import { useState, useEffect } from 'react';
import { useSeoMeta } from '@unhead/react';
import { useNavigate, useParams } from 'react-router-dom';
import ngeohash from 'ngeohash';
import { Layout } from '@/components/Layout';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Textarea } from '@/components/ui/textarea';
import { Label } from '@/components/ui/label';
import { Badge } from '@/components/ui/badge';
import { Skeleton } from '@/components/ui/skeleton';
import { useNostrPublish } from '@/hooks/useNostrPublish';
import { useCurrentUser } from '@/hooks/useCurrentUser';
import { useUploadFile } from '@/hooks/useUploadFile';
import { useToast } from '@/hooks/useToast';
import { useSkateEvent } from '@/hooks/useSkateEvents';
import { useEventRsvps, eventCoord } from '@/hooks/useEventRsvps';
import { usePostEventUpdate } from '@/hooks/useEventUpdates';
import { LoginArea } from '@/components/auth/LoginArea';
import { CALENDAR_EVENT_KIND, EVENT_TYPE_LABELS, type EventUpdateKind } from '@/lib/types';
import { cn } from '@/lib/utils';
import {
  Calendar,
  Upload,
  X,
  Loader2,
  ArrowLeft,
  MapPin,
  AlertTriangle,
} from 'lucide-react';
import { Link } from 'react-router-dom';
import NotFound from './NotFound';

const EVENT_TYPES = Object.entries(EVENT_TYPE_LABELS);

function formatDateForInput(timestamp: number): string {
  const date = new Date(timestamp * 1000);
  return date.toISOString().split('T')[0];
}

function formatTimeForInput(timestamp: number): string {
  const date = new Date(timestamp * 1000);
  return date.toTimeString().slice(0, 5);
}

function EditEventSkeleton() {
  return (
    <Layout>
      <div className="container px-4 py-8 max-w-2xl">
        <Skeleton className="h-6 w-32 mb-4" />
        <Skeleton className="h-10 w-64 mb-2" />
        <Skeleton className="h-5 w-48 mb-6" />
        <Card>
          <CardHeader>
            <Skeleton className="h-6 w-32" />
            <Skeleton className="h-4 w-64" />
          </CardHeader>
          <CardContent className="space-y-6">
            <Skeleton className="h-10 w-full" />
            <Skeleton className="h-24 w-full" />
            <div className="grid grid-cols-2 gap-4">
              <Skeleton className="h-10 w-full" />
              <Skeleton className="h-10 w-full" />
            </div>
            <Skeleton className="h-10 w-full" />
          </CardContent>
        </Card>
      </div>
    </Layout>
  );
}

export default function EditEventPage() {
  const { pubkey, identifier } = useParams<{ pubkey: string; identifier: string }>();
  const navigate = useNavigate();
  const { user } = useCurrentUser();
  const { data: event, isLoading, error } = useSkateEvent(identifier || '', pubkey);
  const { mutateAsync: createEvent, isPending: isPublishing } = useNostrPublish();
  const { mutateAsync: uploadFile, isPending: isUploading } = useUploadFile();
  const { toast } = useToast();

  // RSVP audience + host-update poster, so edits can auto-notify attendees.
  const rsvpSummary = useEventRsvps(event ? eventCoord(event) : undefined);
  const { mutateAsync: postUpdate } = usePostEventUpdate();

  // Form state
  const [title, setTitle] = useState('');
  const [description, setDescription] = useState('');
  const [location, setLocation] = useState('');
  const [latitude, setLatitude] = useState('');
  const [longitude, setLongitude] = useState('');
  const [startDate, setStartDate] = useState('');
  const [startTime, setStartTime] = useState('');
  const [endDate, setEndDate] = useState('');
  const [endTime, setEndTime] = useState('');
  const [selectedTypes, setSelectedTypes] = useState<string[]>([]);
  const [image, setImage] = useState<string | null>(null);
  const [isGettingLocation, setIsGettingLocation] = useState(false);
  const [initialized, setInitialized] = useState(false);

  useSeoMeta({
    title: event ? `Edit ${event.title} - SkateSpots` : 'Edit Event - SkateSpots',
    description: 'Edit your skateboarding event.',
  });

  // Initialize form with existing data
  useEffect(() => {
    if (event && !initialized) {
      setTitle(event.title);
      setDescription(event.description || '');
      setLocation(event.location || '');
      setSelectedTypes(event.types);
      setImage(event.image || null);

      // Set dates and times
      setStartDate(formatDateForInput(event.start));
      setStartTime(formatTimeForInput(event.start));

      if (event.end) {
        setEndDate(formatDateForInput(event.end));
        setEndTime(formatTimeForInput(event.end));
      }

