import { useState } from 'react'
import { useMutation, useQuery } from '@tanstack/react-query'
import { Link, useParams } from '@tanstack/react-router'
import { CalendarX2, CheckCircle2, Loader2, Moon, Sun } from 'lucide-react'
import { Badge, Button, useToast } from '../components/ui'
import { Logo } from '../components/brand'
import { useTheme } from '../context/ThemeProvider'
import { ApiError, getAbsenceDetails, publicNotifyAbsence } from '../lib/api'

export function AbsenceNotifyView() {
  const { token } = useParams({ strict: false }) as { token: string }
  const { setTheme, isDark } = useTheme()
  const toast = useToast()

  const [locallyNotified, setLocallyNotified] = useState<string[]>([])

  const detailsQuery = useQuery({
    queryKey: ['absence-details', token],
    queryFn: () => getAbsenceDetails(token),
    enabled: Boolean(token),
    retry: 1,
  })

  const notifyMutation = useMutation({
    mutationFn: (sessionId: string) =>
      publicNotifyAbsence({ token, classSessionId: sessionId }),
    onSuccess: (_data, sessionId) => {
      setLocallyNotified((prev) => [...prev, sessionId])
      toast.success(
        'Tu profesor ya tiene registrado el aviso. Gracias por avisar.',
        'Ausencia avisada',
      )
    },
    onError: (error: unknown) => {
      if (error instanceof ApiError && error.problem?.status === 404) {
        toast.error('Este enlace ya no es válido. Consultá a tu profesor.')
        return
      }
      toast.error(
        error instanceof Error ? error.message : 'No pudimos registrar el aviso.',
      )
    },
  })

  const details = detailsQuery.data

  return (
    <div className="flex min-h-screen flex-col justify-between bg-background text-primary selection:bg-accent selection:text-white">
      <header className="sticky top-0 z-10 flex items-center justify-between border-b border-border bg-surface/80 px-4 py-3 backdrop-blur-md sm:px-8">
        <Link to="/" className="flex items-center gap-2">
          <Logo className="h-7 w-auto" />
        </Link>
        <button
          type="button"
          onClick={() => setTheme(isDark ? 'light' : 'dark')}
          className="rounded-xl p-2 text-foreground/70 transition-colors hover:bg-primary-soft hover:text-primary"
          title={isDark ? 'Cambiar a tema claro' : 'Cambiar a tema oscuro'}
        >
          {isDark ? <Sun className="size-4" /> : <Moon className="size-4" />}
        </button>
      </header>

      <main className="flex flex-1 items-center justify-center p-4 sm:p-6 md:p-10">
        <div className="w-full max-w-lg space-y-6">
          {detailsQuery.isPending ? (
            <div className="flex flex-col items-center justify-center gap-3 py-20">
              <Loader2 className="size-8 animate-spin text-accent" />
              <p className="text-sm text-foreground/60">Cargando tus clases...</p>
            </div>
          ) : null}

          {detailsQuery.isError || !details ? (
            <div className="space-y-3 rounded-2xl border border-danger/20 bg-danger-soft p-6 text-center sm:p-8">
              <h2 className="text-xl font-bold text-danger">Enlace no válido</h2>
              <p className="mx-auto max-w-sm text-sm leading-relaxed text-foreground/70">
                No pudimos identificarte con este enlace. Consultá con tu profesor para
                solicitar uno nuevo.
              </p>
            </div>
          ) : null}

          {details ? (
            <div className="animate-step-enter space-y-5 rounded-2xl border border-border bg-surface p-6 shadow-xl sm:p-8">
              <div className="border-b border-border pb-5 text-center">
                <div className="mx-auto mb-3 flex size-14 items-center justify-center rounded-full bg-accent-soft text-accent">
                  <CalendarX2 className="size-7" />
                </div>
                <Badge variant="neutral" className="mb-2">
                  Aviso de ausencia
                </Badge>
                <h1 className="text-2xl font-bold text-primary">Hola, {details.fullName}</h1>
                <p className="mt-1 text-sm font-medium text-foreground/80">
                  Grupo: <span className="text-primary">{details.groupName}</span>
                </p>
              </div>

              {details.sessions.length === 0 ? (
                <p className="rounded-xl border border-dashed border-border bg-primary-soft/40 px-4 py-8 text-center text-sm text-foreground/60">
                  No tenés clases programadas para hoy. Si necesitás avisar de todas formas,
                  contactá a tu profesor.
                </p>
              ) : (
                <ul className="space-y-3">
                  {details.sessions.map((session) => {
                    const time = new Date(session.startsAt).toLocaleTimeString('es-MX', {
                      hour: '2-digit',
                      minute: '2-digit',
                      hour12: false,
                    })
                    const notified =
                      session.notified || locallyNotified.includes(session.sessionId)

                    return (
                      <li
                        key={session.sessionId}
                        className="flex items-center justify-between gap-3 rounded-xl border border-border bg-primary-soft/30 px-4 py-3"
                      >
                        <div className="min-w-0">
                          <p className="text-sm font-semibold text-primary">
                            Hoy · {time} hs
                          </p>
                          <p className="truncate text-xs text-foreground/60">
                            {session.groupName}
                          </p>
                        </div>
                        {notified ? (
                          <span className="inline-flex shrink-0 items-center gap-1.5 rounded-full bg-success-soft px-2.5 py-1 text-xs font-medium text-success">
                            <CheckCircle2 className="size-3.5" />
                            Ya avisaste
                          </span>
                        ) : (
                          <Button
                            variant="primary"
                            size="sm"
                            disabled={notifyMutation.isPending}
                            onClick={() => notifyMutation.mutate(session.sessionId)}
                          >
                            {notifyMutation.isPending &&
                            notifyMutation.variables === session.sessionId ? (
                              <Loader2 className="size-4 animate-spin" />
                            ) : null}
                            Avisar ausencia
                          </Button>
                        )}
                      </li>
                    )
                  })}
                </ul>
              )}

              <p className="text-center text-xs leading-relaxed text-foreground/50">
                Si avisás con anticipación, tu cupo se libera para una clase de recuperación.
              </p>
            </div>
          ) : null}
        </div>
      </main>

      <footer className="border-t border-border px-4 py-4 text-center text-xs text-foreground/40">
        Gruperly — Gestión sencilla de cobros y grupos
      </footer>
    </div>
  )
}