<?php

namespace App\Element;

use App\Set\Set;
use App\Set\SetLevel;
use App\Set\SetLevelRepository;
use DomainException;
use RuntimeException;

class EloquentElementRepository implements ElementRepository
{
    public function __construct(
        private SetLevelRepository $setLevelRepository,
    ) {}

    public function create(CreateElementDto $dto): Element
    {
        $this->validateLevel($dto);
        $position = $this->nextPosition(
            $dto->level,
            $dto->parentElement,
        );
        $model = ElementModel::create([
            'set_level_id' => $dto->level->getId(),
            'name' => $dto->name,
            'parent_element_id' => $dto->parentElement?->getId(),
            'position' => $position,
        ]);

        return new Element(
            id: $model->id,
            name: $model->name,
            level: $dto->level,
            parentElement: $dto->parentElement,
            position: $model->position,
        );
    }

    public function find(int $id): ?Element
    {
        $model = ElementModel::find($id);

        return $model === null ? null : $this->toDomain($model);
    }

    public function findBySet(Set $set): array
    {
        $levelsById = [];
        foreach ($this->setLevelRepository->findBySet($set) as $level) {
            $levelsById[$level->getId()] = $level;
        }
        if ($levelsById === []) {
            return [];
        }

        $models = ElementModel::query()
            ->whereIn('set_level_id', array_keys($levelsById))
            ->orderBy('id')
            ->get();
        $elements = [];
        $elementsById = [];

        foreach ($models as $model) {
            $level = $levelsById[$model->set_level_id] ?? null;
            if ($level === null) {
                throw new RuntimeException('element level not found');
            }

            $parentElement = null;
            if ($model->parent_element_id !== null) {
                $parentElement = $elementsById[$model->parent_element_id]
                    ?? null;
                if ($parentElement === null) {
                    throw new RuntimeException('element parent not found');
                }
            }

            $element = $this->toDomainWithRelations(
                model: $model,
                level: $level,
                parentElement: $parentElement,
            );
            $elements[] = $element;
            $elementsById[$element->getId()] = $element;
        }

        return $elements;
    }

    public function findTopLevelBySet(Set $set): array
    {
        $levels = $this->setLevelRepository->findBySet($set);
        if ($levels === []) {
            return [];
        }

        $topLevel = $levels[0];
        $models = ElementModel::query()
            ->where('set_level_id', $topLevel->getId())
            ->whereNull('parent_element_id')
            ->orderBy('position')
            ->orderBy('id')
            ->get();
        $elements = [];

        foreach ($models as $model) {
            $elements[] = $this->toDomainWithRelations(
                model: $model,
                level: $topLevel,
                parentElement: null,
            );
        }

        return $elements;
    }

    public function findByParentElement(Element $parentElement): array
    {
        $models = ElementModel::query()
            ->where('parent_element_id', $parentElement->getId())
            ->orderBy('position')
            ->orderBy('id')
            ->get();
        $elements = [];

        foreach ($models as $model) {
            $level = $this->findLevel($model->set_level_id);
            $elements[] = $this->toDomainWithRelations(
                model: $model,
                level: $level,
                parentElement: $parentElement,
            );
        }

        return $elements;
    }

    /**
     * @throws DomainException
     */
    private function validateLevel(CreateElementDto $dto): void
    {
        $parentElement = $dto->parentElement;
        if ($parentElement === null) {
            if ($dto->level->getDepth() !== 0) {
                throw new DomainException(
                    'root element must use the first set level',
                );
            }

            return;
        }

        if (
            $parentElement->getSet()->getId()
            !== $dto->level->getSet()->getId()
        ) {
            throw new DomainException(
                'parent element must belong to the same set',
            );
        }

        if (
            $dto->level->getDepth()
            !== $parentElement->getLevel()->getDepth() + 1
        ) {
            throw new DomainException(
                'child element must use the next set level',
            );
        }
    }

    private function nextPosition(
        SetLevel $level,
        ?Element $parentElement,
    ): int {
        $query = ElementModel::query()
            ->where('set_level_id', $level->getId());
        if ($parentElement === null) {
            $query->whereNull('parent_element_id');
        } else {
            $query->where('parent_element_id', $parentElement->getId());
        }

        $currentMaximum = $query->max('position');
        if ($currentMaximum === null) {
            return 1;
        }

        return (int) $currentMaximum + 1;
    }

    private function toDomain(ElementModel $model): Element
    {
        $level = $this->findLevel($model->set_level_id);

        $parentElement = null;
        if ($model->parent_element_id !== null) {
            $parentElement = $this->find($model->parent_element_id);
            if ($parentElement === null) {
                throw new RuntimeException('element parent not found');
            }
        }

        return $this->toDomainWithRelations(
            model: $model,
            level: $level,
            parentElement: $parentElement,
        );
    }

    private function toDomainWithRelations(
        ElementModel $model,
        SetLevel $level,
        ?Element $parentElement,
    ): Element {
        return new Element(
            id: $model->id,
            name: $model->name,
            level: $level,
            parentElement: $parentElement,
            position: $model->position,
        );
    }

    private function findLevel(int $id): SetLevel
    {
        $level = $this->setLevelRepository->find($id);
        if ($level !== null) {
            return $level;
        }

        throw new RuntimeException('element level not found');
    }
}