import { NextRequest, NextResponse } from 'next/server'
import { prisma } from '@/lib/db'
import { getSession } from '@/lib/auth'
import { sendEmail, getSmtpConfig } from '@/lib/email'
import { z } from 'zod'

const upgradeSchema = z.object({
  requestedPlan: z.enum(['PRO']),
  message: z.string().max(1000).optional(),
})

// GET: List upgrade requests for current tenant (TENANT_ADMIN) or all (SERVER_ADMIN)
export async function GET() {
  try {
    const user = await getSession()
    if (!user) return NextResponse.json({ error: 'Nicht autorisiert' }, { status: 401 })

    let where: any = {}
    if (user.role === 'SERVER_ADMIN') {
      // Server admin sees all
    } else if (user.role === 'TENANT_ADMIN' && user.tenantId) {
      where = { tenantId: user.tenantId }
    } else {
      return NextResponse.json({ error: 'Keine Berechtigung' }, { status: 403 })
    }

    const requests = await (prisma as any).upgradeRequest.findMany({
      where,
      include: {
        tenant: { select: { name: true, slug: true, plan: true, subscriptionStatus: true } },
        requestedBy: { select: { name: true, email: true } },
      },
      orderBy: { createdAt: 'desc' },
    })

    return NextResponse.json({ requests })
  } catch (error) {
    console.error('Error fetching upgrade requests:', error)
    return NextResponse.json({ error: 'Serverfehler' }, { status: 500 })
  }
}

// POST: Create a new upgrade request (TENANT_ADMIN only)
export async function POST(req: NextRequest) {
  try {
    const user = await getSession()
    if (!user) return NextResponse.json({ error: 'Nicht autorisiert' }, { status: 401 })
    if (user.role !== 'TENANT_ADMIN' || !user.tenantId) {
      return NextResponse.json({ error: 'Nur Mandanten-Administratoren können Upgrades anfordern' }, { status: 403 })
    }

    const body = await req.json()
    const validated = upgradeSchema.safeParse(body)
    if (!validated.success) {
      return NextResponse.json({ error: 'Ungültige Eingabe', details: validated.error.flatten() }, { status: 400 })
    }

    // Get current tenant
    const tenant = await (prisma as any).tenant.findUnique({
      where: { id: user.tenantId },
      select: { id: true, name: true, plan: true, contactEmail: true },
    })
    if (!tenant) {
      return NextResponse.json({ error: 'Mandant nicht gefunden' }, { status: 404 })
    }

    // Check for existing pending request
    const existingPending = await (prisma as any).upgradeRequest.findFirst({
      where: { tenantId: user.tenantId, status: 'PENDING' },
    })
    if (existingPending) {
      return NextResponse.json({
        error: 'Es gibt bereits eine offene Upgrade-Anfrage. Bitte warten Sie auf die Bearbeitung.',
      }, { status: 409 })
    }

    // Don't allow "downgrade" requests or same plan
    const planOrder = { FREE: 0, PRO: 1 }
    if ((planOrder[validated.data.requestedPlan as keyof typeof planOrder] || 0) <= (planOrder[tenant.plan as keyof typeof planOrder] || 0)) {
      return NextResponse.json({ error: 'Der gewählte Plan ist kein Upgrade gegenüber dem aktuellen Plan.' }, { status: 400 })
    }

    // Create request
    const request = await (prisma as any).upgradeRequest.create({
      data: {
        tenantId: user.tenantId,
        requestedById: user.id,
        requestedPlan: validated.data.requestedPlan,
        currentPlan: tenant.plan,
        message: validated.data.message || null,
      },
      include: {
        tenant: { select: { name: true } },
        requestedBy: { select: { name: true, email: true } },
      },
    })

    // Send emails
    const smtpConfig = await getSmtpConfig()
    if (smtpConfig) {
      const planLabels: Record<string, string> = {
        FREE: 'Free', PRO: 'Pro',
      }

