import type { NextApiRequest, NextApiResponse } from 'next'
import { db, schema } from '../../../lib/db/connection'
import { eq, and, gte, count } from 'drizzle-orm'

interface DashboardStats {
  total_sources: number
  pending_sources: number
  pending_reports: number
  high_risk_sources: number
  sources_added_week: number
  reports_today: number
}

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse<DashboardStats | { error: string }>
) {
  if (req.method !== 'GET') {
    return res.status(405).json({ error: 'Method not allowed' })
  }

  try {
    // Get all stats in parallel
    const weekAgo = new Date()
    weekAgo.setDate(weekAgo.getDate() - 7)
    
    const dayAgo = new Date()
    dayAgo.setDate(dayAgo.getDate() - 1)
    
    const [
      totalSources,
      pendingSources,
      pendingReports,
      highRiskSources,
      sourcesAddedWeek,
      reportsToday
    ] = await Promise.all([
      db.select({ count: count() })
        .from(schema.sources)
        .where(eq(schema.sources.status, 'verified')),
      
      db.select({ count: count() })
        .from(schema.sources)
        .where(eq(schema.sources.status, 'pending')),
      
      db.select({ count: count() })
        .from(schema.reports)
        .where(eq(schema.reports.status, 'pending')),
      
      db.select({ count: count() })
        .from(schema.sources)
        .where(
          and(
            eq(schema.sources.status, 'verified'),
            gte(schema.sources.riskLevel, 4)
          )
        ),
      
      db.select({ count: count() })
        .from(schema.sources)
        .where(gte(schema.sources.createdAt, weekAgo)),
      
      db.select({ count: count() })
        .from(schema.reports)
        .where(gte(schema.reports.createdAt, dayAgo))
    ])
    
    const stats: DashboardStats = {
      total_sources: totalSources[0].count,
      pending_sources: pendingSources[0].count,
      pending_reports: pendingReports[0].count,
      high_risk_sources: highRiskSources[0].count,
      sources_added_week: sourcesAddedWeek[0].count,
      reports_today: reportsToday[0].count
    }

    return res.status(200).json(stats)

  } catch (error) {
    console.error('Database error:', error)
    return res.status(500).json({ error: 'Internal server error' })
  }
}