<?php

declare (strict_types=1);
namespace Matomo\Dependencies\MaxMind\Db;

use Matomo\Dependencies\MaxMind\Db\Reader\Decoder;
use Matomo\Dependencies\MaxMind\Db\Reader\InvalidDatabaseException;
use Matomo\Dependencies\MaxMind\Db\Reader\Metadata;
use Matomo\Dependencies\MaxMind\Db\Reader\Util;
/**
 * Instances of this class provide a reader for the MaxMind DB format. IP
 * addresses can be looked up using the get method.
 */
class Reader
{
    /**
     * @var int
     */
    private static $DATA_SECTION_SEPARATOR_SIZE = 16;
    /**
     * @var string
     */
    private static $METADATA_START_MARKER = "\xab\xcd\xefMaxMind.com";
    /**
     * @var int<0, max>
     */
    private static $METADATA_START_MARKER_LENGTH = 14;
    /**
     * @var int
     */
    private static $METADATA_MAX_SIZE = 131072;
    // 128 * 1024 = 128KiB
    /**
     * @var Decoder
     */
    private $decoder;
    /**
     * @var resource
     */
    private $fileHandle;
    /**
     * @var int
     */
    private $fileSize;
    /**
     * @var int
     */
    private $ipV4Start;
    /**
     * @var Metadata
     */
    private $metadata;
    /**
     * Constructs a Reader for the MaxMind DB format. The file passed to it must
     * be a valid MaxMind DB file such as a GeoIp2 database file.
     *
     * @param string $database the MaxMind DB file to use
     *
     * @throws \InvalidArgumentException for invalid database path or unknown arguments
     * @throws InvalidDatabaseException
     *                                   if the database is invalid or there is an error reading
     *                                   from it
     */
    public function __construct(string $database)
    {
        if (\func_num_args() !== 1) {
            throw new \ArgumentCountError(\sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args()));
        }
        if (is_dir($database)) {
            // This matches the error that the C extension throws.
            throw new InvalidDatabaseException("Error opening database file ({$database}). Is this a valid MaxMind DB file?");
        }
        $fileHandle = @fopen($database, 'rb');
        if ($fileHandle === \false) {
            throw new \InvalidArgumentException("The file \"{$database}\" does not exist or is not readable.");
        }
        $this->fileHandle = $fileHandle;
        $fstat = fstat($fileHandle);
        if ($fstat === \false) {
            throw new \UnexpectedValueException("Error determining the size of \"{$database}\".");
        }
        $this->fileSize = $fstat['size'];
        $start = $this->findMetadataStart($database);
        $metadataDecoder = new Decoder($this->fileHandle, $start);
        [$metadataArray] = $metadataDecoder->decode($start);
        $this->metadata = new Metadata($metadataArray);
        $this->decoder = new Decoder($this->fileHandle, $this->metadata->searchTreeSize + self::$DATA_SECTION_SEPARATOR_SIZE);
        $this->ipV4Start = $this->ipV4StartNode();
    }
    /**
     * Retrieves the record for the IP address.
     *
     * @param string $ipAddress the IP address to look up
     *
     * @throws \BadMethodCallException   if this method is called on a closed database
     * @throws \InvalidArgumentException if something other than a single IP address is passed to the method
     * @throws InvalidDatabaseException
     *                                   if the database is invalid or there is an error reading
     *                                   from it
     *
     * @return mixed the record for the IP address
     */
    public function get(string $ipAddress)
    {
        if (\func_num_args() !== 1) {
            throw new \ArgumentCountError(\sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args()));
        }
        [$record] = $this->getWithPrefixLen($ipAddress);
        return $record;
    }
    /**
     * Retrieves the record for the IP address and its associated network prefix length.
     *
     * @param string $ipAddress the IP address to look up
     *
     * @throws \BadMethodCallException   if this method is called on a closed database
     * @throws \InvalidArgumentException if something other than a single IP address is passed to the method
     * @throws InvalidDatabaseException
     *                                   if the database is invalid or there is an error reading
     *                                   from it
     *
     * @return array{0:mixed, 1:int} an array where the first element is the record and the
     *                               second the network prefix length for the record
     */
    public function getWithPrefixLen(string $ipAddress) : array
    {
        if (\func_num_args() !== 1) {
            throw new \ArgumentCountError(\sprintf('%s() expects exactly 1 parameter, %d given', __METHOD__, \func_num_args()));
        }
        if (!\is_resource($this->fileHandle)) {
            throw new \BadMethodCallException('Attempt to read from a closed MaxMind DB.');
        }
        [$pointer, $prefixLen] = $this->findAddressInTree($ipAddress);
        if ($pointer === 0) {
            return [null, $prefixLen];
        }
        return [$this->resolveDataPointer($pointer), $prefixLen];
    }
    /**
     * @return array{0:int, 1:int}
     */
    private function findAddressInTree(string $ipAddress) : array
    {
        $packedAddr = @inet_pton($ipAddress);
        if ($packedAddr === \false) {
            throw new \InvalidArgumentException("The value \"{$ipAddress}\" is not a valid IP address.");
        }
        $rawAddress = unpack('C*', $packedAddr);
        if ($rawAddress === \false) {
            throw new InvalidDatabaseException('Could not unpack the unsigned char of the packed in_addr representation.');
        }
        $bitCount = \count($rawAddress) * 8;
        // The first node of the tree is always node 0, at the beginning of the
        // value
        $node = 0;
        $metadata = $this->metadata;
        // Check if we are looking up an IPv4 address in an IPv6 tree. If this
        // is the case, we can skip over the first 96 nodes.
