import { NextRequest, NextResponse } from 'next/server'
import { createServerSupabaseClient } from '@/lib/supabase'

export async function POST(request: NextRequest) {
  try {
    const { userId, tier } = await request.json()
    
    if (!userId || !tier) {
      return NextResponse.json({ error: 'Missing required fields' }, { status: 400 })
    }

    const supabase = createServerSupabaseClient()

    // Get user's subscription to determine limits (handle free tier users)
    const { data: subscriptionData, error: subscriptionError } = await supabase
      .from('subscriptions')
      .select('price_id, status')
      .eq('user_id', userId)
      .eq('status', 'active')
      .order('created_at', { ascending: false })
      .limit(1)

    if (subscriptionError) {
      console.error('Error getting subscription:', subscriptionError)
      // Continue with free tier limits if subscription query fails
    }

    // Get the first subscription or null if none exists
    const subscription = subscriptionData && subscriptionData.length > 0 ? subscriptionData[0] : null

    // Default to free tier limits
    const { PRICING_TIERS } = await import('@/lib/stripe')
        let limit = tier === 'smart'
      ? PRICING_TIERS.FREE.maxSmartPrompts
      : (PRICING_TIERS.FREE.hasUnlimitedFastPrompts ? 999999 : PRICING_TIERS.FREE.maxFastPrompts)

    // Set limits based on subscription
    if (subscription?.price_id) {
      const { getPlanByPriceId } = await import('@/lib/stripe')
      const plan = getPlanByPriceId(subscription.price_id)
      
      if (plan) {
        limit = tier === 'smart'
          ? plan.maxSmartPrompts
          : (plan.hasUnlimitedFastPrompts ? 999999 : plan.maxFastPrompts)
      }
    }

    // Query user_usage table directly for real-time accuracy
    const { data: usageRecords, error } = await supabase
      .from('user_usage')
      .select('*')
      .eq('user_id', userId)
      .order('updated_at', { ascending: false })
      .limit(1)

    if (error) {
      console.error('Error checking usage limit:', error)
      return NextResponse.json({ error: 'Failed to check usage limit' }, { status: 500 })
    }

    const currentUsageRecord = usageRecords?.[0] || null
    
    // Get current usage for the specific tier
    const currentUsage = currentUsageRecord 
      ? (tier === 'smart' ? currentUsageRecord.smart_prompts_used : currentUsageRecord.fast_prompts_used)
      : 0

    // Return usage info and whether request can proceed
    const result = {
      can_proceed: currentUsage < limit || limit === 0,
      current_usage: currentUsage,
      limit: limit,
      remaining: Math.max(0, limit - currentUsage)
    }

    return NextResponse.json(result)

  } catch (error) {
    console.error('Error in usage limit check:', error)
    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
  }
}