<?php

namespace App\Http\Livewire\Traits;

use Illuminate\Support\Facades\DB;

trait WithSort {

	/**
	 * Sort column
	 */
	public string $sort = '';

	/**
	 * Sort direction
	 */
	public string $dir = 'asc';

	/**
     * Sort by column.
	 */
	public function sort($column)
	{
		if (!array_key_exists($column, $this->sort_columns)) {
			return;
		}

		if ($this->sort === $column) {
			$this->dir = $this->dir === 'asc' ? 'desc' : 'asc';
		} else {
			$this->sort = $column;
			$this->reset('dir');
		}
	}

	protected function sortApply($query)
	{
		// No sorting. bail out.
		if (!strlen($this->sort)) {
			return;
		}

		$columns = $this->sort_columns[$this->sort];

		if (!is_array($columns)) {
			$columns = [ $columns ];
		}

		foreach($columns as $column) {

			// If column is a relationship
			$p = strrpos($column, '.');
			if ($p !== false) {
				$rel = substr($column, 0, $p);
				$col = substr($column, $p + 1);
				try {
					$query->orderByLeftPowerJoins([$rel, $this->orderExpr($col)], $this->dir);
				} catch(\BadMethodCallException $e) {
					$class = get_class($query->getModel());
					throw new \Error("Failed to sort column '$column': '$class' "
						. "must use 'Kirschbaum\PowerJoins\PowerJoins' "
						. "trait to be able to sort by relationship.");
				}
			} else {
				$query->orderBy($this->orderExpr($column), $this->dir);
			}
		}
	}

	/**
	 * Bit of a hack to get nulls to appear last.
	 */
	private function orderExpr(string $col) : \Illuminate\Database\Query\Expression
	{
		return DB::raw("ISNULL(`$col`), `$col`");
	}
}