export interface TelemetryConfig {
  /** Base URL of the telemetry server (e.g., "https://tel.mosaicstack.dev") */
  serverUrl: string;
  /** API key for authentication (64-char hex string) */
  apiKey: string;
  /** Instance UUID for this client */
  instanceId: string;
  /** Whether telemetry collection is enabled. Default: true */
  enabled?: boolean;
  /** Interval between automatic batch submissions in ms. Default: 300_000 (5 min) */
  submitIntervalMs?: number;
  /** Maximum number of events held in queue. Default: 1000 */
  maxQueueSize?: number;
  /** Maximum events per batch submission. Default: 100 */
  batchSize?: number;
  /** HTTP request timeout in ms. Default: 10_000 */
  requestTimeoutMs?: number;
  /** TTL for cached predictions in ms. Default: 21_600_000 (6 hours) */
  predictionCacheTtlMs?: number;
  /** If true, log events instead of sending them. Default: false */
  dryRun?: boolean;
  /** Maximum number of retries on failure. Default: 3 */
  maxRetries?: number;
  /** Optional callback invoked on errors */
  onError?: (error: Error) => void;
}

export interface ResolvedConfig {
  serverUrl: string;
  apiKey: string;
  instanceId: string;
  enabled: boolean;
  submitIntervalMs: number;
  maxQueueSize: number;
  batchSize: number;
  requestTimeoutMs: number;
  predictionCacheTtlMs: number;
  dryRun: boolean;
  maxRetries: number;
  onError: (error: Error) => void;
}

const DEFAULT_ON_ERROR = (_error: Error): void => {
  // Silent by default
};

export function resolveConfig(config: TelemetryConfig): ResolvedConfig {
  return {
    serverUrl: config.serverUrl.replace(/\/+$/, ""),
    apiKey: config.apiKey,
    instanceId: config.instanceId,
    enabled: config.enabled ?? true,
    submitIntervalMs: config.submitIntervalMs ?? 300_000,
    maxQueueSize: config.maxQueueSize ?? 1000,
    batchSize: config.batchSize ?? 100,
    requestTimeoutMs: config.requestTimeoutMs ?? 10_000,
    predictionCacheTtlMs: config.predictionCacheTtlMs ?? 21_600_000,
    dryRun: config.dryRun ?? false,
    maxRetries: config.maxRetries ?? 3,
    onError: config.onError ?? DEFAULT_ON_ERROR,
  };
}