import { type FormEvent, useState } from "react";
import { parsePhoneNumberFromString } from "libphonenumber-js";
import { Eye, EyeOff, Mail, Smartphone, UserRound } from "lucide-react";
import { useNavigate } from "react-router-dom";

import { useAuth } from "@/auth/useAuth";

type LoginMode = "email" | "phone" | "username";

const loginModes: Array<{
  value: LoginMode;
  label: string;
  icon: typeof Mail;
  placeholder: string;
}> = [
  { value: "email", label: "Email", icon: Mail, placeholder: "name@company.com" },
  { value: "phone", label: "Phone", icon: Smartphone, placeholder: "09XXXXXXXX" },
  { value: "username", label: "Username", icon: UserRound, placeholder: "username" },
];

const emailPattern = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
const usernamePattern = /^[a-zA-Z0-9._-]{3,32}$/;

const normalizeIdentifier = (mode: LoginMode, value: string) => {
  const trimmed = value.trim();

  if (mode === "email") {
    if (!emailPattern.test(trimmed.toLowerCase())) {
      throw new Error("Enter a valid email address.");
    }

    return trimmed.toLowerCase();
  }

  if (mode === "phone") {
    const parsed = parsePhoneNumberFromString(trimmed, "ET");

    if (!parsed?.isValid()) {
      throw new Error("Enter a valid Ethiopian phone number.");
    }

    return parsed.number;
  }

  if (!usernamePattern.test(trimmed)) {
    throw new Error("Username must be 3-32 characters and use letters, numbers, ., _, or -.");
  }

  return trimmed;
};

const LoginPage = () => {
  const navigate = useNavigate();
  const { login, verifyMfa } = useAuth();
  const [mode, setMode] = useState<LoginMode>("email");
  const [identifier, setIdentifier] = useState("");
  const [password, setPassword] = useState("");
  const [otp, setOtp] = useState("");
  const [needsMfa, setNeedsMfa] = useState(false);
  const [submitting, setSubmitting] = useState(false);
  const [showPassword, setShowPassword] = useState(false);
  const [normalizedIdentifier, setNormalizedIdentifier] = useState("");
  const [error, setError] = useState<string | null>(null);

  const currentMode = loginModes.find((item) => item.value === mode)!;
  const ModeIcon = currentMode.icon;

  const handleSubmit = async (event: FormEvent<HTMLFormElement>) => {
    event.preventDefault();
    setSubmitting(true);
    setError(null);

    try {
      const normalized = normalizeIdentifier(mode, identifier);
      setNormalizedIdentifier(normalized);

      const result = await login({ email: normalized, password });
      if (result.mfaRequired) {
        setNeedsMfa(true);
        return;
      }

      navigate("/dashboard/overview", { replace: true });
    } catch {
      setError("Unable to sign in with those credentials.");
    } finally {
      setSubmitting(false);
    }
  };

  const handleVerifyMfa = async (event: FormEvent<HTMLFormElement>) => {
    event.preventDefault();
    setSubmitting(true);
    setError(null);

    try {
      await verifyMfa({ email: normalizedIdentifier, otp: otp.trim() });
      navigate("/dashboard/overview", { replace: true });
    } catch {
      setError("Unable to verify the one-time code.");
    } finally {
      setSubmitting(false);
    }
  };

  return (
    <div className="min-h-screen px-6 py-10">
      <div className="mx-auto grid min-h-[calc(100vh-5rem)] max-w-6xl gap-8 lg:grid-cols-[1.1fr_0.9fr]">
        <section className="flex items-center">
          <div className="w-full rounded-[2rem] border border-border/60 bg-card p-8 shadow-[0_20px_60px_rgba(15,23,42,0.12)] md:p-10">
            {!needsMfa ? (
              <form className="space-y-6" onSubmit={handleSubmit}>
                <div>
                  <p className="text-sm font-medium uppercase tracking-[0.2em] text-[#0f766e]">
                    Sign in
                  </p>
                  <h2 className="mt-3 text-3xl font-semibold text-foreground">
                    EDR Backoffice
                  </h2>
                  <p className="mt-2 text-sm text-muted-foreground">
                    Use your email, phone number, or username to access the internal freight dashboard.
                  </p>
                </div>

