<?php

namespace App\Services;

use App\Actions\Prompts\ListPrompts;
use App\Models\Prompt;
use App\Models\Tag;
use Illuminate\Contracts\Pagination\LengthAwarePaginator;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Collection;

/**
 * Read side of the prompt domain (queries).
 */
class PromptCatalog
{
    public const PER_PAGE = 10;

    /**
     * Paginated prompt list with search, tag/favorite filters, and
     * whitelisted sorting. `last_used_at` keeps NULLs last.
     */
    public function list(ListPrompts $query): LengthAwarePaginator
    {
        $sort = $query->normalizedSort();
        $direction = $query->normalizedDirection();
        $like = '%' . $query->search . '%';

        return Prompt::query()
            ->with('tags')
            ->when(
                $query->search !== null && $query->search !== '',
                fn (Builder $q) => $q->where(
                    fn (Builder $w) => $w
                        ->where('name', 'like', $like)
                        ->orWhere('description', 'like', $like)
                        ->orWhere('body', 'like', $like)
                ),
            )
            ->when(
                $query->tag !== null && $query->tag !== '',
                fn (Builder $q) => $q->whereHas('tags', fn (Builder $t) => $t->where('name', $query->tag)),
            )
            ->when($query->favoritesOnly, fn (Builder $q) => $q->where('is_favorite', true))
            ->when(
                $sort === 'last_used_at',
                // NULLs always sort last: `IS NULL` is 0/1, so a first
                // ascending pass groups non-NULLs before NULLs in either
                // direction, then the value itself orders within the group.
                fn (Builder $q) => $q
                    ->orderByRaw('last_used_at IS NULL')
                    ->orderBy('last_used_at', $direction),
                fn (Builder $q) => $q->orderBy($sort, $direction),
            )
            ->orderBy('id', 'desc')
            ->paginate(self::PER_PAGE);
    }

    /**
     * All tags, alphabetically (for filter dropdowns).
     */
    public function tags(): Collection
    {
        return Tag::query()->orderBy('name')->get();
    }
}