<?php

namespace DishPlanner\Schedule\Actions;

use App\Models\Planner;
use App\Models\Schedule;
use App\Models\ScheduledUserDish;
use App\Models\User;
use Carbon\Carbon;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;

class GenerateScheduleForMonthAction
{
    public function execute(
        Planner $planner,
        int $month,
        int $year,
        array $userIds,
        bool $clearExisting = true
    ): void {
        DB::transaction(function () use ($planner, $month, $year, $userIds, $clearExisting) {
            $startDate = Carbon::createFromDate($year, $month, 1);
            $endDate = $startDate->copy()->endOfMonth();

            if ($clearExisting) {
                $this->clearExistingSchedules($planner, $startDate, $endDate, $userIds);
            }

            $userDishesMap = $this->loadUserDishes($planner, $userIds);

            $this->generateSchedulesForPeriod($planner, $startDate, $endDate, $userIds, $userDishesMap);
        });
    }

    private function clearExistingSchedules(
        Planner $planner,
        Carbon $startDate,
        Carbon $endDate,
        array $userIds
    ): void {
        $scheduleIds = Schedule::withoutGlobalScopes()
            ->where('planner_id', $planner->id)
            ->whereBetween('date', [$startDate, $endDate])
            ->pluck('id');

        ScheduledUserDish::whereIn('schedule_id', $scheduleIds)
            ->whereIn('user_id', $userIds)
            ->delete();
    }

    private function loadUserDishes(Planner $planner, array $userIds): array
    {
        $users = User::query()
            ->with('userDishes.dish')
            ->whereIn('id', $userIds)
            ->where('planner_id', $planner->id)
            ->get()
            ->keyBy('id');

        $userDishesMap = [];
        foreach ($users as $userId => $user) {
            if ($user->userDishes->isNotEmpty()) {
                $userDishesMap[$userId] = $user->userDishes;
            }
        }

        return $userDishesMap;
    }

    private function generateSchedulesForPeriod(
        Planner $planner,
        Carbon $startDate,
        Carbon $endDate,
        array $userIds,
        array $userDishesMap
    ): void {
        $currentDate = $startDate->copy();

        while ($currentDate <= $endDate) {
            $schedule = Schedule::firstOrCreate(
                ['planner_id' => $planner->id, 'date' => $currentDate->format('Y-m-d')],
                ['is_skipped' => false]
            );

            foreach ($userIds as $userId) {
                if (!isset($userDishesMap[$userId]) || $userDishesMap[$userId]->isEmpty()) {
                    continue;
                }

                $randomUserDish = $userDishesMap[$userId]->random();

                ScheduledUserDish::firstOrCreate(
                    ['schedule_id' => $schedule->id, 'user_id' => $userId],
                    ['user_dish_id' => $randomUserDish->id, 'is_skipped' => false]
                );
            }

            $currentDate->addDay();
        }
    }
}