<?php

namespace Caxy\HtmlDiff;

/**
 * Class AbstractDiff
 * @package Caxy\HtmlDiff
 */
abstract class AbstractDiff
{
    /**
     * @var array
     *
     * @deprecated since 0.1.0
     */
    public static $defaultSpecialCaseTags = array('strong', 'b', 'i', 'big', 'small', 'u', 'sub', 'sup', 'strike', 's', 'p');
    /**
     * @var array
     *
     * @deprecated since 0.1.0
     */
    public static $defaultSpecialCaseChars = array('.', ',', '(', ')', '\'');
    /**
     * @var bool
     *
     * @deprecated since 0.1.0
     */
    public static $defaultGroupDiffs = true;

    /**
     * @var HtmlDiffConfig
     */
    protected $config;

    /**
     * @var string
     */
    protected $content;
    /**
     * @var string
     */
    protected $oldText;
    /**
     * @var string
     */
    protected $newText;
    /**
     * @var array
     */
    protected $oldWords = array();
    /**
     * @var array
     */
    protected $newWords = array();

    /**
     * @var DiffCache[]
     */
    private $diffCaches = array();

    /**
     * AbstractDiff constructor.
     *
     * @param string     $oldText
     * @param string     $newText
     * @param string     $encoding
     * @param null|array $specialCaseTags
     * @param null|bool  $groupDiffs
     */
    public function __construct($oldText, $newText, $encoding = 'UTF-8', $specialCaseTags = null, $groupDiffs = null)
    {
        mb_substitute_character(0x20);

        $this->config = HtmlDiffConfig::create()->setEncoding($encoding);

        if ($specialCaseTags !== null) {
            $this->config->setSpecialCaseTags($specialCaseTags);
        }

        if ($groupDiffs !== null) {
            $this->config->setGroupDiffs($groupDiffs);
        }

        $this->oldText = $this->purifyHtml(trim($oldText));
        $this->newText = $this->purifyHtml(trim($newText));
        $this->content = '';
    }

    /**
     * @return bool|string
     */
    abstract public function build();

    /**
     * @return DiffCache|null
     */
    protected function getDiffCache()
    {
        if (!$this->hasDiffCache()) {
            return null;
        }

        $hash = spl_object_hash($this->getConfig()->getCacheProvider());

        if (!array_key_exists($hash, $this->diffCaches)) {
            $this->diffCaches[$hash] = new DiffCache($this->getConfig()->getCacheProvider());
        }

        return $this->diffCaches[$hash];
    }

    /**
     * @return bool
     */
    protected function hasDiffCache()
    {
        return null !== $this->getConfig()->getCacheProvider();
    }

    /**
     * @return HtmlDiffConfig
     */
    public function getConfig()
    {
        return $this->config;
    }

    /**
     * @param HtmlDiffConfig $config
     *
     * @return AbstractDiff
     */
    public function setConfig(HtmlDiffConfig $config)
    {
        $this->config = $config;

        return $this;
    }

    /**
     * @return int
     *
     * @deprecated since 0.1.0
     */
    public function getMatchThreshold()
    {
        return $this->config->getMatchThreshold();
    }

    /**
     * @param int $matchThreshold
     *
     * @return AbstractDiff
     *
     * @deprecated since 0.1.0
     */
    public function setMatchThreshold($matchThreshold)
    {
        $this->config->setMatchThreshold($matchThreshold);

        return $this;
    }

    /**
     * @param array $chars
     *
     * @deprecated since 0.1.0
     */
    public function setSpecialCaseChars(array $chars)
    {
        $this->config->setSpecialCaseChars($chars);
    }

    /**
     * @return array|null
     *
     * @deprecated since 0.1.0
     */
    public function getSpecialCaseChars()
    {
        return $this->config->getSpecialCaseChars();
    }

    /**
     * @param string $char
     *
     * @deprecated since 0.1.0
     */
    public function addSpecialCaseChar($char)
    {
        $this->config->addSpecialCaseChar($char);
    }

    /**
     * @param string $char
     *
     * @deprecated since 0.1.0
     */
    public function removeSpecialCaseChar($char)
    {
        $this->config->removeSpecialCaseChar($char);
    }

    /**
     * @param array $tags
     *
     * @deprecated since 0.1.0
     */
    public function setSpecialCaseTags(array $tags = array())
    {
        $this->config->setSpecialCaseChars($tags);
    }

    /**
     * @param string $tag
     *
     * @deprecated since 0.1.0
     */
    public function addSpecialCaseTag($tag)
    {
        $this->config->addSpecialCaseTag($tag);
    }

    /**
     * @param string $tag
     *
     * @deprecated since 0.1.0
     */
    public function removeSpecialCaseTag($tag)
    {
        $this->config->removeSpecialCaseTag($tag);
    }

    /**
     * @return array|null
     *
     * @deprecated since 0.1.0
     */
    public function getSpecialCaseTags()
    {
        return $this->config->getSpecialCaseTags();
    }

    /**
     * @return string
     */
    public function getOldHtml()
    {
        return $this->oldText;
    }

