import { createClient } from '@/lib/supabase/server'
import { NextResponse } from 'next/server'
import { validatePeriodDuration } from '@/lib/bookkeeping/validate-period-duration'
import { validateBody } from '@/lib/api/validate'
import { CreateFiscalPeriodSchema } from '@/lib/api/schemas'

export async function GET() {
  const supabase = await createClient()
  const { data: { user } } = await supabase.auth.getUser()

  if (!user) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const { data, error } = await supabase
    .from('fiscal_periods')
    .select('*')
    .eq('user_id', user.id)
    .order('period_start', { ascending: false })

  if (error) {
    return NextResponse.json({ error: error.message }, { status: 500 })
  }

  return NextResponse.json({ data })
}

export async function POST(request: Request) {
  const supabase = await createClient()
  const { data: { user } } = await supabase.auth.getUser()

  if (!user) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  const validation = await validateBody(request, CreateFiscalPeriodSchema)
  if (!validation.success) return validation.response
  const body = validation.data

  // Validate period duration (max 18 months per BFL 3 kap.)
  const durationError = validatePeriodDuration(body.period_start, body.period_end)
  if (durationError) {
    return NextResponse.json({ error: durationError }, { status: 400 })
  }

  // Check for overlapping periods
  const { data: overlapping } = await supabase
    .from('fiscal_periods')
    .select('id, name')
    .eq('user_id', user.id)
    .lte('period_start', body.period_end)
    .gte('period_end', body.period_start)
    .limit(1)

  if (overlapping && overlapping.length > 0) {
    return NextResponse.json(
      { error: `Overlaps with existing period: ${overlapping[0].name}` },
      { status: 409 }
    )
  }

  const { data, error } = await supabase
    .from('fiscal_periods')
    .insert({
      user_id: user.id,
      name: body.name,
      period_start: body.period_start,
      period_end: body.period_end,
    })
    .select()
    .single()

  if (error) {
    return NextResponse.json({ error: error.message }, { status: 500 })
  }

  return NextResponse.json({ data })
}