exchange/app/Http/Controllers/Api/TradingsController.php

<?php

namespace App\Http\Controllers\Api;

use App\Models\Category;
use App\Models\Group;
use App\Models\Trading;
use App\Transformers\TradingTransformer;

class TradingsController extends ApiController
{
    public function index()
    {
        $last_tradings = Group::where("type", "trading")->with("tradings")->latest()->first()->tradings;
        foreach($last_tradings as $trading){
            $trading->title = trim(strtok($trading->title, '('));;
        }
        $last_tradings = $last_tradings->unique('title');

        $tradings = [];
        foreach($last_tradings as $trading){
            $title = trim(strtok($trading->title, '('));
            $before_last_trading = Trading::where("title",'LIKE', "%{$title}%")->where('group_id', '!=', $trading->group_id)->latest()->first();

            $difference = !$before_last_trading ? 0 : $this->getPercentageDifference($trading->price ?? 0, $before_last_trading->price ?? 0);
            
            array_push($tradings, (object)[
                    'id' => $trading->id,
                    'title' => $title,
                    'price' => $trading->price,
                    'old_price' => !$before_last_trading ? 0 : $before_last_trading->price,
                    'price_change' => number_format($difference, 1, ".", "")."%",
                    'currency' => $trading->currency,
            ]);
        }

        $tradings = Trading::hydrate($tradings);

        return $this->respondWithCollection($tradings, new TradingTransformer);
    }

    public function selectedTradings($id){        
        if($id){
            $category = Category::with('selectedTradings')->find($id);
            if($category){
                $selectedTradings = $category->selectedTradings;
                $myTradings = array();
                foreach ($selectedTradings as $item) {
                    $tradings = Trading::where("title", 'LIKE', "%{$item->title}%")->orderBy('created_at', 'DESC')->get();
                    $tradings = $tradings->unique('group_id')->slice(0, 10)->values();
                    
                    $prices = array();
                    foreach ($tradings as $trading) {
                        array_push($prices, (object)[
                            'price' => $trading->price,
                            'date' => $trading->created_at->todatetimestring(),
                        ]);
                    }
                    
                    $last_trading = $tradings[0];
                    $before_last_trading = count($tradings) > 1 ? $tradings[1] : null;
                    $difference = !$before_last_trading ? 0 : $this->getPercentageDifference($last_trading->price ?? 0, $before_last_trading->price ?? 0);
                    
                    array_push($myTradings, (object)[
                        'id' => $last_trading->id,
                        'title' => trim(strtok($last_trading->title, '(')),
                        'price' => $last_trading->price,
                        'old_price' => !$before_last_trading ? 0 : $before_last_trading->price,
                        'price_change' => !$before_last_trading ? '100%' : number_format($difference, 1, ".", "")."%",
                        'currency' => $last_trading->currency,
                        'all_prices' => $prices
                    ]);
                }

                $tradings = Trading::hydrate($myTradings);
                return $this->respondWithCollection($tradings, new TradingTransformer('selected'));
            }
            return $this->errorNotFound();
        }
        return $this->errorWrongArgs();
    }
    function getPercentageDifference($new, $old){
        return (($new - $old) / abs($old)) * 100;
    }
}