"use client";

import {
  ArrowRightIcon,
  CheckCircleIcon,
  ExclamationTriangleIcon,
  SparklesIcon,
} from "@heroicons/react/24/outline";
import Link from "next/link";
import { useRouter } from "next/navigation";
import { useEffect, useState } from "react";
import { useSession } from "@/lib/auth-client";
import {
  ActivityLevel,
  HealthGoal,
  HealthProfile,
  WeightLossPace,
  buildCoachRecommendations,
  buildGoalsFromProfile,
  loadHellthData,
  saveHellthData,
} from "@/lib/hellth-data";

type FormState = {
  goal: HealthGoal;
  age: string;
  heightCm: string;
  currentWeightKg: string;
  targetWeightKg: string;
  activityLevel: ActivityLevel;
  pace: WeightLossPace;
  mealsPerDay: string;
  dietStyle: HealthProfile["dietStyle"];
  cookingTime: HealthProfile["cookingTime"];
  budgetFocus: boolean;
  excludedFoods: string;
  biggestChallenge: string;
  medicalNote: boolean;
};

const initialForm: FormState = {
  goal: "lose_weight",
  age: "",
  heightCm: "",
  currentWeightKg: "",
  targetWeightKg: "",
  activityLevel: "moderate",
  pace: "normal",
  mealsPerDay: "3",
  dietStyle: "mixed",
  cookingTime: "medium",
  budgetFocus: false,
  excludedFoods: "",
  biggestChallenge: "",
  medicalNote: false,
};

function numberFrom(value: string) {
  return Number(value.replace(",", ".")) || 0;
}

function OptionButton({
  active,
  label,
  description,
  onClick,
}: {
  active: boolean;
  label: string;
  description: string;
  onClick: () => void;
}) {
  return (
    <button
      type="button"
      onClick={onClick}
      className={`rounded-3xl border p-4 text-left transition ${
        active ? "border-[#0F766E] bg-emerald-50 ring-2 ring-emerald-100" : "border-gray-100 bg-white hover:bg-gray-50"
      }`}
    >
      <p className="text-base font-black text-gray-950">{label}</p>
      <p className="mt-1 text-sm font-semibold text-gray-400">{description}</p>
    </button>
  );
}

export default function OnboardingPage() {
  const router = useRouter();
  const { data: session } = useSession();
  const userKey = session?.user?.id ?? session?.user?.email ?? null;
  const [form, setForm] = useState<FormState>(initialForm);
  const [savedProfile, setSavedProfile] = useState<HealthProfile | null>(null);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!userKey) return;
    const profile = loadHellthData(userKey).healthProfile;
    if (profile) {
      setSavedProfile(profile);
      setForm({
        goal: profile.goal,
        age: String(profile.age),
        heightCm: String(profile.heightCm),
        currentWeightKg: String(profile.currentWeightKg),
        targetWeightKg: profile.targetWeightKg ? String(profile.targetWeightKg) : "",
        activityLevel: profile.activityLevel,
        pace: profile.pace,
        mealsPerDay: String(profile.mealsPerDay),
        dietStyle: profile.dietStyle,
        cookingTime: profile.cookingTime,
        budgetFocus: profile.budgetFocus,
        excludedFoods: profile.excludedFoods,
        biggestChallenge: profile.biggestChallenge,
        medicalNote: profile.medicalNote,
      });
    }
  }, [userKey]);

  function saveProfile() {
    if (!userKey) return;
    const age = numberFrom(form.age);
    const heightCm = numberFrom(form.heightCm);
    const currentWeightKg = numberFrom(form.currentWeightKg);
    const targetWeightKg = numberFrom(form.targetWeightKg);

    if (age < 16 || heightCm < 120 || currentWeightKg < 35) {
      setError("Bitte Alter, Größe und aktuelles Gewicht plausibel ausfüllen.");
      return;
    }

    if (form.goal === "lose_weight" && targetWeightKg > 0 && targetWeightKg >= currentWeightKg) {
      setError("Für Abnehmen sollte das Zielgewicht unter dem aktuellen Gewicht liegen.");
      return;
    }

