/**
 * What a failed provider call proves about the side effect:
 * - "rejected": the provider answered and definitively did not perform it.
 * - "unknown": the request may have been applied (5xx/transport loss on a
 *   non-idempotent request) — never resend without a provider dedupe key.
 */
export type DeliveryCertainty = "rejected" | "unknown";

export class ConnectorError extends Error {
  constructor(
    message: string,
    readonly provider: string,
    override readonly cause?: unknown,
  ) {
    super(message);
    this.name = "ConnectorError";
  }
}

export class UnknownProviderError extends ConnectorError {
  constructor(providerId: string) {
    super(`no connector registered for provider "${providerId}"`, providerId);
    this.name = "UnknownProviderError";
  }
}

export class AuthError extends ConnectorError {
  constructor(message: string, provider: string, readonly retryable: boolean) {
    super(message, provider);
    this.name = "AuthError";
  }
}

export class RateLimitError extends ConnectorError {
  /** A 429 is a refusal before processing, so nothing was delivered. */
  readonly delivery: DeliveryCertainty = "rejected";

  constructor(
    provider: string,
    readonly retryAfterMs?: number,
    readonly status = 429,
  ) {
    super(`rate limited by ${provider}`, provider);
    this.name = "RateLimitError";
  }
}

/** The provider answered with a non-2xx status that is a definite refusal (4xx). */
export class ProviderRejectedError extends ConnectorError {
  readonly delivery: DeliveryCertainty = "rejected";

  constructor(
    message: string,
    provider: string,
    readonly status: number,
    readonly retryAfterMs?: number,
  ) {
    // cause keeps the `{ status }` shape connectors already inspect.
    super(message, provider, { status });
    this.name = "ProviderRejectedError";
  }
}

/**
 * 5xx answer the SDK client did not retry (or stopped retrying). For
 * non-idempotent requests delivery is "unknown": the server may have applied
 * the write before failing.
 */
export class ProviderServerError extends ConnectorError {
  constructor(
    provider: string,
    readonly status: number,
    readonly method: string,
    readonly delivery: DeliveryCertainty,
    readonly retryAfterMs?: number,
  ) {
    super(`${provider}: HTTP ${status} on ${method}`, provider, { status });
    this.name = "ProviderServerError";
  }
}

/** fetch itself failed (socket loss, DNS, abort) on a non-idempotent request. */
export class ProviderTransportError extends ConnectorError {
  readonly delivery: DeliveryCertainty = "unknown";

  constructor(
    provider: string,
    readonly method: string,
    cause: unknown,
  ) {
    super(`${provider}: transport failure on ${method}`, provider, cause);
    this.name = "ProviderTransportError";
  }
}

/** Delivery certainty carried by an SDK error, if the error type records one. */
export function deliveryCertaintyOf(error: unknown): DeliveryCertainty | undefined {
  if (error instanceof AuthError) return "rejected";
  if (
    error instanceof RateLimitError ||
    error instanceof ProviderRejectedError ||
    error instanceof ProviderServerError ||
    error instanceof ProviderTransportError
  ) {
    return error.delivery;
  }
  return undefined;
}

export class CapabilityNotSupportedError extends ConnectorError {
  constructor(provider: string, capability: string) {
    super(`${provider} does not support "${capability}"`, provider);
    this.name = "CapabilityNotSupportedError";
  }
}