      // 1. Confirmation to tenant admin
      try {
        await sendEmail(
          user.email,
          `Upgrade-Anfrage bestätigt — ${planLabels[validated.data.requestedPlan]}`,
          `
          <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 520px; margin: 0 auto;">
            <div style="background: #2563eb; color: white; padding: 16px 24px; border-radius: 8px 8px 0 0;">
              <h2 style="margin: 0; font-size: 18px;">Upgrade-Anfrage eingegangen</h2>
            </div>
            <div style="border: 1px solid #e5e7eb; border-top: none; padding: 24px; border-radius: 0 0 8px 8px;">
              <p style="margin: 0 0 16px; line-height: 1.6; color: #374151;">
                Ihre Upgrade-Anfrage für <strong>${tenant.name}</strong> wurde erfolgreich übermittelt.
              </p>
              <table style="width: 100%; border-collapse: collapse; margin: 16px 0;">
                <tr>
                  <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Aktueller Plan</td>
                  <td style="padding: 8px 0; font-weight: 600; text-align: right;">${planLabels[tenant.plan] || tenant.plan}</td>
                </tr>
                <tr>
                  <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Gewünschter Plan</td>
                  <td style="padding: 8px 0; font-weight: 600; text-align: right; color: #2563eb;">${planLabels[validated.data.requestedPlan]}</td>
                </tr>
                <tr>
                  <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Status</td>
                  <td style="padding: 8px 0; font-weight: 600; text-align: right;">
                    <span style="background: #fef3c7; color: #92400e; padding: 2px 8px; border-radius: 4px; font-size: 12px;">Wird geprüft</span>
                  </td>
                </tr>
              </table>
              ${validated.data.message ? `<p style="margin: 16px 0 0; padding: 12px; background: #f9fafb; border-radius: 6px; font-size: 14px; color: #374151;"><strong>Ihre Nachricht:</strong><br/>${validated.data.message.replace(/\n/g, '<br/>')}</p>` : ''}
              <p style="margin: 16px 0 0; font-size: 13px; color: #6b7280;">
                Wir werden Ihre Anfrage so schnell wie möglich bearbeiten. Sie erhalten eine Benachrichtigung, sobald Ihr Plan aktiviert wurde.
              </p>
              <hr style="border: none; border-top: 1px solid #e5e7eb; margin: 20px 0;" />
              <p style="margin: 0; font-size: 12px; color: #9ca3af;">Lageplan — Digitale Lagepläne für die Feuerwehr</p>
            </div>
          </div>
          `
        )
      } catch (e) {
        console.error('Failed to send upgrade confirmation email:', e)
      }

      // 2. Notification to all server admins
      try {
        const serverAdmins = await (prisma as any).user.findMany({
          where: { role: 'SERVER_ADMIN' },
          select: { email: true, name: true },
        })
        for (const admin of serverAdmins) {
          await sendEmail(
            admin.email,
            `Neue Upgrade-Anfrage: ${tenant.name} → ${planLabels[validated.data.requestedPlan]}`,
            `
            <div style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; max-width: 520px; margin: 0 auto;">
              <div style="background: #dc2626; color: white; padding: 16px 24px; border-radius: 8px 8px 0 0;">
                <h2 style="margin: 0; font-size: 18px;">Neue Upgrade-Anfrage</h2>
              </div>
              <div style="border: 1px solid #e5e7eb; border-top: none; padding: 24px; border-radius: 0 0 8px 8px;">
                <table style="width: 100%; border-collapse: collapse; margin: 0 0 16px;">
                  <tr>
                    <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Organisation</td>
                    <td style="padding: 8px 0; font-weight: 600; text-align: right;">${tenant.name}</td>
                  </tr>
                  <tr>
                    <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Angefragt von</td>
                    <td style="padding: 8px 0; font-weight: 600; text-align: right;">${user.name} (${user.email})</td>
                  </tr>
                  <tr>
                    <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Aktueller Plan</td>
                    <td style="padding: 8px 0; text-align: right;">${planLabels[tenant.plan] || tenant.plan}</td>
                  </tr>
                  <tr>
                    <td style="padding: 8px 0; color: #6b7280; font-size: 14px;">Gewünschter Plan</td>
                    <td style="padding: 8px 0; font-weight: 600; text-align: right; color: #2563eb;">${planLabels[validated.data.requestedPlan]}</td>
                  </tr>
                </table>
                ${validated.data.message ? `<p style="margin: 0 0 16px; padding: 12px; background: #f9fafb; border-radius: 6px; font-size: 14px; color: #374151;"><strong>Nachricht:</strong><br/>${validated.data.message.replace(/\n/g, '<br/>')}</p>` : ''}
                <p style="margin: 0; font-size: 13px; color: #6b7280;">
                  Bitte prüfen und bestätigen Sie die Anfrage im Admin-Panel unter "Upgrade-Anfragen".
                </p>
                <hr style="border: none; border-top: 1px solid #e5e7eb; margin: 20px 0;" />
                <p style="margin: 0; font-size: 12px; color: #9ca3af;">Lageplan — Automatische Benachrichtigung</p>
              </div>
            </div>
            `
          )
        }
      } catch (e) {
        console.error('Failed to send admin notification email:', e)
      }
    }

    return NextResponse.json({ request }, { status: 201 })
  } catch (error) {
    console.error('Error creating upgrade request:', error)
    return NextResponse.json({ error: 'Serverfehler' }, { status: 500 })
  }
}