    const profile: HealthProfile = {
      completedAt: new Date().toISOString(),
      goal: form.goal,
      age,
      heightCm,
      currentWeightKg,
      targetWeightKg: targetWeightKg || undefined,
      activityLevel: form.activityLevel,
      pace: form.pace,
      mealsPerDay: Math.max(1, Math.min(6, numberFrom(form.mealsPerDay) || 3)),
      dietStyle: form.dietStyle,
      cookingTime: form.cookingTime,
      budgetFocus: form.budgetFocus,
      excludedFoods: form.excludedFoods.trim(),
      biggestChallenge: form.biggestChallenge.trim(),
      medicalNote: form.medicalNote,
    };
    const goals = buildGoalsFromProfile(profile);
    const coachRecommendations = buildCoachRecommendations(profile, goals);
    const data = loadHellthData(userKey);
    saveHellthData({ ...data, healthProfile: profile, goals, coachRecommendations }, userKey);
    setSavedProfile(profile);
    setError(null);
  }

  const previewProfile: HealthProfile | null =
    numberFrom(form.age) >= 16 && numberFrom(form.heightCm) >= 120 && numberFrom(form.currentWeightKg) >= 35
      ? {
          completedAt: new Date().toISOString(),
          goal: form.goal,
          age: numberFrom(form.age),
          heightCm: numberFrom(form.heightCm),
          currentWeightKg: numberFrom(form.currentWeightKg),
          targetWeightKg: numberFrom(form.targetWeightKg) || undefined,
          activityLevel: form.activityLevel,
          pace: form.pace,
          mealsPerDay: numberFrom(form.mealsPerDay) || 3,
          dietStyle: form.dietStyle,
          cookingTime: form.cookingTime,
          budgetFocus: form.budgetFocus,
          excludedFoods: form.excludedFoods,
          biggestChallenge: form.biggestChallenge,
          medicalNote: form.medicalNote,
        }
      : null;
  const previewGoals = previewProfile ? buildGoalsFromProfile(previewProfile) : null;
  const previewRecommendations = previewProfile && previewGoals ? buildCoachRecommendations(previewProfile, previewGoals) : [];

  return (
    <div className="mx-auto max-w-6xl space-y-5 pb-24">
      <header className="rounded-[2rem] bg-white p-6 shadow-sm ring-1 ring-gray-100">
        <div className="flex items-center gap-3">
          <div className="grid h-12 w-12 place-items-center rounded-2xl bg-[#0F766E] text-white">
            <SparklesIcon className="h-7 w-7" />
          </div>
          <div>
            <p className="text-sm font-black uppercase text-[#0F766E]">Erster Start</p>
            <h1 className="text-4xl font-black tracking-normal text-gray-950">Dein Health-Profil</h1>
          </div>
        </div>
        <p className="mt-4 max-w-3xl text-sm font-semibold text-gray-500">
          Hellth Hub nutzt diese Antworten, um alltagstaugliche Ziele und konkrete Vorschläge zu erzeugen. Die Werte sind Startpunkte und werden später über deinen echten Verlauf verbessert.
        </p>
      </header>

      <section className="grid gap-5 xl:grid-cols-[1fr_0.8fr]">
        <div className="space-y-5">
          <div className="rounded-[2rem] bg-white p-6 shadow-sm ring-1 ring-gray-100">
            <h2 className="text-xl font-black text-gray-950">1. Ziel</h2>
            <div className="mt-4 grid gap-3 md:grid-cols-3">
              <OptionButton active={form.goal === "lose_weight"} label="Abnehmen" description="Fokus auf moderates Defizit und Sättigung." onClick={() => setForm((current) => ({ ...current, goal: "lose_weight" }))} />
              <OptionButton active={form.goal === "maintain"} label="Gewicht halten" description="Routine, Energie und Stabilität verbessern." onClick={() => setForm((current) => ({ ...current, goal: "maintain" }))} />
              <OptionButton active={form.goal === "healthier"} label="Gesünder leben" description="Mehr Struktur, bessere Lebensmittelauswahl." onClick={() => setForm((current) => ({ ...current, goal: "healthier" }))} />
            </div>
          </div>

