<?php

declare(strict_types=1);

namespace App\Services;

use App\Models\Artwork;
use App\Models\Tag;
use App\Support\AvatarUrl;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;
use Illuminate\Database\QueryException;

/**
 * HomepageService
 *
 * Aggregates all data sections needed for the Nova homepage.
 * All results are cached for CACHE_TTL seconds.
 * Controllers stay thin — only call the aggregator.
 */
final class HomepageService
{
    private const CACHE_TTL = 300; // 5 minutes

    public function __construct(private readonly ArtworkService $artworks) {}

    // ─────────────────────────────────────────────────────────────────────────
    // Public aggregator
    // ─────────────────────────────────────────────────────────────────────────

    /**
     * Return all homepage section data as a single array ready to JSON-encode.
     */
    public function all(): array
    {
        return [
            'hero'     => $this->getHeroArtwork(),
            'trending' => $this->getTrending(),
            'fresh'    => $this->getFreshUploads(),
            'tags'     => $this->getPopularTags(),
            'creators' => $this->getCreatorSpotlight(),
            'news'     => $this->getNews(),
        ];
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Sections
    // ─────────────────────────────────────────────────────────────────────────

    /**
     * Hero artwork: first item from the featured list.
     */
    public function getHeroArtwork(): ?array
    {
        return Cache::remember('homepage.hero', self::CACHE_TTL, function (): ?array {
            $result = $this->artworks->getFeaturedArtworks(null, 1);

            /** @var \Illuminate\Database\Eloquent\Model|\null $artwork */
            if ($result instanceof \Illuminate\Pagination\LengthAwarePaginator) {
                $artwork = $result->getCollection()->first();
            } elseif ($result instanceof \Illuminate\Support\Collection) {
                $artwork = $result->first();
            } elseif (is_array($result)) {
                $artwork = $result[0] ?? null;
            } else {
                $artwork = null;
            }

            return $artwork ? $this->serializeArtwork($artwork, 'lg') : null;
        });
    }

    /**
     * Trending: up to 12 artworks ordered by award score, views, downloads, recent activity.
     *
     * Award score = SUM(weight × medal_value) where gold=3, silver=2, bronze=1.
     * Uses correlated subqueries to avoid GROUP BY issues with MySQL strict mode.
     */
    public function getTrending(int $limit = 12): array
    {
        return Cache::remember("homepage.trending.{$limit}", self::CACHE_TTL, function () use ($limit): array {
            $ids = DB::table('artworks')
                ->select('id')
                ->selectRaw(
                    '(SELECT COALESCE(SUM(weight * CASE medal'
                    . ' WHEN \'gold\' THEN 3'
                    . ' WHEN \'silver\' THEN 2'
                    . ' ELSE 1 END), 0)'
                    . ' FROM artwork_awards WHERE artwork_awards.artwork_id = artworks.id) AS award_score'
                )
                ->selectRaw('COALESCE((SELECT views     FROM artwork_stats WHERE artwork_stats.artwork_id = artworks.id), 0) AS stat_views')
                ->selectRaw('COALESCE((SELECT downloads FROM artwork_stats WHERE artwork_stats.artwork_id = artworks.id), 0) AS stat_downloads')
                ->where('is_public', true)
                ->where('is_approved', true)
                ->whereNull('deleted_at')
                ->whereNotNull('published_at')
                ->where('published_at', '>=', now()->subDays(30))
                ->orderByDesc('award_score')
                ->orderByDesc('stat_views')
                ->orderByDesc('stat_downloads')
                ->orderByDesc('published_at')
                ->limit($limit)
                ->pluck('id');

            if ($ids->isEmpty()) {
                return [];
            }

            $indexed = Artwork::with(['user:id,name,username', 'user.profile:user_id,avatar_hash'])
                ->whereIn('id', $ids)
                ->get()
                ->keyBy('id');

            return $ids
                ->filter(fn ($id) => $indexed->has($id))
                ->map(fn ($id) => $this->serializeArtwork($indexed[$id]))
                ->values()
                ->all();
        });
    }

    /**
     * Fresh uploads: latest 12 approved public artworks.
     */
    public function getFreshUploads(int $limit = 12): array
    {
        return Cache::remember("homepage.fresh.{$limit}", self::CACHE_TTL, function () use ($limit): array {
            $artworks = Artwork::public()
                ->published()
                ->with(['user:id,name,username', 'user.profile:user_id,avatar_hash'])
                ->orderByDesc('published_at')
                ->limit($limit)
                ->get();

            return $artworks->map(fn ($a) => $this->serializeArtwork($a))->values()->all();
        });
    }

    /**
     * Top 12 popular tags by usage_count.
     */
    public function getPopularTags(int $limit = 12): array
    {
        return Cache::remember("homepage.tags.{$limit}", self::CACHE_TTL, function () use ($limit): array {
            return Tag::query()
                ->where('is_active', true)
                ->orderByDesc('usage_count')
                ->limit($limit)
                ->get(['id', 'name', 'slug', 'usage_count'])
                ->map(fn ($t) => [
                    'id'    => $t->id,
                    'name'  => $t->name,
                    'slug'  => $t->slug,
                    'count' => (int) $t->usage_count,
                ])
                ->values()
                ->all();
        });
    }

    /**
     * Creator spotlight: top 6 creators by weekly uploads, awards, and engagement.
     * "Weekly uploads" drives ranking per spec; ties broken by total awards then views.
     */
    public function getCreatorSpotlight(int $limit = 6): array
    {
        return Cache::remember("homepage.creators.{$limit}", self::CACHE_TTL, function () use ($limit): array {
            try {
                $since = now()->subWeek();

