'use client'

import { useState } from 'react'
import Link from 'next/link'
import { useRouter } from 'next/navigation'
import { useTranslations } from 'next-intl'
import { Badge } from '@/components/ui/badge'
import { Button } from '@/components/ui/button'
import { Input } from '@/components/ui/input'
import { DetailSection } from '@/components/ui/detail-section'
import { TH_CLASS, TD_CLASS } from '@/components/ui/dry-table'
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select'
import { FileDown, Loader2, Trash2 } from 'lucide-react'
import { cn, formatCurrency } from '@/lib/utils'
import { roundOre } from '@/lib/money'
import type { EmployeeMasked, SalaryRunEmployee } from '@/types'
import { periodLabelOf, type RunDetail } from './types'

type SreWithEmployee = SalaryRunEmployee & {
  employee?: {
    first_name: string
    last_name: string
    // The run detail endpoint returns the masked display form under this key;
    // the encrypted `personnummer` column never reaches the client.
    personnummer_masked: string
    default_dimensions?: Record<string, string>
  }
}

interface RunEmployeesTableProps {
  run: RunDetail
  runId: string
  employees: SalaryRunEmployee[]
  availableEmployees: EmployeeMasked[]
  canWrite: boolean
  actionLoading: string | null
  dimensionsEnabled: boolean
  isCalculated: boolean
  onAddEmployee: (employeeId: string) => void
  onRemoveEmployee: (employeeId: string, name: string) => void
  onSalaryEdit: (employeeId: string, raw: string, previous: number) => void
}

export function RunEmployeesTable({
  run,
  runId,
  employees,
  availableEmployees,
  canWrite,
  actionLoading,
  dimensionsEnabled,
  isCalculated,
  onAddEmployee,
  onRemoveEmployee,
  onSalaryEdit,
}: RunEmployeesTableProps) {
  const t = useTranslations('salary_run')
  const router = useRouter()
  const [addEmployeeKey, setAddEmployeeKey] = useState(0)

  const addedEmployeeIds = new Set(employees.map(e => e.employee_id))
  const notAdded = availableEmployees.filter(e => !addedEmployeeIds.has(e.id))
  const canRemoveEmployee = run.status === 'draft' && canWrite
  const isDraft = run.status === 'draft'

  // Δ vs the latest booked run: hidden on the first-ever run and before
  // calculation (gross is 0 until then, the diff would be noise).
  const previous = run.previous_run ?? null
  const showDiff = previous != null && isCalculated

  function diffNode(sre: SalaryRunEmployee) {
    if (!previous) return null
    const prev = previous.by_employee[sre.employee_id]
    if (!prev) {
      // A new employee is the exception worth a chip; a plain delta is text.
      return (
        <Badge variant="secondary" className="font-normal">
          {t('diff_new_employee')}
        </Badge>
      )
    }
    const delta = roundOre(sre.gross_salary - prev.gross)
    if (delta === 0) return null
    const sign = delta > 0 ? '+' : '−'
    return (
      <span className="text-xs text-muted-foreground tabular-nums">
        {sign}
        {formatCurrency(Math.abs(delta))}
      </span>
    )
  }

  const numericTh = cn(TH_CLASS, 'text-right')
  const numericTd = cn(TD_CLASS, 'text-right tabular-nums')

  return (
    <DetailSection
      kicker={t('employees_title', { count: employees.length })}
      aside={
        isDraft && canWrite && notAdded.length > 0 ? (
          <Select
            key={addEmployeeKey}
            onValueChange={value => {
              onAddEmployee(value)
              setAddEmployeeKey(k => k + 1)
            }}
          >
            <SelectTrigger className="-my-1 h-8 w-[200px] text-sm">
              <SelectValue placeholder={t('add_employee_placeholder')} />
            </SelectTrigger>
            <SelectContent>
              {notAdded.map(emp => (
                <SelectItem key={emp.id} value={emp.id}>
                  {emp.first_name} {emp.last_name}
                </SelectItem>
              ))}
            </SelectContent>
          </Select>
        ) : undefined
      }
    >
      {employees.length === 0 ? (
        <p className="text-sm text-muted-foreground">{t('no_employees_yet')}</p>
      ) : (
        <div className="overflow-x-auto">
          <table className="w-full border-collapse text-[13px]">
            <thead>
              <tr>
                <th className={cn(TH_CLASS, 'pl-0')}>{t('th_employee')}</th>
                {showDiff && previous && (
                  <th className={TH_CLASS}>{t('th_diff', { period: periodLabelOf(previous) })}</th>
                )}
                <th className={numericTh}>{isDraft ? t('th_monthly_salary') : t('th_gross')}</th>
                {isCalculated && (
                  <>
                    <th className={numericTh}>{t('th_tax')}</th>
                    <th className={numericTh}>{t('th_net')}</th>
                    <th className={numericTh}>{t('th_avgifter')}</th>
                    <th className={numericTh}>{t('th_vacation')}</th>
                  </>
                )}
                <th className={cn(TH_CLASS, 'pr-0 text-right')}>
                  <span className="sr-only">{t('th_payslip')}</span>
                </th>
              </tr>
            </thead>
            <tbody>
              {employees.map(sre => {
                const employee = (sre as SreWithEmployee).employee
                const name = employee
                  ? `${employee.first_name} ${employee.last_name}`
                  : `${t('employee_fallback')} ${sre.employee_id.slice(0, 8)}...`
                const dims = employee?.default_dimensions ?? {}
                const dimLabel = Object.keys(dims)
                  .sort((a, b) => Number(a) - Number(b))
                  .map(k => dims[k])
                  .join(' · ')
                const taxValue = sre.tax_withheld_override ?? sre.tax_withheld
                const avgifterValue = sre.avgifter_amount_override ?? sre.avgifter_amount
                const netValue = sre.net_salary + (sre.tax_withheld - taxValue)
                const editableSalary = isDraft && canWrite && sre.salary_type === 'monthly'
                const primaryNumber = isDraft ? sre.monthly_salary : sre.gross_salary
                // In a draft the number on the row is the full-time monthly salary
                // the engine multiplies by the employee's sysselsättningsgrad. Below
                // 100 % that product is not obvious from the input alone (a 10 %
                // employee typed 45 310 to get a 4 531 kr gross), so spell it out
                // as a muted suffix right after the number instead of only in
                // Beräkningsdetaljer.
                const degree = Number(sre.employment_degree)
                const showDegreeHint =
                  isDraft && sre.salary_type === 'monthly' && Number.isFinite(degree) && degree < 100
                const degreeHint = showDegreeHint ? (
                  <span className="text-[11px] text-muted-foreground tabular-nums whitespace-nowrap">
                    {t('degree_hint', {
                      degree: degree.toLocaleString('sv-SE'),
                      amount: formatCurrency(roundOre((sre.monthly_salary || 0) * (degree / 100))),
                    })}
                  </span>
                ) : null
                const removing = actionLoading === `remove-${sre.employee_id}`

