class CsvEncoder

class CsvEncoder implements EncoderInterface, DecoderInterface {
    public const FORMAT = 'csv';
    public const DELIMITER_KEY = 'csv_delimiter';
    public const ENCLOSURE_KEY = 'csv_enclosure';
    
    /**
     * @deprecated since Symfony 7.2, to be removed in 8.0
     */
    public const ESCAPE_CHAR_KEY = 'csv_escape_char';
    public const KEY_SEPARATOR_KEY = 'csv_key_separator';
    public const HEADERS_KEY = 'csv_headers';
    public const ESCAPE_FORMULAS_KEY = 'csv_escape_formulas';
    public const AS_COLLECTION_KEY = 'as_collection';
    public const NO_HEADERS_KEY = 'no_headers';
    public const END_OF_LINE = 'csv_end_of_line';
    public const OUTPUT_UTF8_BOM_KEY = 'output_utf8_bom';
    private const UTF8_BOM = "";
    private const FORMULAS_START_CHARACTERS = [
        '=',
        '-',
        '+',
        '@',
        "\t",
        "\r",
    ];
    private array $defaultContext = [
        self::DELIMITER_KEY => ',',
        self::ENCLOSURE_KEY => '"',
        self::ESCAPE_CHAR_KEY => '',
        self::END_OF_LINE => "\n",
        self::ESCAPE_FORMULAS_KEY => false,
        self::HEADERS_KEY => [],
        self::KEY_SEPARATOR_KEY => '.',
        self::NO_HEADERS_KEY => false,
        self::AS_COLLECTION_KEY => true,
        self::OUTPUT_UTF8_BOM_KEY => false,
    ];
    public function __construct(array $defaultContext = []) {
        if (\array_key_exists(self::ESCAPE_CHAR_KEY, $defaultContext)) {
            trigger_deprecation('symfony/serializer', '7.2', 'Setting the "csv_escape_char" option is deprecated. The option will be removed in 8.0.');
        }
        $this->defaultContext = array_merge($this->defaultContext, $defaultContext);
    }
    public function encode(mixed $data, string $format, array $context = []) : string {
        $handle = fopen('php://temp,', 'w+');
        if (!is_iterable($data)) {
            $data = [
                [
                    $data,
                ],
            ];
        }
        elseif (!$data) {
            $data = [
                [],
            ];
        }
        else {
            // Sequential arrays of arrays are considered as collections
            $i = 0;
            foreach ($data as $key => $value) {
                if ($i !== $key || !\is_array($value)) {
                    $data = [
                        $data,
                    ];
                    break;
                }
                ++$i;
            }
        }
        [
            $delimiter,
            $enclosure,
            $escapeChar,
            $keySeparator,
            $headers,
            $escapeFormulas,
            $outputBom,
        ] = $this->getCsvOptions($context);
        foreach ($data as &$value) {
            $flattened = [];
            $this->flatten($value, $flattened, $keySeparator, '', $escapeFormulas);
            $value = $flattened;
        }
        unset($value);
        $headers = array_merge(array_values($headers), array_diff($this->extractHeaders($data), $headers));
        $endOfLine = $context[self::END_OF_LINE] ?? $this->defaultContext[self::END_OF_LINE];
        if (!($context[self::NO_HEADERS_KEY] ?? $this->defaultContext[self::NO_HEADERS_KEY])) {
            fputcsv($handle, $headers, $delimiter, $enclosure, $escapeChar);
            if ("\n" !== $endOfLine && 0 === fseek($handle, -1, \SEEK_CUR)) {
                fwrite($handle, $endOfLine);
            }
        }
        $headers = array_fill_keys($headers, '');
        foreach ($data as $row) {
            fputcsv($handle, array_replace($headers, $row), $delimiter, $enclosure, $escapeChar);
            if ("\n" !== $endOfLine && 0 === fseek($handle, -1, \SEEK_CUR)) {
                fwrite($handle, $endOfLine);
            }
        }
        rewind($handle);
        $value = stream_get_contents($handle);
        fclose($handle);
        if ($outputBom) {
            if (!preg_match('//u', $value)) {
                throw new UnexpectedValueException('You are trying to add a UTF-8 BOM to a non UTF-8 text.');
            }
            $value = self::UTF8_BOM . $value;
        }
        return $value;
    }
    public function supportsEncoding(string $format) : bool {
        return self::FORMAT === $format;
    }
    public function decode(string $data, string $format, array $context = []) : mixed {
        $handle = fopen('php://temp', 'r+');
        fwrite($handle, $data);
        rewind($handle);
        if (str_starts_with($data, self::UTF8_BOM)) {
            fseek($handle, \strlen(self::UTF8_BOM));
        }
        $headers = null;
        $nbHeaders = 0;
        $headerCount = [];
        $result = [];
        [
            $delimiter,
            $enclosure,
            $escapeChar,
            $keySeparator,
            ,
            ,
            ,
            $asCollection,
        ] = $this->getCsvOptions($context);
        while (false !== ($cols = fgetcsv($handle, 0, $delimiter, $enclosure, $escapeChar))) {
            $nbCols = \count($cols);
            if (null === $headers) {
                $nbHeaders = $nbCols;
                if ($context[self::NO_HEADERS_KEY] ?? $this->defaultContext[self::NO_HEADERS_KEY]) {
                    for ($i = 0; $i < $nbCols; ++$i) {
                        $headers[] = [
                            $i,
                        ];
                    }
                    $headerCount = array_fill(0, $nbCols, 1);
                }
                else {
                    foreach ($cols as $col) {
                        $header = explode($keySeparator, $col ?? '');
                        $headers[] = $header;
                        $headerCount[] = \count($header);
                    }
                    continue;
                }
            }
            $item = [];
            for ($i = 0; $i < $nbCols && $i < $nbHeaders; ++$i) {
                $depth = $headerCount[$i];
                $arr =& $item;
                for ($j = 0; $j < $depth; ++$j) {
                    $headerName = $headers[$i][$j];
                    if ('' === $headerName) {
                        $headerName = $i;
                    }
                    // Handle nested arrays
                    if ($j === $depth - 1) {
                        $arr[$headerName] = $cols[$i];
                        continue;
                    }
                    if (!isset($arr[$headerName])) {
                        $arr[$headerName] = [];
                    }
                    $arr =& $arr[$headerName];
                }
            }
            $result[] = $item;
        }
        fclose($handle);
        if ($asCollection) {
            return $result;
        }
        if (!$result || isset($result[1])) {
            return $result;
        }
        // If there is only one data line in the document, return it (the line), the result is not considered as a collection
        return $result[0];
    }
    public function supportsDecoding(string $format) : bool {
        return self::FORMAT === $format;
    }
    
