'use client';

import { useState, useEffect, useCallback } from 'react';
import { useSession } from 'next-auth/react';
import api from '@/services/api';

type DigestFrequency = 'instant' | 'daily' | 'weekly' | 'off';

interface NotificationCategory {
  id: string;
  label: string;
  description: string;
  email: boolean;
  inApp: boolean;
}

interface NotificationsFormProps {
  onSave?: (data: {
    notifications: NotificationCategory[];
    digestFrequency: DigestFrequency;
  }) => void;
}

const DEFAULT_NOTIFICATIONS: NotificationCategory[] = [
  {
    id: 'new_lead_alerts',
    label: 'New Lead Alerts',
    description: 'Choose what you want to be notified about and how.',
    email: true,
    inApp: true,
  },
  {
    id: 'message_updates',
    label: 'Message Updates',
    description: 'Notices about new messages from clients or other agents.',
    email: false,
    inApp: true,
  },
  {
    id: 'urgent_requests_tours',
    label: 'Urgent Requests & Tours',
    description: 'Immediate notifications for tour requests and time-sensitive items.',
    email: true,
    inApp: true,
  },
];

export function NotificationsForm({ onSave }: NotificationsFormProps) {
  const { data: session } = useSession();
  const [isLoading, setIsLoading] = useState(true);
  const [isSaving, setIsSaving] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [success, setSuccess] = useState<string | null>(null);

  const [notifications, setNotifications] = useState<NotificationCategory[]>(DEFAULT_NOTIFICATIONS);
  const [digestFrequency, setDigestFrequency] = useState<DigestFrequency>('instant');
  const [savedNotifications, setSavedNotifications] = useState<NotificationCategory[]>(DEFAULT_NOTIFICATIONS);
  const [savedDigestFrequency, setSavedDigestFrequency] = useState<DigestFrequency>('instant');

  const fetchPreferences = useCallback(async () => {
    if (!session) return;

    try {
      setIsLoading(true);
      const role = (session?.user as any)?.role;
      const endpoint = role === 'AGENT' ? '/agents/preferences/notifications' : '/users/preferences/notifications';

      const response = await api.get(endpoint);
      const savedPrefs = response.data?.data || response.data || {};

      if (savedPrefs.notifications) {
        const updated = DEFAULT_NOTIFICATIONS.map((item) => {
          const saved = savedPrefs.notifications[item.id];
          if (saved) {
            return {
              ...item,
              email: saved.email ?? item.email,
              inApp: saved.inApp ?? item.inApp,
            };
          }
          return item;
        });
        setNotifications(updated);
        setSavedNotifications(updated);
      }

      if (savedPrefs.digestFrequency) {
        setDigestFrequency(savedPrefs.digestFrequency);
        setSavedDigestFrequency(savedPrefs.digestFrequency);
      }
    } catch {
      console.log('No saved notification preferences found, using defaults');
    } finally {
      setIsLoading(false);
    }
  }, [session]);

  useEffect(() => {
    fetchPreferences();
  }, [fetchPreferences]);

  const toggleNotification = (id: string, type: 'email' | 'inApp') => {
    setNotifications((prev) =>
      prev.map((item) =>
        item.id === id ? { ...item, [type]: !item[type] } : item
      )
    );
  };

  const handleSave = async () => {
    setIsSaving(true);
    setError(null);
    setSuccess(null);

    try {
      const role = (session?.user as any)?.role;
      const endpoint = role === 'AGENT' ? '/agents/preferences/notifications' : '/users/preferences/notifications';

      const preferences = {
        notifications: notifications.reduce(
          (acc, item) => ({
            ...acc,
            [item.id]: { email: item.email, inApp: item.inApp },
          }),
          {}
        ),
        digestFrequency,
      };

      await api.put(endpoint, preferences);

      setSavedNotifications([...notifications]);
      setSavedDigestFrequency(digestFrequency);
      setSuccess('Notification preferences saved successfully!');

      if (onSave) {
        onSave({ notifications, digestFrequency });
      }

      setTimeout(() => setSuccess(null), 3000);
    } catch (err: unknown) {
      const error = err as { response?: { data?: { message?: string } } };
      setError(error.response?.data?.message || 'Failed to save notification preferences. Please try again.');
    } finally {
      setIsSaving(false);
    }
  };

  const hasChanges = JSON.stringify(notifications) !== JSON.stringify(savedNotifications) || digestFrequency !== savedDigestFrequency;

  const handleCancel = () => {
    if (!hasChanges) return;
    setNotifications([...savedNotifications]);
    setDigestFrequency(savedDigestFrequency);
    setError(null);
    setSuccess(null);
  };

