import { NextRequest, NextResponse } from 'next/server'
import nodemailer from 'nodemailer'
import { createClient } from '@supabase/supabase-js'

export const dynamic = 'force-dynamic'
export const runtime = 'nodejs'

const createTransporter = () => {
  const smtpHost = process.env.SMTP_HOST
  const smtpPort = process.env.SMTP_PORT ? parseInt(process.env.SMTP_PORT, 10) : 587
  const smtpUser = process.env.SMTP_USER?.trim()
  const smtpPassword = (process.env.SMTP_PASSWORD || '').replace(/\s/g, '').trim()
  const smtpFromEmail = process.env.SMTP_FROM_EMAIL || 'BUILDMATE <noreply@buildmate.com>'

  const isPlaceholder =
    (smtpHost?.trim() === 'your_smtp_host') ||
    (smtpUser === 'your_smtp_user') ||
    (smtpPassword === 'your_smtp_password')

  if (isPlaceholder) {
    throw new Error('SMTP credentials are still placeholders. Please update .env.local.')
  }

  if (!smtpHost || !smtpUser || !smtpPassword) {
    throw new Error('SMTP credentials are missing in environment variables.')
  }

  const isGmail = smtpHost.toLowerCase().includes('gmail.com')
  const port = smtpPort || 587
  const secure = port === 465

  return nodemailer.createTransport({
    host: smtpHost,
    port,
    secure,
    ...(isGmail && { requireTLS: true }),
    auth: { user: smtpUser, pass: smtpPassword },
  })
}

export async function POST(request: NextRequest) {
  try {
    const supabase = createClient(
      process.env.NEXT_PUBLIC_SUPABASE_URL || '',
      process.env.SUPABASE_SERVICE_ROLE_KEY || ''
    )

    const body = await request.json()
    const { title, content, featuredBuilds } = body

    if (!title || !content) {
      return NextResponse.json(
        { error: 'Title and content are required' },
        { status: 400 }
      )
    }

    // Get all users who opted in to newsletter
    const { data: preferences, error: prefsError } = await supabase
      .from('notification_preferences')
      .select('user_id')
      .eq('newsletter', true)

    if (prefsError) {
      console.error('Error fetching preferences:', prefsError)
      return NextResponse.json(
        { error: 'Failed to fetch preferences' },
        { status: 500 }
      )
    }

    if (!preferences || preferences.length === 0) {
      return NextResponse.json(
        {
          success: true,
          message: 'No users with newsletter enabled',
          sent: 0,
        },
        { status: 200 }
      )
    }

    const userIds = preferences.map((p: any) => p.user_id)

    // Get user emails
    const { data: users, error: usersError } = await supabase
      .from('users')
      .select('user_id, user_name, email')
      .in('user_id', userIds)

    if (usersError) {
      console.error('Error fetching users:', usersError)
      return NextResponse.json(
        { error: 'Failed to fetch users' },
        { status: 500 }
      )
    }

    if (!users || users.length === 0) {
      return NextResponse.json(
        {
          success: true,
          message: 'No users with newsletter enabled',
          sent: 0,
        },
        { status: 200 }
      )
    }

    const transporter = createTransporter()
    let successCount = 0
    let failureCount = 0

    // Send newsletter to each user
    for (const user of users) {
      try {
        // Build featured builds section if provided
        let featuredSection = ''
        if (featuredBuilds && Array.isArray(featuredBuilds) && featuredBuilds.length > 0) {
          featuredSection = `
            <div>
              <div class="section-title">Featured Builds</div>
              ${featuredBuilds
                .slice(0, 3)
                .map(
                  (build: any) => `
                <div class="build-card">
                  <div class="build-name">${build.name}</div>
                  <div class="build-creator">by ${build.createdBy}</div>
                  <div class="build-description">${build.description}</div>
                  <a href="${process.env.NEXT_PUBLIC_APP_URL || 'https://buildmate.com'}/builds/${build.id}" class="build-link">View Build →</a>
                </div>
              `
                )
                .join('')}
            </div>
          `
        }