                $rows = DB::table('artworks')
                    ->join('users as u', 'u.id', '=', 'artworks.user_id')
                    ->leftJoin('user_profiles as up', 'up.user_id', '=', 'u.id')
                    ->leftJoin('artwork_awards as aw', 'aw.artwork_id', '=', 'artworks.id')
                    ->leftJoin('artwork_stats as s', 's.artwork_id', '=', 'artworks.id')
                    ->select(
                        'u.id',
                        'u.name',
                        'u.username',
                        'up.avatar_hash',
                        DB::raw('COUNT(DISTINCT artworks.id) as upload_count'),
                        DB::raw('SUM(CASE WHEN artworks.published_at >= \'' . $since->toDateTimeString() . '\' THEN 1 ELSE 0 END) as weekly_uploads'),
                        DB::raw('COALESCE(SUM(s.views), 0) as total_views'),
                        DB::raw('COUNT(DISTINCT aw.id) as total_awards')
                    )
                    ->where('artworks.is_public', true)
                    ->where('artworks.is_approved', true)
                    ->whereNull('artworks.deleted_at')
                    ->whereNotNull('artworks.published_at')
                    ->groupBy('u.id', 'u.name', 'u.username', 'up.avatar_hash')
                    ->orderByDesc('weekly_uploads')
                    ->orderByDesc('total_awards')
                    ->orderByDesc('total_views')
                    ->limit($limit)
                    ->get();

                $userIds = $rows->pluck('id')->all();

                // Pick one random artwork thumbnail per creator for the card background.
                $thumbsByUser = Artwork::public()
                    ->published()
                    ->whereIn('user_id', $userIds)
                    ->whereNotNull('hash')
                    ->whereNotNull('thumb_ext')
                    ->inRandomOrder()
                    ->get(['id', 'user_id', 'hash', 'thumb_ext'])
                    ->groupBy('user_id');

                return $rows->map(function ($u) use ($thumbsByUser) {
                    $artworkForBg = $thumbsByUser->get($u->id)?->first();
                    $bgThumb      = $artworkForBg ? $artworkForBg->thumbUrl('md') : null;

                    return [
                        'id'             => $u->id,
                        'name'           => $u->name,
                        'uploads'        => (int) $u->upload_count,
                        'weekly_uploads' => (int) $u->weekly_uploads,
                        'views'          => (int) $u->total_views,
                        'awards'         => (int) $u->total_awards,
                        'url'            => $u->username ? '/@' . $u->username : '/profile/' . $u->id,
                        'avatar'         => AvatarUrl::forUser((int) $u->id, $u->avatar_hash ?: null, 128),
                        'bg_thumb'       => $bgThumb,
                    ];
                })->values()->all();
            } catch (QueryException $e) {
                Log::warning('HomepageService::getCreatorSpotlight DB error', [
                    'exception' => $e->getMessage(),
                ]);

                return [];
            }
        });
    }

    /**
     * Latest 5 news posts from the forum news category.
     */
    public function getNews(int $limit = 5): array
    {
        return Cache::remember("homepage.news.{$limit}", self::CACHE_TTL, function () use ($limit): array {
            try {
                $items = DB::table('forum_threads as t')
                    ->leftJoin('forum_categories as c', 'c.id', '=', 't.category_id')
                    ->select('t.id', 't.title', 't.created_at', 't.slug as thread_slug')
                    ->where(function ($q) {
                        $q->where('t.category_id', 2876)
                          ->orWhereIn('c.slug', ['news', 'forum-news']);
                    })
                    ->whereNull('t.deleted_at')
                    ->orderByDesc('t.created_at')
                    ->limit($limit)
                    ->get();

                return $items->map(fn ($row) => [
                    'id'    => $row->id,
                    'title' => $row->title,
                    'date'  => $row->created_at,
                    'url'   => '/forum/thread/' . $row->id . '-' . ($row->thread_slug ?? 'post'),
                ])->values()->all();
            } catch (QueryException $e) {
                Log::warning('HomepageService::getNews DB error', [
                    'exception' => $e->getMessage(),
                ]);

                return [];
            }
        });
    }

    // ─────────────────────────────────────────────────────────────────────────
    // Helpers
    // ─────────────────────────────────────────────────────────────────────────

    private function serializeArtwork(Artwork $artwork, string $preferSize = 'md'): array
    {
        $thumbMd = $artwork->thumbUrl('md');
        $thumbLg = $artwork->thumbUrl('lg');
        $thumb   = $preferSize === 'lg' ? ($thumbLg ?? $thumbMd) : ($thumbMd ?? $thumbLg);

        $authorId       = $artwork->user_id;
        $authorName     = $artwork->user?->name ?? 'Artist';
        $authorUsername = $artwork->user?->username ?? '';
        $avatarHash     = $artwork->user?->profile?->avatar_hash ?? null;
        $authorAvatar   = AvatarUrl::forUser((int) $authorId, $avatarHash, 40);

        return [
            'id'              => $artwork->id,
            'title'           => $artwork->title ?? 'Untitled',
            'slug'            => $artwork->slug,
            'author'          => $authorName,
            'author_id'       => $authorId,
            'author_username' => $authorUsername,
            'author_avatar'   => $authorAvatar,
            'thumb'           => $thumb,
            'thumb_md'        => $thumbMd,
            'thumb_lg'        => $thumbLg,
            'url'             => '/art/' . $artwork->id . '/' . ($artwork->slug ?? ''),
            'width'           => $artwork->width,
            'height'          => $artwork->height,
            'published_at'    => $artwork->published_at?->toIso8601String(),
        ];
    }
}