    /**
     * Flattens an array and generates keys including the path.
     */
    private function flatten(iterable $array, array &$result, string $keySeparator, string $parentKey = '', bool $escapeFormulas = false) : void {
        foreach ($array as $key => $value) {
            if (is_iterable($value)) {
                $this->flatten($value, $result, $keySeparator, $parentKey . $key . $keySeparator, $escapeFormulas);
            }
            else {
                if ($escapeFormulas && \in_array(substr((string) $value, 0, 1), self::FORMULAS_START_CHARACTERS, true)) {
                    $result[$parentKey . $key] = "'" . $value;
                }
                else {
                    // Ensures an actual value is used when dealing with true and false
                    $result[$parentKey . $key] = false === $value ? 0 : (true === $value ? 1 : $value);
                }
            }
        }
    }
    private function getCsvOptions(array $context) : array {
        $delimiter = $context[self::DELIMITER_KEY] ?? $this->defaultContext[self::DELIMITER_KEY];
        $enclosure = $context[self::ENCLOSURE_KEY] ?? $this->defaultContext[self::ENCLOSURE_KEY];
        $escapeChar = $context[self::ESCAPE_CHAR_KEY] ?? $this->defaultContext[self::ESCAPE_CHAR_KEY];
        $keySeparator = $context[self::KEY_SEPARATOR_KEY] ?? $this->defaultContext[self::KEY_SEPARATOR_KEY];
        $headers = $context[self::HEADERS_KEY] ?? $this->defaultContext[self::HEADERS_KEY];
        $escapeFormulas = $context[self::ESCAPE_FORMULAS_KEY] ?? $this->defaultContext[self::ESCAPE_FORMULAS_KEY];
        $outputBom = $context[self::OUTPUT_UTF8_BOM_KEY] ?? $this->defaultContext[self::OUTPUT_UTF8_BOM_KEY];
        $asCollection = $context[self::AS_COLLECTION_KEY] ?? $this->defaultContext[self::AS_COLLECTION_KEY];
        if (!\is_array($headers)) {
            throw new InvalidArgumentException(\sprintf('The "%s" context variable must be an array or null, given "%s".', self::HEADERS_KEY, get_debug_type($headers)));
        }
        return [
            $delimiter,
            $enclosure,
            $escapeChar,
            $keySeparator,
            $headers,
            $escapeFormulas,
            $outputBom,
            $asCollection,
        ];
    }
    
    /**
     * @return string[]
     */
    private function extractHeaders(iterable $data) : array {
        $headers = [];
        $flippedHeaders = [];
        foreach ($data as $row) {
            $previousHeader = null;
            foreach ($row as $header => $_) {
                if (isset($flippedHeaders[$header])) {
                    $previousHeader = $header;
                    continue;
                }
                if (null === $previousHeader) {
                    $n = \count($headers);
                }
                else {
                    $n = $flippedHeaders[$previousHeader] + 1;
                    for ($j = \count($headers); $j > $n; --$j) {
                        ++$flippedHeaders[$headers[$j] = $headers[$j - 1]];
                    }
                }
                $headers[$n] = $header;
                $flippedHeaders[$header] = $n;
                $previousHeader = $header;
            }
        }
        return $headers;
    }

}