      // Decode geohash to get coordinates
      if (event.geohash) {
        const { latitude: lat, longitude: lng } = ngeohash.decode(event.geohash);
        setLatitude(lat.toFixed(6));
        setLongitude(lng.toFixed(6));
      }

      setInitialized(true);
    }
  }, [event, initialized]);

  const toggleType = (type: string) => {
    setSelectedTypes((prev) =>
      prev.includes(type) ? prev.filter((t) => t !== type) : [...prev, type]
    );
  };

  const getCurrentLocation = () => {
    if (!navigator.geolocation) {
      toast({
        title: 'Geolocation not supported',
        description: 'Your browser does not support geolocation.',
        variant: 'destructive',
      });
      return;
    }

    setIsGettingLocation(true);
    navigator.geolocation.getCurrentPosition(
      (position) => {
        setLatitude(position.coords.latitude.toFixed(6));
        setLongitude(position.coords.longitude.toFixed(6));
        setIsGettingLocation(false);
        toast({
          title: 'Location found',
          description: 'Your current location has been set.',
        });
      },
      (error) => {
        setIsGettingLocation(false);
        toast({
          title: 'Location error',
          description: error.message,
          variant: 'destructive',
        });
      }
    );
  };

  const handleImageUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
    const files = e.target.files;
    if (!files || files.length === 0) return;

    try {
      const file = files[0];
      const tags = await uploadFile(file);
      const url = tags[0]?.[1];
      if (url) {
        setImage(url);
        toast({
          title: 'Image uploaded',
          description: 'Your image has been uploaded successfully.',
        });
      }
    } catch (error) {
      toast({
        title: 'Upload failed',
        description: error instanceof Error ? error.message : 'Failed to upload image',
        variant: 'destructive',
      });
    }

    e.target.value = '';
  };

  const removeImage = () => {
    setImage(null);
  };

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();

    if (!event) return;

    if (!title.trim()) {
      toast({
        title: 'Title required',
        description: 'Please enter a name for this event.',
        variant: 'destructive',
      });
      return;
    }

    if (!startDate || !startTime) {
      toast({
        title: 'Start time required',
        description: 'Please enter when the event starts.',
        variant: 'destructive',
      });
      return;
    }

    // Parse start time
    const startDateTime = new Date(`${startDate}T${startTime}`);
    const startTimestamp = Math.floor(startDateTime.getTime() / 1000);

    if (isNaN(startTimestamp)) {
      toast({
        title: 'Invalid date',
        description: 'Please enter a valid start date and time.',
        variant: 'destructive',
      });
      return;
    }

    // Parse end time if provided
    let endTimestamp: number | undefined;
    if (endDate && endTime) {
      const endDateTime = new Date(`${endDate}T${endTime}`);
      endTimestamp = Math.floor(endDateTime.getTime() / 1000);

      if (isNaN(endTimestamp) || endTimestamp <= startTimestamp) {
        toast({
          title: 'Invalid end time',
          description: 'End time must be after start time.',
          variant: 'destructive',
        });
        return;
      }
    }

    try {
      // Build tags - use the same identifier to update the addressable event
      const tags: string[][] = [
        ['d', event.identifier],
        ['title', title.trim()],
        ['start', startTimestamp.toString()],
        ['t', 'skateboarding'],
        ['alt', `Skate event: ${title.trim()}`],
      ];

      if (endTimestamp) {
        tags.push(['end', endTimestamp.toString()]);
      }

      if (location.trim()) {
        tags.push(['location', location.trim()]);
      }

      // Add geohash if coordinates provided
      if (latitude && longitude) {
        const lat = parseFloat(latitude);
        const lng = parseFloat(longitude);
        if (!isNaN(lat) && !isNaN(lng) && lat >= -90 && lat <= 90 && lng >= -180 && lng <= 180) {
          const geohash = ngeohash.encode(lat, lng, 7);
          tags.push(['g', geohash]);
        }
      }

      for (const type of selectedTypes) {
        tags.push(['t', type]);
      }

      if (image) {
        tags.push(['image', image]);
      }

      // Preserve sponsors from the original event (the edit form doesn't manage
      // them yet, so carry them through untouched instead of dropping them).
      for (const sponsorTag of event.event.tags.filter(([name]) => name === 'sponsor')) {
        tags.push(sponsorTag);
      }

      // Detect the changes attendees care about (time / location) BEFORE we
      // overwrite the event, so we can auto-notify RSVPers.
      const newLocation = location.trim();
      const timeChanged = startTimestamp !== event.start || endTimestamp !== event.end;
      const locationChanged = newLocation !== (event.location || '');

      await createEvent({
        kind: CALENDAR_EVENT_KIND,
        content: description.trim(),
        tags,
      });

