import { Fragment, useMemo, useState } from 'react'
import { Link, useNavigate, useParams } from 'react-router-dom'
import type { Pago, PlanPago } from '../types'
import { agregarNota, cancelarPlan, obtenerPlan, registrarAbonoEnPlan } from '../services/repository'
import {
  avancePlan,
  diasAtraso,
  moraDePago,
  pagadoTotal,
  round2,
  saldoPlan,
  statusPago,
  statusPlan,
  totalMora,
} from '../lib/cobranza'
import { formatoFechaCorta, formatoMoneda, formatoPorcentaje } from '../lib/formatters'
import { descargar } from '../lib/pdf/estadoCuenta'
import { descargarRecibo } from '../lib/pdf/reciboAbono'
import BadgeStatus from '../components/BadgeStatus'
import KpiCard from '../components/KpiCard'
import ModalAbono from '../components/ModalAbono'

export default function PlanDetallePage() {
  const { id } = useParams<{ id: string }>()
  const navigate = useNavigate()
  const [plan, setPlan] = useState<PlanPago | undefined>(() => (id ? obtenerPlan(id) : undefined))
  const [pagoAbono, setPagoAbono] = useState<Pago | null>(null)
  const [expandidos, setExpandidos] = useState<Set<string>>(new Set())
  const [error, setError] = useState<string | null>(null)
  const [notaTexto, setNotaTexto] = useState('')
  const [errorNota, setErrorNota] = useState<string | null>(null)
  const hoy = useMemo(() => new Date(), [])

  if (!plan) {
    return (
      <div className="border border-neutral-200 bg-white p-16 text-center">
        <p className="text-neutral-500">Plan no encontrado.</p>
        <Link to="/" className="mt-4 inline-block text-accent hover:underline">
          Volver al dashboard
        </Link>
      </div>
    )
  }

  const status = statusPlan(plan)
  const saldo = saldoPlan(plan)
  const atraso = diasAtraso(plan, hoy)
  const tasaMora = plan.tasaMoraMensual ?? 0
  const mora = totalMora(plan, hoy)

  const toggleExpandido = (pagoId: string) => {
    setExpandidos((prev) => {
      const next = new Set(prev)
      if (next.has(pagoId)) next.delete(pagoId)
      else next.add(pagoId)
      return next
    })
  }

  const guardarAbono = (datos: { monto: number; fechaPago: string; referencia: string }) => {
    if (!pagoAbono) return
    try {
      const actualizado = registrarAbonoEnPlan(plan.id, datos, pagoAbono.id)
      setPlan(actualizado)
      setPagoAbono(null)
      setError(null)
    } catch (e) {
      setError(e instanceof Error ? e.message : 'Error al registrar el abono')
    }
  }

  const cancelar = () => {
    if (!window.confirm('¿Cancelar este plan? El saldo pendiente dejará de cobrarse.')) return
    setPlan(cancelarPlan(plan.id))
  }

  const guardarNota = () => {
    try {
      setPlan(agregarNota(plan.id, notaTexto))
      setNotaTexto('')
      setErrorNota(null)
    } catch (e) {
      setErrorNota(e instanceof Error ? e.message : 'Error al guardar la nota')
    }
  }

  return (
    <div className="space-y-16">
      <div className="flex flex-wrap items-start justify-between gap-6">
        <div>
          <Link to="/" className="text-sm text-accent hover:underline">
            ← Volver al dashboard
          </Link>
          <h1 className="mt-2 text-3xl font-light text-neutral-900">{plan.clienteNombre}</h1>
          <p className="mt-1 text-sm text-neutral-500">
            {plan.unidadCodigo} · {plan.proyecto} · Venta {plan.ventaRef || '—'} ·{' '}
            <span className="font-bold text-neutral-900">{status}</span>
            {atraso > 0 && <span className="text-red-700"> · {atraso} días de atraso</span>}
          </p>
          <p className="mt-1 text-sm text-neutral-500">
            Tel. {plan.clienteTelefono || '—'}
            {tasaMora > 0 && <span> · Mora {tasaMora}% mensual</span>}
          </p>
        </div>
        <div className="flex gap-3">
          <button
            onClick={() => descargar(plan)}
            className="border border-neutral-900 bg-transparent px-5 py-2.5 text-xs font-bold uppercase tracking-widest text-neutral-900 transition-colors duration-150 hover:bg-neutral-900 hover:text-white"
          >
            Estado de cuenta PDF
          </button>
          {status === 'ACTIVO' && saldo > 0 && (
            <button
              onClick={cancelar}
              className="border border-red-300 bg-white px-5 py-2.5 text-xs font-bold uppercase tracking-widest text-red-700 transition-colors duration-150 hover:bg-red-700 hover:text-white"
            >
              Cancelar plan
            </button>
          )}
        </div>
      </div>

