import "server-only";

import type { WorldLabsProviderConfig } from "./types";

type WorldLabsRequestOptions = {
  method?: "GET" | "POST";
  path: string;
  json?: Record<string, unknown>;
  headers?: Record<string, string>;
  timeoutMs?: number;
};

export const DEFAULT_WORLDLABS_BASE_URL = "https://api.vip98k.com";
export const WORLDLABS_EXTERNAL_TASK_MODEL = "world-generation";
const DEFAULT_WORLDLABS_REQUEST_TIMEOUT_MS = 180_000;

function toIntMs(value: string | undefined) {
  const parsed = Number.parseInt(String(value || "").trim(), 10);
  if (!Number.isFinite(parsed) || parsed <= 0) {
    return null;
  }
  return parsed;
}

function getDefaultWorldLabsTimeoutMs() {
  return toIntMs(process.env.WORLDLABS_API_TIMEOUT_MS) || DEFAULT_WORLDLABS_REQUEST_TIMEOUT_MS;
}

function createRequestSignal(timeoutMs: number) {
  const timeoutSignal = (globalThis as Record<string, unknown>).AbortSignal;
  if (timeoutSignal && typeof (timeoutSignal as typeof AbortSignal).timeout === "function") {
    return {
      signal: (timeoutSignal as typeof AbortSignal).timeout(timeoutMs),
      cancel: () => undefined,
    };
  }

  const controller = new AbortController();
  const timer = setTimeout(() => {
    controller.abort(`World Labs 请求超时 (${timeoutMs}ms)`);
  }, timeoutMs);

  return {
    signal: controller.signal,
    cancel: () => clearTimeout(timer),
  };
}

export class WorldLabsApiError extends Error {
  httpStatus: number;
  payload: unknown;

  constructor(params: {
    message: string;
    httpStatus: number;
    payload?: unknown;
  }) {
    super(params.message);
    this.name = "WorldLabsApiError";
    this.httpStatus = params.httpStatus;
    this.payload = params.payload;
  }
}

function normalizeBaseUrl(baseUrl?: string) {
  const resolved = String(baseUrl || "").trim() || DEFAULT_WORLDLABS_BASE_URL;
  return resolved.replace(/\/+$/, "");
}

export function isWorldLabsExternalTaskApi(baseUrl?: string | null) {
  const normalized = normalizeBaseUrl(baseUrl || "");
  try {
    const parsed = new URL(normalized);
    const hostname = parsed.hostname.toLowerCase();
    return hostname === "api.vip98k.com" || normalized.includes("/api/external/task");
  } catch {
    return normalized.includes("api.vip98k.com") || normalized.includes("/api/external/task");
  }
}

function sanitizeApiKey(value: string): string {
  return String(value || "")
    .replace(/[\u2028\u2029]/g, "")
    .replace(/[\u0000-\u001F\u007F]/g, "")
    .trim();
}

async function parseResponseBody(response: Response): Promise<unknown> {
  const contentType = response.headers.get("content-type") || "";
  if (contentType.includes("application/json")) {
    return response.json().catch(() => null);
  }
  const text = await response.text().catch(() => "");
  return text || null;
}

function extractErrorMessage(payload: unknown, fallback: string) {
  if (!payload) return fallback;
  if (typeof payload === "string") return payload || fallback;
  if (typeof payload !== "object") return fallback;

  const record = payload as Record<string, unknown>;
  if (typeof record.message === "string" && record.message.trim()) {
    return record.message.trim();
  }
  if (typeof record.detail === "string" && record.detail.trim()) {
    return record.detail.trim();
  }
  if (Array.isArray(record.detail) && record.detail.length > 0) {
    const firstDetail = record.detail[0];
    if (firstDetail && typeof firstDetail === "object") {
      const msg = (firstDetail as Record<string, unknown>).msg;
      if (typeof msg === "string" && msg.trim()) {
        return msg.trim();
      }
    }
  }
  return fallback;
}

export async function worldLabsRequest<T = unknown>(
  config: WorldLabsProviderConfig,
  options: WorldLabsRequestOptions
): Promise<T> {
  const path = options.path.startsWith("/") ? options.path : `/${options.path}`;
  const url = `${normalizeBaseUrl(config.baseUrl)}${path}`;

  const headers = new Headers(options.headers || {});
  const normalizedApiKey = sanitizeApiKey(String(config.apiKey || "")).replace(/\s+/g, "");
  if (!normalizedApiKey) {
    throw new WorldLabsApiError({
      message: "World Labs API Key 为空，请在本地AI设置中重新保存",
      httpStatus: 400,
    });
  }

  if (isWorldLabsExternalTaskApi(config.baseUrl)) {
    headers.set("Authorization", `Bearer ${normalizedApiKey}`);
  } else {
    headers.set("WLT-Api-Key", normalizedApiKey);
  }
  headers.set("Accept", "application/json");

  let body: BodyInit | undefined;
  if (options.json) {
    headers.set("Content-Type", "application/json");
    body = JSON.stringify(options.json);
  }

  const timeoutMs = options.timeoutMs || getDefaultWorldLabsTimeoutMs();
  const { signal, cancel } = createRequestSignal(timeoutMs);

  try {
    const response = await fetch(url, {
      method: options.method || "GET",
      headers,
      body,
      cache: "no-store",
      signal,
    });
    const parsed = await parseResponseBody(response);

    if (!response.ok) {
      throw new WorldLabsApiError({
        message: extractErrorMessage(parsed, `World Labs 请求失败（HTTP ${response.status}）`),
        httpStatus: response.status,
        payload: parsed,
      });
    }

    return parsed as T;
  } catch (error) {
    if (error instanceof Error && error.name === "AbortError") {
      throw new WorldLabsApiError({
        message: `World Labs 请求超时（${timeoutMs}ms）`,
        httpStatus: 504,
      });
    }
    throw error;
  } finally {
    cancel();
  }
}