/**
 * Drafting Engine - Draft API
 *
 * Erstellt strukturierte Compliance-Dokument-Entwuerfe.
 * Baut dokument-spezifische Prompts aus SOUL-Template + State-Projection.
 * Gibt strukturiertes JSON zurueck.
 */

import { NextRequest, NextResponse } from 'next/server'

const OLLAMA_URL = process.env.OLLAMA_URL || 'http://host.docker.internal:11434'
const LLM_MODEL = process.env.COMPLIANCE_LLM_MODEL || 'qwen2.5vl:32b'

// Import prompt builders
import { buildVVTDraftPrompt } from '@/lib/sdk/drafting-engine/prompts/draft-vvt'
import { buildTOMDraftPrompt } from '@/lib/sdk/drafting-engine/prompts/draft-tom'
import { buildDSFADraftPrompt } from '@/lib/sdk/drafting-engine/prompts/draft-dsfa'
import { buildPrivacyPolicyDraftPrompt } from '@/lib/sdk/drafting-engine/prompts/draft-privacy-policy'
import { buildLoeschfristenDraftPrompt } from '@/lib/sdk/drafting-engine/prompts/draft-loeschfristen'
import type { DraftContext, DraftResponse, DraftRevision, DraftSection } from '@/lib/sdk/drafting-engine/types'
import type { ScopeDocumentType } from '@/lib/sdk/compliance-scope-types'
import { ConstraintEnforcer } from '@/lib/sdk/drafting-engine/constraint-enforcer'

const constraintEnforcer = new ConstraintEnforcer()

const DRAFTING_SYSTEM_PROMPT = `Du bist ein DSGVO-Compliance-Experte und erstellst strukturierte Dokument-Entwuerfe.
Du MUSST immer im JSON-Format antworten mit einem "sections" Array.
Jede Section hat: id, title, content, schemaField.
Halte die Tiefe strikt am vorgegebenen Level.
Markiere fehlende Informationen mit [PLATZHALTER: Beschreibung].
Sprache: Deutsch.`

function buildPromptForDocumentType(
  documentType: ScopeDocumentType,
  context: DraftContext,
  instructions?: string
): string {
  switch (documentType) {
    case 'vvt':
      return buildVVTDraftPrompt({ context, instructions })
    case 'tom':
      return buildTOMDraftPrompt({ context, instructions })
    case 'dsfa':
      return buildDSFADraftPrompt({ context, instructions })
    case 'dsi':
      return buildPrivacyPolicyDraftPrompt({ context, instructions })
    case 'lf':
      return buildLoeschfristenDraftPrompt({ context, instructions })
    default:
      return `## Aufgabe: Entwurf fuer ${documentType}

### Level: ${context.decisions.level}
### Tiefe: ${context.constraints.depthRequirements.depth}
### Erforderliche Inhalte:
${context.constraints.depthRequirements.detailItems.map((item, i) => `${i + 1}. ${item}`).join('\n')}

${instructions ? `### Anweisungen: ${instructions}` : ''}

Antworte als JSON mit "sections" Array.`
  }
}

export async function POST(request: NextRequest) {
  try {
    const body = await request.json()
    const { documentType, draftContext, instructions, existingDraft } = body

    if (!documentType || !draftContext) {
      return NextResponse.json(
        { error: 'documentType und draftContext sind erforderlich' },
        { status: 400 }
      )
    }

    // 1. Constraint Check (Hard Gate)
    const constraintCheck = constraintEnforcer.checkFromContext(documentType, draftContext)

    if (!constraintCheck.allowed) {
      return NextResponse.json({
        draft: null,
        constraintCheck,
        tokensUsed: 0,
        error: 'Constraint-Verletzung: ' + constraintCheck.violations.join('; '),
      }, { status: 403 })
    }

    // 2. Build document-specific prompt
    const draftPrompt = buildPromptForDocumentType(documentType, draftContext, instructions)

    // 3. Build messages
    const messages = [
      { role: 'system', content: DRAFTING_SYSTEM_PROMPT },
      ...(existingDraft ? [{
        role: 'assistant',
        content: `Bisheriger Entwurf:\n${JSON.stringify(existingDraft.sections, null, 2)}`,
      }] : []),
      { role: 'user', content: draftPrompt },
    ]

    // 4. Call LLM (non-streaming for structured output)
    const ollamaResponse = await fetch(`${OLLAMA_URL}/api/chat`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        model: LLM_MODEL,
        messages,
        stream: false,
        options: {
          temperature: 0.15,
          num_predict: 16384,
        },
        format: 'json',
      }),
      signal: AbortSignal.timeout(180000),
    })

    if (!ollamaResponse.ok) {
      return NextResponse.json(
        { error: `LLM nicht erreichbar (Status ${ollamaResponse.status})` },
        { status: 502 }
      )
    }

    const result = await ollamaResponse.json()
    const content = result.message?.content || ''

    // 5. Parse JSON response
    let sections: DraftSection[] = []
    try {
      const parsed = JSON.parse(content)
      sections = (parsed.sections || []).map((s: Record<string, unknown>, i: number) => ({
        id: String(s.id || `section-${i}`),
        title: String(s.title || ''),
        content: String(s.content || ''),
        schemaField: s.schemaField ? String(s.schemaField) : undefined,
      }))
    } catch {
      // If not JSON, wrap raw content as single section
      sections = [{
        id: 'raw',
        title: 'Entwurf',
        content: content,
      }]
    }

    const draft: DraftRevision = {
      id: `draft-${Date.now()}`,
      content: sections.map(s => `## ${s.title}\n\n${s.content}`).join('\n\n'),
      sections,
      createdAt: new Date().toISOString(),
      instruction: instructions,
    }

    const response: DraftResponse = {
      draft,
      constraintCheck,
      tokensUsed: result.eval_count || 0,
    }

    return NextResponse.json(response)
  } catch (error) {
    console.error('Draft generation error:', error)
    return NextResponse.json(
      { error: 'Draft-Generierung fehlgeschlagen.' },
      { status: 503 }
    )
  }
}