"use client";

import { useState } from "react";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import { useBaby } from "@/contexts/baby-context";
import { Plus, Trash2, Bell, BellOff, Clock, CheckCircle2, RotateCcw } from "lucide-react";
import { formatDistanceToNow } from "date-fns";
import { fr } from "date-fns/locale";

interface Reminder {
  id: string;
  name: string;
  dose: string | null;
  unit: string | null;
  intervalHours: number;
  startAt: string;
  enabled: boolean;
  lastSentAt: string | null;
}

const inputCls = "w-full px-3 py-2.5 rounded-lg border border-slate-200 dark:border-slate-700 text-sm focus:outline-none focus:ring-2 focus:ring-indigo-400 bg-white dark:bg-slate-800 dark:text-slate-100";

function localNowString() {
  const now = new Date();
  return new Date(now.getTime() - now.getTimezoneOffset() * 60000).toISOString().slice(0, 16);
}

function nextDueLabel(reminder: Reminder): string {
  const intervalMs = reminder.intervalHours * 60 * 60 * 1000;
  const base = reminder.lastSentAt ?? reminder.startAt;
  const next = new Date(new Date(base).getTime() + intervalMs);
  const now = new Date();
  const diff = next.getTime() - now.getTime();
  if (diff <= 0) return "En attente d'envoi";
  const h = Math.floor(diff / 3600000);
  const m = Math.floor((diff % 3600000) / 60000);
  return h > 0 ? `Dans ${h}h${m.toString().padStart(2, "0")}` : `Dans ${m} min`;
}

export default function RemindersPage() {
  const qc = useQueryClient();
  const { selectedBaby } = useBaby();
  const [showForm, setShowForm] = useState(false);
  const [form, setForm] = useState({ name: "", dose: "", unit: "mL", intervalHours: "8", startAt: localNowString() });
  const [saving, setSaving] = useState(false);

  const { data: reminders = [], isLoading } = useQuery<Reminder[]>({
    queryKey: ["reminders", selectedBaby?.id],
    queryFn: () => fetch(`/api/reminders?babyId=${selectedBaby!.id}`).then((r) => r.json()),
    enabled: !!selectedBaby?.id,
  });

  async function handleCreate(e: React.FormEvent) {
    e.preventDefault();
    if (!selectedBaby) return;
    setSaving(true);
    await fetch("/api/reminders", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ babyId: selectedBaby.id, ...form, intervalHours: parseFloat(form.intervalHours) }),
    });
    qc.invalidateQueries({ queryKey: ["reminders"] });
    setForm({ name: "", dose: "", unit: "mL", intervalHours: "8", startAt: localNowString() });
    setShowForm(false);
    setSaving(false);
  }

  async function toggleEnabled(id: string, enabled: boolean) {
    await fetch(`/api/reminders/${id}`, {
      method: "PATCH",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ enabled: !enabled }),
    });
    qc.invalidateQueries({ queryKey: ["reminders"] });
  }

  async function markTaken(id: string) {
    await fetch(`/api/reminders/${id}`, {
      method: "PATCH",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ lastSentAt: new Date().toISOString() }),
    });
    qc.invalidateQueries({ queryKey: ["reminders"] });
  }

  async function unmarkTaken(id: string) {
    await fetch(`/api/reminders/${id}`, {
      method: "PATCH",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ lastSentAt: null }),
    });
    qc.invalidateQueries({ queryKey: ["reminders"] });
  }

  async function deleteReminder(id: string) {
    if (!confirm("Supprimer ce rappel ?")) return;
    await fetch(`/api/reminders/${id}`, { method: "DELETE" });
    qc.invalidateQueries({ queryKey: ["reminders"] });
  }

  return (
    <div className="p-4 md:p-8 pb-28 md:pb-8">
      <div className="flex items-center justify-between mb-6">
        <div>
          <h1 className="text-2xl font-bold text-slate-900 dark:text-slate-100">Rappels médicaments</h1>
          {selectedBaby && <p className="text-sm text-slate-500 dark:text-slate-400 mt-0.5">{selectedBaby.name}</p>}
        </div>
        <button
          onClick={() => setShowForm((v) => !v)}
          className="flex items-center gap-2 px-3 py-2 bg-indigo-600 text-white rounded-xl text-sm font-medium hover:bg-indigo-700 transition"
        >
          <Plus className="w-4 h-4" />
          Nouveau
        </button>
      </div>

      {showForm && (
        <form onSubmit={handleCreate} className="bg-white dark:bg-slate-900 border border-slate-200 dark:border-slate-700 rounded-xl p-4 mb-4 space-y-3">
          <p className="text-xs font-semibold text-slate-400 dark:text-slate-500 uppercase tracking-wider">Nouveau rappel</p>
          <div>
            <label className="block text-xs font-medium text-slate-600 dark:text-slate-400 mb-1.5">Médicament</label>
            <input type="text" value={form.name} onChange={(e) => setForm((f) => ({ ...f, name: e.target.value }))}
              required className={inputCls} placeholder="Doliprane" />
          </div>
          <div className="grid grid-cols-2 gap-3">
            <div>
              <label className="block text-xs font-medium text-slate-600 dark:text-slate-400 mb-1.5">Dose</label>
              <input type="text" value={form.dose} onChange={(e) => setForm((f) => ({ ...f, dose: e.target.value }))}
                className={inputCls} placeholder="2.4" />
            </div>
            <div>
              <label className="block text-xs font-medium text-slate-600 dark:text-slate-400 mb-1.5">Unité</label>
              <select value={form.unit} onChange={(e) => setForm((f) => ({ ...f, unit: e.target.value }))} className={inputCls}>
                <option value="mL">mL</option>
                <option value="mg">mg</option>
                <option value="gouttes">gouttes</option>
              </select>
            </div>
          </div>
          <div>
            <label className="block text-xs font-medium text-slate-600 dark:text-slate-400 mb-1.5">Intervalle (heures)</label>
            <select value={form.intervalHours} onChange={(e) => setForm((f) => ({ ...f, intervalHours: e.target.value }))} className={inputCls}>
              {[4, 6, 8, 12, 24].map((h) => (
                <option key={h} value={h}>{h}h</option>
              ))}
            </select>
          </div>
          <div>
            <label className="block text-xs font-medium text-slate-600 dark:text-slate-400 mb-1.5">Première prise</label>
            <input type="datetime-local" value={form.startAt} onChange={(e) => setForm((f) => ({ ...f, startAt: e.target.value }))}
              required className={inputCls} />
          </div>
          <div className="flex gap-2 pt-1">
            <button type="button" onClick={() => setShowForm(false)}
              className="flex-1 py-2 border border-slate-200 dark:border-slate-700 rounded-lg text-sm text-slate-600 dark:text-slate-400">
              Annuler
            </button>
            <button type="submit" disabled={saving}
              className="flex-[2] py-2 bg-indigo-600 text-white rounded-lg text-sm font-medium disabled:opacity-50">
              {saving ? "..." : "Créer"}
            </button>
          </div>
        </form>
      )}

