src/app/api/documents/route.ts

import { NextRequest, NextResponse } from 'next/server';
import db from '@/lib/db';
import { startYuqueSync, getSyncStatus, stopYuqueSync, backfillNoteTags } from '@/lib/yuque-service';

export async function POST() {
  try {
    const status = getSyncStatus();
    
    if (status.status === 'running') {
        return NextResponse.json({ message: 'Sync already running', status });
    }

    // Start background sync
    startYuqueSync();
    
    return NextResponse.json({ 
        message: 'Sync started', 
        status: getSyncStatus() 
    });

  } catch (error) {
    console.error('Failed to start sync:', error);
    return NextResponse.json({ error: 'Failed to start sync' }, { status: 500 });
  }
}

export async function GET(req: NextRequest) {
  try {
    const isDemoEnv = process.env.NEXT_PUBLIC_DEMO_MODE === 'true';
    const isDemoParam = req.nextUrl.searchParams.get('mode') === 'demo';
    const isDemoMode = isDemoEnv || isDemoParam;

    // Select all columns EXCEPT content_preview to reduce payload size, but include length for stats
    // Use word_count if available (more accurate), otherwise fallback to 0 (will be updated on next sync)
    type DocRow = {
      id: string;
      yuque_id: number;
      title: string;
      slug: string;
      url: string;
      namespace: string;
      synced_at: number;
      parent_uuid?: string | null;
      uuid?: string | null;
      sort_order?: number | null;
      content_length?: number | null;
      updated_at?: number | null;
      tags?: string | string[] | null;
    };
    
    const docs = db.prepare(`
      SELECT id, yuque_id, title, slug, url, namespace, synced_at, parent_uuid, uuid, sort_order, word_count as content_length, updated_at, tags
      FROM documents 
      ORDER BY namespace ASC, sort_order ASC, synced_at DESC
    `).all() as DocRow[];
    
    const normalizedDocs = docs.map((d: DocRow) => {
      let tags: string[] = [];
      if (typeof d.tags === 'string' && d.tags.length > 0) {
        try {
          const parsed = JSON.parse(d.tags);
          if (Array.isArray(parsed)) {
            tags = parsed.map((x: unknown) => {
                if (typeof x === 'string') return x;
                if (typeof x === 'object' && x !== null) {
                    const obj = x as Record<string, unknown>;
                    const val = obj.title || obj.name;
                    return typeof val === 'string' ? val : '';
                }
                return '';
            }).filter((x: string) => x.length > 0);
          }
        } catch {
          tags = [];
        }
      } else if (Array.isArray(d.tags)) {
        tags = d.tags.map((x: unknown) => {
             if (typeof x === 'string') return x;
             if (typeof x === 'object' && x !== null) {
                 const obj = x as Record<string, unknown>;
                 const val = obj.title || obj.name;
                 return typeof val === 'string' ? val : '';
             }
             return '';
        }).filter((x: string) => x.length > 0);
      }
      return { ...d, tags };
    });

    const kbs = db.prepare(`
      SELECT * FROM knowledge_bases ORDER BY synced_at DESC
    `).all();

    const status = getSyncStatus();
    
