'use client';

import { useMemo, useState, useTransition } from 'react';
import {
  DndContext,
  closestCenter,
  PointerSensor,
  useSensor,
  useSensors,
  type DragEndEvent,
} from '@dnd-kit/core';
import {
  SortableContext,
  rectSortingStrategy,
  useSortable,
  arrayMove,
} from '@dnd-kit/sortable';
import { CSS } from '@dnd-kit/utilities';
import { setGifMoodUserRating, reorderGifMoodItems } from '@/actions/gif-mood';
import { Avatar } from '@/components/ui/Avatar';
import { GifMoodCard } from './GifMoodCard';
import { GifMoodAddForm } from './GifMoodAddForm';
import { GIF_MOOD_MAX_ITEMS } from '@/lib/types';

interface GifMoodItem {
  id: string;
  gifUrl: string;
  note: string | null;
  order: number;
  userId: string;
  user: {
    id: string;
    name: string | null;
    email: string;
  };
}

interface Share {
  id: string;
  userId: string;
  user: {
    id: string;
    name: string | null;
    email: string;
  };
}

interface GifMoodBoardProps {
  sessionId: string;
  currentUserId: string;
  items: GifMoodItem[];
  shares: Share[];
  owner: {
    id: string;
    name: string | null;
    email: string;
  };
  ratings: { userId: string; rating: number }[];
  canEdit: boolean;
}

function WeekRating({
  sessionId,
  isCurrentUser,
  canEdit,
  initialRating,
}: {
  sessionId: string;
  isCurrentUser: boolean;
  canEdit: boolean;
  initialRating: number | null;
}) {
  const [prevInitialRating, setPrevInitialRating] = useState(initialRating);
  const [rating, setRating] = useState<number | null>(initialRating);
  const [hovered, setHovered] = useState<number | null>(null);
  const [isPending, startTransition] = useTransition();

  if (prevInitialRating !== initialRating) {
    setPrevInitialRating(initialRating);
    setRating(initialRating);
  }

  const interactive = isCurrentUser && canEdit;
  const display = hovered ?? rating;

  function handleClick(n: number) {
    if (!interactive) return;
    setRating(n);
    startTransition(async () => {
      await setGifMoodUserRating(sessionId, n);
    });
  }

  return (
    <div
      className="flex items-center gap-0.5"
      onMouseLeave={() => setHovered(null)}
    >
      {[1, 2, 3, 4, 5].map((n) => {
        const filled = display !== null && n <= display;
        return (
          <button
            key={n}
            type="button"
            onClick={() => handleClick(n)}
            onMouseEnter={() => interactive && setHovered(n)}
            disabled={!interactive || isPending}
            className={`transition-all duration-100 ${interactive ? 'cursor-pointer hover:scale-125' : 'cursor-default'}`}
          >
            <svg
              width="16"
              height="16"
              viewBox="0 0 24 24"
              className={`transition-colors duration-100 ${
                filled ? 'text-amber-400' : 'text-border'
              }`}
            >
              <path
                d="M12 2l3.09 6.26L22 9.27l-5 4.87 1.18 6.88L12 17.77l-6.18 3.25L7 14.14 2 9.27l6.91-1.01L12 2z"
                fill="currentColor"
                stroke="currentColor"
                strokeWidth="1"
                strokeLinejoin="round"
              />
            </svg>
          </button>
        );
      })}
    </div>
  );
}

function DragHandle(props: React.HTMLAttributes<HTMLDivElement>) {
  return (
    <div
      {...props}
      className="absolute top-2 left-2 z-10 p-1.5 rounded-full bg-black/50 text-white opacity-0 group-hover/card:opacity-100 cursor-grab active:cursor-grabbing backdrop-blur-sm transition-opacity"
      title="Réorganiser"
    >
      <svg width="12" height="12" viewBox="0 0 12 12" fill="currentColor" aria-hidden>
        <circle cx="4" cy="2.5" r="1.2" />
        <circle cx="8" cy="2.5" r="1.2" />
        <circle cx="4" cy="6" r="1.2" />
        <circle cx="8" cy="6" r="1.2" />
        <circle cx="4" cy="9.5" r="1.2" />
        <circle cx="8" cy="9.5" r="1.2" />
      </svg>
    </div>
  );
}

