import type { components } from "./api-types.gen";

/** Schemas generated from the backend OpenAPI spec (pnpm gen:api). Aliasing
 * the app's read types to them makes backend schema drift a typecheck error
 * instead of a runtime surprise (review ARCH-16 / FE-14 / plan 3.4). */
type Schema<K extends keyof components["schemas"]> = components["schemas"][K];

const BASE_URL = "/api/v1";

class ApiError extends Error {
  response: { status: number; data: unknown };
  constructor(status: number, data: unknown) {
    super(`Request failed with status ${status}`);
    this.response = { status, data };
  }
}

interface RequestConfig {
  params?: Record<string, string | number | boolean | undefined>;
  /** Caller cancellation (TanStack Query passes this); combined with the
   * default 30s timeout. */
  signal?: AbortSignal;
}

const REQUEST_TIMEOUT_MS = 30_000;

async function request<T>(
  method: string,
  url: string,
  body?: unknown,
  config?: RequestConfig,
): Promise<{ data: T }> {
  let fullUrl = `${BASE_URL}${url}`;

  if (config?.params) {
    const search = new URLSearchParams();
    for (const [k, v] of Object.entries(config.params)) {
      if (v !== undefined) search.set(k, String(v));
    }
    const qs = search.toString();
    if (qs) fullUrl += `?${qs}`;
  }

  const headers: Record<string, string> = {};
  let fetchBody: BodyInit | undefined;
  if (body instanceof FormData || body instanceof URLSearchParams) {
    fetchBody = body;
  } else if (body !== undefined) {
    headers["Content-Type"] = "application/json";
    fetchBody = JSON.stringify(body);
  }

  const timeout = AbortSignal.timeout(REQUEST_TIMEOUT_MS);
  const signal = config?.signal
    ? AbortSignal.any([config.signal, timeout])
    : timeout;

  const res = await fetch(fullUrl, {
    method,
    headers,
    body: fetchBody,
    credentials: "same-origin",
    signal,
  });

  if (res.status === 401) {
    // Don't logout/redirect from the login page itself — that would loop.
    if (
      typeof window !== "undefined" &&
      !window.location.pathname.startsWith("/login")
    ) {
      await fetch("/api/auth/logout", { method: "POST" }).catch(() => {});
      window.location.replace("/login");
    }
    throw new ApiError(401, null);
  }

  if (!res.ok) {
    let data: unknown = null;
    try {
      data = await res.json();
    } catch {}
    throw new ApiError(res.status, data);
  }

  if (res.status === 204) return { data: null as T };

  const data = await res.json();
  return { data };
}

const api = {
  get<T = unknown>(url: string, config?: RequestConfig) {
    return request<T>("GET", url, undefined, config);
  },
  post<T = unknown>(url: string, body?: unknown, config?: RequestConfig) {
    return request<T>("POST", url, body, config);
  },
  patch<T = unknown>(url: string, body?: unknown, config?: RequestConfig) {
    return request<T>("PATCH", url, body, config);
  },
  put<T = unknown>(url: string, body?: unknown, config?: RequestConfig) {
    return request<T>("PUT", url, body, config);
  },
  delete<T = unknown>(url: string, config?: RequestConfig) {
    return request<T>("DELETE", url, undefined, config);
  },
};

export default api;

export async function login(username: string, password: string) {
  const res = await fetch("/api/auth/login", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ username, password }),
    credentials: "same-origin",
  });
  if (!res.ok) {
    let data: unknown = null;
    try {
      data = await res.json();
    } catch {}
    throw new ApiError(res.status, data);
  }
  return res.json();
}

export async function logout() {
  await fetch("/api/auth/logout", { method: "POST", credentials: "same-origin" });
}

// ─── Types ──────────────────────────────────────────────────────────────────

export type Account = Schema<'AccountRead'>;

export type Category = Schema<'CategoryRead'>;

export type SkippedDuplicate = Schema<'SkippedDuplicate'>;

export type ImportResult = Schema<'PasteImportResult'>;

export type Transaction = Schema<'TransactionRead'>;

// --- Budget / Recurring Items ---

export type RecurringItemType = Schema<"RecurringItemType">;
export type RecurringFrequency = Schema<"RecurringFrequency">;

export type RecurringItem = Schema<'RecurringItemRead'>;

export interface RecurringItemCreate {
  name: string;
  amount: number;
  currency?: string;
  item_type: RecurringItemType;
  frequency?: RecurringFrequency;
  day_of_month?: number | null;
  month_of_year?: number | null;
  override_amounts?: Record<string, number> | null;
  category_id?: number | null;
  is_active?: boolean;
  notes?: string | null;
}

export interface RecurringItemUpdate {
  name?: string;
  amount?: number;
  currency?: string;
  item_type?: RecurringItemType;
  frequency?: RecurringFrequency;
  day_of_month?: number | null;
  month_of_year?: number | null;
  override_amounts?: Record<string, number> | null;
  category_id?: number | null;
  is_active?: boolean;
  notes?: string | null;
}

export type RecurringItemDetail = Schema<'RecurringItemDetail'>;

export type ActualsBySource = Schema<'ActualsBySource'>;

export type MonthlyProjection = Schema<'MonthlyProjectionResponse'>;

export type YearlyProjection = Schema<'YearlyProjectionResponse'>;

export type MonthlyDetail = Schema<'MonthlyDetailResponse'>;

