import { NextResponse } from 'next/server'
import { ensureInitialized } from '@/lib/init'
import { withRouteContext } from '@/lib/api/with-route-context'
import { generateKU10Xml } from '@/lib/salary/ku/ku10-generator'
import type { KU10EmployeeData, KU10CompanyData } from '@/lib/salary/ku/ku10-generator'
import { getErrorMessage as getUserErrorMessage } from '@/lib/errors/get-error-message'

ensureInitialized()

/**
 * Generate KU10 (Kontrolluppgift) XML for a calendar year.
 *
 * Per Skatteförfarandelagen 15 kap: Must be filed by January 31 of the
 * following year. Reports total annual income, tax, and benefits per employee.
 *
 * The XML is räkenskapsinformation per BFL 7 kap, 7-year retention.
 */
export const GET = withRouteContext<{ params: Promise<{ year: string }> }>(
  'salary.ku.export',
  async (request, { supabase, companyId, user }, { params }) => {
    const { year } = await params
    const yearNum = parseInt(year)

    if (isNaN(yearNum) || yearNum < 2020 || yearNum > 2100) {
      return NextResponse.json({ error: 'Ogiltigt år' }, { status: 400 })
    }

    // Load company
    const { data: company } = await supabase
      .from('companies')
      .select('name, org_number')
      .eq('id', companyId)
      .single()

    if (!company) return NextResponse.json({ error: 'Företag hittades inte' }, { status: 404 })

    const { data: settings } = await supabase
      .from('company_settings')
      .select('company_name, org_number, phone, email')
      .eq('company_id', companyId)
      .single()

    const { data: profile } = await supabase
      .from('profiles')
      .select('full_name, email')
      .eq('id', user.id)
      .single()

    // Load all booked salary run employees for the year, grouped by employee
    const { data: runEmployees, error } = await supabase
      .from('salary_run_employees')
      .select(`
        employee_id, gross_salary, tax_withheld, tax_withheld_override,
        avgifter_basis, avgifter_basis_override,
        employee:employees(personnummer, specification_number, employment_start, employment_end),
        salary_run:salary_runs!inner(period_year, status),
        line_items:salary_line_items(item_type, amount)
      `)
      .eq('company_id', companyId)

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

    // Filter to booked runs for the year
    const bookedForYear = (runEmployees || []).filter(sre => {
      const run = sre.salary_run as unknown as { period_year: number; status: string } | null
      return run && run.period_year === yearNum && run.status === 'booked'
    })

    // Aggregate per employee
    const byEmployee = new Map<string, {
      personnummer: string
      specificationNumber: number
      employmentStart: string | null
      employmentEnd: string | null
      totalGross: number
      totalTax: number
      totalAvgifterBasis: number
      benefitCar: number
      benefitHousing: number
      benefitMeals: number
      benefitOther: number
    }>()

    for (const sre of bookedForYear) {
      const emp = sre.employee as unknown as { personnummer: string; specification_number: number; employment_start: string; employment_end: string | null } | null
      if (!emp) continue

      const current = byEmployee.get(sre.employee_id) || {
        personnummer: emp.personnummer,
        specificationNumber: emp.specification_number,
        employmentStart: emp.employment_start,
        employmentEnd: emp.employment_end,
        totalGross: 0, totalTax: 0, totalAvgifterBasis: 0,
        benefitCar: 0, benefitHousing: 0, benefitMeals: 0, benefitOther: 0,
      }

      current.totalGross += sre.gross_salary
      // Honor advanced-mode override so KU matches AGI + the ledger.
      current.totalTax += sre.tax_withheld_override ?? sre.tax_withheld
      current.totalAvgifterBasis += sre.avgifter_basis_override ?? sre.avgifter_basis

      // Sum benefits by type from line items
      const lineItems = (sre.line_items || []) as Array<{ item_type: string; amount: number }>
      for (const li of lineItems) {
        if (li.item_type === 'benefit_car') current.benefitCar += li.amount
        else if (li.item_type === 'benefit_housing') current.benefitHousing += li.amount
        else if (li.item_type === 'benefit_meals') current.benefitMeals += li.amount
        else if (['benefit_wellness', 'benefit_other'].includes(li.item_type)) current.benefitOther += li.amount
      }

      byEmployee.set(sre.employee_id, current)
    }

    if (byEmployee.size === 0) {
      return NextResponse.json({ error: `Inga bokförda lönekörningar för ${yearNum}` }, { status: 404 })
    }

    // Employer name on the KU10 follows the current company name
    // (company_settings.company_name), not the frozen onboarding companies.name.
    const companyName = settings?.company_name || company.name
    const companyData: KU10CompanyData = {
      orgNumber: (settings?.org_number || company.org_number || '').trim(),
      companyName,
      year: yearNum,
      contactName: (profile?.full_name || companyName || '').trim(),
      contactPhone: (settings?.phone || '').trim(),
      contactEmail: (settings?.email || profile?.email || user.email || '').trim(),
    }

    const r = (x: number) => Math.round(x * 100) / 100
    const employeeData: KU10EmployeeData[] = Array.from(byEmployee.values()).map(emp => ({
      personnummer: emp.personnummer,
      specificationNumber: emp.specificationNumber,
      totalGross: r(emp.totalGross),
      totalTax: r(emp.totalTax),
      totalAvgifterBasis: r(emp.totalAvgifterBasis),
      benefitCar: emp.benefitCar > 0 ? r(emp.benefitCar) : undefined,
      benefitHousing: emp.benefitHousing > 0 ? r(emp.benefitHousing) : undefined,
      benefitMeals: emp.benefitMeals > 0 ? r(emp.benefitMeals) : undefined,
      benefitOther: emp.benefitOther > 0 ? r(emp.benefitOther) : undefined,
      employmentStart: emp.employmentStart || undefined,
      employmentEnd: emp.employmentEnd || undefined,
    }))

    const xml = generateKU10Xml(companyData, employeeData)

    return new Response(xml, {
      headers: {
        'Content-Type': 'application/xml; charset=utf-8',
        'Content-Disposition': `attachment; filename="KU10_${company.org_number}_${yearNum}.xml"`,
      },
    })
  },
)