SimplifyIfElseToTernaryRector.php

<?php

declare(strict_types=1);

namespace Rector\CodeQuality\Rector\If_;

use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\BinaryOp;
use PhpParser\Node\Expr\Ternary;
use PhpParser\Node\Stmt;
use PhpParser\Node\Stmt\Else_;
use PhpParser\Node\Stmt\Expression;
use PhpParser\Node\Stmt\If_;
use Rector\NodeTypeResolver\Node\AttributeKey;
use Rector\PhpParser\Node\BetterNodeFinder;
use Rector\PhpParser\Printer\BetterStandardPrinter;
use Rector\Rector\AbstractRector;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;

/**
 * @see \Rector\Tests\CodeQuality\Rector\If_\SimplifyIfElseToTernaryRector\SimplifyIfElseToTernaryRectorTest
 */
final class SimplifyIfElseToTernaryRector extends AbstractRector
{
    private const int LINE_LENGTH_LIMIT = 120;

    public function __construct(
        private readonly BetterStandardPrinter $betterStandardPrinter,
        private readonly BetterNodeFinder $betterNodeFinder
    ) {
    }

    public function getRuleDefinition(): RuleDefinition
    {
        return new RuleDefinition(
            'Changes if/else for same value as assign to ternary',
            [
                new CodeSample(
                    <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        if (empty($value)) {
            $this->arrayBuilt[][$key] = true;
        } else {
            $this->arrayBuilt[][$key] = $value;
        }
    }
}
CODE_SAMPLE
                    ,
                    <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $this->arrayBuilt[][$key] = empty($value) ? true : $value;
    }
}
CODE_SAMPLE
                ),
            ]
        );
    }

    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [If_::class];
    }

    /**
     * @param If_ $node
     */
    public function refactor(Node $node): ?Node
    {
        if (! $node->else instanceof Else_) {
            return null;
        }

        if ($node->elseifs !== []) {
            return null;
        }

        $ifAssignVarExpr = $this->resolveOnlyStmtAssignVar($node->stmts);
        if (! $ifAssignVarExpr instanceof Expr) {
            return null;
        }

        $elseAssignExpr = $this->resolveOnlyStmtAssignVar($node->else->stmts);
        if (! $elseAssignExpr instanceof Expr) {
            return null;
        }

        if (! $this->nodeComparator->areNodesEqual($ifAssignVarExpr, $elseAssignExpr)) {
            return null;
        }

        $ternaryIfExpr = $this->resolveOnlyStmtAssignExpr($node->stmts);
        $expr = $this->resolveOnlyStmtAssignExpr($node->else->stmts);
        if (! $ternaryIfExpr instanceof Expr) {
            return null;
        }

        if (! $expr instanceof Expr) {
            return null;
        }

        // has nested ternary → skip, it's super hard to read
        if ($this->haveNestedTernary([$node->cond, $ternaryIfExpr, $expr])) {
            return null;
        }

        $ternary = new Ternary($node->cond, $ternaryIfExpr, $expr);
        $assign = new Assign($ifAssignVarExpr, $ternary);

        // do not create super long lines
        if ($this->isNodeTooLong($assign)) {
            return null;
        }

        if ($ternary->cond instanceof BinaryOp || $ternary->cond instanceof Assign) {
            $ternary->cond->setAttribute(AttributeKey::ORIGINAL_NODE, null);
        }

        $expression = new Expression($assign);
        $this->mirrorComments($expression, $node);

        return $expression;
    }

    /**
     * @param Stmt[] $stmts
     */
    private function resolveOnlyStmtAssignVar(array $stmts): ?Expr
    {
        if (count($stmts) !== 1) {
            return null;
        }

        $stmt = $stmts[0];
        if (! $stmt instanceof Expression) {
            return null;
        }

        $stmtExpr = $stmt->expr;
        if (! $stmtExpr instanceof Assign) {
            return null;
        }

        return $stmtExpr->var;
    }

    /**
     * @param Stmt[] $stmts
     */
    private function resolveOnlyStmtAssignExpr(array $stmts): ?Expr
    {
        if (count($stmts) !== 1) {
            return null;
        }

        $stmt = $stmts[0];
        if (! $stmt instanceof Expression) {
            return null;
        }

        if ($stmt->getComments() !== []) {
            return null;
        }

        $stmtExpr = $stmt->expr;
        if (! $stmtExpr instanceof Assign) {
            return null;
        }

        return $stmtExpr->expr;
    }

    /**
     * @param Node[] $nodes
     */
    private function haveNestedTernary(array $nodes): bool
    {
        foreach ($nodes as $node) {
            $ternary = $this->betterNodeFinder->findFirstInstanceOf($node, Ternary::class);
            if ($ternary instanceof Ternary) {
                return true;
            }
        }

        return false;
    }

    private function isNodeTooLong(Assign $assign): bool
    {
        $assignContent = $this->betterStandardPrinter->print($assign);
        return strlen($assignContent) > self::LINE_LENGTH_LIMIT;
    }
}