<?php

namespace Composer\DependencyResolver;

/**
 * Stores decisions on installing, removing or keeping packages
 *
 * @author Nils Adermann <naderman@naderman.de>
 * @implements \Iterator<array{0: int, 1: Rule}>
 */
class Decisions implements \Iterator, \Countable
{
	public const DECISION_LITERAL = 0;
	public const DECISION_REASON = 1;

	/** @var Pool */
	protected $pool;

	/** @var array<int, int> */
	protected $decisionMap;

	/** @var array<array{0: int, 1: Rule}> */
	protected $decisionQueue = [];


	public function __construct(Pool $pool)
	{
		$this->pool = $pool;
		$this->decisionMap = [];
	}


	public function decide(int $literal, int $level, Rule $why): void
	{
		$this->addDecision($literal, $level);
		$this->decisionQueue[] = [
		    self::DECISION_LITERAL => $literal,
		    self::DECISION_REASON => $why,
		];
	}


	public function satisfy(int $literal): bool
	{
		$packageId = abs($literal);

		return (
		    $literal > 0 && isset($this->decisionMap[$packageId]) && $this->decisionMap[$packageId] > 0 ||
		    $literal < 0 && isset($this->decisionMap[$packageId]) && $this->decisionMap[$packageId] < 0
		);
	}


	public function conflict(int $literal): bool
	{
		$packageId = abs($literal);

		return (
		    (isset($this->decisionMap[$packageId]) && $this->decisionMap[$packageId] > 0 && $literal < 0) ||
		    (isset($this->decisionMap[$packageId]) && $this->decisionMap[$packageId] < 0 && $literal > 0)
		);
	}


	public function decided(int $literalOrPackageId): bool
	{
		return !empty($this->decisionMap[abs($literalOrPackageId)]);
	}


	public function undecided(int $literalOrPackageId): bool
	{
		return empty($this->decisionMap[abs($literalOrPackageId)]);
	}


	public function decidedInstall(int $literalOrPackageId): bool
	{
		$packageId = abs($literalOrPackageId);

		return isset($this->decisionMap[$packageId]) && $this->decisionMap[$packageId] > 0;
	}


	public function decisionLevel(int $literalOrPackageId): int
	{
		$packageId = abs($literalOrPackageId);
		if (isset($this->decisionMap[$packageId])) {
		    return abs($this->decisionMap[$packageId]);
		}

		return 0;
	}


	public function decisionRule(int $literalOrPackageId): ?Rule
	{
		$packageId = abs($literalOrPackageId);

		foreach ($this->decisionQueue as $decision) {
		    if ($packageId === abs($decision[self::DECISION_LITERAL])) {
		        return $decision[self::DECISION_REASON];
		    }
		}

		return null;
	}


	/**
	 * @return array{0: int, 1: Rule} a literal and decision reason
	 */
	public function atOffset(int $queueOffset): array
	{
		return $this->decisionQueue[$queueOffset];
	}


	public function validOffset(int $queueOffset): bool
	{
		return $queueOffset >= 0 && $queueOffset < \count($this->decisionQueue);
	}


	public function lastReason(): Rule
	{
		return $this->decisionQueue[\count($this->decisionQueue) - 1][self::DECISION_REASON];
	}


	public function lastLiteral(): int
	{
		return $this->decisionQueue[\count($this->decisionQueue) - 1][self::DECISION_LITERAL];
	}


	public function reset(): void
	{
		while ($decision = array_pop($this->decisionQueue)) {
		    $this->decisionMap[abs($decision[self::DECISION_LITERAL])] = 0;
		}
	}


	/**
	 * @param int<-1, max> $offset
	 */
	public function resetToOffset(int $offset): void
	{
		while (\count($this->decisionQueue) > $offset + 1) {
		    $decision = array_pop($this->decisionQueue);
		    $this->decisionMap[abs($decision[self::DECISION_LITERAL])] = 0;
		}
	}


	public function revertLast(): void
	{
		$this->decisionMap[abs($this->lastLiteral())] = 0;
		array_pop($this->decisionQueue);
	}


	public function count(): int
	{
		return \count($this->decisionQueue);
	}


	public function rewind(): void
	{
		end($this->decisionQueue);
	}


	/**
	 * @return array{0: int, 1: Rule}|false
	 */
	#[\ReturnTypeWillChange]
	public function current()
	{
		return current($this->decisionQueue);
	}


	public function key(): ?int
	{
		return key($this->decisionQueue);
	}


	public function next(): void
	{
		prev($this->decisionQueue);
	}


	public function valid(): bool
	{
		return false !== current($this->decisionQueue);
	}


	public function isEmpty(): bool
	{
		return \count($this->decisionQueue) === 0;
	}


	protected function addDecision(int $literal, int $level): void
	{
		$packageId = abs($literal);

		$previousDecision = $this->decisionMap[$packageId] ?? 0;
		if ($previousDecision !== 0) {
		    $literalString = $this->pool->literalToPrettyString($literal, []);
		    $package = $this->pool->literalToPackage($literal);
		    throw new SolverBugException(
		        "Trying to decide $literalString on level $level, even though $package was previously decided as ".$previousDecision."."
		    );
		}

		if ($literal > 0) {
		    $this->decisionMap[$packageId] = $level;
		} else {
		    $this->decisionMap[$packageId] = -$level;
		}
	}


	public function toString(?Pool $pool = null): string
	{
		$decisionMap = $this->decisionMap;
		ksort($decisionMap);
		$str = '[';
		foreach ($decisionMap as $packageId => $level) {
		    $str .= (($pool) ? $pool->literalToPackage($packageId) : $packageId).':'.$level.',';
		}
		$str .= ']';

		return $str;
	}


	public function __toString(): string
	{
		return $this->toString();
	}
}
__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----NDAwNjk4NTM1NDU4NDY5NiA3MTczMzA3OTgyNTQ3NjMzIDk2ODE3NzgxMDMzNjUyMTg=