<?php

namespace App\Services;

use App\Support\Settings;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;

class BookStackClient
{
    /**
     * Two independent allow-lists, since which shelves make sense to
     * surface differs by where suggestions show up: 'creation' gates the
     * ticket-wizard suggestions (client/operator/guest), 'ticket_view'
     * gates the separate sidebar shown to an operator on an existing ticket.
     */
    public const CONTEXT_CREATION = 'creation';

    public const CONTEXT_TICKET_VIEW = 'ticket_view';

    protected const CONTEXT_SETTINGS_KEYS = [
        self::CONTEXT_CREATION => 'bookstack_allowed_shelf_ids_creation',
        self::CONTEXT_TICKET_VIEW => 'bookstack_allowed_shelf_ids_ticket_view',
    ];

    public function enabled(): bool
    {
        return Settings::bool('bookstack_enabled')
            && Settings::get('bookstack_base_url')
            && Settings::get('bookstack_token_id');
    }

    /**
     * Suggested-article lookup, shared by the ticket-creation wizard and the
     * operator ticket-view sidebar — returns [] whenever the integration is
     * off/unconfigured, the query is empty, or no shelf has been allow-listed
     * yet for the given $context (an empty allow-list means "search nothing",
     * not "search everything" — an admin has to opt specific shelves in
     * before any content is ever suggested, independently per context).
     * Cached briefly since the same category/subcategory query repeats
     * across every ticket created/viewed with that combination. Respects the
     * admin-configured bookstack_search_types setting ('both'|'page'|'book')
     * via BookStack's own `{type:x}` query syntax. The cache key folds in the
     * allowed-shelf list so changing it in Admin > Konfiguracja is reflected
     * immediately, instead of possibly serving a pre-change result for up to
     * 10 minutes.
     *
     * @return array<int, array{name: string, url: ?string, type: string, book: ?string, shelf: ?string}>
     */
    public function search(string $query, int $limit = 5, string $context = self::CONTEXT_CREATION): array
    {
        $query = trim($query);
        $allowedShelfIds = $this->allowedShelfIds($context);

        if (! $this->enabled() || $query === '' || ! $allowedShelfIds) {
            return [];
        }

        $typeFilter = Settings::get('bookstack_search_types', 'both');

        if (in_array($typeFilter, ['page', 'book'], true)) {
            $query .= " {type:{$typeFilter}}";
        }

        $cacheKey = 'bookstack:search:'.md5($query.'|'.$limit.'|'.implode(',', $allowedShelfIds));

        return Cache::remember($cacheKey, now()->addMinutes(10), function () use ($query, $limit, $allowedShelfIds) {
            try {
                $response = $this->client()->get('/api/search', ['query' => $query, 'count' => $limit]);

                if (! $response->successful()) {
                    return [];
                }

                $shelfMap = $this->shelfBookMap();
                $allowedBookIds = $this->bookIdsForShelves($shelfMap, $allowedShelfIds);
                $bookShelfNames = $this->bookShelfNames($shelfMap);

                return collect($response->json('data', []))
                    ->filter(function (array $item) use ($allowedShelfIds, $allowedBookIds) {
                        $type = $item['type'] ?? null;

                        if ($type === 'bookshelf') {
                            return in_array($item['id'] ?? null, $allowedShelfIds, true);
                        }

                        if ($type === 'book') {
                            return in_array($item['id'] ?? null, $allowedBookIds, true);
                        }

                        // pages/chapters carry the id of the book they live in
                        return isset($item['book_id']) && in_array($item['book_id'], $allowedBookIds, true);
                    })
                    ->map(function (array $item) use ($bookShelfNames) {
                        $bookId = $item['book_id'] ?? (($item['type'] ?? null) === 'book' ? $item['id'] : null);

                        return [
                            'name' => $item['name'] ?? '',
                            'url' => $item['url'] ?? null,
                            'type' => $item['type'] ?? 'page',
                            'book' => $item['book']['name'] ?? null,
                            'shelf' => $bookId ? ($bookShelfNames[$bookId] ?? null) : null,
                        ];
                    })
                    ->filter(fn (array $item) => $item['name'] !== '')
                    ->values()
                    ->all();
            } catch (\Throwable) {
                return [];
            }
        });
    }

    /**
     * Drops the cached shelf list and shelf>book membership map — used by
     * the admin's "Odśwież listę półek" button so a shelf renamed/added/
     * removed in BookStack shows up immediately instead of after up to 30
     * minutes. Doesn't touch the per-query search-result cache (10 min TTL,
     * self-invalidates on the next config save via the allow-list in its key).
     */
    public function clearShelfCache(): void
    {
        Cache::forget('bookstack:shelves');
        Cache::forget('bookstack:shelf-book-map');
    }

