import { NextRequest, NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/app/api/auth/[...nextauth]/route';
import * as candidateService from '@/lib/services/candidateService';

// Demo data for when MongoDB is not available
const DEMO_CANDIDATES = [
  {
    _id: "1",
    name: "John Doe",
    email: "john.doe@example.com",
    phone: "123-456-7890",
    technology: "React, Node.js",
    visaStatus: "H1B",
    location: "New York, NY",
    openToRelocate: true,
    experience: "5 years",
    currentStatus: "In marketing",
    status: "Active",
    marketingStartDate: "2023-04-15",
    dayRecruiter: "Jane Smith",
    nightRecruiter: "Mike Johnson",
  },
  {
    _id: "2",
    name: "Jane Smith",
    email: "jane.smith@example.com",
    phone: "234-567-8901",
    technology: "Angular, Python",
    visaStatus: "Green Card",
    location: "San Francisco, CA",
    openToRelocate: false,
    experience: "3 years",
    currentStatus: "In marketing",
    status: "Active",
    marketingStartDate: "2023-04-10",
    dayRecruiter: "Bob Williams",
    nightRecruiter: "Alice Brown",
  },
  {
    _id: "3",
    name: "Mike Johnson",
    email: "mike.johnson@example.com",
    phone: "345-678-9012",
    technology: "Java, Spring",
    visaStatus: "OPT",
    location: "Austin, TX",
    openToRelocate: true,
    experience: "2 years",
    currentStatus: "In marketing",
    status: "Active",
    marketingStartDate: "2023-04-05",
    dayRecruiter: "Jane Smith",
    nightRecruiter: "Bob Williams",
  },
  {
    _id: "4",
    name: "Sarah Williams",
    email: "sarah.williams@example.com",
    phone: "456-789-0123",
    technology: "Python, Django",
    visaStatus: "H1B",
    location: "Chicago, IL",
    openToRelocate: true,
    experience: "4 years",
    currentStatus: "Hold",
    status: "Hold",
    marketingStartDate: "2023-03-25",
    dayRecruiter: "Mike Johnson",
    nightRecruiter: "Jane Smith",
  },
  {
    _id: "5",
    name: "David Brown",
    email: "david.brown@example.com",
    phone: "567-890-1234",
    technology: "React, Redux, TypeScript",
    visaStatus: "Citizen",
    location: "Seattle, WA",
    openToRelocate: false,
    experience: "6 years",
    currentStatus: "Placed",
    status: "Inactive",
    marketingStartDate: "2023-03-15",
    dayRecruiter: "Alice Brown",
    nightRecruiter: "Bob Williams",
  }
];

// GET all candidates, with optional filtering
export async function GET(request: NextRequest) {
  try {
    const { searchParams } = new URL(request.url);
    const status = searchParams.get('status');
    const technology = searchParams.get('technology');
    const visaStatus = searchParams.get('visaStatus');
    const openToRelocate = searchParams.get('openToRelocate');
    const currentStatus = searchParams.get('currentStatus');
    const search = searchParams.get('search');
    const limit = Number(searchParams.get('limit') || '50');
    const page = Number(searchParams.get('page') || '1');

    try {
      // Try to get candidates using the service
      const result = await candidateService.getCandidates({
        status,
        technology,
        visaStatus,
        openToRelocate: openToRelocate === 'true',
        currentStatus,
        search,
        limit,
        page
      });
console.log('mongo result', result);
      return NextResponse.json(result);
    } catch (error) {
      console.log("MongoDB connection error, using demo candidates", error);

      // Fall back to demo data
      let candidates = [...DEMO_CANDIDATES];

      // Filter demo data based on query params
      if (status) {
        candidates = candidates.filter(c => c.status === status);
      }

      if (technology) {
        candidates = candidates.filter(c =>
          c.technology.toLowerCase().includes(technology.toLowerCase())
        );
      }

      if (visaStatus) {
        candidates = candidates.filter(c => c.visaStatus === visaStatus);
      }

      if (openToRelocate) {
        candidates = candidates.filter(c =>
          c.openToRelocate === (openToRelocate === 'true')
        );
      }

      if (currentStatus) {
        candidates = candidates.filter(c => c.currentStatus === currentStatus);
      }

      if (search) {
        const query = search.toLowerCase();
        candidates = candidates.filter(c =>
          c.name.toLowerCase().includes(query) ||
          c.email.toLowerCase().includes(query) ||
          c.technology.toLowerCase().includes(query)
        );
      }

      const total = candidates.length;
      const skip = (page - 1) * limit;
      candidates = candidates.slice(skip, skip + limit);

      return NextResponse.json({
        candidates,
        pagination: {
          total,
          page,
          limit,
          totalPages: Math.ceil(total / limit)
        }
      });
    }
  } catch (error) {
    console.error('Error fetching candidates:', error);
    return NextResponse.json(
      { error: 'Failed to fetch candidates' },
      { status: 500 }
    );
  }
}

// POST a new candidate
export async function POST(request: NextRequest) {
  try {
    // Get the session to associate the candidate with the user
    const session = await getServerSession(authOptions);

    if (!session?.user) {
      return NextResponse.json(
        { error: 'Authentication required' },
        { status: 401 }
      );
    }

    const body = await request.json();

    try {
      // Try to create a candidate using the service
      const newCandidate = await candidateService.createCandidate(
        body,
        session.user.id
      );

      return NextResponse.json(
        { message: 'Candidate created successfully', candidate: newCandidate },
        { status: 201 }
      );
    } catch (error) {
      // Check if it's a duplicate email error
      if ((error as Error).message === 'A candidate with this email already exists') {
        return NextResponse.json(
          { error: (error as Error).message },
          { status: 409 }
        );
      }

      console.log("MongoDB connection error, handling demo creation", error);

      // Check for duplicate in demo data
      const existingCandidate = DEMO_CANDIDATES.find(c => c.email === body.email);
      if (existingCandidate) {
        return NextResponse.json(
          { error: 'A candidate with this email already exists' },
          { status: 409 }
        );
      }

      // Create demo candidate with generated ID
      const newCandidate = {
        _id: (DEMO_CANDIDATES.length + 1).toString(),
        ...body,
        createdBy: session.user.id,
        createdAt: new Date().toISOString(),
        updatedAt: new Date().toISOString()
      };

      // Add to demo candidates array
      DEMO_CANDIDATES.push(newCandidate);

      return NextResponse.json(
        { message: 'Candidate created successfully', candidate: newCandidate },
        { status: 201 }
      );
    }
  } catch (error) {
    console.error('Error creating candidate:', error);
    return NextResponse.json(
      { error: 'Failed to create candidate' },
      { status: 500 }
    );
  }
}