function SortableGifMoodCard({
  sessionId,
  item,
  currentUserId,
  canEdit,
}: {
  sessionId: string;
  item: GifMoodItem;
  currentUserId: string;
  canEdit: boolean;
}) {
  const { attributes, listeners, setNodeRef, transform, transition, isDragging } = useSortable({
    id: item.id,
  });

  return (
    <div
      ref={setNodeRef}
      style={{ transform: CSS.Transform.toString(transform), transition }}
      className={`group/card relative ${isDragging ? 'opacity-50 z-50' : ''}`}
    >
      <DragHandle {...attributes} {...listeners} />
      <GifMoodCard
        sessionId={sessionId}
        item={item}
        currentUserId={currentUserId}
        canEdit={canEdit}
      />
    </div>
  );
}

// Subtle accent colors for each user section
const SECTION_COLORS = ['#ec4899', '#8b5cf6', '#3b82f6', '#10b981', '#f59e0b', '#ef4444'];

const GRID_COLS: Record<number, string> = {
  4: 'grid-cols-1 sm:grid-cols-2 md:grid-cols-3 lg:grid-cols-4',
  5: 'grid-cols-2 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-5',
  6: 'grid-cols-2 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-6',
};

function GridIcon({ cols }: { cols: number }) {
  return (
    <svg width="20" height="14" viewBox="0 0 20 14" fill="none" aria-hidden>
      {Array.from({ length: cols }).map((_, i) => {
        const w = (20 - (cols - 1) * 2) / cols;
        const x = i * (w + 2);
        return (
          <g key={i}>
            <rect x={x} y={0} width={w} height={6} rx={1} fill="currentColor" opacity={0.7} />
            <rect x={x} y={8} width={w} height={6} rx={1} fill="currentColor" opacity={0.4} />
          </g>
        );
      })}
    </svg>
  );
}

export function GifMoodBoard({
  sessionId,
  currentUserId,
  items,
  shares,
  owner,
  ratings,
  canEdit,
}: GifMoodBoardProps) {
  const [cols, setCols] = useState(4);
  const [, startReorderTransition] = useTransition();

  // Optimistic reorder state for the current user's items
  const [optimisticItems, setOptimisticItems] = useState<GifMoodItem[]>([]);
  const [prevPropsItems, setPrevPropsItems] = useState(items);
  if (prevPropsItems !== items) {
    setPrevPropsItems(items);
    setOptimisticItems([]);
  }

  const sensors = useSensors(
    useSensor(PointerSensor, { activationConstraint: { distance: 5 } })
  );

  const allUsers = useMemo(() => {
    const map = new Map<string, { id: string; name: string | null; email: string }>();
    map.set(owner.id, owner);
    shares.forEach((s) => map.set(s.userId, s.user));
    return Array.from(map.values());
  }, [owner, shares]);

  const itemsByUser = useMemo(() => {
    const map = new Map<string, GifMoodItem[]>();
    items.forEach((item) => {
      const existing = map.get(item.userId) ?? [];
      existing.push(item);
      map.set(item.userId, existing);
    });
    return map;
  }, [items]);

  const sortedUsers = useMemo(() => {
    return [...allUsers].sort((a, b) => {
      if (a.id === currentUserId) return -1;
      if (b.id === currentUserId) return 1;
      if (a.id === owner.id) return -1;
      if (b.id === owner.id) return 1;
      return (a.name || a.email).localeCompare(b.name || b.email, 'fr');
    });
  }, [allUsers, currentUserId, owner.id]);

  function handleDragEnd(event: DragEndEvent) {
    const { active, over } = event;
    if (!over || active.id === over.id) return;

    const currentItems =
      optimisticItems.length > 0 ? optimisticItems : (itemsByUser.get(currentUserId) ?? []);
    const oldIndex = currentItems.findIndex((i) => i.id === active.id);
    const newIndex = currentItems.findIndex((i) => i.id === over.id);
    if (oldIndex === -1 || newIndex === -1) return;

    const reordered = arrayMove(currentItems, oldIndex, newIndex);
    setOptimisticItems(reordered);

    startReorderTransition(async () => {
      await reorderGifMoodItems(sessionId, reordered.map((i) => i.id));
    });
  }

