import { useState, useEffect, useRef, useCallback } from 'react';
import { toast } from 'sonner';
import { useQueryClient } from '@tanstack/react-query';
import {
  Settings,
  User,
  Palette,
  Cloud,
  CalendarDays,
  LayoutDashboard,
  MapPin,
  X,
  Search,
  Loader2,
} from 'lucide-react';
import { useSettings } from '@/hooks/useSettings';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import { cn } from '@/lib/utils';
import api from '@/lib/api';
import type { GeoLocation } from '@/types';

const accentColors = [
  { name: 'cyan', label: 'Cyan', color: '#06b6d4' },
  { name: 'blue', label: 'Blue', color: '#3b82f6' },
  { name: 'purple', label: 'Purple', color: '#8b5cf6' },
  { name: 'orange', label: 'Orange', color: '#f97316' },
  { name: 'green', label: 'Green', color: '#22c55e' },
];

export default function SettingsPage() {
  const queryClient = useQueryClient();
  const { settings, updateSettings, isUpdating } = useSettings();

  const [selectedColor, setSelectedColor] = useState(settings?.accent_color || 'cyan');
  const [upcomingDays, setUpcomingDays] = useState(settings?.upcoming_days || 7);
  const [preferredName, setPreferredName] = useState(settings?.preferred_name ?? '');
  const [locationQuery, setLocationQuery] = useState('');
  const [locationResults, setLocationResults] = useState<GeoLocation[]>([]);
  const [isSearching, setIsSearching] = useState(false);
  const [showDropdown, setShowDropdown] = useState(false);
  const searchRef = useRef<HTMLDivElement>(null);
  const debounceRef = useRef<ReturnType<typeof setTimeout>>();
  const [firstDayOfWeek, setFirstDayOfWeek] = useState(settings?.first_day_of_week ?? 0);

  // Sync state when settings load
  useEffect(() => {
    if (settings) {
      setSelectedColor(settings.accent_color);
      setUpcomingDays(settings.upcoming_days);
      setPreferredName(settings.preferred_name ?? '');
      setFirstDayOfWeek(settings.first_day_of_week);
    }
  }, [settings?.id]); // only re-sync on initial load (settings.id won't change)

  const hasLocation = settings?.weather_lat != null && settings?.weather_lon != null;

  const searchLocations = useCallback(async (query: string) => {
    if (query.length < 2) {
      setLocationResults([]);
      setShowDropdown(false);
      return;
    }
    setIsSearching(true);
    try {
      const { data } = await api.get<GeoLocation[]>('/weather/search', { params: { q: query } });
      setLocationResults(data);
      setShowDropdown(data.length > 0);
    } catch {
      setLocationResults([]);
      setShowDropdown(false);
    } finally {
      setIsSearching(false);
    }
  }, []);

  const handleLocationInputChange = (value: string) => {
    setLocationQuery(value);
    if (debounceRef.current) clearTimeout(debounceRef.current);
    debounceRef.current = setTimeout(() => searchLocations(value), 300);
  };

  const handleLocationSelect = async (loc: GeoLocation) => {
    const displayName = [loc.name, loc.state, loc.country].filter(Boolean).join(', ');
    setShowDropdown(false);
    setLocationQuery('');
    setLocationResults([]);
    try {
      await updateSettings({
        weather_city: displayName,
        weather_lat: loc.lat,
        weather_lon: loc.lon,
      });
      queryClient.invalidateQueries({ queryKey: ['weather'] });
      toast.success(`Weather location set to ${displayName}`);
    } catch {
      toast.error('Failed to update weather location');
    }
  };

  const handleLocationClear = async () => {
    try {
      await updateSettings({ weather_city: null, weather_lat: null, weather_lon: null });
      queryClient.invalidateQueries({ queryKey: ['weather'] });
      toast.success('Weather location cleared');
    } catch {
      toast.error('Failed to clear weather location');
    }
  };

