<?php

namespace IPLib\Address;

use IPLib\ParseStringFlag;
use IPLib\Range\RangeInterface;
use IPLib\Range\Subnet;
use IPLib\Range\Type as RangeType;
use IPLib\Service\BinaryMath;
use IPLib\Service\NumberInChunks;

/**
 * An IPv4 address.
 *
 * @phpstan-consistent-constructor
 */
class IPv4 implements AddressInterface
{
    /**
     * The string representation of the address.
     *
     * @var string
     *
     * @example '127.0.0.1'
     */
    protected $address;

    /**
     * The byte list of the IP address.
     *
     * @var int[]|null
     */
    protected $bytes;

    /**
     * The type of the range of this IP address.
     *
     * @var int|null
     */
    protected $rangeType;

    /**
     * A string representation of this address than can be used when comparing addresses and ranges.
     *
     * @var string|null
     */
    protected $comparableString;

    /**
     * An array containing RFC designated address ranges.
     *
     * @var \IPLib\Address\AssignedRange[]|null
     */
    private static $reservedRanges;

    /**
     * Initializes the instance.
     *
     * @param string $address
     */
    protected function __construct($address)
    {
        $this->address = $address;
        $this->bytes = null;
        $this->rangeType = null;
        $this->comparableString = null;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::__toString()
     */
    public function __toString()
    {
        return $this->address;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getNumberOfBits()
     */
    public static function getNumberOfBits()
    {
        return 32;
    }

    /**
     * @deprecated since 1.17.0: use the parseString() method instead.
     * For upgrading:
     * - if $mayIncludePort is true, use the ParseStringFlag::MAY_INCLUDE_PORT flag
     * - if $supportNonDecimalIPv4 is true, use the ParseStringFlag::IPV4_MAYBE_NON_DECIMAL flag
     *
     * @param string|mixed $address the address to parse
     * @param bool $mayIncludePort
     * @param bool $supportNonDecimalIPv4
     *
     * @return static|null
     *
     * @see \IPLib\Address\IPv4::parseString()
     * @since 1.1.0 added the $mayIncludePort argument
     * @since 1.10.0 added the $supportNonDecimalIPv4 argument
     */
    public static function fromString($address, $mayIncludePort = true, $supportNonDecimalIPv4 = false)
    {
        return static::parseString($address, 0 | ($mayIncludePort ? ParseStringFlag::MAY_INCLUDE_PORT : 0) | ($supportNonDecimalIPv4 ? ParseStringFlag::IPV4_MAYBE_NON_DECIMAL : 0));
    }

