type FrontendActionArgs = Record<string, unknown> & {
  __frontend_action_call_id?: string;
  reason?: string;
};

type FrontendActionBridgeResult = {
  version: "frontend-action-result@1";
  status: "succeeded" | "failed" | "rejected" | "cancelled" | "expired";
  output?: unknown;
  error?: { code?: string; message?: string };
};

const internalBaseUrl =
  process.env.TJWATER_AGENT_INTERNAL_BASE_URL ?? "http://127.0.0.1:8787";
const internalToken = process.env.TJWATER_AGENT_INTERNAL_TOKEN ?? "";

export const executeFrontendAction = async (
  name: "render_scada_analysis" | "clear_scada_analysis",
  args: FrontendActionArgs,
  context: { sessionID: string },
) => {
  const callId = args.__frontend_action_call_id;
  if (!callId) {
    throw new Error("frontend action bridge did not inject the OpenCode call ID");
  }
  const { __frontend_action_call_id: _callId, reason, ...params } = args;
  let response: Response;
  try {
    response = await fetch(`${internalBaseUrl}/internal/frontend-actions/request`, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "x-agent-internal-token": internalToken,
      },
      body: JSON.stringify({
        session_id: context.sessionID,
        call_id: callId,
        name,
        params,
        fallback_text: reason,
      }),
    });
  } catch (error) {
    throw new Error(
      `frontend action bridge unavailable: ${error instanceof Error ? error.message : String(error)}`,
    );
  }
  const text = await response.text();
  if (!response.ok) {
    throw new Error(
      `frontend action bridge rejected request (${response.status}): ${text}`,
    );
  }
  return unwrapFrontendActionResult(text);
};

export const unwrapFrontendActionResult = (text: string) => {
  let result: FrontendActionBridgeResult;
  try {
    result = JSON.parse(text) as FrontendActionBridgeResult;
  } catch {
    throw new Error("frontend action bridge returned invalid JSON");
  }
  if (result.version !== "frontend-action-result@1" || typeof result.status !== "string") {
    throw new Error("frontend action bridge returned an invalid result");
  }
  if (result.status !== "succeeded") {
    const code = result.error?.code?.trim() || `ACTION_${result.status.toUpperCase()}`;
    const message = result.error?.message?.trim() || `browser action ${result.status}`;
    throw new Error(`${code}: ${message}`);
  }
  if (result.output === undefined) {
    throw new Error("frontend action bridge returned no output");
  }
  return JSON.stringify(result.output);
};