import { NextRequest, NextResponse } from 'next/server'
import pool from '@/lib/db'
import bcrypt from 'bcrypt'

// GET /api/buyers/[id] - Get a specific buyer
export async function GET(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const id = parseInt(params.id, 10)
    if (isNaN(id)) {
      return NextResponse.json(
        { error: 'Invalid buyer ID' },
        { status: 400 }
      )
    }

    const [rows] = await pool.execute(
      'SELECT id, username, email, created_at FROM buyers WHERE id = ?',
      [id]
    )

    const buyers = rows as any[]
    if (buyers.length === 0) {
      return NextResponse.json(
        { error: 'Buyer not found' },
        { status: 404 }
      )
    }

    return NextResponse.json(buyers[0])
  } catch (error) {
    console.error('Error fetching buyer:', error)
    return NextResponse.json(
      { error: 'Failed to fetch buyer' },
      { status: 500 }
    )
  }
}

// PUT /api/buyers/[id] - Update a buyer
export async function PUT(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const id = parseInt(params.id, 10)
    if (isNaN(id)) {
      return NextResponse.json(
        { error: 'Invalid buyer ID' },
        { status: 400 }
      )
    }

    const body = await request.json()
    const { username, email, password } = body

    // Check if buyer exists
    const [existingRows] = await pool.execute(
      'SELECT id FROM buyers WHERE id = ?',
      [id]
    )
    const existing = existingRows as any[]
    if (existing.length === 0) {
      return NextResponse.json(
        { error: 'Buyer not found' },
        { status: 404 }
      )
    }

    // Build update query dynamically based on provided fields
    const updates: string[] = []
    const values: any[] = []

    if (username !== undefined) {
      // Check if username already exists (excluding current buyer)
      const [usernameCheck] = await pool.execute(
        'SELECT id FROM buyers WHERE username = ? AND id != ?',
        [username, id]
      )
      if ((usernameCheck as any[]).length > 0) {
        return NextResponse.json(
          { error: 'Username already exists' },
          { status: 400 }
        )
      }
      updates.push('username = ?')
      values.push(username)
    }

    if (email !== undefined) {
      // Validate email format
      const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
      if (!emailRegex.test(email)) {
        return NextResponse.json(
          { error: 'Invalid email format' },
          { status: 400 }
        )
      }
      // Check if email already exists (excluding current buyer)
      const [emailCheck] = await pool.execute(
        'SELECT id FROM buyers WHERE email = ? AND id != ?',
        [email, id]
      )
      if ((emailCheck as any[]).length > 0) {
        return NextResponse.json(
          { error: 'Email already exists' },
          { status: 400 }
        )
      }
      updates.push('email = ?')
      values.push(email)
    }

    if (password !== undefined) {
      if (password.length < 6) {
        return NextResponse.json(
          { error: 'Password must be at least 6 characters' },
          { status: 400 }
        )
      }
      const hashedPassword = await bcrypt.hash(password, 10)
      updates.push('password = ?')
      values.push(hashedPassword)
    }

    if (updates.length === 0) {
      return NextResponse.json(
        { error: 'No fields to update' },
        { status: 400 }
      )
    }

    values.push(id)
    const query = `UPDATE buyers SET ${updates.join(', ')} WHERE id = ?`
    await pool.execute(query, values)

    // Fetch updated buyer
    const [rows] = await pool.execute(
      'SELECT id, username, email, created_at FROM buyers WHERE id = ?',
      [id]
    )

    return NextResponse.json((rows as any[])[0])
  } catch (error) {
    console.error('Error updating buyer:', error)
    return NextResponse.json(
      { error: 'Failed to update buyer' },
      { status: 500 }
    )
  }
}

// DELETE /api/buyers/[id] - Delete a buyer
export async function DELETE(
  request: NextRequest,
  { params }: { params: { id: string } }
) {
  try {
    const id = parseInt(params.id, 10)
    if (isNaN(id)) {
      return NextResponse.json(
        { error: 'Invalid buyer ID' },
        { status: 400 }
      )
    }

    // Check if buyer exists
    const [existingRows] = await pool.execute(
      'SELECT id FROM buyers WHERE id = ?',
      [id]
    )
    const existing = existingRows as any[]
    if (existing.length === 0) {
      return NextResponse.json(
        { error: 'Buyer not found' },
        { status: 404 }
      )
    }

    // Delete buyer (cascade will handle related sales)
    await pool.execute('DELETE FROM buyers WHERE id = ?', [id])

    return NextResponse.json({ success: true })
  } catch (error) {
    console.error('Error deleting buyer:', error)
    return NextResponse.json(
      { error: 'Failed to delete buyer' },
      { status: 500 }
    )
  }
}