<?php

namespace LWVendor\PhpOffice\PhpSpreadsheet\Reader\Csv;

class Delimiter
{
    protected const POTENTIAL_DELIMETERS = [',', ';', "\t", '|', ':', ' ', '~'];
    /** @var resource */
    protected $fileHandle;
    /** @var string */
    protected $escapeCharacter;
    /** @var string */
    protected $enclosure;
    /** @var array */
    protected $counts = [];
    /** @var int */
    protected $numberLines = 0;
    /** @var ?string */
    protected $delimiter;
    /**
     * @param resource $fileHandle
     */
    public function __construct($fileHandle, string $escapeCharacter, string $enclosure)
    {
        $this->fileHandle = $fileHandle;
        $this->escapeCharacter = $escapeCharacter;
        $this->enclosure = $enclosure;
        $this->countPotentialDelimiters();
    }
    public function getDefaultDelimiter() : string
    {
        return self::POTENTIAL_DELIMETERS[0];
    }
    public function linesCounted() : int
    {
        return $this->numberLines;
    }
    protected function countPotentialDelimiters() : void
    {
        $this->counts = \array_fill_keys(self::POTENTIAL_DELIMETERS, []);
        $delimiterKeys = \array_flip(self::POTENTIAL_DELIMETERS);
        // Count how many times each of the potential delimiters appears in each line
        $this->numberLines = 0;
        while (($line = $this->getNextLine()) !== \false && ++$this->numberLines < 1000) {
            $this->countDelimiterValues($line, $delimiterKeys);
        }
    }
    protected function countDelimiterValues(string $line, array $delimiterKeys) : void
    {
        $splitString = \str_split($line, 1);
        if (\is_array($splitString)) {
            $distribution = \array_count_values($splitString);
            $countLine = \array_intersect_key($distribution, $delimiterKeys);
            foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
                $this->counts[$delimiter][] = $countLine[$delimiter] ?? 0;
            }
        }
    }
    public function infer() : ?string
    {
        // Calculate the mean square deviations for each delimiter
        //     (ignoring delimiters that haven't been found consistently)
        $meanSquareDeviations = [];
        $middleIdx = \floor(($this->numberLines - 1) / 2);
        foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
            $series = $this->counts[$delimiter];
            \sort($series);
            $median = $this->numberLines % 2 ? $series[$middleIdx] : ($series[$middleIdx] + $series[$middleIdx + 1]) / 2;
            if ($median === 0) {
                continue;
            }
            $meanSquareDeviations[$delimiter] = \array_reduce($series, function ($sum, $value) use($median) {
                return $sum + ($value - $median) ** 2;
            }) / \count($series);
        }
        // ... and pick the delimiter with the smallest mean square deviation
        //         (in case of ties, the order in potentialDelimiters is respected)
        $min = \INF;
        foreach (self::POTENTIAL_DELIMETERS as $delimiter) {
            if (!isset($meanSquareDeviations[$delimiter])) {
                continue;
            }
            if ($meanSquareDeviations[$delimiter] < $min) {
                $min = $meanSquareDeviations[$delimiter];
                $this->delimiter = $delimiter;
            }
        }
        return $this->delimiter;
    }
    /**
     * Get the next full line from the file.
     *
     * @return false|string
     */
    public function getNextLine()
    {
        $line = '';
        $enclosure = ($this->escapeCharacter === '' ? '' : '(?<!' . \preg_quote($this->escapeCharacter, '/') . ')') . \preg_quote($this->enclosure, '/');
        do {
            // Get the next line in the file
            $newLine = \fgets($this->fileHandle);
            // Return false if there is no next line
            if ($newLine === \false) {
                return \false;
            }
            // Add the new line to the line passed in
            $line = $line . $newLine;
            // Drop everything that is enclosed to avoid counting false positives in enclosures
            $line = (string) \preg_replace('/(' . $enclosure . '.*' . $enclosure . ')/Us', '', $line);
            // See if we have any enclosures left in the line
            // if we still have an enclosure then we need to read the next line as well
        } while (\preg_match('/(' . $enclosure . ')/', $line) > 0);
        return $line !== '' ? $line : \false;
    }
}