"use client";

import { useEffect, useMemo, useState } from "react";
import Link from "next/link";
import { useRouter } from "next/navigation";
import { useToast } from "@/lib/toast";
import { useI18n } from "@/lib/i18n";
import { compareUrl } from "@/lib/compareScore";
import {
  EMPTY_MATCHER_PREFS,
  loadMatcherPrefs,
  matcherPrefsComplete,
  saveMatcherPrefs,
  clearMatcherPrefs,
  type MatcherPrefs,
  type MatcherBudget,
  type MatcherClimate,
  type MatcherPriority,
  type MatcherRegion,
} from "@/lib/matcherPrefs";
import { mergeDestinationsIntoTrip } from "@/lib/tripActions";
import type { Destination } from "@/lib/types";

interface Props {
  destinations: Destination[];
  open: boolean;
  onClose: () => void;
}

const STEP_KEYS = ["budget", "climate", "priority", "region"] as const;

function parseNomads(n: string): number {
  return parseInt(n.replace(/[^0-9]/g, ""), 10) || 0;
}

function scoreDestination(
  d: Destination,
  prefs: Required<Pick<MatcherPrefs, "budget" | "climate" | "priority" | "region">>
): number {
  let score = 0;

  if (prefs.budget === "low") score += d.cost <= 5000 ? 35 : Math.max(0, 35 - (d.cost - 5000) / 200);
  else if (prefs.budget === "medium") score += d.cost >= 4500 && d.cost <= 9500 ? 35 : 35 - Math.abs(d.cost - 7000) / 300;
  else score += d.cost >= 9000 ? 35 : Math.max(0, 35 - (9000 - d.cost) / 200);

  if (prefs.climate === "warm") score += d.temperature >= 25 ? 25 : Math.max(0, 25 - (25 - d.temperature) * 3);
  else if (prefs.climate === "mild") score += d.temperature >= 18 && d.temperature <= 25 ? 25 : 25 - Math.abs(d.temperature - 21) * 2;
  else score += d.temperature <= 18 ? 25 : Math.max(0, 25 - (d.temperature - 18) * 3);

  if (prefs.priority === "cost") score += (12000 - d.cost) / 80;
  else if (prefs.priority === "speed") score += d.speed / 4;
  else if (prefs.priority === "community") score += parseNomads(d.nomads_count) / 500;
  else score += d.rating * 3;

  if (prefs.region === "any" || d.region === prefs.region) score += 20;
  else score -= 10;

  score += d.rating * 2;
  return Math.round(score);
}

export default function DestinationMatcher({ destinations, open, onClose }: Props) {
  const router = useRouter();
  const { toast } = useToast();
  const { t } = useI18n();
  const [step, setStep] = useState(0);
  const [prefs, setPrefs] = useState<MatcherPrefs>(EMPTY_MATCHER_PREFS);
  const [direction, setDirection] = useState<"forward" | "back">("forward");
  const [hydrated, setHydrated] = useState(false);

  const steps = useMemo(
    () => [
      { title: t.matcher.budgetTitle, subtitle: t.matcher.budgetSub, key: "budget" as const },
      { title: t.matcher.climateTitle, subtitle: t.matcher.climateSub, key: "climate" as const },
      { title: t.matcher.priorityTitle, subtitle: t.matcher.prioritySub, key: "priority" as const },
      { title: t.matcher.regionTitle, subtitle: t.matcher.regionSub, key: "region" as const },
    ],
    [t]
  );

  const options = useMemo(
    () => ({
      budget: [
        { value: "low" as MatcherBudget, emoji: "💰", label: t.matcher.budgetLow, desc: t.matcher.budgetLowDesc },
        { value: "medium" as MatcherBudget, emoji: "💳", label: t.matcher.budgetMed, desc: t.matcher.budgetMedDesc },
        { value: "high" as MatcherBudget, emoji: "💎", label: t.matcher.budgetHigh, desc: t.matcher.budgetHighDesc },
      ],
      climate: [
        { value: "warm" as MatcherClimate, emoji: "☀️", label: t.matcher.climateWarm, desc: t.matcher.climateWarmDesc },
        { value: "mild" as MatcherClimate, emoji: "🌤️", label: t.matcher.climateMild, desc: t.matcher.climateMildDesc },
        { value: "cool" as MatcherClimate, emoji: "🍂", label: t.matcher.climateCool, desc: t.matcher.climateCoolDesc },
      ],
      priority: [
        { value: "cost" as MatcherPriority, emoji: "💰", label: t.matcher.priCost, desc: t.matcher.priCostDesc },
        { value: "speed" as MatcherPriority, emoji: "📶", label: t.matcher.priSpeed, desc: t.matcher.priSpeedDesc },
        { value: "community" as MatcherPriority, emoji: "🤝", label: t.matcher.priCommunity, desc: t.matcher.priCommunityDesc },
        { value: "lifestyle" as MatcherPriority, emoji: "🎨", label: t.matcher.priLifestyle, desc: t.matcher.priLifestyleDesc },
      ],
      region: [
        { value: "any" as MatcherRegion, emoji: "🌏", label: t.matcher.regionAny, desc: t.matcher.regionAnyDesc },
        { value: "sea" as MatcherRegion, emoji: "🌴", label: t.matcher.regionSea, desc: t.matcher.regionSeaDesc },
        { value: "europe" as MatcherRegion, emoji: "🏰", label: t.matcher.regionEurope, desc: t.matcher.regionEuropeDesc },
        { value: "latam" as MatcherRegion, emoji: "🌮", label: t.matcher.regionLatam, desc: t.matcher.regionLatamDesc },
        { value: "asia" as MatcherRegion, emoji: "🏯", label: t.matcher.regionAsia, desc: t.matcher.regionAsiaDesc },
      ],
    }),
    [t]
  );

