import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@/auth'
import prisma from '@/lib/prisma'
import { clusteringService } from '@/lib/ai/services/clustering.service'
import { bridgeNotesService } from '@/lib/ai/services/bridge-notes.service'

/**
 * Cron endpoint for automatic cluster recalculation.
 *
 * This endpoint is designed to be called by a cron job or scheduler.
 * It processes users who need cluster updates based on:
 * 1. Data change percentage (> 5%)
 * 2. Time since last calculation (> 24 hours)
 *
 * GET /api/cron/clusters?secret=CRON_SECRET
 *
 * The secret parameter must match the environment variable CRON_SECRET.
 */
export async function GET(request: NextRequest) {
  try {
    // Verify cron secret
    const { searchParams } = new URL(request.url)
    const secret = searchParams.get('secret')

    if (secret !== process.env.CRON_SECRET) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    // Find users who need recalculation
    // Users who either:
    // 1. Have no clusters calculated yet
    // 2. Have data changes > 5% since last calculation
    // 3. Haven't had calculations in > 24 hours

    const oneDayAgo = new Date(Date.now() - 24 * 60 * 60 * 1000)

    const usersToProcess = await prisma.user.findMany({
      where: {
        // Only active users
        OR: [
          // Users who never had clusters calculated
          {
            noteClusters: {
              none: {}
            }
          },
          // Users with stale cluster data
          {
            noteClusters: {
              some: {
                lastCalculated: {
                  lt: oneDayAgo
                }
              }
            }
          }
        ]
      },
      select: {
        id: true,
        email: true
      },
      take: 50 // Process up to 50 users per run
    })

    const results = {
      processed: 0,
      skipped: 0,
      errors: 0,
      details: [] as Array<{ userId: string; clusters: number; bridges: number; error?: string }>
    }

    for (const user of usersToProcess) {
      try {
        // Check if recalculation is needed based on data change
        const shouldRecalc = await clusteringService.shouldRecalculate(user.id)

        if (!shouldRecalc) {
          results.skipped++
          continue
        }

        // Perform clustering
        const clusterResults = await clusteringService.clusterNotes(user.id)

        if (clusterResults.clusters.length === 0) {
          results.details.push({
            userId: user.id,
            clusters: 0,
            bridges: 0,
            error: 'Could not generate clusters'
          })
          continue
        }

        // Generate cluster names
        for (const cluster of clusterResults.clusters) {
          cluster.name = await clusteringService.generateClusterName(cluster.clusterId, user.id)
        }

        // Save results
        await clusteringService.saveClusteringResults(user.id, clusterResults)

        // Detect and save bridge notes
        const bridgeNotes = await bridgeNotesService.detectBridgeNotes(user.id)
        await bridgeNotesService.saveBridgeNotes(user.id, bridgeNotes)

        results.processed++
        results.details.push({
          userId: user.id,
          clusters: clusterResults.clusters.length,
          bridges: bridgeNotes.length
        })
      } catch (error) {
        console.error(`Error processing user ${user.id}:`, error)
        results.errors++
        results.details.push({
          userId: user.id,
          clusters: 0,
          bridges: 0,
          error: error instanceof Error ? error.message : 'Unknown error'
        })
      }
    }

    return NextResponse.json({
      success: true,
      ...results,
      message: `Processed ${results.processed} users, skipped ${results.skipped}, ${results.errors} errors`
    })
  } catch (error) {
    console.error('Error in cluster cron job:', error)
    return NextResponse.json(
      { error: 'Cron job failed', details: error instanceof Error ? error.message : 'Unknown error' },
      { status: 500 }
    )
  }
}

/**
 * POST /api/cron/clusters
 * Manual trigger for cluster recalculation (admin only).
 * Requires admin authentication.
 */
export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    // Check if user is admin
    const user = await prisma.user.findUnique({
      where: { id: session.user.id },
      select: { role: true }
    })

    if (user?.role !== 'ADMIN') {
      return NextResponse.json({ error: 'Forbidden' }, { status: 403 })
    }

    const body = await request.json()
    const { userId, forceAll } = body

    if (userId) {
      // Process specific user
      const clusterResults = await clusteringService.clusterNotes(userId)
      const bridgeNotes = await bridgeNotesService.detectBridgeNotes(userId)

      await clusteringService.saveClusteringResults(userId, clusterResults)
      await bridgeNotesService.saveBridgeNotes(userId, bridgeNotes)

      return NextResponse.json({
        success: true,
        userId,
        clusters: clusterResults.clusters.length,
        bridges: bridgeNotes.length
      })
    }

    if (forceAll) {
      // Process all users (use with caution)
      const users = await prisma.user.findMany({
        select: { id: true },
        take: 100 // Limit to 100 users per request
      })

      const results = {
        processed: 0,
        errors: 0
      }

      for (const user of users) {
        try {
          const clusterResults = await clusteringService.clusterNotes(user.id)
          const bridgeNotes = await bridgeNotesService.detectBridgeNotes(user.id)

          await clusteringService.saveClusteringResults(user.id, clusterResults)
          await bridgeNotesService.saveBridgeNotes(user.id, bridgeNotes)

          results.processed++
        } catch {
          results.errors++
        }
      }

      return NextResponse.json({
        success: true,
        ...results
      })
    }

    return NextResponse.json(
      { error: 'Must provide userId or forceAll=true' },
      { status: 400 }
    )
  } catch (error) {
    console.error('Error in manual cluster trigger:', error)
    return NextResponse.json(
      { error: 'Failed to trigger recalculation' },
      { status: 500 }
    )
  }
}