      {error && (
        <div className="border border-red-300 bg-white px-4 py-3 text-sm text-red-700">{error}</div>
      )}

      {/* KPIs del plan */}
      <div className="grid grid-cols-2 gap-6 lg:grid-cols-5">
        <KpiCard titulo="Enganche total" valor={formatoMoneda(plan.engancheTotal)} />
        <KpiCard titulo="Pagado" valor={formatoMoneda(pagadoTotal(plan))} />
        <KpiCard titulo="Saldo" valor={formatoMoneda(saldo)} />
        <KpiCard titulo="% avance" valor={formatoPorcentaje(avancePlan(plan))} />
        <KpiCard titulo="Mensualidad" valor={formatoMoneda(plan.mensualidad)} detalle={`${plan.numPagos} pagos`} />
        {mora > 0 && (
          <KpiCard
            titulo="Mora acumulada"
            valor={<span className="text-red-700">{formatoMoneda(mora)}</span>}
            detalle={`Tasa ${tasaMora}% mensual`}
          />
        )}
      </div>

      {/* Tabla de pagos */}
      <div className="overflow-x-auto">
        <table className="w-full text-left text-sm">
          <thead>
            <tr className="border-b border-neutral-900 text-xs font-bold uppercase tracking-widest text-neutral-500">
              <th scope="col" className="py-3 pr-4">#</th>
              <th scope="col" className="py-3 pr-4">Vencimiento</th>
              <th scope="col" className="py-3 pr-4 text-right">Monto</th>
              <th scope="col" className="py-3 pr-4 text-right">Pagado</th>
              <th scope="col" className="py-3 pr-4 text-right">Restante</th>
              {tasaMora > 0 && <th scope="col" className="py-3 pr-4 text-right">Mora</th>}
              <th scope="col" className="py-3 pr-4">Status</th>
              <th scope="col" className="py-3 pr-4">Abonos</th>
              <th scope="col" className="py-3" />
            </tr>
          </thead>
          <tbody>
            {plan.pagos.map((pago) => {
              const st = statusPago(pago, hoy)
              const restante = round2(pago.monto - pago.montoPagado)
              const moraPago = tasaMora > 0 ? moraDePago(pago, tasaMora, hoy) : 0
              const expandido = expandidos.has(pago.id)
              return (
                <Fragment key={pago.id}>
                  <tr className="border-b border-neutral-200 transition-colors duration-150 hover:bg-neutral-50">
                    <td className="py-3 pr-4 font-medium">{pago.numPago}</td>
                    <td className="py-3 pr-4">{formatoFechaCorta(pago.fechaVencimiento)}</td>
                    <td className="py-3 pr-4 text-right">{formatoMoneda(pago.monto)}</td>
                    <td className="py-3 pr-4 text-right">{formatoMoneda(pago.montoPagado)}</td>
                    <td className="py-3 pr-4 text-right font-medium">{formatoMoneda(restante)}</td>
                    {tasaMora > 0 && (
                      <td className="py-3 pr-4 text-right">
                        {moraPago > 0 ? (
                          <span className="text-red-700">{formatoMoneda(moraPago)}</span>
                        ) : (
                          <span className="text-neutral-400">—</span>
                        )}
                      </td>
                    )}
                    <td className="py-3 pr-4">
                      <BadgeStatus status={st} />
                    </td>
                    <td className="py-3 pr-4">
                      {pago.aplicaciones.length > 0 ? (
                        <button
                          onClick={() => toggleExpandido(pago.id)}
                          className="text-accent hover:underline"
                        >
                          {expandido ? 'Ocultar' : `Ver (${pago.aplicaciones.length})`}
                        </button>
                      ) : (
                        <span className="text-neutral-400">—</span>
                      )}
                    </td>
                    <td className="py-3 text-right">
                      {st !== 'PAGADO' && status === 'ACTIVO' && (
                        <button
                          onClick={() => setPagoAbono(pago)}
                          className="bg-accent px-4 py-2 text-xs font-bold uppercase tracking-widest text-white transition-colors duration-150 hover:opacity-90"
                        >
                          Registrar abono
                        </button>
                      )}
                    </td>
                  </tr>
                  {expandido && (
                    <tr className="border-b border-neutral-200 bg-neutral-50">
                      <td colSpan={tasaMora > 0 ? 9 : 8} className="px-4 py-4">
                        <table className="w-full text-xs">
                          <thead>
                            <tr className="text-left font-bold uppercase tracking-widest text-neutral-500">
                              <th scope="col" className="py-1">Fecha</th>
                              <th scope="col" className="py-1 text-right">Monto</th>
                              <th scope="col" className="py-1">Referencia</th>
                              <th scope="col" className="py-1 text-right">Recibo</th>
                            </tr>
                          </thead>
                          <tbody>
                            {pago.aplicaciones.map((a) => (
                              <tr key={a.id} className="border-t border-neutral-200">
                                <td className="py-1">{formatoFechaCorta(a.fechaPago)}</td>
                                <td className="py-1 text-right">{formatoMoneda(a.monto)}</td>
                                <td className="py-1">{a.referencia}</td>
                                <td className="py-1 text-right">
                                  <button
                                    onClick={() => descargarRecibo(plan, pago, a)}
                                    aria-label={`Descargar recibo PDF del abono ${a.referencia}`}
                                    className="text-accent hover:underline"
                                  >
                                    Recibo PDF
                                  </button>
                                </td>
                              </tr>
                            ))}
                          </tbody>
                        </table>
                      </td>
                    </tr>
                  )}
                </Fragment>
              )
            })}
          </tbody>
        </table>
      </div>