  useEffect(() => {
    if (!open) {
      setHydrated(false);
      return;
    }
    const saved = loadMatcherPrefs();
    setPrefs(saved);
    if (matcherPrefsComplete(saved)) setStep(STEP_KEYS.length);
    else {
      const filled = STEP_KEYS.findIndex((k) => !saved[k]);
      setStep(filled === -1 ? 0 : filled);
    }
    setHydrated(true);
  }, [open]);

  useEffect(() => {
    if (!open) return;
    const onKey = (e: KeyboardEvent) => {
      if (e.key === "Escape") onClose();
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [open, onClose]);

  const results = useMemo(() => {
    if (!matcherPrefsComplete(prefs)) return [];
    return [...destinations]
      .map((d) => ({ dest: d, score: scoreDestination(d, prefs) }))
      .sort((a, b) => b.score - a.score);
  }, [destinations, prefs]);

  const top3 = results.slice(0, 3).map((r) => r.dest);

  const currentKey = steps[step]?.key;
  const isComplete = step >= STEP_KEYS.length;
  const progress = isComplete ? 100 : ((step + 1) / STEP_KEYS.length) * 100;

  const select = (value: string) => {
    if (!currentKey) return;
    setDirection("forward");
    const next = { ...prefs, [currentKey]: value };
    setPrefs(next);
    saveMatcherPrefs(next);
    setTimeout(() => setStep((s) => s + 1), 280);
  };

  const goBack = () => {
    if (step === 0) {
      onClose();
      return;
    }
    setDirection("back");
    setStep((s) => s - 1);
  };

  const reset = () => {
    setStep(0);
    setPrefs(EMPTY_MATCHER_PREFS);
    clearMatcherPrefs();
    setDirection("forward");
  };

  const buildPlanFromTop = () => {
    if (top3.length === 0) return;
    const { added, skipped } = mergeDestinationsIntoTrip(top3, 1);
    onClose();
    if (added === 0) {
      toast(skipped ? t.matcher.alreadyAll : t.matcher.addFail, "info", {
        href: "/plan",
        label: t.strip.openPlan,
      });
      router.push("/plan");
      return;
    }
    toast(
      t.matcher.addedTop.replace("{n}", String(added)) +
        (skipped ? t.matcher.skipped.replace("{n}", String(skipped)) : ""),
      "success",
      { href: "/plan", label: t.strip.openPlan }
    );
    router.push("/plan");
  };

  const addOne = (dest: Destination, e: React.MouseEvent) => {
    e.preventDefault();
    e.stopPropagation();
    const { added } = mergeDestinationsIntoTrip([dest], 1);
    toast(
      added ? `${dest.emoji} ${dest.name} ${t.plan.addedToPlan}` : t.common.alreadyInPlan,
      added ? "success" : "info",
      { href: "/plan", label: t.strip.openPlan }
    );
  };

  if (!open) return null;

  return (
    <div
      className="modal-overlay open matcher-overlay"
      role="dialog"
      aria-modal="true"
      aria-label={t.matcher.tag.replace("{n}", "1").replace("{total}", String(STEP_KEYS.length))}
      onClick={(e) => e.target === e.currentTarget && onClose()}
    >
      {!hydrated ? (
        <div className="modal matcher-modal">
          <button className="modal-close" onClick={onClose} aria-label={t.matcher.close}>
            ✕
          </button>
          <p className="dest-empty">{t.common.loading}</p>
        </div>
      ) : (
      <div className="modal matcher-modal">
        <button className="modal-close" onClick={onClose} aria-label={t.matcher.close}>✕</button>