        if ($metadata->ipVersion === 6) {
            if ($bitCount === 32) {
                $node = $this->ipV4Start;
            }
        } elseif ($metadata->ipVersion === 4 && $bitCount === 128) {
            throw new \InvalidArgumentException("Error looking up {$ipAddress}. You attempted to look up an" . ' IPv6 address in an IPv4-only database.');
        }
        $nodeCount = $metadata->nodeCount;
        for ($i = 0; $i < $bitCount && $node < $nodeCount; ++$i) {
            $tempBit = 0xff & $rawAddress[($i >> 3) + 1];
            $bit = 1 & $tempBit >> 7 - $i % 8;
            $node = $this->readNode($node, $bit);
        }
        if ($node === $nodeCount) {
            // Record is empty
            return [0, $i];
        }
        if ($node > $nodeCount) {
            // Record is a data pointer
            return [$node, $i];
        }
        throw new InvalidDatabaseException('Invalid or corrupt database. Maximum search depth reached without finding a leaf node');
    }
    private function ipV4StartNode() : int
    {
        // If we have an IPv4 database, the start node is the first node
        if ($this->metadata->ipVersion === 4) {
            return 0;
        }
        $node = 0;
        for ($i = 0; $i < 96 && $node < $this->metadata->nodeCount; ++$i) {
            $node = $this->readNode($node, 0);
        }
        return $node;
    }
    private function readNode(int $nodeNumber, int $index) : int
    {
        $baseOffset = $nodeNumber * $this->metadata->nodeByteSize;
        switch ($this->metadata->recordSize) {
            case 24:
                $bytes = Util::read($this->fileHandle, $baseOffset + $index * 3, 3);
                $rc = unpack('N', "\x00" . $bytes);
                if ($rc === \false) {
                    throw new InvalidDatabaseException('Could not unpack the unsigned long of the node.');
                }
                [, $node] = $rc;
                return $node;
            case 28:
                $bytes = Util::read($this->fileHandle, $baseOffset + 3 * $index, 4);
                if ($index === 0) {
                    $middle = (0xf0 & \ord($bytes[3])) >> 4;
                } else {
                    $middle = 0xf & \ord($bytes[0]);
                }
                $rc = unpack('N', \chr($middle) . substr($bytes, $index, 3));
                if ($rc === \false) {
                    throw new InvalidDatabaseException('Could not unpack the unsigned long of the node.');
                }
                [, $node] = $rc;
                return $node;
            case 32:
                $bytes = Util::read($this->fileHandle, $baseOffset + $index * 4, 4);
                $rc = unpack('N', $bytes);
                if ($rc === \false) {
                    throw new InvalidDatabaseException('Could not unpack the unsigned long of the node.');
                }
                [, $node] = $rc;
                return $node;
            default:
                throw new InvalidDatabaseException('Unknown record size: ' . $this->metadata->recordSize);
        }
    }
    /**
     * @return mixed
     */
    private function resolveDataPointer(int $pointer)
    {
        $resolved = $pointer - $this->metadata->nodeCount + $this->metadata->searchTreeSize;
        if ($resolved >= $this->fileSize) {
            throw new InvalidDatabaseException("The MaxMind DB file's search tree is corrupt");
        }
        [$data] = $this->decoder->decode($resolved);
        return $data;
    }
    /*
     * This is an extremely naive but reasonably readable implementation. There
     * are much faster algorithms (e.g., Boyer-Moore) for this if speed is ever
     * an issue, but I suspect it won't be.
     */
    private function findMetadataStart(string $filename) : int
    {
        $handle = $this->fileHandle;
        $fileSize = $this->fileSize;
        $marker = self::$METADATA_START_MARKER;
        $markerLength = self::$METADATA_START_MARKER_LENGTH;
        $minStart = $fileSize - min(self::$METADATA_MAX_SIZE, $fileSize);
        for ($offset = $fileSize - $markerLength; $offset >= $minStart; --$offset) {
            if (fseek($handle, $offset) !== 0) {
                break;
            }
            $value = fread($handle, $markerLength);
            if ($value === $marker) {
                return $offset + $markerLength;
            }
        }
        throw new InvalidDatabaseException("Error opening database file ({$filename}). " . 'Is this a valid MaxMind DB file?');
    }
    /**
     * @throws \InvalidArgumentException if arguments are passed to the method
     * @throws \BadMethodCallException   if the database has been closed
     *
     * @return Metadata object for the database
     */
    public function metadata() : Metadata
    {
        if (\func_num_args()) {
            throw new \ArgumentCountError(\sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args()));
        }
        // Not technically required, but this makes it consistent with
        // C extension and it allows us to change our implementation later.
        if (!\is_resource($this->fileHandle)) {
            throw new \BadMethodCallException('Attempt to read from a closed MaxMind DB.');
        }
        return clone $this->metadata;
    }
    /**
     * Closes the MaxMind DB and returns resources to the system.
     *
     * @throws \Exception
     *                    if an I/O error occurs
     */
    public function close() : void
    {
        if (\func_num_args()) {
            throw new \ArgumentCountError(\sprintf('%s() expects exactly 0 parameters, %d given', __METHOD__, \func_num_args()));
        }
        if (!\is_resource($this->fileHandle)) {
            throw new \BadMethodCallException('Attempt to close a closed MaxMind DB.');
        }
        fclose($this->fileHandle);
    }
}