      // Auto-alert attendees when the when/where changed.
      const audience = [...rsvpSummary.going, ...rsvpSummary.tentative];
      if ((timeChanged || locationChanged) && audience.length > 0) {
        const updateKind: EventUpdateKind = timeChanged ? 'reschedule' : 'relocation';
        const parts: string[] = [];
        if (timeChanged) {
          parts.push(
            `New time: ${startDateTime.toLocaleDateString(undefined, { weekday: 'short', month: 'short', day: 'numeric' })} at ${startDateTime.toLocaleTimeString(undefined, { hour: 'numeric', minute: '2-digit' })}.`,
          );
        }
        if (locationChanged) {
          parts.push(newLocation ? `New spot: ${newLocation}.` : 'Location updated.');
        }
        try {
          await postUpdate({
            event: { ...event, start: startTimestamp, end: endTimestamp, location: newLocation },
            message: `${parts.join(' ')} — see the event for details.`,
            updateKind,
            notifyPubkeys: audience,
          });
        } catch {
          // Non-fatal: the edit still succeeded even if the alert didn't post.
        }
      }

      const notified = (timeChanged || locationChanged) && audience.length > 0;
      toast({
        title: 'Event updated!',
        description: notified
          ? `Changes published — ${new Set(audience).size} attendee${new Set(audience).size === 1 ? '' : 's'} notified.`
          : 'Your changes have been published to the network.',
      });

      navigate(`/event/${user?.pubkey}/${event.identifier}`);
    } catch (error) {
      toast({
        title: 'Failed to update',
        description: error instanceof Error ? error.message : 'Something went wrong',
        variant: 'destructive',
      });
    }
  };

  if (isLoading) {
    return <EditEventSkeleton />;
  }

  if (error || !event) {
    return <NotFound />;
  }

  // Check if user is logged in
  if (!user) {
    return (
      <Layout>
        <div className="container px-4 py-8">
          <Card className="max-w-xl mx-auto border-dashed">
            <CardContent className="py-12 text-center">
              <Calendar className="h-12 w-12 mx-auto mb-4 text-muted-foreground/50" />
              <h2 className="text-xl font-bold mb-2">Login Required</h2>
              <p className="text-muted-foreground mb-6">
                You need to log in to edit this event.
              </p>
              <LoginArea className="justify-center" />
            </CardContent>
          </Card>
        </div>
      </Layout>
    );
  }

  // Check if user is the owner
  if (user.pubkey !== event.pubkey) {
    return (
      <Layout>
        <div className="container px-4 py-8">
          <Card className="max-w-xl mx-auto border-destructive">
            <CardContent className="py-12 text-center">
              <AlertTriangle className="h-12 w-12 mx-auto mb-4 text-destructive" />
              <h2 className="text-xl font-bold mb-2">Access Denied</h2>
              <p className="text-muted-foreground mb-6">
                You can only edit events that you created.
              </p>
              <Link to={`/event/${event.pubkey}/${event.identifier}`}>
                <Button variant="outline">Back to Event</Button>
              </Link>
            </CardContent>
          </Card>
        </div>
      </Layout>
    );
  }

  return (
    <Layout>
      <div className="container px-4 py-8 max-w-2xl">
        <div className="mb-6">
          <Link
            to={`/event/${event.pubkey}/${event.identifier}`}
            className="inline-flex items-center text-muted-foreground hover:text-foreground transition-colors mb-4"
          >
            <ArrowLeft className="h-4 w-4 mr-2" />
            Back to Event
          </Link>
          <h1 className="text-3xl font-bold">Edit Event</h1>
          <p className="text-muted-foreground mt-1">
            Update the details for {event.title}
          </p>
        </div>

        <form onSubmit={handleSubmit}>
          <Card>
            <CardHeader>
              <CardTitle>Event Details</CardTitle>
              <CardDescription>
                Update the information about this event. All fields marked with * are required.
              </CardDescription>
            </CardHeader>
            <CardContent className="space-y-6">
              {/* Title */}
              <div className="space-y-2">
                <Label htmlFor="title">Event Name *</Label>
                <Input
                  id="title"
                  placeholder="e.g., Summer Skate Session"
                  value={title}
                  onChange={(e) => setTitle(e.target.value)}
                  required
                />
              </div>

              {/* Description */}
              <div className="space-y-2">
                <Label htmlFor="description">Description</Label>
                <Textarea
                  id="description"
                  placeholder="Describe the event, what to expect, rules, prizes, etc."
                  value={description}
                  onChange={(e) => setDescription(e.target.value)}
                  rows={4}
                />
              </div>