      {isLoading && (
        <div className="flex justify-center py-16">
          <div className="w-6 h-6 border-2 border-indigo-600 border-t-transparent rounded-full animate-spin" />
        </div>
      )}

      {!isLoading && reminders.length === 0 && !showForm && (
        <div className="text-center py-16 text-slate-400 dark:text-slate-500">
          <Bell className="w-8 h-8 mx-auto mb-3 opacity-30" />
          <p className="text-sm">Aucun rappel configuré</p>
        </div>
      )}

      <div className="space-y-3">
        {reminders.map((r) => (
          <div key={r.id} className={`bg-white dark:bg-slate-900 border rounded-xl p-4 transition ${r.enabled ? "border-slate-200 dark:border-slate-700" : "border-slate-100 dark:border-slate-800 opacity-60"}`}>
            <div className="flex items-start gap-3">
              <div className={`w-9 h-9 rounded-xl flex items-center justify-center flex-shrink-0 ${r.enabled ? "bg-green-50 dark:bg-green-950" : "bg-slate-100 dark:bg-slate-800"}`}>
                {r.enabled ? <Bell className="w-4 h-4 text-green-600 dark:text-green-400" /> : <BellOff className="w-4 h-4 text-slate-400" />}
              </div>
              <div className="flex-1 min-w-0">
                <p className="text-sm font-semibold text-slate-800 dark:text-slate-100">{r.name}</p>
                {(r.dose || r.unit) && (
                  <p className="text-xs text-slate-500 dark:text-slate-400">{[r.dose, r.unit].filter(Boolean).join(" ")}</p>
                )}
                <div className="flex items-center gap-1.5 mt-1">
                  <Clock className="w-3 h-3 text-slate-400" />
                  <span className="text-xs text-slate-400 dark:text-slate-500">Toutes les {r.intervalHours}h</span>
                  {r.enabled && (
                    <span className="text-xs text-indigo-600 dark:text-indigo-400 ml-2">{nextDueLabel(r)}</span>
                  )}
                </div>
                {r.lastSentAt && (
                  <p className="text-xs text-green-600 dark:text-green-400 mt-0.5 flex items-center gap-1">
                    <CheckCircle2 className="w-3 h-3" />
                    Pris {formatDistanceToNow(new Date(r.lastSentAt), { locale: fr, addSuffix: true })}
                  </p>
                )}
              </div>
              <div className="flex items-center gap-1.5 flex-shrink-0">
                {r.lastSentAt ? (
                  <button
                    onClick={() => unmarkTaken(r.id)}
                    title="Annuler la prise"
                    className="w-8 h-8 flex items-center justify-center rounded-lg text-green-500 hover:text-slate-400 hover:bg-slate-100 dark:hover:bg-slate-800 transition"
                  >
                    <RotateCcw className="w-3.5 h-3.5" />
                  </button>
                ) : (
                  <button
                    onClick={() => markTaken(r.id)}
                    title="Marquer comme pris"
                    className="w-8 h-8 flex items-center justify-center rounded-lg text-slate-400 hover:text-green-600 hover:bg-green-50 dark:hover:bg-green-950 transition"
                  >
                    <CheckCircle2 className="w-4 h-4" />
                  </button>
                )}
                <button
                  onClick={() => toggleEnabled(r.id, r.enabled)}
                  className={`w-9 h-5 rounded-full transition relative overflow-hidden ${r.enabled ? "bg-green-500" : "bg-slate-200 dark:bg-slate-700"}`}
                >
                  <span className={`absolute top-0.5 left-0.5 w-4 h-4 bg-white rounded-full shadow transition-transform ${r.enabled ? "translate-x-[14px]" : "translate-x-0"}`} />
                </button>
                <button onClick={() => deleteReminder(r.id)}
                  className="w-8 h-8 flex items-center justify-center rounded-lg text-slate-400 hover:text-red-500 hover:bg-red-50 dark:hover:bg-red-950 transition">
                  <Trash2 className="w-3.5 h-3.5" />
                </button>
              </div>
            </div>
          </div>
        ))}
      </div>

      {reminders.length > 0 && (
        <p className="mt-6 text-center text-xs text-slate-400 dark:text-slate-500">
          Appelez <code className="bg-slate-100 dark:bg-slate-800 px-1 py-0.5 rounded">/api/reminders/check</code> régulièrement (cron) pour envoyer les rappels via Pushover.
        </p>
      )}
    </div>
  );
}