<?php

namespace Phabel\Target\Php73;

use Phabel\Context;
use Phabel\Plugin;
use PhpParser\Node\Expr\Array_;
use PhpParser\Node\Expr\ArrayDimFetch;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\AssignRef;
use PhpParser\Node\Expr\List_;
use PhpParser\Node\Expr\Variable;
use PhpParser\Node\Stmt\Foreach_;

/**
 * Polyfills list assignment by reference.
 */
class ListReference extends Plugin
{
    /**
     * Parse list foreach with custom keys.
     *
     * @param Foreach_ $node Foreach
     *
     * @return void
     */
    public function enterForeach(Foreach_ $node, Context $ctx): void
    {
        if (!($node->valueVar instanceof List_ || $node->valueVar instanceof Array_) || !$this->shouldSplit($node->valueVar)) {
            return;
        }
        $list = $node->valueVar;
        $var = $node->valueVar = $ctx->getVariable();
        $assignments = self::splitList($list, $var);
        $node->stmts
    }
    /**
     * Parse list assignment with custom keys.
     *
     * @param Assign $node List assignment
     *
     * @return void
     */
    public function enterAssign(Assign $node, Context $ctx): void
    {
        if (!($node->var instanceof List_ || $node->var instanceof Array_) || !$this->shouldSplit($node->var)) {
            return;
        }
        [$node->var, $array] = $this->splitList($node->var, $ctx);
        $node->expr = self::callPoly('destructure', $array, $node->expr);
    }
    /**
     * Split referenced list into multiple assignments.
     *
     * @param Array_|List_ $list List
     * @param Variable     $var  Variable
     *
     * @return (Assign|AssignRef)[]
     */
    private static function splitList($list, Variable $var): array
    {
        $assignments = [];
        $key = 0; // Technically a list assignment does not support mixed keys, but we need this for nested assignments
        foreach ($list->items as $item) {
            if (!$item) {
                continue;
            }
            $curKey = $item->key ?? $key++;
            if ($item->value instanceof List_ || $item->value instanceof Array_) {
                // Do nothing, will re-split later if needed
            } else if ($item->byRef) {
                $assignments []= new AssignRef($item->value, new ArrayDimFetch($var, $curKey));
            } else {
                $assignments []= new Assign($item->value, new ArrayDimFetch($var, $curKey));
            }
        }
        return $assignments;
    }
    /**
     * Whether this is a referenced list.
     *
     * @param List_|Array_ $list List
     *
     * @return boolean
     */
    private function shouldSplit($list): bool
    {
        foreach ($list->items ?? [] as $item) {
            if ($item->byRef) {
                return true;
            }
        }
        return false;
    }
}