class ScopeManager

class ScopeManager {
    
    /**
     * An associative array of a list of token index pairs which start and end
     * scopes and will be used to check for unused variables.
     *
     * The outer array of scopes is keyed by a string containing the filename.
     * The inner array of scopes in keyed by the scope start token index.
     *
     * @var array<string, array<int, ScopeInfo>>
     */
    private $scopes = [];
    
    /**
     * Add a scope's start and end index to our record for the file.
     *
     * @param File $phpcsFile
     * @param int  $scopeStartIndex
     *
     * @return ScopeInfo
     */
    public function recordScopeStartAndEnd(File $phpcsFile, $scopeStartIndex) {
        $scopeEndIndex = Helpers::getScopeCloseForScopeOpen($phpcsFile, $scopeStartIndex);
        $filename = $phpcsFile->getFilename();
        if (!isset($this->scopes[$filename])) {
            $this->scopes[$filename] = [];
        }
        Helpers::debug('recording scope for file', $filename, 'start/end', $scopeStartIndex, $scopeEndIndex);
        $scope = new ScopeInfo($scopeStartIndex, $scopeEndIndex);
        $this->scopes[$filename][$scopeStartIndex] = $scope;
        return $scope;
    }
    
    /**
     * Return the scopes for a file.
     *
     * @param string $filename
     *
     * @return ScopeInfo[]
     */
    public function getScopesForFilename($filename) {
        if (empty($this->scopes[$filename])) {
            return [];
        }
        return array_values($this->scopes[$filename]);
    }
    
    /**
     * Return the scope for a scope start index.
     *
     * @param string $filename
     * @param int    $scopeStartIndex
     *
     * @return ScopeInfo|null
     */
    public function getScopeForScopeStart($filename, $scopeStartIndex) {
        if (empty($this->scopes[$filename][$scopeStartIndex])) {
            return null;
        }
        return $this->scopes[$filename][$scopeStartIndex];
    }
    
    /**
     * Find scopes closed by a scope close index.
     *
     * @param string $filename
     * @param int    $scopeEndIndex
     *
     * @return ScopeInfo[]
     */
    public function getScopesForScopeEnd($filename, $scopeEndIndex) {
        $scopePairsForFile = $this->getScopesForFilename($filename);
        $scopeIndicesThisCloses = array_reduce($scopePairsForFile, function ($found, $scope) use ($scopeEndIndex) {
            if (!is_int($scope->scopeEndIndex)) {
                Helpers::debug('No scope closer found for scope start', $scope->scopeStartIndex);
                return $found;
            }
            if ($scopeEndIndex === $scope->scopeEndIndex) {
                $found[] = $scope;
            }
            return $found;
        }, []);
        return $scopeIndicesThisCloses;
    }

}