to,
          args.accountId,
          accounts,
          transactionsByAccount,
        );
        return { ...result, provider: "fints" as const, awaitingTan: false };
      } catch (error) {
        if (error instanceof Error && error.message.includes("TAN-Freigabe Timeout")) {
          await ctx.runMutation(internal.bank.internal.updateSyncState, {
            userId: args.userId,
            lastError: error.message,
          });
          throw error;
        }
        throw error;
      }
    };

    const useFinTsDirect =
      preference === "fints" || (preference === "auto" && !comdirectReady);

    if (useFinTsDirect) {
      return await tryFinTs(
        !comdirectReady
          ? "comdirect-Credentials fehlen"
          : "Provider-Präferenz FinTS",
      );
    }

    try {
      await logProvider(ctx, args.userId, "comdirect", "REST-Versuch");
      const { accounts, transactionsByAccount } = await fetchComdirectData(
        ctx,
        args.userId,
        args.from,
        args.to,
        args.accountId,
        ownNames,
        salaryShift,
      );
      const result = await persistSyncResults(
        ctx,
        args.userId,
        "comdirect",
        args.from,
        args.to,
        args.accountId,
        accounts,
        transactionsByAccount,
      );
      return { ...result, provider: "comdirect" as const, awaitingTan: false };
    } catch (error) {
      if (!isRestFallbackError(error)) throw error;
      const reason = error instanceof Error ? error.message : "REST-Fehler";
      console.warn("[bank-sync] REST fehlgeschlagen, Fallback FinTS:", reason);
      return await tryFinTs(`REST-Fallback: ${reason}`);
    }
  },
});

export const pollTan = internalAction({
  args: {
    userId: v.id("users"),
    attempt: v.optional(v.number()),
  },
  returns: v.null(),
  handler: async (ctx, args) => {
    const pending = await ctx.runQuery(internal.bank.internal.getPendingTan, {
      userId: args.userId,
    });
    if (!pending || pending.status !== "awaiting") {
      return null;
    }

    const attempt = args.attempt ?? (pending.pollAttempt ?? 0) + 1;
    if (attempt > TAN_MAX_POLL_ATTEMPTS) {
      await ctx.runMutation(internal.bank.internal.upsertPendingTan, {
        userId: args.userId,
        status: "error",
        errorMessage: "TAN-Freigabe Timeout (5 Minuten)",
        pollAttempt: attempt,
      });
      return null;
    }

    await ctx.scheduler.runAfter(TAN_POLL_INTERVAL_MS, internal.bank.orchestrator.pollTan, {
      userId: args.userId,
      attempt: attempt + 1,
    });
    return null;
  },
});