import { PolyProviderError, type PolyErrorCode, type ProviderId } from "./types";
import { redactSecrets } from "@/lib/crypto/keys";

export function isRetryableStatus(status?: number): boolean {
  return status === 408 || status === 409 || status === 429 || (status !== undefined && status >= 500 && status <= 599);
}

export function codeFromStatus(status: number | undefined): PolyErrorCode {
  switch (status) {
    case 401:
      return "INVALID_API_KEY";
    case 402:
      return "INSUFFICIENT_CREDITS";
    case 403:
      return "PERMISSION_DENIED";
    case 404:
      return "MODEL_NOT_FOUND";
    case 408:
      return "REQUEST_TIMEOUT";
    case 413:
      return "CONTEXT_TOO_LONG";
    case 422:
    case 400:
      return "INVALID_PARAMETER";
    case 429:
      return "RATE_LIMITED";
    case 500:
    case 502:
    case 503:
    case 504:
    case 529:
      return "PROVIDER_UNAVAILABLE";
    default:
      return "UNKNOWN_PROVIDER_ERROR";
  }
}

/** Refine a 400-ish error using the provider's message text (all providers put the reason in prose). */
export function refineByMessage(code: PolyErrorCode, message: string): PolyErrorCode {
  const m = message.toLowerCase();
  if (/context.length|context_length|too many tokens|maximum context|prompt is too long|exceeds the (model'?s )?(maximum )?(context|token)|input token count|token limit|max_tokens.*(too large|exceed)/.test(m)) return "CONTEXT_TOO_LONG";
  if (/(insufficient|exceeded your current) (quota|credits|balance)|billing|credit balance is too low|payment/.test(m)) return "INSUFFICIENT_CREDITS";
  if (/(model|deployment).*(not found|does not exist|not exist|unknown|unsupported model)|not found for model|no such model/.test(m)) return "MODEL_NOT_FOUND";
  if (/(invalid|incorrect) (api key|x-api-key|authentication)|api key (not valid|invalid|expired)|bad credentials|unauthenticated|authentication_error/.test(m)) return "INVALID_API_KEY";
  if (/rate.?limit|too many requests|resource.?exhausted|overloaded|quota exceeded/.test(m)) return "RATE_LIMITED";
  if (/safety|content (policy|filter|management)|blocked|prohibited|refus|harm_category/.test(m)) return "CONTENT_REJECTED";
  if (/timed? ?out|deadline exceeded/.test(m)) return "REQUEST_TIMEOUT";
  return code;
}

export function parseRetryAfter(headers?: Headers | Record<string, string | string[] | undefined> | null): number | undefined {
  if (!headers) return undefined;
  const get = (k: string): string | undefined => {
    if (headers instanceof Headers) return headers.get(k) ?? undefined;
    const v = headers[k] ?? headers[k.toLowerCase()];
    return Array.isArray(v) ? v[0] : v;
  };
  const ra = get("retry-after");
  if (ra) {
    const secs = Number(ra);
    if (!Number.isNaN(secs)) return Math.min(secs * 1000, 60_000);
    const date = Date.parse(ra);
    if (!Number.isNaN(date)) return Math.max(0, Math.min(date - Date.now(), 60_000));
  }
  const raMs = get("retry-after-ms");
  if (raMs && !Number.isNaN(Number(raMs))) return Math.min(Number(raMs), 60_000);
  return undefined;
}

/** Human-readable, non-technical explanations shown in the UI. */
export const ERROR_MESSAGES: Record<PolyErrorCode, string> = {
  INVALID_API_KEY: "The API key for this provider was rejected. Check it in Settings → Providers.",
  PERMISSION_DENIED: "This key isn't allowed to use that model or feature.",
  RATE_LIMITED: "The provider is rate-limiting your key. Wait a moment and try again.",
  MODEL_NOT_FOUND: "This model isn't available for your account or was renamed. Refresh the model list.",
  CONTEXT_TOO_LONG: "The conversation is longer than this model's context window. Start a new chat or pick a long-context model.",
  INSUFFICIENT_CREDITS: "Your provider account has no remaining credit or quota.",
  REQUEST_TIMEOUT: "The provider took too long to respond.",
  PROVIDER_UNAVAILABLE: "The provider is temporarily unavailable. Try again shortly.",
  INVALID_PARAMETER: "A setting isn't accepted by this model. Reset the model configuration and retry.",
  CONTENT_REJECTED: "The provider declined to answer this request (content policy).",
  NETWORK_ERROR: "PolyLLM couldn't reach the provider.",
  CANCELLED: "Generation stopped.",
  UNKNOWN_PROVIDER_ERROR: "The provider returned an unexpected error.",
};

/**
 * Generic normalizer used by adapters as a fallback: works on SDK error objects
 * exposing `status`, `message`, `headers`, `error.code/type`. Provider-specific
 * adapters call this then refine.
 */
export function normalizeGenericError(provider: ProviderId, error: unknown): PolyProviderError {
  if (error instanceof PolyProviderError) return error;
  const e = error as { status?: number; statusCode?: number; message?: string; name?: string; code?: string; headers?: Headers | Record<string, string>; error?: { code?: string; type?: string; message?: string; status?: string } } | undefined;
  const status = e?.status ?? e?.statusCode;
  const rawMessage = e?.error?.message ?? e?.message ?? String(error);
  const message = redactSecrets(rawMessage).slice(0, 600);

  if (e?.name === "AbortError" || /aborted|abort/i.test(e?.name ?? "") || (e?.code === "ABORT_ERR")) {
    return new PolyProviderError({ code: "CANCELLED", message: "Cancelled", provider, retryable: false, cause: error });
  }
  if (e?.name === "APIConnectionTimeoutError" || /timeout/i.test(e?.name ?? "")) {
    return new PolyProviderError({ code: "REQUEST_TIMEOUT", message, provider, retryable: true, cause: error });
  }
  if (e?.name === "APIConnectionError" || e?.code === "ECONNRESET" || e?.code === "ENOTFOUND" || e?.code === "ECONNREFUSED" || e?.code === "UND_ERR_SOCKET" || /fetch failed/i.test(message)) {
    return new PolyProviderError({ code: "NETWORK_ERROR", message, provider, retryable: true, cause: error });
  }

  let code = codeFromStatus(status);
  code = refineByMessage(code, message);
  const retryAfterMs = parseRetryAfter(e?.headers ?? null);
  return new PolyProviderError({
    code,
    message: code === "INVALID_API_KEY" ? "Invalid API key" : message,
    provider,
    status,
    retryable: isRetryableStatus(status) && code !== "INSUFFICIENT_CREDITS" && code !== "INVALID_API_KEY",
    retryAfterMs,
    providerCode: e?.error?.code ?? e?.error?.type ?? e?.error?.status ?? e?.code,
    cause: error,
  });
}