import { NextResponse } from 'next/server';
import Anthropic from '@anthropic-ai/sdk';
import postgresClient from '@/lib/services/postgres-client';

const MODEL = 'claude-sonnet-4-6';
const SYSTEM = 'You are a senior MSP consultant. Respond with valid JSON only — no markdown fences, no prose before or after the JSON object.';

export async function POST() {
  const apiKey = process.env.ANTHROPIC_API_KEY;
  if (!apiKey) {
    return NextResponse.json({ error: 'ANTHROPIC_API_KEY not configured' }, { status: 503 });
  }

  try {
    const [statsRes, categoryRes, resolutionRes, skillsRes, complexityRes, proceduresRes] =
      await Promise.all([
        postgresClient.query(`
          SELECT
            COUNT(*)                                                                              AS total_analyzed,
            ROUND(AVG(hours_worked)::numeric, 2)                                                 AS avg_hours,
            ROUND(100.0 * COUNT(*) FILTER (WHERE same_day_close)
              / NULLIF(COUNT(*), 0), 1)                                                          AS same_day_pct,
            ROUND(100.0 * COUNT(*) FILTER (WHERE preventable = true)
              / NULLIF(COUNT(*) FILTER (WHERE preventable IS NOT NULL), 0), 1)                   AS preventable_pct,
            ROUND(100.0 * COUNT(*) FILTER (WHERE device_was_offline = true)
              / NULLIF(COUNT(*) FILTER (WHERE device_was_offline IS NOT NULL), 0), 1)            AS offline_pct,
            ROUND(100.0 * COUNT(*) FILTER (WHERE backup_completed_before_tech = true)
              / NULLIF(COUNT(*) FILTER (WHERE backup_completed_before_tech IS NOT NULL), 0), 1)  AS auto_resolved_pct,
            SUM(hours_worked)                                                                     AS total_hours
          FROM veeam_ticket_analysis
          WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
        `),

        postgresClient.query(`
          SELECT problem_category,
                 COUNT(*)                                                      AS count,
                 ROUND(AVG(hours_worked)::numeric, 2)                         AS avg_hours,
                 ROUND(100.0 * COUNT(*) FILTER (WHERE same_day_close)
                   / NULLIF(COUNT(*), 0), 1)                                   AS same_day_pct,
                 ROUND(100.0 * COUNT(*) FILTER (WHERE preventable = true)
                   / NULLIF(COUNT(*) FILTER (WHERE preventable IS NOT NULL), 0), 1) AS preventable_pct,
                 ROUND(100.0 * COUNT(*) FILTER (WHERE device_was_offline = true)
                   / NULLIF(COUNT(*) FILTER (WHERE device_was_offline IS NOT NULL), 0), 1) AS offline_pct
          FROM veeam_ticket_analysis
          WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
          GROUP BY problem_category
          ORDER BY count DESC
        `),

        postgresClient.query(`
          SELECT resolution_type, COUNT(*) AS count
          FROM veeam_ticket_analysis
          WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
          GROUP BY resolution_type ORDER BY count DESC
        `),

        postgresClient.query(`
          SELECT skill, COUNT(*) AS count
          FROM veeam_ticket_analysis, unnest(skills_required) AS skill
          WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
          GROUP BY skill ORDER BY count DESC LIMIT 20
        `),

        postgresClient.query(`
          SELECT complexity, COUNT(*) AS count
          FROM veeam_ticket_analysis
          WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
          GROUP BY complexity
          ORDER BY CASE complexity WHEN 'trivial' THEN 1 WHEN 'low' THEN 2 WHEN 'medium' THEN 3 WHEN 'high' THEN 4 ELSE 5 END
        `),

