<?php

namespace Composer\DependencyResolver;

/**
 * Wrapper around a Rule which keeps track of the two literals it watches
 *
 * Used by RuleWatchGraph to store rules in two RuleWatchChains.
 *
 * @author Nils Adermann <naderman@naderman.de>
 */
class RuleWatchNode
{
    /** @var int */
    public $watch1;

    /** @var int */
    public $watch2;

    /** @var Rule */
    protected $rule;

    /**
     * Creates a new node watching the first and second literals of the rule.
     *
     * @param Rule $rule The rule to wrap
     */
    public function __construct(Rule $rule)
    {
        $this->rule = $rule;

        $literals = $rule->getLiterals();

        $literalCount = \count($literals);
        $this->watch1 = $literalCount > 0 ? $literals[0] : 0;
        $this->watch2 = $literalCount > 1 ? $literals[1] : 0;
    }

    /**
     * Places the second watch on the rule's literal, decided at the highest level
     *
     * Useful for learned rules where the literal for the highest rule is most
     * likely to quickly lead to further decisions.
     *
     * @param Decisions $decisions The decisions made so far by the solver
     */
    public function watch2OnHighest(Decisions $decisions): void
    {
        $literals = $this->rule->getLiterals();

        // if there are only 2 elements, both are being watched anyway
        if (\count($literals) < 3 || $this->rule instanceof MultiConflictRule) {
            return;
        }

        $watchLevel = 0;

        foreach ($literals as $literal) {
            $level = $decisions->decisionLevel($literal);

            if ($level > $watchLevel) {
                $this->watch2 = $literal;
                $watchLevel = $level;
            }
        }
    }

    /**
     * Returns the rule this node wraps
     */
    public function getRule(): Rule
    {
        return $this->rule;
    }

    /**
     * Given one watched literal, this method returns the other watched literal
     *
     * @param  int $literal The watched literal that should not be returned
     * @return int A literal
     */
    public function getOtherWatch(int $literal): int
    {
        if ($this->watch1 === $literal) {
            return $this->watch2;
        }

        return $this->watch1;
    }

    /**
     * Moves a watch from one literal to another
     *
     * @param int $from The previously watched literal
     * @param int $to   The literal to be watched now
     */
    public function moveWatch(int $from, int $to): void
    {
        if ($this->watch1 === $from) {
            $this->watch1 = $to;
        } else {
            $this->watch2 = $to;
        }
    }
}__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----MTg2NDAxOTQyNDU5NzU0OCA3OTg1MDc2ODYxMzg2NzM4IDEyNzQwNzQ3MzIwMTMyNw==