  // Close dropdown on outside click
  useEffect(() => {
    const handler = (e: MouseEvent) => {
      if (searchRef.current && !searchRef.current.contains(e.target as Node)) {
        setShowDropdown(false);
      }
    };
    document.addEventListener('mousedown', handler);
    return () => document.removeEventListener('mousedown', handler);
  }, []);

  useEffect(() => {
    return () => {
      if (debounceRef.current) clearTimeout(debounceRef.current);
    };
  }, []);

  const handleNameSave = async () => {
    const trimmed = preferredName.trim();
    if (trimmed === (settings?.preferred_name || '')) return;
    try {
      await updateSettings({ preferred_name: trimmed || null });
      toast.success('Name updated');
    } catch {
      toast.error('Failed to update name');
    }
  };

  const handleColorChange = async (color: string) => {
    setSelectedColor(color);
    try {
      await updateSettings({ accent_color: color });
      toast.success('Accent color updated');
    } catch {
      toast.error('Failed to update accent color');
    }
  };

  const handleFirstDayChange = async (value: number) => {
    const previous = firstDayOfWeek;
    setFirstDayOfWeek(value);
    try {
      await updateSettings({ first_day_of_week: value });
      queryClient.invalidateQueries({ queryKey: ['calendar-events'] });
      toast.success(value === 0 ? 'Week starts on Sunday' : 'Week starts on Monday');
    } catch {
      setFirstDayOfWeek(previous);
      toast.error('Failed to update first day of week');
    }
  };

  const handleUpcomingDaysSave = async () => {
    if (isNaN(upcomingDays) || upcomingDays < 1 || upcomingDays > 30) return;
    if (upcomingDays === settings?.upcoming_days) return;
    try {
      await updateSettings({ upcoming_days: upcomingDays });
      toast.success('Settings updated');
    } catch {
      toast.error('Failed to update settings');
    }
  };

  return (
    <div className="flex flex-col h-full">
      {/* Page header — matches Stage 4-5 pages */}
      <div className="border-b bg-card px-6 h-16 flex items-center gap-3 shrink-0">
        <Settings className="h-5 w-5 text-accent" aria-hidden="true" />
        <h1 className="text-xl font-semibold font-heading">Settings</h1>
      </div>

      <div className="flex-1 overflow-y-auto p-6">
        <div className="max-w-5xl mx-auto">
          <div className="grid gap-6 lg:grid-cols-2">

            {/* ── Left column: Profile, Appearance, Weather ── */}
            <div className="space-y-6">

              {/* Profile */}
              <Card>
                <CardHeader>
                  <div className="flex items-center gap-3">
                    <div className="p-1.5 rounded-md bg-accent/10">
                      <User className="h-4 w-4 text-accent" aria-hidden="true" />
                    </div>
                    <div>
                      <CardTitle>Profile</CardTitle>
                      <CardDescription>Personalize how UMBRA greets you</CardDescription>
                    </div>
                  </div>
                </CardHeader>
                <CardContent>
                  <div className="space-y-2">
                    <Label htmlFor="preferred_name">Preferred Name</Label>
                    <Input
                      id="preferred_name"
                      type="text"
                      placeholder="Enter your name"
                      value={preferredName}
                      onChange={(e) => setPreferredName(e.target.value)}
                      onBlur={handleNameSave}
                      onKeyDown={(e) => { if (e.key === 'Enter') handleNameSave(); }}
                      maxLength={100}
                    />
                    <p className="text-sm text-muted-foreground">
                      Used in the dashboard greeting, e.g. "Good morning, {preferredName || 'Kyle'}."
                    </p>
                  </div>
                </CardContent>
              </Card>