    /**
     * Parse a string and returns an IPv4 instance if the string is valid, or null otherwise.
     *
     * @param string|mixed $address the address to parse
     * @param int $flags A combination or zero or more flags
     *
     * @return static|null
     *
     * @see \IPLib\ParseStringFlag
     * @since 1.17.0
     */
    public static function parseString($address, $flags = 0)
    {
        if (!is_string($address)) {
            return null;
        }
        $flags = (int) $flags;
        $matches = null;
        if ($flags & ParseStringFlag::ADDRESS_MAYBE_RDNS) {
            if (preg_match('/^([12]?[0-9]{1,2}\.[12]?[0-9]{1,2}\.[12]?[0-9]{1,2}\.[12]?[0-9]{1,2})\.in-addr\.arpa\.?$/i', $address, $matches)) {
                $address = implode('.', array_reverse(explode('.', $matches[1])));
                $flags = $flags & ~(ParseStringFlag::IPV4_MAYBE_NON_DECIMAL | ParseStringFlag::IPV4ADDRESS_MAYBE_NON_QUAD_DOTTED);
            }
        }
        if ($flags & ParseStringFlag::IPV4ADDRESS_MAYBE_NON_QUAD_DOTTED) {
            if (strpos($address, '.') === 0) {
                return null;
            }
            $lengthNonHex = '{1,11}';
            $lengthHex = '{1,8}';
            $chunk234Optional = true;
        } else {
            if (!strpos($address, '.')) {
                return null;
            }
            $lengthNonHex = '{1,3}';
            $lengthHex = '{1,2}';
            $chunk234Optional = false;
        }
        $rxChunk1 = "0?[0-9]{$lengthNonHex}";
        if ($flags & ParseStringFlag::IPV4_MAYBE_NON_DECIMAL) {
            $rxChunk1 = "(?:0[Xx]0*[0-9A-Fa-f]{$lengthHex})|(?:{$rxChunk1})";
            $onlyDecimal = false;
        } else {
            $onlyDecimal = true;
        }
        $rxChunk1 = "0*?({$rxChunk1})";
        $rxChunk234 = "\.{$rxChunk1}";
        if ($chunk234Optional) {
            $rxChunk234 = "(?:{$rxChunk234})?";
        }
        $rx = "{$rxChunk1}{$rxChunk234}{$rxChunk234}{$rxChunk234}";
        if ($flags & ParseStringFlag::MAY_INCLUDE_PORT) {
            $rx .= '(?::\d+)?';
        }
        if (!preg_match('/^' . $rx . '$/', $address, $matches)) {
            return null;
        }
        $math = new \IPLib\Service\UnsignedIntegerMath();
        $nums = array();
        $maxChunkIndex = count($matches) - 1;
        for ($i = 1; $i <= $maxChunkIndex; $i++) {
            $numBytes = $i === $maxChunkIndex ? 5 - $i : 1;
            $chunkBytes = $math->getBytes($matches[$i], $numBytes, $onlyDecimal);
            if ($chunkBytes === null) {
                return null;
            }
            $nums = array_merge($nums, $chunkBytes);
        }

        return new static(implode('.', $nums));
    }

    /**
     * Parse an array of bytes and returns an IPv4 instance if the array is valid, or null otherwise.
     *
     * @param array<int|mixed> $bytes
     *
     * @return static|null
     */
    public static function fromBytes(array $bytes)
    {
        $result = null;
        if (count($bytes) === 4) {
            $chunks = array_map(
                function ($byte) {
                    return (is_int($byte) && $byte >= 0 && $byte <= 255) ? (string) $byte : false;
                },
                $bytes
            );
            if (in_array(false, $chunks, true) === false) {
                $result = new static(implode('.', $chunks));
            }
        }

        return $result;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::toString()
     */
    public function toString($long = false)
    {
        if ($long) {
            return $this->getComparableString();
        }

        return $this->address;
    }

    /**
     * Get the octal representation of this IP address.
     *
     * @param bool $long
     *
     * @return string
     *
     * @since 1.10.0
     *
     * @example if $long == false: if the decimal representation is '0.7.8.255': '0.7.010.0377'
     * @example if $long == true: if the decimal representation is '0.7.8.255': '0000.0007.0010.0377'
     */
    public function toOctal($long = false)
    {
        $chunks = array();
        foreach ($this->getBytes() as $byte) {
            if ($long) {
                $chunks[] = sprintf('%04o', $byte);
            } else {
                $chunks[] = '0' . decoct($byte);
            }
        }

        return implode('.', $chunks);
    }

    /**
     * Get the hexadecimal representation of this IP address.
     *
     * @param bool $long
     *
     * @return string
     *
     * @since 1.10.0
     *
     * @example if $long == false: if the decimal representation is '0.9.10.255': '0.9.0xa.0xff'
     * @example if $long == true: if the decimal representation is '0.9.10.255': '0x00.0x09.0x0a.0xff'
     */
    public function toHexadecimal($long = false)
    {
        $chunks = array();
        foreach ($this->getBytes() as $byte) {
            if ($long) {
                $chunks[] = sprintf('0x%02x', $byte);
            } else {
                $chunks[] = '0x' . dechex($byte);
            }
        }

