/**
 * Configuration — reads from standard OTel and plugin-specific env vars.
 */

export interface Config {
  /** OTLP endpoint (e.g. http://localhost:4318, https://api.honeycomb.io) */
  endpoint: string;
  /** OTLP headers (e.g. x-honeycomb-team=KEY) */
  headers: Record<string, string>;
  /** OTel service.name resource attribute */
  serviceName: string;
  /** Path to the persistent state JSON file */
  stateFilePath: string;
  /** Enable verbose debug logging */
  debug: boolean;
  /** W3C traceparent to nest all traces under an external parent span */
  parentTraceparent?: string;
}

function parseHeaders(raw: string): Record<string, string> {
  const headers: Record<string, string> = {};
  if (!raw) return headers;
  for (const pair of raw.split(",")) {
    const eq = pair.indexOf("=");
    if (eq > 0) {
      headers[pair.slice(0, eq).trim()] = pair.slice(eq + 1).trim();
    }
  }
  return headers;
}

export function loadConfig(): Config {
  const endpoint =
    process.env.OTEL_EXPORTER_OTLP_TRACES_ENDPOINT ??
    process.env.OTEL_EXPORTER_OTLP_ENDPOINT ??
    "http://localhost:4318";

  const headerStr =
    process.env.OTEL_EXPORTER_OTLP_TRACES_HEADERS ??
    process.env.OTEL_EXPORTER_OTLP_HEADERS ??
    "";
  const headers = parseHeaders(headerStr);

  const serviceName = process.env.OTEL_SERVICE_NAME ?? "claude-code";

  const homeDir = process.env.HOME ?? process.env.USERPROFILE ?? "";
  const stateFilePath =
    process.env.CC_OTEL_STATE_FILE ?? `${homeDir}/.claude/state/otel_tracing_state.json`;

  const debug = (process.env.CC_OTEL_DEBUG ?? "").toLowerCase() === "true";

  const parentTraceparent = process.env.CC_OTEL_TRACEPARENT || undefined;

  return { endpoint, headers, serviceName, stateFilePath, debug, parentTraceparent };
}