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'

/**
 * GET /api/clusters
 * Get all clusters for the current user.
 */
export async function GET(request: NextRequest) {
  try {
    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const userId = session.user.id

    // Check for cached results
    const cached = await clusteringService.getCachedClusters(userId)
    if (cached) {
      return NextResponse.json({
        clusters: cached,
        cached: true,
        totalNotes: cached.reduce((sum, c) => sum + c.noteIds.length, 0)
      })
    }

    // No cached results, check if user has enough notes
    const notesCount = await prisma.note.count({
      where: { userId, trashedAt: null }
    })

    if (notesCount < 10) {
      return NextResponse.json({
        clusters: [],
        message: 'Need at least 10 notes to generate clusters',
        totalNotes: notesCount
      })
    }

    // Trigger background recalculation
    return NextResponse.json({
      clusters: [],
      message: 'Calculating clusters... Please check back later',
      totalNotes: notesCount
    })
  } catch (error) {
    console.error('Error fetching clusters:', error)
    return NextResponse.json(
      { error: 'Failed to fetch clusters' },
      { status: 500 }
    )
  }
}

/**
 * POST /api/clusters/recalculate
 * Trigger a full recalculation of clusters and bridge notes.
 */
export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const userId = session.user.id
    const body = await request.json()
    const force = body.force === true

    // Check if recalculation is needed
    const shouldRecalc = force || await clusteringService.shouldRecalculate(userId)

    if (!shouldRecalc) {
      const cached = await clusteringService.getCachedClusters(userId)
      if (cached) {
        return NextResponse.json({
          clusters: cached,
          cached: true,
          message: 'Using cached results (data has not changed significantly)'
        })
      }
    }

    // Perform clustering
    const results = await clusteringService.clusterNotes(userId)

    if (results.clusters.length === 0) {
      return NextResponse.json({
        clusters: [],
        message: 'Could not generate clusters. Need more diverse notes.',
        noiseCount: results.noiseCount
      })
    }

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

    // Save results
    await clusteringService.saveClusteringResults(userId, results)

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

    return NextResponse.json({
      clusters: results.clusters,
      bridgeNotes: bridgeNotes.slice(0, 10), // Return top 10
      totalNotes: results.clusters.reduce((sum, c) => sum + c.noteIds.length, 0) + results.noiseCount,
      noiseCount: results.noiseCount,
      message: `Generated ${results.clusters.length} clusters`
    })
  } catch (error) {
    console.error('Error recalculating clusters:', error)
    return NextResponse.json(
      { error: 'Failed to recalculate clusters' },
      { status: 500 }
    )
  }
}