<?php

namespace App\Entity;

class Term
{
    public ?string $kanji;
    public ?string $definitionJp;
    public ?string $definitionEn;

    public function getReading(): ?string
    {
        return self::parseFurigana($this->kanji)['reading'];
    }

    public function getKanji(): string
    {
        return self::parseFurigana($this->kanji)['kanji'];
    }

    public static function parseFurigana(string $furigana): array
    {
        // 0: all, 1: (kanji/hiragana), 2: ([reading]): 3: (reading)
        preg_match_all('/([^ \[]+)(\[([^\]]*)\])? ?/', $furigana, $matches, PREG_SET_ORDER);

        $matchedKanji   = array_map(fn($x) => $x[1],          $matches);
        $matchedReading = array_map(fn($x) => $x[3] ?? $x[1], $matches);


        return [
            'kanji'   => join('', $matchedKanji),
            'reading' => $matchedKanji == $matchedReading
                ? null
                : join('', $matchedReading),
        ];
    }

    public function toAnkiVocabDef()
    {
        $ret = '<span ' . Note::HIGHLIGHT_ATTR_KANJI . '>' . $this->kanji;

        $ret .= match ([null !== $this->definitionJp, null !== $this->definitionEn]) {
            [false, false] => '：</span>＿',
            [false,  true] => ':</span> ' . $this->definitionEn,
            [true,  false] => '：</span>' . $this->definitionJp,
            [true,   true] => '：</span>' . $this->definitionJp . '<span style="color: #aacebe;">(' . $this->definitionEn . ')</span>',
        };

        return $ret;
    }

    private static function fromVocabDefLine(string $vocabDefLine): ?Term
    {
        $term = new Term();

        // ------------------------------------------------------ Get Kanji ---

        $jpStart = mb_strpos($vocabDefLine, '：');
        $enStart = mb_strpos($vocabDefLine, ':');

        // Get the kanji, as it may not be in the same order for some reason
        if (false !== $jpStart) {
            $term->kanji = mb_substr($vocabDefLine, 0,            $jpStart);
            $def         = mb_substr($vocabDefLine, $jpStart + 1, null);
            $jpStart = 0;
        } elseif (false !== $enStart) {
            $term->kanji = mb_substr($vocabDefLine, 0,            $enStart);
            $def         = mb_substr($vocabDefLine, $enStart + 1, null);
            $enStart = 0;
        } else {
            // Can't extract term from definition, it doesn't conform to the
            // established pattern.
            return null;
        }

        // Convert 「this」 into [this]
        $term->kanji = mb_trim(strtr($term->kanji, [
            '「' => '[',
            '」' => ']',
            '　' => ' ',
        ]));
        $def         = mb_trim($def);
        if (!is_string($term->kanji)) {
            return null;
        }

        // -------------------------------------------------- No definition ---

        // Special case where there's no definitions
        if ($def === '' or $def === '_' or $def === '＿') {
            $term->definitionJp = null;
            $term->definitionEn = null;
            return $term;
        }

        // This means there's both en and jp
        $parentStart = mb_strpos($def, '(');

        // -------------------------------------------------- Only Japanese ---

        if (false !== $jpStart and false === $parentStart) {
            // It's all japanese, start to finish
            $term->definitionJp = mb_trim(mb_substr($def, 0));
            $term->definitionEn = null;
            return $term;
        }

        // -------------------------------------- Both Japanese and English ---

        if (false !== $jpStart and false !== $parentStart) {
            $term->definitionJp = mb_trim(mb_substr($def, 0, $parentStart));
            // -1 to remove the parenthesis end
            $term->definitionEn = mb_trim(mb_substr($def, $parentStart + 1, -1));
            return $term;
        }

        // --------------------------------------------------- Only english ---

        if (false !== $enStart) {
            $term->definitionJp = null;
            $term->definitionEn = mb_trim(mb_substr($def, 0));
            return $term;
        }

        // ------------------------------------------------- Unvalid syntax ---

        dd("Unexpected error, couldn't parse definition line", $vocabDefLine);
    }

    /** Turns a def like "<def>" turn into "<kanji>:<def>" */
    private static function fromLegacyLine(string $kanji, string $def): ?Term
    {
        // Select appropriate semicolon for the job
        $separator = preg_match('/[[:alpha:]]/u', $def)
            ? ': '
            : '：';

        // Stick the kanji at the start and see if it makes sense
        return Term::fromVocabDefLine($kanji . $separator . $def);
    }

    public static function fromNoteFields(array $fields): ?array
    {
        // -------------------- Trying to extract it with the modern syntax ---
        // 言葉: word
        // 上げる：上に動くこと。
        // 雨：水粒を降ること。(rain)

        $terms = [];
        foreach (preg_split('|<br ?/?>|', $fields['VocabDef']) as $line) {
            $terms[] = self::fromVocabDefLine(strip_tags($line));
        };
        // If there's no nulls, everything went good
        if (!in_array(null, $terms, true)) return $terms;


        // ------------ Extracting failed, try to infer from other syntaxes ---

        $kanjis = explode('｜', $fields['VocabKanji']);
        $defs   = explode('｜', $fields['VocabDef']);
        // Number of legacy definitions is different from number of kanji
        if (count($kanjis) !== count($defs)) return null;

        $terms = [];
        foreach (array_combine($kanjis, $defs) as $kanji => $def) {
            $terms[] = self::fromLegacyLine($kanji, $def);
        }

        // Search for nulls, if found, it's owari da
        return in_array(null, $terms, true) ? null : $terms;
    }
}