"use client";

// Chamadas feitas pelo navegador. Vão para /api/v1 na mesma origem; o Next
// repassa para a API Go. Toda mutação envia o token CSRF (double submit).
import type { Problem } from "./types";

export class ApiError extends Error {
  status: number;
  problem: Problem | null;

  constructor(status: number, problem: Problem | null) {
    super(problem?.title ?? `Erro ${status}`);
    this.status = status;
    this.problem = problem;
  }

  /** Mensagem com os erros de campo, se houver. */
  details(): string {
    const fields = this.problem?.errors ?? [];
    if (fields.length === 0) return this.message;
    return `${this.message}: ${fields.map((e) => `${e.field} — ${e.message}`).join("; ")}`;
  }
}

function readCookie(name: string): string {
  const match = document.cookie.split("; ").find((c) => c.startsWith(`${name}=`));
  return match ? decodeURIComponent(match.slice(name.length + 1)) : "";
}

export async function apiFetch<T = unknown>(
  path: string,
  options: { method?: string; body?: unknown } = {},
): Promise<T> {
  const method = options.method ?? "GET";
  const headers: Record<string, string> = { accept: "application/json" };
  if (method !== "GET") {
    headers["X-CSRF-Token"] = readCookie("bp_csrf");
  }
  if (options.body !== undefined) {
    headers["content-type"] = "application/json";
  }

  const res = await fetch(`/api/v1${path}`, {
    method,
    headers,
    body: options.body === undefined ? undefined : JSON.stringify(options.body),
    credentials: "same-origin",
  });

  if (res.status === 401 && path !== "/auth/login") {
    window.location.href = "/login";
    throw new ApiError(401, null);
  }
  if (!res.ok) {
    const problem = (await res.json().catch(() => null)) as Problem | null;
    throw new ApiError(res.status, problem);
  }
  if (res.status === 204) {
    return undefined as T;
  }
  return (await res.json()) as T;
}

export function errorMessage(err: unknown): string {
  if (err instanceof ApiError) return err.details();
  if (err instanceof Error) return err.message;
  return "Erro inesperado";
}