'use client';

import { Input, Label } from '@/components/input';
import { Logo } from '@/components/logo';
import { Button } from '@/components/ui/button';
import { apiFetch, apiUrl } from '@/lib/api';
import Link from 'next/link';
import { useEffect, useState } from 'react';

const ERROR_COPY: Record<string, string> = {
  google_failed: 'Google sign-in could not be completed. Please try again.',
  google_state: 'Google sign-in expired or was interrupted. Please try again.',
  github_failed: 'GitHub sign-in could not be completed. Please try again.',
  github_state: 'GitHub sign-in expired or was interrupted. Please try again.',
  invalid_phone: 'Enter your number in international format, e.g. +41 79 123 45 67.',
  rate_limited: 'Too many requests. Wait a few minutes and try again.',
  sms_request_failed: 'Could not send the SMS. Check the number and try again.',
  invalid_or_expired_code: 'That code has expired. Request a new one.',
  invalid_code: 'Wrong code. Check the SMS and try again.',
  too_many_attempts: 'Too many wrong attempts. Request a new code.',
  sms_verify_failed: 'Could not verify the code. Try again.',
};

function errCode(err: unknown): string {
  const detail = (err as { detail?: { error?: string } }).detail;
  return detail?.error ?? (err as Error).message ?? 'unknown';
}

export default function LoginPage() {
  const [providers, setProviders] = useState({ google: false, github: false, sms: false });
  const [method, setMethod] = useState<'email' | 'phone'>('email');
  const [error, setError] = useState<string | null>(null);

  // Email magic-link
  const [email, setEmail] = useState('');
  const [emailState, setEmailState] = useState<'idle' | 'sending' | 'sent'>('idle');

  // SMS one-time code
  const [phone, setPhone] = useState('');
  const [code, setCode] = useState('');
  const [smsStep, setSmsStep] = useState<'phone' | 'code'>('phone');
  const [smsBusy, setSmsBusy] = useState(false);

  useEffect(() => {
    apiFetch<{ google: boolean; github: boolean; sms: boolean }>('/v1/auth/providers')
      .then(setProviders)
      .catch(() => undefined);
    const err = new URLSearchParams(window.location.search).get('error');
    if (err) setError(ERROR_COPY[err] ?? 'Sign-in failed. Please try again.');
  }, []);

  async function sendMagicLink(e: React.FormEvent) {
    e.preventDefault();
    setEmailState('sending');
    setError(null);
    try {
      await apiFetch('/v1/auth/magic-link', { method: 'POST', body: JSON.stringify({ email }) });
      setEmailState('sent');
    } catch (err) {
      setEmailState('idle');
      setError(ERROR_COPY[errCode(err)] ?? 'Could not send the link.');
    }
  }

  async function requestSmsCode(e: React.FormEvent) {
    e.preventDefault();
    setSmsBusy(true);
    setError(null);
    try {
      await apiFetch('/v1/auth/sms/request', { method: 'POST', body: JSON.stringify({ phone }) });
      setSmsStep('code');
    } catch (err) {
      setError(ERROR_COPY[errCode(err)] ?? 'Could not send the SMS.');
    } finally {
      setSmsBusy(false);
    }
  }

  async function verifySmsCode(e: React.FormEvent) {
    e.preventDefault();
    setSmsBusy(true);
    setError(null);
    try {
      await apiFetch('/v1/auth/sms/verify', {
        method: 'POST',
        body: JSON.stringify({ phone, code }),
      });
      window.location.href = '/dashboard';
    } catch (err) {
      setError(ERROR_COPY[errCode(err)] ?? 'Could not verify the code.');
      setSmsBusy(false);
    }
  }

  const hasOAuth = providers.google || providers.github;

  return (
    <div className="flex min-h-screen items-center justify-center px-6">
      <div className="w-full max-w-sm">
        <Logo className="mb-10" />
        <h1 className="text-[20px] font-semibold tracking-tight">Sign in to your workspace</h1>
        <p className="mt-1 text-[13px] text-[--color-fg-muted]">
          Passwordless — pick whichever is easiest.
        </p>

        {hasOAuth && (
          <div className="mt-7 space-y-2">
            {providers.google && (
              <a
                href={apiUrl('/v1/auth/google')}
                className="flex h-10 w-full items-center justify-center gap-2.5 rounded-md border border-[--color-border] bg-[--color-bg-elevated] text-[13px] font-medium text-[--color-fg] transition-colors duration-200 hover:border-[--color-border-strong]"
              >
                <GoogleIcon />
                Continue with Google
              </a>
            )}
            {providers.github && (
              <a
                href={apiUrl('/v1/auth/github')}
                className="flex h-10 w-full items-center justify-center gap-2.5 rounded-md border border-[--color-border] bg-[--color-bg-elevated] text-[13px] font-medium text-[--color-fg] transition-colors duration-200 hover:border-[--color-border-strong]"
              >
                <GitHubIcon />
                Continue with GitHub
              </a>
            )}
          </div>
        )}

        {hasOAuth && (
          <div className="my-5 flex items-center gap-3">
            <span className="h-px flex-1 bg-[--color-border]" />
            <span className="text-[11px] uppercase tracking-wider text-[--color-fg-subtle]">
              or
            </span>
            <span className="h-px flex-1 bg-[--color-border]" />
          </div>
        )}

