"use client";

import { useState } from "react";
import { useRouter } from "next/navigation";
import Link from "next/link";
import { register } from "@/lib/api";
import { useAuth } from "@/lib/auth";
import { useTranslation } from "@/lib/i18n";

function getPasswordStrength(pw: string): { level: number; label: string; color: string } {
  if (!pw) return { level: 0, label: "", color: "" };
  let score = 0;
  if (pw.length >= 6) score++;
  if (pw.length >= 10) score++;
  if (/[A-Z]/.test(pw)) score++;
  if (/[0-9]/.test(pw)) score++;
  if (/[^A-Za-z0-9]/.test(pw)) score++;

  if (score <= 1) return { level: 1, label: "weak", color: "bg-red-500" };
  if (score <= 2) return { level: 2, label: "fair", color: "bg-orange-500" };
  if (score <= 3) return { level: 3, label: "good", color: "bg-yellow-500" };
  if (score <= 4) return { level: 4, label: "strong", color: "bg-green-500" };
  return { level: 5, label: "excellent", color: "bg-emerald-500" };
}

export default function RegisterPage() {
  const [email, setEmail] = useState("");
  const [name, setName] = useState("");
  const [phone, setPhone] = useState("");
  const [password, setPassword] = useState("");
  const [confirmPassword, setConfirmPassword] = useState("");
  const [showPassword, setShowPassword] = useState(false);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState("");
  const { setAuth } = useAuth();
  const { t } = useTranslation();
  const router = useRouter();

  const strength = getPasswordStrength(password);
  const passwordsMatch = password === confirmPassword;

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    if (!email.trim() || !name.trim()) {
      setError(t("common.error"));
      return;
    }
    if (!password || password.length < 6) {
      setError(t("auth.passwordMinLength"));
      return;
    }
    if (password !== confirmPassword) {
      setError(t("auth.passwordMismatch"));
      return;
    }
    setLoading(true);
    setError("");
    try {
      const result = await register({
        email: email.trim(),
        name: name.trim(),
        phone: phone.trim() || undefined,
        password: password,
      });
      setAuth(result.data.token, result.data.user);
      router.push("/tasks");
    } catch (err) {
      setError(err instanceof Error ? err.message : t("common.error"));
    } finally {
      setLoading(false);
    }
  }

  return (
    <div className="min-h-[70vh] flex items-center justify-center">
      <div className="w-full max-w-sm">
        <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-2xl p-6 shadow-sm">
          <h1 className="text-2xl font-bold text-center mb-6">{t("auth.register")}</h1>

          {error && (
            <div className="bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-800 text-red-700 dark:text-red-300 px-4 py-3 rounded-lg text-sm mb-4">
              {error}
            </div>
          )}

          <form onSubmit={handleSubmit} className="space-y-4">
            <div>
              <label className="block text-sm font-medium mb-1">{t("auth.name")} *</label>
              <input
                type="text"
                value={name}
                onChange={(e) => setName(e.target.value)}
                className="w-full px-3 py-2.5 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none"
                autoFocus
              />
            </div>

            <div>
              <label className="block text-sm font-medium mb-1">{t("auth.email")} *</label>
              <input
                type="email"
                value={email}
                onChange={(e) => setEmail(e.target.value)}
                className="w-full px-3 py-2.5 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none"
                autoComplete="email"
              />
            </div>

            <div>
              <label className="block text-sm font-medium mb-1">{t("auth.phone")}</label>
              <input
                type="tel"
                value={phone}
                onChange={(e) => setPhone(e.target.value)}
                className="w-full px-3 py-2.5 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none"
                placeholder="+420 123 456 789"
              />
            </div>

            <div>
              <label className="block text-sm font-medium mb-1">{t("auth.password")} *</label>
              <div className="relative">
                <input
                  type={showPassword ? "text" : "password"}
                  value={password}
                  onChange={(e) => setPassword(e.target.value)}
                  className="w-full px-3 py-2.5 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none pr-10"
                  placeholder="******"
                  autoComplete="new-password"
                />
                <button
                  type="button"
                  onClick={() => setShowPassword(!showPassword)}
                  className="absolute right-3 top-1/2 -translate-y-1/2 text-gray-400 hover:text-gray-600 dark:hover:text-gray-300 text-sm"
                  tabIndex={-1}
                >
                  {showPassword ? t("auth.hidePassword") : t("auth.showPassword")}
                </button>
              </div>
              {password && (
                <div className="mt-2">
                  <div className="flex gap-1 mb-1">
                    {[1, 2, 3, 4, 5].map((i) => (
                      <div
                        key={i}
                        className={`h-1.5 flex-1 rounded-full ${
                          i <= strength.level ? strength.color : "bg-gray-200 dark:bg-gray-700"
                        }`}
                      />
                    ))}
                  </div>
                  <p className="text-xs text-muted">{t(`auth.strength.${strength.label}`)}</p>
                </div>
              )}
              <p className="text-xs text-muted mt-1">{t("auth.passwordMinLength")}</p>
            </div>

            <div>
              <label className="block text-sm font-medium mb-1">{t("auth.confirmPassword")} *</label>
              <input
                type={showPassword ? "text" : "password"}
                value={confirmPassword}
                onChange={(e) => setConfirmPassword(e.target.value)}
                className={`w-full px-3 py-2.5 border rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent outline-none ${
                  confirmPassword && !passwordsMatch
                    ? "border-red-400 dark:border-red-600"
                    : "border-gray-300 dark:border-gray-600"
                }`}
                placeholder="******"
                autoComplete="new-password"
              />
              {confirmPassword && !passwordsMatch && (
                <p className="text-xs text-red-500 mt-1">{t("auth.passwordMismatch")}</p>
              )}
            </div>

            <button
              type="submit"
              disabled={loading || (!!confirmPassword && !passwordsMatch)}
              className="w-full bg-blue-600 hover:bg-blue-700 text-white font-medium py-2.5 px-4 rounded-lg transition-colors disabled:opacity-50"
            >
              {loading ? t("common.loading") : t("auth.registerBtn")}
            </button>
          </form>

          <p className="text-center text-sm text-muted mt-4">
            {t("auth.hasAccount")}{" "}
            <Link href="/login" className="text-blue-600 hover:underline">
              {t("auth.submit")}
            </Link>
          </p>
        </div>
      </div>
    </div>
  );
}