// --- Savings Accrual ---

export type SavingsAccrual = Schema<'SavingsAccrualRead'>;

export interface SavingsAccrualCreate {
  year: number;
  month: number;
  memp_amount?: number;
  mpat_amount?: number;
  trigger_transaction_id?: number | null;
  notes?: string | null;
}

export interface SavingsAccrualUpdate {
  memp_amount?: number;
  mpat_amount?: number;
  notes?: string | null;
}

export const getSavingsAccruals = () =>
  api.get<SavingsAccrual[]>("/savings-accrual/");
export const createSavingsAccrual = (data: SavingsAccrualCreate) =>
  api.post<SavingsAccrual>("/savings-accrual/", data);
export const updateSavingsAccrual = (id: number, data: SavingsAccrualUpdate) =>
  api.patch<SavingsAccrual>(`/savings-accrual/${id}`, data);
export const deleteSavingsAccrual = (id: number) =>
  api.delete(`/savings-accrual/${id}`);

// --- Budget ---

export const getRecurringItems = (params?: {
  item_type?: string;
  is_active?: boolean;
}) => api.get<RecurringItem[]>("/budget/recurring", { params });
export const createRecurringItem = (data: RecurringItemCreate) =>
  api.post<RecurringItem>("/budget/recurring", data);
export const updateRecurringItem = (id: number, data: RecurringItemUpdate) =>
  api.patch<RecurringItem>(`/budget/recurring/${id}`, data);
export const deleteRecurringItem = (id: number) =>
  api.delete(`/budget/recurring/${id}`);
export const getYearlyProjection = (year: number) =>
  api.get<YearlyProjection>(`/budget/projection/${year}`);
export const getMonthlyDetail = (year: number, month: number) =>
  api.get<MonthlyDetail>(`/budget/month/${year}/${month}`);
export const upsertBalanceOverride = (
  year: number,
  month: number,
  override_balance: number,
) =>
  api.put(`/budget/balance-override/${year}/${month}`, { override_balance });
export const deleteBalanceOverride = (year: number, month: number) =>
  api.delete(`/budget/balance-override/${year}/${month}`);

// --- Salarios ---

export type SalariosSummary = Schema<'SalariosSummary'>;

export const getSalarios = (params?: { limit?: number; offset?: number }) =>
  api.get<Transaction[]>("/salarios/", { params });
export const getSalariosSummary = () =>
  api.get<SalariosSummary>("/salarios/summary");

// --- Pensions ---

export type PensionSnapshot = Schema<'PensionSnapshotRead'>;

export type PensionUploadResult = Schema<'PensionUploadResult'>;

export interface PensionManualEntry {
  fund: string;
  period_start: string;
  period_end: string;
  saldo_anterior: number;
  aportes: number;
  rendimientos: number;
  retiros: number;
  traslados: number;
  comision: number;
  correccion: number;
  bonificacion: number;
  saldo_final: number;
}

export const uploadPensionPDFs = (files: File[]) => {
  const form = new FormData();
  files.forEach((f) => form.append("files", f));
  return api.post<PensionUploadResult>("/pensions/upload", form);
};

export const getPensionSnapshots = () =>
  api.get<PensionSnapshot[]>("/pensions/snapshots");
export const getPensionFundSummary = () =>
  api.get<PensionSnapshot[]>("/pensions/fund-summary");
export const submitPensionManualEntries = (entries: PensionManualEntry[]) =>
  api.post<PensionUploadResult>("/pensions/manual", { entries });

// --- Municipal Receipts ---

export interface MunicipalCharge {
  detail: string;
  amount: number;
}

export type WaterMeterReading = Schema<'WaterMeterReadingRead'>;

export type MunicipalReceipt = Omit<
  Schema<'MunicipalReceiptRead'>,
  'raw_charges'
> & { raw_charges: MunicipalCharge[] };

export type MunicipalReceiptDetail = Omit<
  Schema<'MunicipalReceiptDetailRead'>,
  'raw_charges'
> & { raw_charges: MunicipalCharge[] };

export type MunicipalReceiptUploadResult = Schema<'MunicipalReceiptUploadResult'>;

export const uploadMunicipalReceipt = (file: File) => {
  const form = new FormData();
  form.append("file", file);
  return api.post<MunicipalReceiptUploadResult>(
    "/municipal-receipts/upload",
    form,
  );
};

export const getMunicipalReceipts = () =>
  api.get<MunicipalReceipt[]>("/municipal-receipts/");
export const getMunicipalReceiptDetail = (id: number) =>
  api.get<MunicipalReceiptDetail>(`/municipal-receipts/${id}`);
export const getWaterConsumption = (months?: number) =>
  api.get<WaterMeterReading[]>("/municipal-receipts/water-consumption", {
    params: months ? { months } : undefined,
  });

// --- Sync Status ---

export type SyncSource = Schema<'SyncSourceStatus'>;

export type SyncStatusResponse = Schema<'SyncStatusResponse'>;

export const getSyncStatus = () => api.get<SyncStatusResponse>('/sync-status/');

// --- User Settings ---

export type UserSettingsData = Record<string, unknown>;

export type UserSettingsRead = Schema<'UserSettingsRead'>;

export const getUserSettings = () => api.get<UserSettingsRead>('/settings/');

// --- Exchange Rate ---

export type ExchangeRatePoint = Schema<'ExchangeRateRead'>;

export const getRateHistory = (days = 90) =>
  api.get<ExchangeRatePoint[]>('/exchange-rate/history', { params: { days } });