<?php

namespace App\Services;

use App\Models\InhabitantClassification;
use App\Models\Unit;
use App\Models\UnitInhabitantClassification;
use Illuminate\Database\Eloquent\Collection;

class InhabitantClassificationService
{
    public function getAll(): Collection
    {
        return InhabitantClassification::orderBy('description')->get();
    }

    public function getSelectList(): Collection
    {
        return InhabitantClassification::orderBy('description')
            ->get(['id', 'description', 'acronym']);
    }

    public function findById(int $id): ?InhabitantClassification
    {
        return InhabitantClassification::find($id);
    }

    public function create(array $data): InhabitantClassification
    {
        $model = InhabitantClassification::create($data);
        $this->propagateToAllUnits($model);
        return $model;
    }

    public function update(int $id, array $data): ?InhabitantClassification
    {
        $model = $this->findById($id);

        if (!$model) {
            return null;
        }

        $oldDescription = $model->description;
        $oldAcronym     = $model->acronym;

        $model->update($data);
        $updated = $model->fresh();

        $this->propagateUpdateToUnits($updated, $oldDescription, $oldAcronym);

        return $updated;
    }

    public function delete(int $id): bool
    {
        $model = $this->findById($id);

        if (!$model) {
            return false;
        }

        return $model->delete();
    }

    private function propagateToAllUnits(InhabitantClassification $parent): void
    {
        $existingUnitIds = UnitInhabitantClassification::where('acronym', $parent->acronym)
            ->pluck('unit_id');

        Unit::whereNotIn('id', $existingUnitIds)
            ->each(function (Unit $unit) use ($parent) {
                UnitInhabitantClassification::create([
                    'unit_id'     => $unit->id,
                    'description' => $parent->description,
                    'acronym'     => $parent->acronym,
                ]);
            });
    }

    private function propagateUpdateToUnits(InhabitantClassification $parent, string $oldDescription, string $oldAcronym): void
    {
        // Update copies that were in sync with the old parent values
        UnitInhabitantClassification::where('acronym', $oldAcronym)
            ->where('description', $oldDescription)
            ->update([
                'description' => $parent->description,
                'acronym'     => $parent->acronym,
            ]);

        // Create copies for units that have no record for either the old or new acronym
        $coveredUnitIds = UnitInhabitantClassification::whereIn('acronym', array_unique([$parent->acronym, $oldAcronym]))
            ->pluck('unit_id')
            ->unique();

        Unit::whereNotIn('id', $coveredUnitIds)
            ->each(function (Unit $unit) use ($parent) {
                UnitInhabitantClassification::create([
                    'unit_id'     => $unit->id,
                    'description' => $parent->description,
                    'acronym'     => $parent->acronym,
                ]);
            });
    }
}