              {/* Appearance */}
              <Card>
                <CardHeader>
                  <div className="flex items-center gap-3">
                    <div className="p-1.5 rounded-md bg-purple-500/10">
                      <Palette className="h-4 w-4 text-purple-400" aria-hidden="true" />
                    </div>
                    <div>
                      <CardTitle>Appearance</CardTitle>
                      <CardDescription>Customize the look and feel of your application</CardDescription>
                    </div>
                  </div>
                </CardHeader>
                <CardContent>
                  <div>
                    <Label>Accent Color</Label>
                    <div className="grid grid-cols-5 gap-3 mt-3">
                      {accentColors.map((color) => (
                        <button
                          key={color.name}
                          type="button"
                          onClick={() => handleColorChange(color.name)}
                          aria-pressed={selectedColor === color.name}
                          className={cn(
                            'flex flex-col items-center gap-2 p-3 rounded-lg border transition-all duration-150',
                            selectedColor === color.name
                              ? 'border-accent/50 bg-accent/5'
                              : 'border-border hover:border-border/80 hover:bg-card-elevated'
                          )}
                        >
                          <div
                            className="h-8 w-8 rounded-full"
                            style={{ backgroundColor: color.color }}
                          />
                          <span className="text-[10px] tracking-wider uppercase text-muted-foreground">
                            {color.label}
                          </span>
                        </button>
                      ))}
                    </div>
                  </div>
                </CardContent>
              </Card>

              {/* Weather */}
              <Card>
                <CardHeader>
                  <div className="flex items-center gap-3">
                    <div className="p-1.5 rounded-md bg-amber-500/10">
                      <Cloud className="h-4 w-4 text-amber-400" aria-hidden="true" />
                    </div>
                    <div>
                      <CardTitle>Weather</CardTitle>
                      <CardDescription>Configure the weather widget on your dashboard</CardDescription>
                    </div>
                  </div>
                </CardHeader>
                <CardContent>
                  <div className="space-y-2">
                    <Label>Location</Label>
                    {hasLocation ? (
                      <div className="flex items-center gap-2">
                        <span className="inline-flex items-center gap-2 rounded-md border border-accent/30 bg-accent/10 px-3 py-1.5 text-sm text-foreground">
                          <MapPin className="h-3.5 w-3.5 text-accent" />
                          {settings?.weather_city || `${settings?.weather_lat}, ${settings?.weather_lon}`}
                        </span>
                        <button
                          type="button"
                          onClick={handleLocationClear}
                          className="inline-flex items-center justify-center rounded-md h-7 w-7 text-muted-foreground hover:text-foreground hover:bg-muted transition-colors"
                          title="Clear location"
                          aria-label="Clear weather location"
                        >
                          <X className="h-4 w-4" />
                        </button>
                      </div>
                    ) : (
                      <div ref={searchRef} className="relative">
                        <div className="relative">
                          <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground pointer-events-none" />
                          <Input
                            type="text"
                            placeholder="Search for a city..."
                            value={locationQuery}
                            onChange={(e) => handleLocationInputChange(e.target.value)}
                            onFocus={() => { if (locationResults.length > 0) setShowDropdown(true); }}
                            className="pl-9 pr-9"
                          />
                          {isSearching && (
                            <Loader2 className="absolute right-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground animate-spin" />
                          )}
                        </div>
                        {showDropdown && (
                          <div className="absolute z-50 mt-1 w-full rounded-md border bg-popover shadow-lg overflow-hidden">
                            {locationResults.map((loc, i) => (
                              <button
                                key={`${loc.lat}-${loc.lon}-${i}`}
                                type="button"
                                onClick={() => handleLocationSelect(loc)}
                                className="flex items-center gap-2.5 w-full px-3 py-2.5 text-sm text-left hover:bg-accent/10 transition-colors"
                              >
                                <MapPin className="h-3.5 w-3.5 text-muted-foreground shrink-0" />
                                <span>
                                  <span className="text-foreground font-medium">{loc.name}</span>
                                  {(loc.state || loc.country) && (
                                    <span className="text-muted-foreground">
                                      {loc.state ? `, ${loc.state}` : ''}{loc.country ? `, ${loc.country}` : ''}
                                    </span>
                                  )}
                                </span>
                              </button>
                            ))}
                          </div>
                        )}
                      </div>
                    )}
                    <p className="text-sm text-muted-foreground">
                      Search and select your city for accurate weather data on the dashboard.
                    </p>
                  </div>
                </CardContent>
              </Card>