    /**
     * @return string
     */
    public function getNewHtml()
    {
        return $this->newText;
    }

    /**
     * @return string
     */
    public function getDifference()
    {
        return $this->content;
    }

    /**
     * @param bool $boolean
     *
     * @return $this
     *
     * @deprecated since 0.1.0
     */
    public function setGroupDiffs($boolean)
    {
        $this->config->setGroupDiffs($boolean);

        return $this;
    }

    /**
     * @return bool
     *
     * @deprecated since 0.1.0
     */
    public function isGroupDiffs()
    {
        return $this->config->isGroupDiffs();
    }

    /**
     * @param string $tag
     *
     * @return string
     */
    protected function getOpeningTag($tag)
    {
        return "/<".$tag."[^>]*/i";
    }

    /**
     * @param string $tag
     *
     * @return string
     */
    protected function getClosingTag($tag)
    {
        return "</".$tag.">";
    }

    /**
     * @param string $str
     * @param string $start
     * @param string $end
     *
     * @return string
     */
    protected function getStringBetween($str, $start, $end)
    {
        $expStr = explode( $start, $str, 2 );
        if ( count( $expStr ) > 1 ) {
            $expStr = explode( $end, $expStr[ 1 ] );
            if ( count( $expStr ) > 1 ) {
                array_pop( $expStr );

                return implode( $end, $expStr );
            }
        }

        return '';
    }

    /**
     * @param string $html
     *
     * @return string
     */
    protected function purifyHtml($html)
    {
        if ( class_exists( 'Tidy' ) && false ) {
            $config = array( 'output-xhtml'   => true, 'indent' => false );
            $tidy = new tidy();
            $tidy->parseString( $html, $config, 'utf8' );
            $html = (string) $tidy;

            return $this->getStringBetween( $html, '<body>' );
        }

        return $html;
    }

    protected function splitInputsToWords()
    {
        $this->oldWords = $this->convertHtmlToListOfWords( $this->explode( $this->oldText ) );
        $this->newWords = $this->convertHtmlToListOfWords( $this->explode( $this->newText ) );
    }

    /**
     * @param string $text
     *
     * @return bool
     */
    protected function isPartOfWord($text)
    {
        return ctype_alnum(str_replace($this->config->getSpecialCaseChars(), '', $text));
    }

    /**
     * @param array $characterString
     *
     * @return array
     */
    protected function convertHtmlToListOfWords($characterString)
    {
        $mode = 'character';
        $current_word = '';
        $words = array();
        foreach ($characterString as $i => $character) {
            switch ($mode) {
                case 'character':
                if ( $this->isStartOfTag( $character ) ) {
                    if ($current_word != '') {
                        $words[] = $current_word;
                    }
                    $current_word = "<";
                    $mode = 'tag';
                } elseif (preg_match("/\s/", $character)) {
                    if ($current_word !== '') {
                        $words[] = $current_word;
                    }
                    $current_word = preg_replace('/\s+/S', ' ', $character);
                    $mode = 'whitespace';
                } else {
                    if (
                        (ctype_alnum($character) && (strlen($current_word) == 0 || $this->isPartOfWord($current_word))) ||
                        (in_array($character, $this->config->getSpecialCaseChars()) && isset($characterString[$i+1]) && $this->isPartOfWord($characterString[$i+1]))
                    ) {
                        $current_word .= $character;
                    } else {
                        $words[] = $current_word;
                        $current_word = $character;
                    }
                }
                break;
                case 'tag' :
                if ( $this->isEndOfTag( $character ) ) {
                    $current_word .= ">";
                    $words[] = $current_word;
                    $current_word = "";

                    if ( !preg_match('[^\s]', $character ) ) {
                        $mode = 'whitespace';
                    } else {
                        $mode = 'character';
                    }
                } else {
                    $current_word .= $character;
                }
                break;
                case 'whitespace':
                if ( $this->isStartOfTag( $character ) ) {
                    if ($current_word !== '') {
                        $words[] = $current_word;
                    }
                    $current_word = "<";
                    $mode = 'tag';
                } elseif ( preg_match( "/\s/", $character ) ) {
                    $current_word .= $character;
                    $current_word = preg_replace('/\s+/S', ' ', $current_word);
                } else {
                    if ($current_word != '') {
                        $words[] = $current_word;
                    }
                    $current_word = $character;
                    $mode = 'character';
                }
                break;
                default:
                break;
            }
        }
        if ($current_word != '') {
            $words[] = $current_word;
        }

        return $words;
    }

    /**
     * @param string $val
     *
     * @return bool
     */
    protected function isStartOfTag($val)
    {
        return $val == "<";
    }

    /**
     * @param string $val
     *
     * @return bool
     */
    protected function isEndOfTag($val)
    {
        return $val == ">";
    }

    /**
     * @param string $value
     *
     * @return bool
     */
    protected function isWhiteSpace($value)
    {
        return !preg_match( '[^\s]', $value );
    }

    /**
     * @param string $value
     *
     * @return array
     */
    protected function explode($value)
    {
        // as suggested by @onassar
        return preg_split( '//u', $value );
    }
}