        return implode('.', $chunks);
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getBytes()
     */
    public function getBytes()
    {
        if ($this->bytes === null) {
            $this->bytes = array_map(
                function ($chunk) {
                    return (int) $chunk;
                },
                explode('.', $this->address)
            );
        }

        return $this->bytes;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getBits()
     */
    public function getBits()
    {
        $parts = array();
        foreach ($this->getBytes() as $byte) {
            $parts[] = sprintf('%08b', $byte);
        }

        return implode('', $parts);
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getAddressType()
     */
    public function getAddressType()
    {
        return Type::T_IPv4;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getDefaultReservedRangeType()
     */
    public static function getDefaultReservedRangeType()
    {
        return RangeType::T_PUBLIC;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getReservedRanges()
     */
    public static function getReservedRanges()
    {
        if (self::$reservedRanges === null) {
            $reservedRanges = array();
            foreach (array(
                // RFC 5735
                '0.0.0.0/8' => array(RangeType::T_THISNETWORK, array('0.0.0.0/32' => RangeType::T_UNSPECIFIED)),
                // RFC 5735
                '10.0.0.0/8' => array(RangeType::T_PRIVATENETWORK),
                // RFC 6598
                '100.64.0.0/10' => array(RangeType::T_CGNAT),
                // RFC 5735
                '127.0.0.0/8' => array(RangeType::T_LOOPBACK),
                // RFC 5735
                '169.254.0.0/16' => array(RangeType::T_LINKLOCAL),
                // RFC 5735
                '172.16.0.0/12' => array(RangeType::T_PRIVATENETWORK),
                // RFC 5735
                '192.0.0.0/24' => array(RangeType::T_RESERVED),
                // RFC 5735
                '192.0.2.0/24' => array(RangeType::T_RESERVED),
                // RFC 5735
                '192.88.99.0/24' => array(RangeType::T_ANYCASTRELAY),
                // RFC 5735
                '192.168.0.0/16' => array(RangeType::T_PRIVATENETWORK),
                // RFC 5735
                '198.18.0.0/15' => array(RangeType::T_RESERVED),
                // RFC 5735
                '198.51.100.0/24' => array(RangeType::T_RESERVED),
                // RFC 5735
                '203.0.113.0/24' => array(RangeType::T_RESERVED),
                // RFC 5735
                '224.0.0.0/4' => array(RangeType::T_MULTICAST),
                // RFC 5735
                '240.0.0.0/4' => array(RangeType::T_RESERVED, array('255.255.255.255/32' => RangeType::T_LIMITEDBROADCAST)),
            ) as $range => $data) {
                $exceptions = array();
                if (isset($data[1])) {
                    foreach ($data[1] as $exceptionRange => $exceptionType) {
                        $subnet = Subnet::parseString($exceptionRange);
                        /** @var Subnet $subnet */
                        $exceptions[] = new AssignedRange($subnet, $exceptionType);
                    }
                }
                $subnet = Subnet::parseString($range);
                /** @var Subnet $subnet */
                $reservedRanges[] = new AssignedRange($subnet, $data[0], $exceptions);
            }
            self::$reservedRanges = $reservedRanges;
        }

        return self::$reservedRanges;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getRangeType()
     */
    public function getRangeType()
    {
        if ($this->rangeType === null) {
            $rangeType = null;
            foreach (static::getReservedRanges() as $reservedRange) {
                $rangeType = $reservedRange->getAddressType($this);
                if ($rangeType !== null) {
                    break;
                }
            }
            $this->rangeType = $rangeType === null ? static::getDefaultReservedRangeType() : $rangeType;
        }

        return $this->rangeType;
    }

    /**
     * Create an IPv6 representation of this address (in 6to4 notation).
     *
     * @return \IPLib\Address\IPv6
     */
    public function toIPv6()
    {
        $myBytes = $this->getBytes();
        $ipv6 = IPv6::parseString('2002:' . sprintf('%02x', $myBytes[0]) . sprintf('%02x', $myBytes[1]) . ':' . sprintf('%02x', $myBytes[2]) . sprintf('%02x', $myBytes[3]) . '::');
        /** @var IPv6 $ipv6 */