        // Sample recommended procedures per category (up to 3 per category)
        postgresClient.query(`
          SELECT problem_category, recommended_procedure
          FROM (
            SELECT problem_category, recommended_procedure,
                   ROW_NUMBER() OVER (PARTITION BY problem_category ORDER BY analyzed_at DESC) AS rn
            FROM veeam_ticket_analysis
            WHERE ticket_created_at >= DATE_TRUNC('year', NOW())
              AND recommended_procedure IS NOT NULL AND recommended_procedure != ''
          ) ranked
          WHERE rn <= 3
          ORDER BY problem_category, rn
        `),
      ]);

    const stats      = statsRes.rows[0];
    const categories = categoryRes.rows;
    const resolutions = resolutionRes.rows;
    const skills     = skillsRes.rows;
    const complexity = complexityRes.rows;
    const procedures = proceduresRes.rows;

    if (parseInt(stats.total_analyzed) === 0) {
      return NextResponse.json({ error: 'No analyzed tickets yet — run the analysis first.' }, { status: 400 });
    }

    const procByCategory: Record<string, string[]> = {};
    for (const p of procedures) {
      if (!procByCategory[p.problem_category]) procByCategory[p.problem_category] = [];
      procByCategory[p.problem_category].push(p.recommended_procedure);
    }

    const prompt = `Review this YTD backup ticket data for a managed services provider and produce a practical operations summary.

## Dataset
- Tickets analyzed: ${stats.total_analyzed} (YTD, all had tech time logged)
- Total tech time: ${parseFloat(stats.total_hours ?? 0).toFixed(1)}h
- Avg hours per ticket: ${stats.avg_hours}h
- Same-day close rate: ${stats.same_day_pct}%
- Device was offline at alert time: ${stats.offline_pct}%
- Backup auto-completed before tech action: ${stats.auto_resolved_pct}%
- Assessed as preventable: ${stats.preventable_pct}%

## Problem Categories
${categories.map(c => `- ${c.problem_category}: ${c.count} tickets, avg ${c.avg_hours}h, ${c.same_day_pct}% same-day close, ${c.offline_pct ?? 0}% offline at time`).join('\n')}

## Resolution Types
${resolutions.map(r => `- ${r.resolution_type}: ${r.count} tickets`).join('\n')}

## Complexity Breakdown
${complexity.map(c => `- ${c.complexity}: ${c.count} tickets`).join('\n')}

## Top Skills Required (by frequency)
${skills.map(s => `- ${s.skill}: ${s.count} tickets`).join('\n')}

## Sample AI-Generated SOP Steps (per category)
${Object.entries(procByCategory).map(([cat, procs]) =>
  `${cat}:\n${procs.map(p => `  • ${p}`).join('\n')}`
).join('\n')}

---

Return a JSON object with exactly this structure:
{
  "headline": "one sentence executive summary",
  "key_findings": ["3-4 bullet point findings with specific numbers"],
  "issue_breakdown": [
    {
      "category": "exact machine key from Problem Categories above (e.g. device_offline, agent_issue)",
      "insight": "1-2 sentence insight about this category",
      "sop": "concrete, actionable SOP recommendation for handling this type"
    }
  ],
  "skills_assessment": "2-3 sentences on the skills picture — what's needed most, any gaps",
  "quick_wins": ["2-3 specific things the MSP could do to reduce ticket volume or time spent"],
  "automation_opportunities": "1-2 sentences on what could be automated or suppressed",
  "training_priority": "one sentence on the highest-value training investment"
}

Be specific and direct. Reference actual numbers from the data. Avoid generic MSP advice.`;

    const client = new Anthropic({ apiKey });
    const message = await client.messages.create({
      model: MODEL,
      max_tokens: 4000,
      system: SYSTEM,
      messages: [{ role: 'user', content: prompt }],
    });

    if (message.stop_reason === 'max_tokens') {
      console.error('[VEEAM-SUMMARY] Response truncated at max_tokens');
      return NextResponse.json({ error: 'Model response was truncated — try again' }, { status: 502 });
    }

    const raw = message.content[0].type === 'text' ? message.content[0].text : '{}';

    const start = raw.indexOf('{');
    const end   = raw.lastIndexOf('}');
    const json  = start !== -1 && end > start ? raw.slice(start, end + 1) : raw;

    let analysis: Record<string, any> = {};
    try {
      analysis = JSON.parse(json);
    } catch (e) {
      console.error('[VEEAM-SUMMARY] JSON parse failed. Raw response:', raw);
      return NextResponse.json({ error: 'Model returned non-JSON response', raw }, { status: 502 });
    }

    return NextResponse.json({ analysis, model: MODEL, generated_at: new Date().toISOString() });
  } catch (e: any) {
    console.error('[VEEAM-SUMMARY] Unexpected error:', e);
    return NextResponse.json({ error: e.message ?? 'Internal server error' }, { status: 500 });
  }
}