            </div>

            {/* ── Right column: Calendar, Dashboard ── */}
            <div className="space-y-6">

              {/* Calendar */}
              <Card>
                <CardHeader>
                  <div className="flex items-center gap-3">
                    <div className="p-1.5 rounded-md bg-blue-500/10">
                      <CalendarDays className="h-4 w-4 text-blue-400" aria-hidden="true" />
                    </div>
                    <div>
                      <CardTitle>Calendar</CardTitle>
                      <CardDescription>Configure your calendar preferences</CardDescription>
                    </div>
                  </div>
                </CardHeader>
                <CardContent>
                  <div className="space-y-2">
                    <Label>First Day of Week</Label>
                    <div className="flex items-center rounded-md border border-border overflow-hidden w-fit">
                      <button
                        type="button"
                        onClick={() => handleFirstDayChange(0)}
                        className={cn(
                          'px-4 py-2 text-sm font-medium transition-colors duration-150',
                          firstDayOfWeek === 0
                            ? 'text-accent'
                            : 'text-muted-foreground hover:text-foreground hover:bg-card-elevated'
                        )}
                        style={{
                          backgroundColor: firstDayOfWeek === 0 ? 'hsl(var(--accent-color) / 0.15)' : undefined,
                          color: firstDayOfWeek === 0 ? 'hsl(var(--accent-color))' : undefined,
                        }}
                      >
                        Sunday
                      </button>
                      <button
                        type="button"
                        onClick={() => handleFirstDayChange(1)}
                        className={cn(
                          'px-4 py-2 text-sm font-medium transition-colors duration-150',
                          firstDayOfWeek === 1
                            ? 'text-accent'
                            : 'text-muted-foreground hover:text-foreground hover:bg-card-elevated'
                        )}
                        style={{
                          backgroundColor: firstDayOfWeek === 1 ? 'hsl(var(--accent-color) / 0.15)' : undefined,
                          color: firstDayOfWeek === 1 ? 'hsl(var(--accent-color))' : undefined,
                        }}
                      >
                        Monday
                      </button>
                    </div>
                    <p className="text-sm text-muted-foreground">
                      Sets which day the calendar week starts on
                    </p>
                  </div>
                </CardContent>
              </Card>

              {/* Dashboard */}
              <Card>
                <CardHeader>
                  <div className="flex items-center gap-3">
                    <div className="p-1.5 rounded-md bg-teal-500/10">
                      <LayoutDashboard className="h-4 w-4 text-teal-400" aria-hidden="true" />
                    </div>
                    <div>
                      <CardTitle>Dashboard</CardTitle>
                      <CardDescription>Configure your dashboard preferences</CardDescription>
                    </div>
                  </div>
                </CardHeader>
                <CardContent>
                  <div className="space-y-2">
                    <Label htmlFor="upcoming_days">Upcoming Days Range</Label>
                    <div className="flex gap-3 items-center">
                      <Input
                        id="upcoming_days"
                        type="number"
                        min="1"
                        max="30"
                        value={upcomingDays}
                        onChange={(e) => setUpcomingDays(parseInt(e.target.value))}
                        onBlur={handleUpcomingDaysSave}
                        onKeyDown={(e) => { if (e.key === 'Enter') handleUpcomingDaysSave(); }}
                        className="w-24"
                        disabled={isUpdating}
                      />
                      <span className="text-sm text-muted-foreground">days</span>
                    </div>
                    <p className="text-sm text-muted-foreground">
                      How many days ahead to show in the upcoming items widget
                    </p>
                  </div>
                </CardContent>
              </Card>

            </div>

          </div>
        </div>
      </div>
    </div>
  );
}