                <div className="grid gap-4">
                  <label className="grid gap-2 text-sm font-medium text-foreground">
                    Sign in method
                    <select
                      value={mode}
                      onChange={(event) => setMode(event.target.value as LoginMode)}
                      className="h-12 rounded-xl border border-input bg-background px-4 text-sm outline-none transition focus:border-[#0f766e] focus:ring-2 focus:ring-[#0f766e]/20"
                    >
                      {loginModes.map((item) => (
                        <option key={item.value} value={item.value}>
                          {item.label}
                        </option>
                      ))}
                    </select>
                  </label>

                  <label className="grid gap-2 text-sm font-medium text-foreground">
                    {currentMode.label}
                    <div className="relative">
                      <ModeIcon className="pointer-events-none absolute left-4 top-1/2 h-4 w-4 -translate-y-1/2 text-muted-foreground" />
                      <input
                        value={identifier}
                        onChange={(event) => setIdentifier(event.target.value)}
                        placeholder={currentMode.placeholder}
                        className="h-12 w-full rounded-xl border border-input bg-background pl-11 pr-4 text-sm outline-none transition focus:border-[#0f766e] focus:ring-2 focus:ring-[#0f766e]/20"
                      />
                    </div>
                  </label>

                  <label className="grid gap-2 text-sm font-medium text-foreground">
                    Password
                    <div className="relative">
                      <input
                        type={showPassword ? "text" : "password"}
                        value={password}
                        onChange={(event) => setPassword(event.target.value)}
                        placeholder="Enter your password"
                        className="h-12 w-full rounded-xl border border-input bg-background px-4 pr-12 text-sm outline-none transition focus:border-[#0f766e] focus:ring-2 focus:ring-[#0f766e]/20"
                      />
                      <button
                        type="button"
                        onClick={() => setShowPassword((current) => !current)}
                        className="absolute right-3 top-1/2 -translate-y-1/2 text-muted-foreground transition hover:text-foreground"
                        aria-label={showPassword ? "Hide password" : "Show password"}
                      >
                        {showPassword ? <EyeOff className="h-4 w-4" /> : <Eye className="h-4 w-4" />}
                      </button>
                    </div>
                  </label>
                </div>

                {error ? (
                  <div className="rounded-xl border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
                    {error}
                  </div>
                ) : null}

                <button
                  type="submit"
                  disabled={submitting}
                  className="inline-flex h-12 w-full items-center justify-center rounded-xl bg-[#0f766e] px-4 text-sm font-semibold text-white transition hover:bg-[#115e59] disabled:cursor-not-allowed disabled:opacity-60"
                >
                  {submitting ? "Signing in..." : "Sign in"}
                </button>
              </form>
            ) : (
              <form className="space-y-6" onSubmit={handleVerifyMfa}>
                <div>
                  <p className="text-sm font-medium uppercase tracking-[0.2em] text-[#0f766e]">
                    Multi-factor verification
                  </p>
                  <h2 className="mt-3 text-3xl font-semibold text-foreground">
                    Confirm one-time code
                  </h2>
                  <p className="mt-2 text-sm text-muted-foreground">
                    We sent a verification code for {normalizedIdentifier}. Enter it below to complete sign in.
                  </p>
                </div>

                <label className="grid gap-2 text-sm font-medium text-foreground">
                  Verification code
                  <input
                    value={otp}
                    onChange={(event) => setOtp(event.target.value)}
                    placeholder="Enter the code"
                    className="h-12 w-full rounded-xl border border-input bg-background px-4 text-sm outline-none transition focus:border-[#0f766e] focus:ring-2 focus:ring-[#0f766e]/20"
                  />
                </label>

                {error ? (
                  <div className="rounded-xl border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-700">
                    {error}
                  </div>
                ) : null}

                <div className="grid gap-3 sm:grid-cols-2">
                  <button
                    type="button"
                    className="inline-flex h-12 items-center justify-center rounded-xl border border-input bg-background px-4 text-sm font-medium text-foreground transition hover:bg-accent"
                    onClick={() => {
                      setNeedsMfa(false);
                      setOtp("");
                      setError(null);
                    }}
                  >
                    Back
                  </button>
                  <button
                    type="submit"
                    disabled={submitting}
                    className="inline-flex h-12 items-center justify-center rounded-xl bg-[#0f766e] px-4 text-sm font-semibold text-white transition hover:bg-[#115e59] disabled:cursor-not-allowed disabled:opacity-60"
                  >
                    {submitting ? "Verifying..." : "Verify code"}
                  </button>
                </div>
              </form>
            )}
          </div>
        </section>
      </div>
    </div>
  );
};

export default LoginPage;