          <div className="rounded-[2rem] bg-white p-6 shadow-sm ring-1 ring-gray-100">
            <h2 className="text-xl font-black text-gray-950">2. Ausgangslage</h2>
            <div className="mt-4 grid gap-3 sm:grid-cols-2 lg:grid-cols-4">
              <input value={form.age} onChange={(event) => setForm((current) => ({ ...current, age: event.target.value }))} placeholder="Alter" className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
              <input value={form.heightCm} onChange={(event) => setForm((current) => ({ ...current, heightCm: event.target.value }))} placeholder="Größe cm" className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
              <input value={form.currentWeightKg} onChange={(event) => setForm((current) => ({ ...current, currentWeightKg: event.target.value }))} placeholder="Aktuelles Gewicht kg" className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
              <input value={form.targetWeightKg} onChange={(event) => setForm((current) => ({ ...current, targetWeightKg: event.target.value }))} placeholder="Zielgewicht kg" className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
            </div>
            <div className="mt-4 grid gap-3 md:grid-cols-3">
              <OptionButton active={form.activityLevel === "low"} label="Wenig aktiv" description="Viel Sitzen, wenig Bewegung." onClick={() => setForm((current) => ({ ...current, activityLevel: "low" }))} />
              <OptionButton active={form.activityLevel === "moderate"} label="Moderat" description="Alltag mit etwas Bewegung." onClick={() => setForm((current) => ({ ...current, activityLevel: "moderate" }))} />
              <OptionButton active={form.activityLevel === "active"} label="Aktiv" description="Regelmäßiges Training oder aktiver Job." onClick={() => setForm((current) => ({ ...current, activityLevel: "active" }))} />
            </div>
          </div>

          <div className="rounded-[2rem] bg-white p-6 shadow-sm ring-1 ring-gray-100">
            <h2 className="text-xl font-black text-gray-950">3. Alltag</h2>
            <div className="mt-4 grid gap-3 md:grid-cols-3">
              <OptionButton active={form.pace === "gentle"} label="Sanft" description="Kleines Defizit, leichter Alltag." onClick={() => setForm((current) => ({ ...current, pace: "gentle" }))} />
              <OptionButton active={form.pace === "normal"} label="Normal" description="Guter Startpunkt für Abnehmen." onClick={() => setForm((current) => ({ ...current, pace: "normal" }))} />
              <OptionButton active={form.pace === "ambitious"} label="Ambitioniert" description="Mehr Struktur, genauer beobachten." onClick={() => setForm((current) => ({ ...current, pace: "ambitious" }))} />
            </div>
            <div className="mt-4 grid gap-3 sm:grid-cols-2 lg:grid-cols-4">
              <input value={form.mealsPerDay} onChange={(event) => setForm((current) => ({ ...current, mealsPerDay: event.target.value }))} placeholder="Mahlzeiten pro Tag" className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
              <select value={form.dietStyle} onChange={(event) => setForm((current) => ({ ...current, dietStyle: event.target.value as FormState["dietStyle"] }))} className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold">
                <option value="mixed">Mischkost</option>
                <option value="flexible">Flexibel</option>
                <option value="vegetarian">Vegetarisch</option>
                <option value="vegan">Vegan</option>
                <option value="low_carb">Low Carb</option>
              </select>
              <select value={form.cookingTime} onChange={(event) => setForm((current) => ({ ...current, cookingTime: event.target.value as FormState["cookingTime"] }))} className="rounded-2xl border border-gray-200 px-4 py-3 text-sm font-semibold">
                <option value="low">Wenig Kochzeit</option>
                <option value="medium">Mittlere Kochzeit</option>
                <option value="high">Koche gern</option>
              </select>
              <label className="flex items-center gap-3 rounded-2xl border border-gray-200 px-4 py-3 text-sm font-black">
                <input type="checkbox" checked={form.budgetFocus} onChange={(event) => setForm((current) => ({ ...current, budgetFocus: event.target.checked }))} />
                Budget wichtig
              </label>
            </div>
            <div className="mt-4 grid gap-3 md:grid-cols-2">
              <textarea value={form.excludedFoods} onChange={(event) => setForm((current) => ({ ...current, excludedFoods: event.target.value }))} placeholder="Allergien, Ausschlüsse, No-Gos" className="min-h-28 rounded-3xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
              <textarea value={form.biggestChallenge} onChange={(event) => setForm((current) => ({ ...current, biggestChallenge: event.target.value }))} placeholder="Was macht Abnehmen oder gesünder essen aktuell schwer?" className="min-h-28 rounded-3xl border border-gray-200 px-4 py-3 text-sm font-semibold" />
            </div>
            <label className="mt-4 flex items-start gap-3 rounded-3xl bg-amber-50 px-4 py-3 text-sm font-semibold text-amber-900">
              <input type="checkbox" checked={form.medicalNote} onChange={(event) => setForm((current) => ({ ...current, medicalNote: event.target.checked }))} className="mt-1" />
              Es gibt Diagnosen, Medikamente, Schwangerschaft, Essstörungs-Vorgeschichte oder andere gesundheitliche Themen, die beachtet werden sollten.
            </label>
          </div>
        </div>