        <div className="matcher-progress">
          <div className="matcher-progress-bar" style={{ width: `${progress}%` }} />
        </div>

        <div className="matcher-body">
          {!isComplete && currentKey ? (
            <div className={`matcher-step matcher-${direction}`} key={step}>
              <div className="matcher-step-meta">
                <span className="section-tag">
                  {t.matcher.tag
                    .replace("{n}", String(step + 1))
                    .replace("{total}", String(STEP_KEYS.length))}
                </span>
                <h2>{steps[step].title}</h2>
                <p>{steps[step].subtitle}</p>
              </div>
              <div className="matcher-options">
                {options[currentKey].map((opt) => (
                  <button
                    key={opt.value}
                    className={`matcher-option${prefs[currentKey] === opt.value ? " selected" : ""}`}
                    onClick={() => select(opt.value)}
                  >
                    <span className="matcher-option-emoji">{opt.emoji}</span>
                    <div>
                      <strong>{opt.label}</strong>
                      <span>{opt.desc}</span>
                    </div>
                    <svg className="matcher-option-arrow" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
                      <path d="M9 18l6-6-6-6" />
                    </svg>
                  </button>
                ))}
              </div>
              <button className="matcher-back" onClick={goBack}>
                {step === 0 ? t.matcher.cancel : t.matcher.back}
              </button>
            </div>
          ) : (
            <div className="matcher-results matcher-forward">
              <div className="matcher-step-meta">
                <span className="section-tag">{t.matcher.resultsTag}</span>
                <h2>{t.matcher.resultsTitle}</h2>
                <p>{t.matcher.resultsSub}</p>
              </div>
              {results.length === 0 ? (
                <div className="notif-empty">
                  <p className="dest-empty">{t.matcher.empty}</p>
                  <div className="dating-empty-actions">
                    <button type="button" className="btn btn-ghost" onClick={reset}>
                      {t.matcher.retry}
                    </button>
                    <Link href="/next-stop" className="btn btn-primary" onClick={onClose}>
                      {t.matcher.goNextStop}
                    </Link>
                  </div>
                </div>
              ) : (
                <>
                  <div className="matcher-result-list">
                    {results.slice(0, 8).map(({ dest, score }, i) => (
                      <div key={dest.slug} className={`matcher-result-card${i === 0 ? " top" : ""}`}>
                        <Link href={`/destinations/${dest.slug}`} className="matcher-result-main" onClick={onClose}>
                          <div className="matcher-result-rank">
                            {i === 0 ? "🥇" : i === 1 ? "🥈" : i === 2 ? "🥉" : `#${i + 1}`}
                          </div>
                          <span className="matcher-result-emoji">{dest.emoji}</span>
                          <div className="matcher-result-info">
                            <strong>{dest.name}</strong>
                            <span>{dest.country} · {dest.tag}</span>
                          </div>
                          <div className="matcher-result-score">
                            <div className="matcher-score-bar">
                              <div className="matcher-score-fill" style={{ width: `${Math.min((score / (results[0]?.score || 1)) * 100, 100)}%` }} />
                            </div>
                            <span>
                              {t.matcher.matchPct.replace(
                                "{n}",
                                String(Math.min(Math.round((score / (results[0]?.score || 1)) * 100), 100))
                              )}
                            </span>
                          </div>
                          <div className="matcher-result-tags">
                            <span>💰 ¥{dest.cost.toLocaleString()}</span>
                            <span>📶 {dest.speed}Mbps</span>
                            <span>⭐ {dest.rating}</span>
                          </div>
                        </Link>
                        <button type="button" className="matcher-add-btn" onClick={(e) => addOne(dest, e)}>
                          {t.matcher.addPlan}
                        </button>
                      </div>
                    ))}
                  </div>
                  <div className="matcher-actions">
                    <button type="button" className="btn btn-ghost" onClick={reset}>{t.matcher.retryBtn}</button>
                    {top3.length >= 2 && (
                      <Link
                        href={compareUrl(top3.map((d) => d.slug))}
                        className="btn btn-ghost"
                        onClick={onClose}
                      >
                        {t.matcher.compareTop.replace("{n}", String(top3.length))}
                      </Link>
                    )}
                    <button type="button" className="btn btn-primary" onClick={buildPlanFromTop} disabled={top3.length === 0}>
                      {t.matcher.writeTop.replace("{n}", String(Math.min(3, top3.length)))}
                    </button>
                  </div>
                </>
              )}
            </div>
          )}
        </div>
      </div>
      )}
    </div>
  );
}