src/app/api/structure/route.ts

import { NextRequest, NextResponse } from 'next/server';
import type { ApiResponse, StructureRequest, StructureData } from '@/types/api';
import type { Slide } from '@/types/carousel';
import { getAnalyticsSummary } from '@/lib/analytics/calculate';
import { generateInsightsFromMetrics, formatInsightsForPrompt } from '@/lib/analytics/insights';
import { filterHighConfidenceInsights } from '@/lib/insights/recommender';
import { structureCarousel } from '@/lib/ai/structure';

export async function POST(req: NextRequest): Promise<NextResponse<ApiResponse<StructureData>>> {
  try {
    const body: StructureRequest = await req.json();

    if (!body.text) {
      return NextResponse.json({ success: false, error: 'Missing text' }, { status: 400 });
    }

    // Phase 13: Fetch insights and inject them into generation context
    let appliedInsights: StructureData['appliedInsights'] = undefined;
    let insightPrompt = '';

    try {
      const summary = await getAnalyticsSummary('weekly');
      const allInsights = generateInsightsFromMetrics(summary.insights);
      const highConfInsights = filterHighConfidenceInsights(allInsights);

      if (highConfInsights.length > 0) {
        insightPrompt = formatInsightsForPrompt(highConfInsights);
        appliedInsights = highConfInsights.slice(0, 3);
      }
    } catch (insightErr) {
      console.warn('[structure] insights fetch failed, continuing without insights:', insightErr);
    }

    // Call the LLM structurer
    const structureResult = await structureCarousel({
      text: body.text,
      template: body.template,
      palette: body.palette,
      insights: insightPrompt
    });

    if (!structureResult.success) {
      return NextResponse.json({ success: false, error: structureResult.error }, { status: 500 });
    }

    const { slides, title } = structureResult.data as StructureData;

    return NextResponse.json({
      success: true,
      data: {
        slides: slides,
        title: title || 'Generated Carousel',
        appliedInsights: appliedInsights && appliedInsights.length > 0 ? appliedInsights : undefined,
      },
    });
  } catch (err) {
    console.error('[structure] failed:', err);
    return NextResponse.json({ success: false, error: 'Something went wrong — please try again' }, { status: 500 });
  }
}