hendrikmaus/spas

<?php

namespace Hmaus\Spas\Formatter;

class JsonFormatter implements Formatter
{
    public function format($data) : string
    {
        return $this->isAlreadyIndented($data);
    }

    public function getContentTypes()
    {
        return [
            'application/json'
        ];
    }

    private function isAlreadyIndented(string $data) : string
    {
        if (strpos(substr($data, 0, 4), "\n")) {
            return $data;
        }

        return $this->indent($data);
    }

    /**
     * Indents a flat JSON string to make it more human-readable.
     *
     * @param string $json The original JSON string to process.
     *
     * @return string Indented version of the original JSON string.
     */
    private function indent($json) : string
    {
        $result = '';
        $pos = 0;
        $strLen = strlen($json);
        $indentStr = '    ';
        $newLine = "\n";
        $prevChar = '';
        $outOfQuotes = true;
        for ($i = 0; $i <= $strLen; $i++) {
            // Grab the next character in the string.
            $char = substr($json, $i, 1);
            // Are we inside a quoted string?
            if ($char == '"' && $prevChar != '\\') {
                $outOfQuotes = !$outOfQuotes;

                // If this character is the end of an element,
                // output a new line and indent the next line.
            } else {
                if (($char == '}' || $char == ']') && $outOfQuotes) {
                    $result .= $newLine;
                    $pos--;
                    for ($j = 0; $j < $pos; $j++) {
                        $result .= $indentStr;
                    }
                }
            }

            // Add the character to the result string.
            $result .= $char;
            // If the last character was the beginning of an element,
            // output a new line and indent the next line.
            if (($char == ',' || $char == '{' || $char == '[') && $outOfQuotes) {
                $result .= $newLine;
                if ($char == '{' || $char == '[') {
                    $pos++;
                }

                for ($j = 0; $j < $pos; $j++) {
                    $result .= $indentStr;
                }
            }

            $prevChar = $char;
        }

        return $result;
    }
}