<?php

namespace App\Services;

use Illuminate\Database\Query\Builder;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;

/** One applicable edition per service. Existing requests keep their immutable version FK. */
final class DeskServiceAvailability
{
    public function scheduled(): bool
    {
        return Schema::hasColumn('desk_service_versions', 'effective_from');
    }

    public function current(): Builder
    {
        $query = DB::table('desk_service_versions')->where('status', 'published')
            ->where(fn (Builder $date) => $date->whereNull('published_at')->orWhere('published_at', '<=', now()))
            ->selectRaw('DISTINCT ON (code) *')->orderBy('code');
        if ($this->scheduled()) {
            $query->where(fn (Builder $date) => $date->whereNull('effective_from')->orWhere('effective_from', '<=', now()->toDateString()))
                ->orderByRaw('effective_from DESC NULLS LAST');
        }

        return $query->orderByDesc('version');
    }

    public function upcoming(): Builder
    {
        $query = DB::table('desk_service_versions');
        if (! $this->scheduled()) {
            return $query->whereRaw('false')->select('code', 'version')->selectRaw('NULL::date AS effective_from');
        }

        return $query->where('status', 'published')->where('effective_from', '>', now()->toDateString())
            ->where(fn (Builder $date) => $date->whereNull('published_at')->orWhere('published_at', '<=', now()))
            ->selectRaw('DISTINCT ON (code,effective_from) code,version,effective_from')->orderBy('code')->orderBy('effective_from')->orderByDesc('version');
    }

    /** @return literal-string */
    public function dateProjection(): string
    {
        return $this->scheduled() ? 'effective_from' : 'NULL::date AS effective_from';
    }
}