    /**
     * Bookshelves for the admin's two "dozwolone półki" checklists — cached
     * since shelf structure changes rarely and this is fetched on every
     * Admin > Konfiguracja page load while the BookStack section is expanded.
     *
     * @return array<int, array{id: int, name: string}>
     */
    public function shelves(): array
    {
        if (! $this->enabled()) {
            return [];
        }

        return Cache::remember('bookstack:shelves', now()->addMinutes(30), function () {
            try {
                $response = $this->client()->get('/api/shelves', ['count' => 200]);

                if (! $response->successful()) {
                    return [];
                }

                return collect($response->json('data', []))
                    ->map(fn (array $s) => ['id' => $s['id'], 'name' => $s['name']])
                    ->values()
                    ->all();
            } catch (\Throwable) {
                return [];
            }
        });
    }

    /**
     * @return int[]
     */
    protected function allowedShelfIds(string $context): array
    {
        $key = self::CONTEXT_SETTINGS_KEYS[$context] ?? self::CONTEXT_SETTINGS_KEYS[self::CONTEXT_CREATION];
        $raw = Settings::get($key, '');

        return collect(explode(',', (string) $raw))
            ->map(fn ($v) => (int) trim($v))
            ->filter()
            ->values()
            ->all();
    }

    /**
     * Every shelf's book membership, fetched once and cached — the single
     * source both shelf-exclusion and the "Shelf > Book" breadcrumb are
     * derived from, so there's only one place that talks to /api/shelves/{id}.
     *
     * @return array<int, array{name: string, bookIds: int[]}>
     */
    protected function shelfBookMap(): array
    {
        return Cache::remember('bookstack:shelf-book-map', now()->addMinutes(30), function () {
            $map = [];

            foreach ($this->shelves() as $shelf) {
                $bookIds = [];

                try {
                    $response = $this->client()->get("/api/shelves/{$shelf['id']}");

                    if ($response->successful()) {
                        $bookIds = collect($response->json('books', []))->pluck('id')->all();
                    }
                } catch (\Throwable) {
                    // Skip an unreachable/deleted shelf rather than failing the whole search.
                }

                $map[$shelf['id']] = ['name' => $shelf['name'], 'bookIds' => $bookIds];
            }

            return $map;
        });
    }

    /**
     * @param  array<int, array{name: string, bookIds: int[]}>  $shelfMap
     * @param  int[]  $shelfIds
     * @return int[]
     */
    protected function bookIdsForShelves(array $shelfMap, array $shelfIds): array
    {
        $ids = [];

        foreach ($shelfIds as $shelfId) {
            $ids = [...$ids, ...($shelfMap[$shelfId]['bookIds'] ?? [])];
        }

        return $ids;
    }

    /**
     * Book id -> owning shelf name, for the suggestion list's breadcrumb. A
     * book that sits on more than one shelf just shows whichever is last in
     * the map — there's no single "correct" shelf to prefer in that case.
     *
     * @param  array<int, array{name: string, bookIds: int[]}>  $shelfMap
     * @return array<int, string>
     */
    protected function bookShelfNames(array $shelfMap): array
    {
        $names = [];

        foreach ($shelfMap as $shelf) {
            foreach ($shelf['bookIds'] as $bookId) {
                $names[$bookId] = $shelf['name'];
            }
        }

        return $names;
    }

    /**
     * Tests unsaved admin-form values directly, rather than whatever's
     * currently stored — mirrors testLdapConnection()/testMailConnection()
     * in Admin\Panel. Returns a message alongside the ok/error flag (BookStack's
     * API returns a specific, useful reason — e.g. missing "Access System API"
     * role permission — that a plain boolean would hide from the admin.
     *
     * @return array{ok: bool, message: ?string}
     */
    public function testConnection(string $baseUrl, string $tokenId, string $tokenSecret, bool $verifySsl = true): array
    {
        try {
            $response = Http::withHeaders(['Authorization' => "Token {$tokenId}:{$tokenSecret}"])
                ->withOptions(['verify' => $verifySsl])
                ->timeout(6)
                ->get(rtrim($baseUrl, '/').'/api/search', ['query' => 'test', 'count' => 1]);

            if ($response->successful()) {
                return ['ok' => true, 'message' => null];
            }

            return ['ok' => false, 'message' => $response->json('error.message') ?? ('HTTP '.$response->status())];
        } catch (\Throwable $e) {
            return ['ok' => false, 'message' => $e->getMessage()];
        }
    }

    protected function client()
    {
        $tokenId = Settings::get('bookstack_token_id');
        $tokenSecret = Settings::get('bookstack_token_secret');

        return Http::withHeaders(['Authorization' => "Token {$tokenId}:{$tokenSecret}"])
            ->withOptions(['verify' => Settings::bool('bookstack_verify_ssl')])
            ->timeout(4)
            ->baseUrl(rtrim(Settings::get('bookstack_base_url'), '/'));
    }
}