  return (
    <div className="space-y-10">
      {/* Column size control */}
      <div className="flex justify-end">
        <div className="inline-flex items-center gap-1 rounded-xl border border-border bg-card p-1">
          {[4, 5, 6].map((n) => (
            <button
              key={n}
              onClick={() => setCols(n)}
              className={`flex items-center justify-center rounded-lg px-2.5 py-1.5 transition-all ${
                cols === n
                  ? 'bg-primary text-primary-foreground shadow-sm'
                  : 'text-muted hover:text-foreground hover:bg-card-hover'
              }`}
              title={`${n} colonnes`}
            >
              <GridIcon cols={n} />
            </button>
          ))}
        </div>
      </div>
      {sortedUsers.map((user, index) => {
        const isCurrentUser = user.id === currentUserId;
        const serverItems = itemsByUser.get(user.id) ?? [];
        const userItems =
          isCurrentUser && optimisticItems.length > 0 ? optimisticItems : serverItems;
        const canAdd = canEdit && isCurrentUser && userItems.length < GIF_MOOD_MAX_ITEMS;
        const accentColor = SECTION_COLORS[index % SECTION_COLORS.length];
        const userRating = ratings.find((r) => r.userId === user.id)?.rating ?? null;

        return (
          <section key={user.id}>
            {/* Section header */}
            <div className="flex items-center gap-4 mb-5">
              {/* Colored accent bar */}
              <div className="w-1 h-8 rounded-full shrink-0" style={{ backgroundColor: accentColor }} />

              <Avatar email={user.email} name={user.name} size={36} />

              <div className="flex-1 min-w-0">
                <div className="flex items-center gap-2 flex-wrap">
                  <span className="font-semibold text-foreground truncate">
                    {user.name || user.email}
                  </span>
                  {isCurrentUser && (
                    <span className="text-xs text-muted bg-card-hover px-2 py-0.5 rounded-full border border-border">
                      vous
                    </span>
                  )}
                </div>
                <div className="flex items-center gap-3 mt-0.5">
                  <p className="text-xs text-muted">
                    {userItems.length} / {GIF_MOOD_MAX_ITEMS} GIF{userItems.length !== 1 ? 's' : ''}
                  </p>
                  <WeekRating
                    sessionId={sessionId}
                    isCurrentUser={isCurrentUser}
                    canEdit={canEdit}
                    initialRating={userRating}
                  />
                </div>
              </div>
            </div>

            {/* Grid */}
            {isCurrentUser && canEdit ? (
              <DndContext
                sensors={sensors}
                collisionDetection={closestCenter}
                onDragEnd={handleDragEnd}
              >
                <SortableContext
                  items={userItems.map((i) => i.id)}
                  strategy={rectSortingStrategy}
                >
                  <div className={`grid ${GRID_COLS[cols]} gap-4 items-start`}>
                    {userItems.map((item) => (
                      <SortableGifMoodCard
                        key={item.id}
                        sessionId={sessionId}
                        item={item}
                        currentUserId={currentUserId}
                        canEdit={canEdit}
                      />
                    ))}
                    {canAdd && (
                      <GifMoodAddForm sessionId={sessionId} currentCount={userItems.length} />
                    )}
                    {!canAdd && userItems.length === 0 && (
                      <div className="col-span-full flex items-center justify-center rounded-2xl border border-dashed border-border/60 py-10">
                        <p className="text-sm text-muted/60">Aucun GIF pour le moment</p>
                      </div>
                    )}
                  </div>
                </SortableContext>
              </DndContext>
            ) : (
              <div className={`grid ${GRID_COLS[cols]} gap-4 items-start`}>
                {userItems.map((item) => (
                  <GifMoodCard
                    key={item.id}
                    sessionId={sessionId}
                    item={item}
                    currentUserId={currentUserId}
                    canEdit={canEdit}
                  />
                ))}
                {!canAdd && userItems.length === 0 && (
                  <div className="col-span-full flex items-center justify-center rounded-2xl border border-dashed border-border/60 py-10">
                    <p className="text-sm text-muted/60">Aucun GIF pour le moment</p>
                  </div>
                )}
              </div>
            )}
          </section>
        );
      })}
    </div>
  );
}