<?php

declare(strict_types=1);

namespace Rector\DeadCode;

use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Array_;
use PhpParser\Node\Expr\BinaryOp;
use PhpParser\Node\Expr\BinaryOp\NotEqual;
use PhpParser\Node\Expr\BinaryOp\NotIdentical;
use PhpParser\Node\Expr\BooleanNot;
use PhpParser\Node\Expr\Empty_;
use PhpParser\Node\Stmt\If_;
use PHPStan\Type\MixedType;
use Rector\Core\PhpParser\Comparing\NodeComparator;
use Rector\NodeTypeResolver\NodeTypeResolver;

final class UselessIfCondBeforeForeachDetector
{
    /**
     * @var NodeTypeResolver
     */
    private $nodeTypeResolver;

    /**
     * @var NodeComparator
     */
    private $nodeComparator;

    public function __construct(NodeTypeResolver $nodeTypeResolver, NodeComparator $nodeComparator)
    {
        $this->nodeTypeResolver = $nodeTypeResolver;
        $this->nodeComparator = $nodeComparator;
    }

    /**
     * Matches:
     * !empty($values)
     */
    public function isMatchingNotEmpty(If_ $if, Expr $foreachExpr): bool
    {
        $cond = $if->cond;
        if (! $cond instanceof BooleanNot) {
            return false;
        }

        if (! $cond->expr instanceof Empty_) {
            return false;
        }

        /** @var Empty_ $empty */
        $empty = $cond->expr;

        if (! $this->nodeComparator->areNodesEqual($empty->expr, $foreachExpr)) {
            return false;
        }

        // is array though?
        $arrayType = $this->nodeTypeResolver->resolve($empty->expr);

        return ! $arrayType instanceof MixedType;
    }

    /**
     * Matches:
     * $values !== []
     * $values != []
     * [] !== $values
     * [] != $values
     */
    public function isMatchingNotIdenticalEmptyArray(If_ $if, Expr $foreachExpr): bool
    {
        if (! $if->cond instanceof NotIdentical && ! $if->cond instanceof NotEqual) {
            return false;
        }

        /** @var NotIdentical|NotEqual $notIdentical */
        $notIdentical = $if->cond;

        return $this->isMatchingNotBinaryOp($notIdentical, $foreachExpr);
    }

    /**
     * @param NotIdentical|NotEqual $binaryOp
     */
    private function isMatchingNotBinaryOp(BinaryOp $binaryOp, Expr $foreachExpr): bool
    {
        if ($this->isEmptyArrayAndForeachedVariable($binaryOp->left, $binaryOp->right, $foreachExpr)) {
            return true;
        }

        return $this->isEmptyArrayAndForeachedVariable($binaryOp->right, $binaryOp->left, $foreachExpr);
    }

    private function isEmptyArrayAndForeachedVariable(Expr $leftExpr, Expr $rightExpr, Expr $foreachExpr): bool
    {
        if (! $this->isEmptyArray($leftExpr)) {
            return false;
        }

        return $this->nodeComparator->areNodesEqual($foreachExpr, $rightExpr);
    }

    private function isEmptyArray(Expr $expr): bool
    {
        if (! $expr instanceof Array_) {
            return false;
        }

        return $expr->items === [];
    }
}