      {/* Bitácora del plan */}
      <section className="border border-neutral-200 bg-white p-8" aria-labelledby="titulo-bitacora">
        <h2 id="titulo-bitacora" className="text-xs font-bold uppercase tracking-widest text-neutral-500">
          Bitácora
        </h2>
        {(plan.notas ?? []).length === 0 ? (
          <p className="mt-6 text-sm text-neutral-500">Sin notas registradas.</p>
        ) : (
          <ul className="mt-6 space-y-4">
            {[...(plan.notas ?? [])]
              .sort((a, b) => b.fecha.localeCompare(a.fecha))
              .map((nota) => (
                <li key={nota.id} className="border-l-2 border-neutral-200 pl-4">
                  <p className="text-xs text-neutral-500">
                    {new Date(nota.fecha).toLocaleString('es-MX', {
                      day: '2-digit',
                      month: '2-digit',
                      year: 'numeric',
                      hour: '2-digit',
                      minute: '2-digit',
                    })}
                  </p>
                  <p className="mt-1 text-sm text-neutral-900">{nota.texto}</p>
                </li>
              ))}
          </ul>
        )}
        <form
          className="mt-8"
          onSubmit={(e) => {
            e.preventDefault()
            guardarNota()
          }}
        >
          <label
            htmlFor="nota-texto"
            className="block text-xs font-bold uppercase tracking-widest text-neutral-500"
          >
            Nueva nota
          </label>
          <textarea
            id="nota-texto"
            value={notaTexto}
            onChange={(e) => setNotaTexto(e.target.value)}
            rows={3}
            placeholder="Gestión realizada, acuerdos con el cliente…"
            className="mt-1 w-full border border-neutral-300 bg-white px-3 py-2.5 text-sm transition-colors duration-150 focus:border-neutral-900 focus:outline-none"
          />
          {errorNota && <p className="mt-1 text-xs text-red-700">{errorNota}</p>}
          <div className="mt-4 flex justify-end">
            <button
              type="submit"
              disabled={notaTexto.trim().length < 3}
              className="bg-accent px-5 py-2.5 text-xs font-bold uppercase tracking-widest text-white transition-colors duration-150 hover:opacity-90 disabled:opacity-40"
            >
              Agregar nota
            </button>
          </div>
        </form>
      </section>

      {status === 'CANCELADO' && (
        <button
          onClick={() => void navigate('/')}
          className="border border-neutral-900 bg-transparent px-5 py-2.5 text-xs font-bold uppercase tracking-widest text-neutral-900 transition-colors duration-150 hover:bg-neutral-900 hover:text-white"
        >
          Volver
        </button>
      )}

      {pagoAbono && (
        <ModalAbono pago={pagoAbono} onCancelar={() => setPagoAbono(null)} onGuardar={guardarAbono} />
      )}
    </div>
  )
}