  const Checkbox = ({
    checked,
    onToggle,
    label,
  }: {
    checked: boolean;
    onToggle: () => void;
    label: string;
  }) => (
    <label className="flex items-center gap-2 cursor-pointer">
      <button
        type="button"
        onClick={onToggle}
        className={`w-[16px] h-[16px] rounded-[2px] border flex items-center justify-center transition-colors ${
          checked
            ? 'bg-[#00293D] border-[#00293D]'
            : 'bg-white border-[#00293D]/30'
        }`}
      >
        {checked && (
          <svg width="10" height="8" viewBox="0 0 10 8" fill="none">
            <path
              d="M1 4L3.5 6.5L9 1"
              stroke="white"
              strokeWidth="1.5"
              strokeLinecap="round"
              strokeLinejoin="round"
            />
          </svg>
        )}
      </button>
      <span className="font-serif text-[14px] text-[#00293D]">{label}</span>
    </label>
  );

  const frequencyOptions: { value: DigestFrequency; label: string }[] = [
    { value: 'instant', label: 'Instant' },
    { value: 'daily', label: 'Daily' },
    { value: 'weekly', label: 'Weekly' },
    { value: 'off', label: 'Off' },
  ];

  if (isLoading) {
    return (
      <div className="flex items-center justify-center py-12">
        <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-[#e58625]"></div>
      </div>
    );
  }

  return (
    <>
      {/* Error Message */}
      {error && (
        <div className="mb-4 p-3 bg-red-50 border border-red-200 rounded-[10px] text-red-700 text-[13px] font-serif">
          {error}
        </div>
      )}

      {/* Success Message */}
      {success && (
        <div className="mb-4 p-3 bg-green-50 border border-green-200 rounded-[10px] text-green-700 text-[13px] font-serif">
          {success}
        </div>
      )}

      {/* Notification Preferences Card */}
      <div className="border border-[#00293d]/10 rounded-[15px] bg-white p-6">
        {/* Title */}
        <h2 className="font-fractul font-bold text-[20px] text-[#00293D] mb-4">
          Notification Preferences
        </h2>

        {/* Divider */}
        <div className="border-b border-[#00293D]/10 mb-6" />

        {/* Notification Categories */}
        <div className="space-y-0">
          {notifications.map((item, index) => (
            <div key={item.id}>
              <div className="flex items-start justify-between py-4">
                <div className="flex-1 pr-4">
                  <h3 className="font-fractul font-bold text-[14px] text-[#00293D] mb-1">
                    {item.label}
                  </h3>
                  <p className="font-serif text-[14px] text-[#00293D]/70">
                    {item.description}
                  </p>
                </div>
                <div className="flex items-center gap-8 flex-shrink-0">
                  <Checkbox
                    checked={item.email}
                    onToggle={() => toggleNotification(item.id, 'email')}
                    label="Email"
                  />
                  <Checkbox
                    checked={item.inApp}
                    onToggle={() => toggleNotification(item.id, 'inApp')}
                    label="In-App"
                  />
                </div>
              </div>
              {index < notifications.length - 1 && (
                <div className="border-b border-[#00293D]/10" />
              )}
            </div>
          ))}
        </div>

        {/* Divider before Email Digest */}
        <div className="border-b border-[#00293D]/10 mt-2 mb-6" />

        {/* Email Digest Frequency */}
        <div className="mb-8">
          <h3 className="font-fractul font-bold text-[14px] text-[#00293D] mb-1">
            Email Digest Frequency
          </h3>
          <p className="font-serif text-[14px] text-[#00293D]/70 mb-4">
            Choose how often you receive non-urgent email summaries
          </p>

          {/* Frequency Tabs */}
          <div className="inline-flex items-center border border-[#00293D]/10 rounded-[7px] h-[49px] px-2">
            {frequencyOptions.map((option, index) => (
              <div key={option.value} className="flex items-center h-full">
                <button
                  type="button"
                  onClick={() => setDigestFrequency(option.value)}
                  className={`px-5 py-1.5 text-[14px] font-fractul transition-colors rounded-[15px] ${
                    digestFrequency === option.value
                      ? 'bg-[#e58625] text-[#00293D]'
                      : 'text-[#00293D] hover:bg-[#00293D]/5'
                  }`}
                >
                  {option.label}
                </button>
                {index < frequencyOptions.length - 1 && (
                  <div className="w-px h-full bg-[#00293D]/10 mx-1" />
                )}
              </div>
            ))}
          </div>
        </div>

        {/* Action Buttons */}
        <div className="flex justify-end gap-4 pt-4 border-t border-[#00293D]/10">
          <button
            type="button"
            onClick={handleCancel}
            disabled={!hasChanges || isSaving}
            className="px-10 py-3 border border-[#00293D]/10 rounded-[15px] font-fractul font-bold text-[14px] text-[#00293D] hover:bg-[#00293D]/5 transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
          >
            Cancel
          </button>
          <button
            type="button"
            onClick={handleSave}
            disabled={isSaving}
            className="px-10 py-3 bg-[#e58625] rounded-[15px] font-fractul font-bold text-[14px] text-[#00293D] hover:bg-[#d47920] transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
          >
            {isSaving ? 'Saving...' : 'Save Changes'}
          </button>
        </div>
      </div>
    </>
  );
}