    // DEMO DATA FALLBACK
    // If database is empty or connection fails, return static demo data for HuggingFace/Demo purposes
    // We check docs.length === 0 because even if KBs exist (e.g. from partial sync), if there are no documents,
    // we should show demo data to provide a better initial experience (especially for HF deployments where sync might fail).
    if (isDemoMode) {
        return NextResponse.json({
            documents: [
                {
                    id: 'demo/kb1/doc1',
                    yuque_id: 1001,
                    title: 'RAG 系统介绍',
                    slug: 'intro',
                    url: '#',
                    namespace: 'demo/product',
                    content_preview: 'RAG (Retrieval-Augmented Generation) 是一种结合了检索和生成的 AI 技术框架...',
                    synced_at: Date.now(),
                    parent_uuid: '',
                    uuid: 'doc-uuid-1',
                    sort_order: 1,
                    content_length: 1500,
                    updated_at: Date.now()
                },
                {
                    id: 'demo/kb1/doc2',
                    yuque_id: 1002,
                    title: '快速开始指南',
                    slug: 'quickstart',
                    url: '#',
                    namespace: 'demo/product',
                    content_preview: '本指南将帮助您在 5 分钟内部署自己的知识库系统...',
                    synced_at: Date.now(),
                    parent_uuid: '',
                    uuid: 'doc-uuid-2',
                    sort_order: 2,
                    content_length: 2300,
                    updated_at: Date.now()
                },
                {
                    id: 'demo/kb2/doc1',
                    yuque_id: 2001,
                    title: 'API 接口文档',
                    slug: 'api-docs',
                    url: '#',
                    namespace: 'demo/tech',
                    content_preview: '系统提供标准的 RESTful API 接口，支持文档上传、检索和对话...',
                    synced_at: Date.now(),
                    parent_uuid: '',
                    uuid: 'doc-uuid-3',
                    sort_order: 1,
                    content_length: 3000,
                    updated_at: Date.now()
                }
            ],
            knowledgeBases: [
                {
                    namespace: 'demo/product',
                    name: '产品手册',
                    description: '包含产品介绍、用户指南和常见问题解答',
                    synced_at: Date.now()
                },
                {
                    namespace: 'demo/tech',
                    name: '技术文档',
                    description: '系统架构、API 接口定义和开发规范',
                    synced_at: Date.now()
                }
            ],
            status: status,
            isDemo: true
        });
    }

    const notesDocs = normalizedDocs.filter((d) => d.namespace === 'NOTES');
    const hasNoteTags = notesDocs.some((d) => d.tags && d.tags.length > 0);
    if (!hasNoteTags && process.env.YUQUE_TOKEN) {
      backfillNoteTags(200, 3).catch(() => {});
    }
    return NextResponse.json({
      documents: normalizedDocs,
      knowledgeBases: kbs,
      status: status,
      isDemo: false
    });
  } catch (error) {
    console.error('Failed to fetch documents:', error);
    // Return demo data on error (e.g. DB not initialized)
    return NextResponse.json({
        documents: [
            {
                id: 'demo/kb1/doc1',
                yuque_id: 1001,
                title: 'RAG 系统介绍',
                slug: 'intro',
                url: '#',
                namespace: 'demo/product',
                content_preview: 'RAG (Retrieval-Augmented Generation) 是一种结合了检索和生成的 AI 技术框架...',
                synced_at: Date.now(),
                parent_uuid: '',
                uuid: 'doc-uuid-1',
                sort_order: 1,
                content_length: 1500,
                updated_at: Date.now()
            },
            {
                id: 'demo/kb1/doc2',
                yuque_id: 1002,
                title: '快速开始指南',
                slug: 'quickstart',
                url: '#',
                namespace: 'demo/product',
                content_preview: '本指南将帮助您在 5 分钟内部署自己的知识库系统...',
                synced_at: Date.now(),
                parent_uuid: '',
                uuid: 'doc-uuid-2',
                sort_order: 2,
                content_length: 2300,
                updated_at: Date.now()
            },
            {
                id: 'demo/kb2/doc1',
                yuque_id: 2001,
                title: 'API 接口文档',
                slug: 'api-docs',
                url: '#',
                namespace: 'demo/tech',
                content_preview: '系统提供标准的 RESTful API 接口，支持文档上传、检索和对话...',
                synced_at: Date.now(),
                parent_uuid: '',
                uuid: 'doc-uuid-3',
                sort_order: 1,
                content_length: 3000,
                updated_at: Date.now()
            }
        ],
        knowledgeBases: [
            {
                namespace: 'demo/product',
                name: '产品手册',
                description: '包含产品介绍、用户指南和常见问题解答',
                synced_at: Date.now()
            },
            {
                namespace: 'demo/tech',
                name: '技术文档',
                description: '系统架构、API 接口定义和开发规范',
                synced_at: Date.now()
            }
        ],
        status: { total: 0, processed: 0, currentBatch: 0, totalBatches: 0, status: 'idle' },
        isDemo: true
    });
  }
}

export async function DELETE() {
  try {
    const status = getSyncStatus();
    
    if (status.status !== 'running') {
        return NextResponse.json({ message: 'Sync not running', status });
    }

    // Stop background sync
    stopYuqueSync();
    
    return NextResponse.json({ 
        message: 'Sync stop requested', 
        status: getSyncStatus() 
    });

  } catch (error) {
    console.error('Failed to stop sync:', error);
    return NextResponse.json({ error: 'Failed to stop sync' }, { status: 500 });
  }
}