/**
 * Coerce a capability result into a JSON value before it becomes an AI SDK tool
 * result. streamText validates every tool output against the ModelMessage
 * schema on each continuation step of a multi-tool turn, and that schema only
 * accepts JSON values. A raw `Date` (Drizzle `{ mode: "timestamp" }` columns) or
 * an `undefined` field is not a JSON value, so it throws
 * `AI_InvalidPromptError: messages do not match the ModelMessage schema` — but
 * only after a SECOND tool runs in the same turn, which is why it slips through
 * single-tool responses. Round-tripping through JSON turns Dates into ISO
 * strings and drops `undefined`, the exact shape the model (and the MCP
 * JSON-RPC transport) already expect. Applied at the chat tool-adapter seam so
 * no individual capability — present or future — can crash the model loop.
 */
export function toJsonSafeToolOutput(value: unknown): unknown {
  return JSON.parse(JSON.stringify(value ?? null));
}

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null;
}

/** ActivityReport shape marker — the container whose raw `events` echo must
 * never ride into a chat context (see {@link toChatSafeToolOutput}). */
function isActivityReportLike(
  value: unknown,
): value is Record<string, unknown> {
  return (
    isRecord(value) &&
    Array.isArray(value.projects) &&
    typeof value.totalEstimatedMinutes === "number"
  );
}

/**
 * Shape a capability result for the AI-chat consumer: JSON-safe (via
 * {@link toJsonSafeToolOutput}) AND without any raw timeline-event echo.
 *
 * An exhaustive report legitimately carries `report.events` — up to 10k full
 * event rows with metadata — for machine consumers (the reports page, PDF
 * export, MCP). Fed back into a model loop as a tool result it is a context
 * bomb: a real 7-day report (2,513 events) serialized to ~509k tokens and
 * blew Grok's 500k window from a four-word prompt. Chat is a conversation
 * surface, not a data export: the model reasons over the structured rollups,
 * the chat UI renders from them too, and the full per-event report belongs
 * behind a link (saveReport returns `url`). So the events echo is removed
 * here — at the chat adapter seam, for every present and future report-shaped
 * output — and replaced with a note telling the model where the full data
 * lives. This is dataset shaping for the consumer, not a size cap: nothing is
 * truncated, summary rollups remain complete, and MCP/REST callers still get
 * the full echo.
 *
 * Handles both nestings: `{ report: ActivityReport }` (generateReport) and
 * `{ report: { report: ActivityReport } }` (getReport).
 */
export function toChatSafeToolOutput(value: unknown): unknown {
  const output = toJsonSafeToolOutput(value);
  if (!isRecord(output)) return output;
  for (const container of [output, output.report]) {
    if (!isRecord(container)) continue;
    const report = container.report;
    if (isActivityReportLike(report) && Array.isArray(report.events)) {
      const count = report.events.length;
      delete report.events;
      container.eventsOmittedFromChat = count;
      container.eventsNote = `The ${count} raw events are not loaded into chat (the structured rollups above are complete). For full per-event detail, use saveReport and give the user its link.`;
    }
  }
  return output;
}