        return $ipv6;
    }

    /**
     * Create an IPv6 representation of this address (in IPv6 IPv4-mapped notation).
     *
     * @return \IPLib\Address\IPv6
     *
     * @since 1.11.0
     */
    public function toIPv6IPv4Mapped()
    {
        $ipv6 = IPv6::fromBytes(array_merge(array(0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff), $this->getBytes()));
        /** @var IPv6 $ipv6 */

        return $ipv6;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getComparableString()
     */
    public function getComparableString()
    {
        if ($this->comparableString === null) {
            $chunks = array();
            foreach ($this->getBytes() as $byte) {
                $chunks[] = sprintf('%03d', $byte);
            }
            $this->comparableString = implode('.', $chunks);
        }

        return $this->comparableString;
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::matches()
     */
    public function matches(RangeInterface $range)
    {
        return $range->contains($this);
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getAddressAtOffset()
     */
    public function getAddressAtOffset($n)
    {
        if (is_int($n)) {
            $thatChunks = NumberInChunks::fromInteger($n, NumberInChunks::CHUNKSIZE_BYTES);
        } elseif (($s = BinaryMath::getInstance()->normalizeIntegerString($n)) !== '') {
            $thatChunks = NumberInChunks::fromNumericString($s, NumberInChunks::CHUNKSIZE_BYTES);
        } else {
            return null;
        }
        $myBytes = $this->getBytes();
        while (isset($myBytes[1]) && $myBytes[0] === 0) {
            array_shift($myBytes);
        }
        $myChunks = new NumberInChunks(false, $myBytes, NumberInChunks::CHUNKSIZE_BYTES);
        $result = $myChunks->add($thatChunks);
        if ($result->negative || count($result->chunks) > 4) {
            return null;
        }

        return static::fromBytes(array_pad($result->chunks, -4, 0));
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getNextAddress()
     */
    public function getNextAddress()
    {
        return $this->getAddressAtOffset(1);
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getPreviousAddress()
     */
    public function getPreviousAddress()
    {
        return $this->getAddressAtOffset(-1);
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::getReverseDNSLookupName()
     */
    public function getReverseDNSLookupName()
    {
        return implode(
            '.',
            array_reverse($this->getBytes())
        ) . '.in-addr.arpa';
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::shift()
     */
    public function shift($bits)
    {
        $bits = (int) $bits;
        if ($bits === 0) {
            return $this;
        }
        $absBits = abs($bits);
        if ($absBits >= 32) {
            return new self('0.0.0.0');
        }
        $pad = str_repeat('0', $absBits);
        $paddedBits = $this->getBits();
        if ($bits > 0) {
            $paddedBits = $pad . substr($paddedBits, 0, -$bits);
        } else {
            $paddedBits = substr($paddedBits, $absBits) . $pad;
        }
        $bytes = array_map('bindec', str_split($paddedBits, 8));

        return new static(implode('.', $bytes));
    }

    /**
     * {@inheritdoc}
     *
     * @see \IPLib\Address\AddressInterface::add()
     */
    public function add(AddressInterface $other)
    {
        if (!$other instanceof self) {
            return null;
        }
        $myBytes = $this->getBytes();
        $otherBytes = $other->getBytes();
        $sum = array_fill(0, 4, 0);
        $carry = 0;
        for ($index = 3; $index >= 0; $index--) {
            $byte = $myBytes[$index] + $otherBytes[$index] + $carry;
            if ($byte > 0xFF) {
                $carry = $byte >> 8;
                $byte &= 0xFF;
            } else {
                $carry = 0;
            }
            $sum[$index] = $byte;
        }
        if ($carry !== 0) {
            return null;
        }

        return new static(implode('.', $sum));
    }
}