              {/* Start Date/Time */}
              <div className="space-y-2">
                <Label>Start Date & Time *</Label>
                <div className="grid grid-cols-2 gap-4">
                  <Input
                    type="date"
                    value={startDate}
                    onChange={(e) => setStartDate(e.target.value)}
                    required
                  />
                  <Input
                    type="time"
                    value={startTime}
                    onChange={(e) => setStartTime(e.target.value)}
                    required
                  />
                </div>
              </div>

              {/* End Date/Time */}
              <div className="space-y-2">
                <Label>End Date & Time (optional)</Label>
                <div className="grid grid-cols-2 gap-4">
                  <Input
                    type="date"
                    value={endDate}
                    onChange={(e) => setEndDate(e.target.value)}
                  />
                  <Input
                    type="time"
                    value={endTime}
                    onChange={(e) => setEndTime(e.target.value)}
                  />
                </div>
              </div>

              {/* Location Address */}
              <div className="space-y-2">
                <Label htmlFor="location">Venue / Address</Label>
                <Input
                  id="location"
                  placeholder="e.g., Venice Beach Skatepark, CA"
                  value={location}
                  onChange={(e) => setLocation(e.target.value)}
                />
              </div>

              {/* Coordinates (optional for events) */}
              <div className="space-y-2">
                <Label>Coordinates (optional)</Label>
                <div className="grid grid-cols-2 gap-4">
                  <Input
                    placeholder="Latitude"
                    value={latitude}
                    onChange={(e) => setLatitude(e.target.value)}
                  />
                  <Input
                    placeholder="Longitude"
                    value={longitude}
                    onChange={(e) => setLongitude(e.target.value)}
                  />
                </div>
                <Button
                  type="button"
                  variant="outline"
                  size="sm"
                  onClick={getCurrentLocation}
                  disabled={isGettingLocation}
                  className="mt-2"
                >
                  {isGettingLocation ? (
                    <>
                      <Loader2 className="h-4 w-4 mr-2 animate-spin" />
                      Getting location...
                    </>
                  ) : (
                    <>
                      <MapPin className="h-4 w-4 mr-2" />
                      Use my current location
                    </>
                  )}
                </Button>
              </div>

              {/* Event Types */}
              <div className="space-y-2">
                <Label>Event Type(s)</Label>
                <div className="flex flex-wrap gap-2">
                  {EVENT_TYPES.map(([type, label]) => (
                    <Badge
                      key={type}
                      variant={selectedTypes.includes(type) ? 'default' : 'outline'}
                      className={cn(
                        'cursor-pointer transition-colors',
                        selectedTypes.includes(type)
                          ? 'bg-primary hover:bg-primary/90'
                          : 'hover:bg-muted'
                      )}
                      onClick={() => toggleType(type)}
                    >
                      {label}
                    </Badge>
                  ))}
                </div>
              </div>

              {/* Cover Image */}
              <div className="space-y-2">
                <Label>Cover Image</Label>
                {image ? (
                  <div className="relative aspect-video rounded-lg overflow-hidden bg-muted max-w-xs">
                    <img src={image} alt="Event cover" className="w-full h-full object-cover" />
                    <button
                      type="button"
                      onClick={removeImage}
                      className="absolute top-2 right-2 p-1 rounded-full bg-background/80 hover:bg-destructive hover:text-destructive-foreground transition-colors"
                    >
                      <X className="h-4 w-4" />
                    </button>
                  </div>
                ) : (
                  <label className="block max-w-xs aspect-video rounded-lg border-2 border-dashed flex flex-col items-center justify-center cursor-pointer hover:bg-muted/50 transition-colors">
                    <input
                      type="file"
                      accept="image/*"
                      className="hidden"
                      onChange={handleImageUpload}
                      disabled={isUploading}
                    />
                    {isUploading ? (
                      <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                    ) : (
                      <>
                        <Upload className="h-6 w-6 text-muted-foreground mb-1" />
                        <span className="text-sm text-muted-foreground">Upload cover image</span>
                      </>
                    )}
                  </label>
                )}
              </div>

              {/* Submit */}
              <Button
                type="submit"
                className="w-full"
                disabled={isPublishing || isUploading}
              >
                {isPublishing ? (
                  <>
                    <Loader2 className="h-4 w-4 mr-2 animate-spin" />
                    Saving...
                  </>
                ) : (
                  <>
                    <Calendar className="h-4 w-4 mr-2" />
                    Save Changes
                  </>
                )}
              </Button>
            </CardContent>
          </Card>
        </form>
      </div>
    </Layout>
  );
}