        const emailHtml = `
          <!DOCTYPE html>
          <html>
            <head>
              <meta charset="UTF-8">
              <style>
                * { margin: 0; padding: 0; box-sizing: border-box; }
                body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif; line-height: 1.6; color: #333333; background-color: #f5f5f5; }
                .wrapper { background-color: #f5f5f5; padding: 20px; }
                .container { max-width: 600px; margin: 0 auto; background-color: #ffffff; }
                .header { background: linear-gradient(135deg, #8b5cf6 0%, #7c3aed 100%); padding: 40px 20px; text-align: center; }
                .header h1 { color: #ffffff; margin: 0; font-size: 32px; font-weight: bold; letter-spacing: 2px; }
                .header p { color: #ede9fe; margin: 8px 0 0 0; font-size: 14px; font-weight: 400; }
                .content { padding: 40px; }
                .greeting { font-size: 18px; font-weight: 600; color: #1a1a1a; margin-bottom: 15px; }
                .message { font-size: 15px; color: #555555; line-height: 1.8; margin-bottom: 25px; }
                .section-title { font-size: 16px; font-weight: 700; color: #1a1a1a; margin: 30px 0 15px 0; padding-bottom: 8px; border-bottom: 2px solid #8b5cf6; }
                .build-card { background-color: #f9f5ff; border: 1px solid #e9d5ff; padding: 16px; margin: 12px 0; border-radius: 6px; }
                .build-name { font-size: 15px; font-weight: 600; color: #7c3aed; margin-bottom: 6px; }
                .build-creator { font-size: 12px; color: #999999; margin-bottom: 8px; }
                .build-description { font-size: 13px; color: #555555; line-height: 1.6; margin-bottom: 10px; }
                .build-link { color: #7c3aed; text-decoration: none; font-weight: 600; font-size: 13px; }
                .build-link:hover { text-decoration: underline; }
                .tip-box { background-color: #fff8e6; border-left: 4px solid #f59e0b; padding: 16px; margin: 25px 0; }
                .tip-title { font-weight: 600; color: #d97706; font-size: 14px; margin-bottom: 8px; }
                .tip-text { font-size: 13px; color: #92400e; line-height: 1.6; }
                .footer { padding: 30px 40px; border-top: 1px solid #eeeeee; text-align: center; }
                .footer-text { font-size: 12px; color: #999999; margin: 8px 0; }
                .footer-link { color: #7c3aed; text-decoration: none; }
                .footer-link:hover { text-decoration: underline; }
              </style>
            </head>
            <body>
              <div class="wrapper">
                <div class="container">
                  <div class="header">
                    <h1>BUILDMATE</h1>
                    <p>📰 Monthly Newsletter</p>
                  </div>
                  
                  <div class="content">
                    <div class="greeting">Hello ${user.user_name},</div>
                    <div class="message">${content}</div>
                    
                    ${featuredSection}
                    
                    <div class="tip-box">
                      <div class="tip-title">💡 Pro Tip</div>
                      <div class="tip-text">Save multiple builds and compare them side-by-side to find the perfect configuration for your needs. Explore featured builds from our community for inspiration!</div>
                    </div>
                  </div>
                  
                  <div class="footer">
                    <div class="footer-text">This is an automated email from BUILDMATE. Please do not reply to this email.</div>
                    <div class="footer-text"><a href="${process.env.NEXT_PUBLIC_APP_URL || 'https://buildmate.com'}/settings" class="footer-link">Manage preferences</a> | <a href="${process.env.NEXT_PUBLIC_APP_URL || 'https://buildmate.com'}" class="footer-link">Visit BUILDMATE</a></div>
                    <div class="footer-text">© 2026 BUILDMATE. All rights reserved.</div>
                  </div>
                </div>
              </div>
            </body>
          </html>
        `

        await transporter.sendMail({
          from: process.env.SMTP_FROM_EMAIL || 'BUILDMATE <noreply@buildmate.com>',
          to: user.email,
          subject: title,
          html: emailHtml,
        })

        successCount++
        console.log(`✅ Newsletter sent to ${user.email}`)
      } catch (emailError) {
        failureCount++
        console.error(`❌ Failed to send newsletter to ${user.email}:`, emailError)
      }
    }

    return NextResponse.json(
      {
        success: true,
        message: `Newsletter sent to ${successCount} users (${failureCount} failures)`,
        sent: successCount,
        failed: failureCount,
      },
      { status: 200 }
    )
  } catch (error) {
    console.error('Send newsletter error:', error)
    return NextResponse.json(
      { error: error instanceof Error ? error.message : 'Failed to send newsletter' },
      { status: 500 }
    )
  }
}