        <aside className="space-y-4">
          <section className="sticky top-6 rounded-[2rem] bg-white p-6 shadow-sm ring-1 ring-gray-100">
            <h2 className="text-xl font-black text-gray-950">Auswertung</h2>
            {previewGoals ? (
              <>
                <div className="mt-4 grid grid-cols-2 gap-3">
                  <div className="rounded-3xl bg-gray-50 p-4"><p className="text-2xl font-black">{previewGoals.calories}</p><p className="text-xs font-bold text-gray-400">kcal/Tag</p></div>
                  <div className="rounded-3xl bg-gray-50 p-4"><p className="text-2xl font-black">{previewGoals.protein} g</p><p className="text-xs font-bold text-gray-400">Protein</p></div>
                  <div className="rounded-3xl bg-gray-50 p-4"><p className="text-2xl font-black">{previewGoals.drinkMl}</p><p className="text-xs font-bold text-gray-400">ml Wasser</p></div>
                  <div className="rounded-3xl bg-gray-50 p-4"><p className="text-2xl font-black">{previewGoals.weightKg}</p><p className="text-xs font-bold text-gray-400">kg Ziel</p></div>
                </div>
                <div className="mt-5 space-y-3">
                  {previewRecommendations.slice(0, 4).map((item) => (
                    <div key={item.id} className="rounded-3xl bg-emerald-50 p-4">
                      <p className="font-black text-emerald-950">{item.title}</p>
                      <p className="mt-1 text-sm font-semibold text-emerald-800">{item.body}</p>
                    </div>
                  ))}
                </div>
              </>
            ) : (
              <p className="mt-3 text-sm font-semibold text-gray-400">Fülle Alter, Größe und Gewicht aus, dann siehst du hier die ersten Vorschläge.</p>
            )}

            {error ? (
              <div className="mt-4 flex gap-2 rounded-3xl bg-red-50 p-4 text-sm font-semibold text-red-700">
                <ExclamationTriangleIcon className="h-5 w-5 shrink-0" />
                {error}
              </div>
            ) : null}

            {savedProfile ? (
              <div className="mt-4 flex gap-2 rounded-3xl bg-green-50 p-4 text-sm font-semibold text-green-700">
                <CheckCircleIcon className="h-5 w-5 shrink-0" />
                Profil gespeichert. Deine Ziele und Coach-Vorschläge sind jetzt userbezogen aktiv.
              </div>
            ) : null}

            <button type="button" onClick={saveProfile} className="mt-5 flex w-full items-center justify-center gap-2 rounded-full bg-gray-950 px-5 py-4 text-sm font-black text-white">
              Profil speichern
              <ArrowRightIcon className="h-5 w-5" />
            </button>
            {savedProfile ? (
              <Link href="/" className="mt-3 flex w-full items-center justify-center rounded-full bg-emerald-600 px-5 py-4 text-sm font-black text-white">
                Zur Tagesansicht
              </Link>
            ) : null}
          </section>
        </aside>
      </section>
    </div>
  );
}