        {providers.sms && (
          <div
            className={`flex gap-1 rounded-md border border-[--color-border] p-1 ${hasOAuth ? '' : 'mt-7'}`}
          >
            {(['email', 'phone'] as const).map((m) => (
              <button
                key={m}
                type="button"
                onClick={() => {
                  setMethod(m);
                  setError(null);
                }}
                className={`h-7 flex-1 rounded text-[12px] font-medium transition-colors ${
                  method === m
                    ? 'bg-[--color-bg-subtle] text-[--color-fg]'
                    : 'text-[--color-fg-muted] hover:text-[--color-fg]'
                }`}
              >
                {m === 'email' ? 'Email' : 'Phone'}
              </button>
            ))}
          </div>
        )}

        <div className={providers.sms ? 'mt-4' : hasOAuth ? '' : 'mt-7'}>
          {method === 'email' && emailState !== 'sent' && (
            <form onSubmit={sendMagicLink} className="space-y-3">
              <div className="space-y-1.5">
                <Label htmlFor="email">Email</Label>
                <Input
                  id="email"
                  type="email"
                  required
                  autoComplete="email"
                  value={email}
                  onChange={(e) => setEmail(e.target.value)}
                  placeholder="you@company.com"
                />
              </div>
              <Button
                type="submit"
                variant="primary"
                size="lg"
                className="w-full"
                disabled={emailState === 'sending'}
              >
                {emailState === 'sending' ? 'Sending…' : 'Send magic link'}
              </Button>
            </form>
          )}

          {method === 'email' && emailState === 'sent' && (
            <div className="panel p-4">
              <p className="text-[13px]">
                Magic link sent to <span className="mono">{email}</span>.
              </p>
              <p className="mt-1.5 text-[12px] text-[--color-fg-muted]">
                Open it on this device to finish signing in.
              </p>
            </div>
          )}

          {method === 'phone' && smsStep === 'phone' && (
            <form onSubmit={requestSmsCode} className="space-y-3">
              <div className="space-y-1.5">
                <Label htmlFor="phone">Phone number</Label>
                <Input
                  id="phone"
                  type="tel"
                  inputMode="tel"
                  required
                  autoComplete="tel"
                  value={phone}
                  onChange={(e) => setPhone(e.target.value)}
                  placeholder="+41 79 123 45 67"
                />
              </div>
              <Button
                type="submit"
                variant="primary"
                size="lg"
                className="w-full"
                disabled={smsBusy}
              >
                {smsBusy ? 'Sending…' : 'Send code'}
              </Button>
            </form>
          )}

          {method === 'phone' && smsStep === 'code' && (
            <form onSubmit={verifySmsCode} className="space-y-3">
              <div className="space-y-1.5">
                <Label htmlFor="code" hint={`sent to ${phone}`}>
                  6-digit code
                </Label>
                <Input
                  id="code"
                  inputMode="numeric"
                  autoComplete="one-time-code"
                  required
                  maxLength={6}
                  value={code}
                  onChange={(e) => setCode(e.target.value.replace(/\D/g, ''))}
                  placeholder="123456"
                  className="mono tracking-[0.3em]"
                />
              </div>
              <Button
                type="submit"
                variant="primary"
                size="lg"
                className="w-full"
                disabled={smsBusy || code.length !== 6}
              >
                {smsBusy ? 'Verifying…' : 'Verify & sign in'}
              </Button>
              <button
                type="button"
                onClick={() => {
                  setSmsStep('phone');
                  setCode('');
                  setError(null);
                }}
                className="w-full text-[12px] text-[--color-fg-muted] transition-colors hover:text-[--color-fg]"
              >
                ← Use a different number
              </button>
            </form>
          )}

          {error && <p className="mt-3 text-[12px] text-[--color-danger]">{error}</p>}
        </div>

        <div className="mt-8 text-[12px] text-[--color-fg-subtle]">
          <Link href="/" className="transition-colors hover:text-[--color-fg]">
            ← Back to home
          </Link>
        </div>
      </div>
    </div>
  );
}

function GoogleIcon() {
  return (
    <svg width="16" height="16" viewBox="0 0 18 18" aria-hidden="true">
      <path
        fill="#4285F4"
        d="M17.64 9.2c0-.637-.057-1.251-.164-1.84H9v3.481h4.844a4.14 4.14 0 0 1-1.796 2.716v2.259h2.908c1.702-1.567 2.684-3.875 2.684-6.615Z"
      />
      <path
        fill="#34A853"
        d="M9 18c2.43 0 4.467-.806 5.956-2.184l-2.908-2.259c-.806.54-1.837.86-3.048.86-2.344 0-4.328-1.584-5.036-3.711H.957v2.332A8.997 8.997 0 0 0 9 18Z"
      />
      <path
        fill="#FBBC05"
        d="M3.964 10.706A5.41 5.41 0 0 1 3.682 9c0-.593.102-1.17.282-1.706V4.962H.957A8.997 8.997 0 0 0 0 9c0 1.452.348 2.827.957 4.038l3.007-2.332Z"
      />
      <path
        fill="#EA4335"
        d="M9 3.58c1.321 0 2.508.454 3.44 1.345l2.582-2.58C13.463.891 11.426 0 9 0A8.997 8.997 0 0 0 .957 4.962L3.964 7.294C4.672 5.167 6.656 3.58 9 3.58Z"
      />
    </svg>
  );
}

function GitHubIcon() {
  return (
    <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor" aria-hidden="true">
      <path d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82a7.6 7.6 0 0 1 2-.27c.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.01 8.01 0 0 0 16 8c0-4.42-3.58-8-8-8Z" />
    </svg>
  );
}