'use strict';

// Resolve a child's source object from a registration payload.
// Payload may be: a string (node id) | { source: {...} } | { config: {...} }.
function resolveChildSource(payload, ctx) {
  if (payload?.source?.config) return payload.source;
  if (payload?.config) return { config: payload.config };
  if (typeof payload === 'string') {
    const childNode = resolveChildNode(payload, ctx);
    return childNode?.source || null;
  }
  return null;
}

function resolveChildNode(childId, ctx) {
  const runtimeNode = ctx.RED?.nodes?.getNode?.(childId);
  if (runtimeNode?.source?.config) return runtimeNode;

  const flowNode = ctx.node?._flow?.getNode?.(childId);
  if (flowNode?.source?.config) return flowNode;

  return runtimeNode || flowNode || null;
}

// On child.register: build the dashboard graph (root + direct children) and
// emit one Grafana upsert HTTP request per dashboard on Port 0.
//
// Diff-skip behavior (PRD F-1, S1 spike #32): if the latest flows:started
// payload's `diff` indicates that NEITHER the dashboardAPI itself NOR this
// child NOR its grandchildren changed, skip composition and log no-diff. The
// first call after startup (no cached diff yet) regenerates unconditionally.
function registerChild(source, msg, ctx) {
  const childSource = resolveChildSource(msg.payload, ctx);
  if (!childSource?.config) {
    throw new Error('Missing or invalid child node');
  }

  const subtreeIds = source.subtreeIdsFor(ctx.node?.id, childSource);
  const changed = source.subtreeChanged(source.lastFlowsStartedDiff, subtreeIds);
  if (!changed) {
    if (source.logger?.info) {
      source.logger.info({
        event: 'regen-skipped',
        outcome: 'no-diff',
        trigger: 'child.register',
        dashboardApiId: ctx.node?.id,
        childId: childSource?.config?.general?.id,
        subtreeSize: subtreeIds.size,
      });
    }
    return;
  }

  const dashboards = source.generateDashboardsForGraph(childSource, {
    includeChildren: Boolean(msg.includeChildren ?? true),
  });

  const url = source.grafanaUpsertUrl();
  const headers = { Accept: 'application/json', 'Content-Type': 'application/json' };
  const token = source.config?.grafanaConnector?.bearerToken;
  if (token) headers.Authorization = `Bearer ${token}`;

  for (const dash of dashboards) {
    ctx.send({
      ...msg,
      topic: 'create',
      url,
      method: 'POST',
      headers,
      payload: source.buildUpsertRequest({
        dashboard: dash.dashboard,
        folderUid: source.config?.grafanaConnector?.folderUid || undefined,
        overwrite: true,
      }),
      meta: {
        nodeId: dash.nodeId,
        softwareType: dash.softwareType,
        uid: dash.uid,
        title: dash.title,
      },
    });
  }
}

module.exports = { registerChild };