                return (
                  <tr
                    key={sre.id}
                    className="group cursor-pointer transition-colors duration-150 hover:bg-secondary/35"
                    onClick={() => router.push(`/salary/runs/${runId}/employees/${sre.employee_id}`)}
                  >
                    <td className={cn(TD_CLASS, 'pl-0')}>
                      <Link
                        href={`/salary/runs/${runId}/employees/${sre.employee_id}`}
                        className="font-medium hover:underline"
                        onClick={e => e.stopPropagation()}
                      >
                        {name}
                      </Link>
                      {dimensionsEnabled && dimLabel && (
                        <span data-ph-mask="" className="ml-2 text-xs text-muted-foreground">
                          {dimLabel}
                        </span>
                      )}
                    </td>
                    {showDiff && <td className={TD_CLASS}>{diffNode(sre)}</td>}
                    <td className={numericTd}>
                      <span className="inline-flex items-center justify-end gap-2">
                        {editableSalary ? (
                          <Input
                            type="number"
                            step="0.01"
                            min="0"
                            defaultValue={sre.monthly_salary}
                            onClick={e => e.stopPropagation()}
                            onBlur={e => onSalaryEdit(sre.employee_id, e.target.value, sre.monthly_salary)}
                            disabled={actionLoading === `salary-${sre.employee_id}`}
                            aria-label={t('salary_input_aria', { name })}
                            className="-my-1 h-8 w-28 text-right tabular-nums"
                          />
                        ) : (
                          <span>{formatCurrency(primaryNumber)}</span>
                        )}
                        {degreeHint}
                      </span>
                    </td>
                    {isCalculated && (
                      <>
                        <td className={numericTd}>{formatCurrency(taxValue)}</td>
                        <td className={numericTd}>{formatCurrency(netValue)}</td>
                        <td className={numericTd}>{formatCurrency(avgifterValue)}</td>
                        <td className={numericTd}>{formatCurrency(sre.vacation_accrual)}</td>
                      </>
                    )}
                    <td className={cn(TD_CLASS, 'pr-0 text-right')}>
                      <span className="-my-1 inline-flex items-center justify-end gap-1">
                        {/* Payslip PDF */}
                        <a
                          href={`/api/salary/runs/${runId}/payslips/${sre.employee_id}/pdf`}
                          target="_blank"
                          rel="noopener noreferrer"
                          onClick={e => e.stopPropagation()}
                          className="inline-flex h-8 w-8 items-center justify-center text-muted-foreground transition-colors hover:text-foreground"
                          title={t('view_payslip_title')}
                          aria-label={t('view_payslip_title')}
                        >
                          <FileDown className="h-4 w-4" />
                        </a>
                        {canRemoveEmployee && (
                          <Button
                            variant="ghost"
                            size="icon"
                            className="h-8 w-8 text-muted-foreground hover:text-destructive"
                            onClick={e => {
                              e.stopPropagation()
                              onRemoveEmployee(sre.employee_id, name)
                            }}
                            disabled={removing}
                            aria-label={t('remove_employee_aria', { name })}
                            title={t('remove_employee_title')}
                          >
                            {removing ? (
                              <Loader2 className="h-4 w-4 animate-spin" />
                            ) : (
                              <Trash2 className="h-4 w-4" />
                            )}
                          </Button>
                        )}
                      </span>
                    </td>
                  </tr>
                )
              })}
            </tbody>
          </table>
        </div>
      )}
    </DetailSection>
  )
}