import { NextRequest, NextResponse } from 'next/server';
import { MongoClient, Db, Collection, ObjectId } from 'mongodb';

// MongoDB connection
let client: MongoClient | null = null;
let db: Db | null = null;

async function getDatabase(): Promise<Db> {
  if (!client) {
    const uri = process.env.MONGODB_URI || 'mongodb://localhost:27017';
    client = new MongoClient(uri);
    await client.connect();
    db = client.db('beanstalk');
  }
  return db!;
}

function convertMongoExtendedJSON(obj: any): any {
  if (obj === null || obj === undefined) {
    return obj;
  }
  
  if (Array.isArray(obj)) {
    return obj.map(item => convertMongoExtendedJSON(item));
  }
  
  if (typeof obj === 'object') {
    const converted: any = {};
    
    for (const [key, value] of Object.entries(obj)) {
      if (key === '$oid' && typeof value === 'string') {
        return new ObjectId(value);
      } else if (key === '$date' && typeof value === 'string') {
        return new Date(value);
      } else {
        converted[key] = convertMongoExtendedJSON(value);
      }
    }
    
    return converted;
  }
  
  return obj;
}

export async function GET(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const filename = searchParams.get('file');

    if (!filename) {
      return NextResponse.json(
        { 
          error: 'file parameter is required',
          message: 'Usage: /api/import-json?file=db_prod.akademyObservations.json'
        },
        { status: 400 }
      );
    }

    // Read JSON file
    const fs = require('fs');
    const path = require('path');
    const filePath = path.join(process.cwd(), '..', filename);
    const fileContent = fs.readFileSync(filePath, 'utf-8');
    const rawDocuments = JSON.parse(fileContent);

    // Convert MongoDB extended JSON to proper MongoDB documents
    const documents = rawDocuments.map((doc: any) => convertMongoExtendedJSON(doc));

    // Get MongoDB collection
    const db = await getDatabase();
    const collection = db.collection('observations');

    // Insert documents
    const result = await collection.insertMany(documents);

    return NextResponse.json({
      success: true,
      message: `Successfully imported ${result.insertedCount} observations`,
      inserted_count: result.insertedCount,
      inserted_ids: Object.values(result.insertedIds)
    });

  } catch (error: any) {
    console.error('Import error:', error);
    
    if (error.code === 'ENOENT') {
      return NextResponse.json(
        { 
          error: 'File not found',
          message: `The file was not found`
        },
        { status: 400 }
      );
    }

    if (error.name === 'SyntaxError') {
      return NextResponse.json(
        { 
          error: 'Failed to parse JSON',
          message: error.message
        },
        { status: 400 }
      );
    }

    return NextResponse.json(
      { 
        error: 'Failed to import data',
        message: error.message
      },
      { status: 500 }
    );
  }
}

export async function POST(request: NextRequest) {
  try {
    const formData = await request.formData();
    const file = formData.get('file') as File;

    if (!file) {
      return NextResponse.json(
        { 
          error: 'No file provided',
          message: 'Please select a JSON file to upload'
        },
        { status: 400 }
      );
    }

    // Validate file type
    if (!file.type.includes('json')) {
      return NextResponse.json(
        { 
          error: 'Invalid file type',
          message: 'Please upload a JSON file'
        },
        { status: 400 }
      );
    }

    // Read file content
    const fileContent = await file.text();
    const rawDocuments = JSON.parse(fileContent);

    // Convert MongoDB extended JSON to proper MongoDB documents
    const documents = rawDocuments.map((doc: any) => convertMongoExtendedJSON(doc));

    // Get MongoDB collection
    const db = await getDatabase();
    const collection = db.collection('observations');

    // Insert documents
    const result = await collection.insertMany(documents);

    return NextResponse.json({
      success: true,
      message: `Successfully imported ${result.insertedCount} observations from ${file.name}`,
      inserted_count: result.insertedCount,
      inserted_ids: Object.values(result.insertedIds),
      filename: file.name,
      size: `${(file.size / 1024).toFixed(2)} KB`
    });

  } catch (error: any) {
    console.error('Import error:', error);
    
    if (error.name === 'SyntaxError') {
      return NextResponse.json(
        { 
          error: 'Failed to parse JSON',
          message: error.message
        },
        { status: 400 }
      );
    }

    return NextResponse.json(
      { 
        error: 'Failed to import data',
        message: error.message
      },
      { status: 500 }
    );
  }
}