<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\helpers;

use yii\base\InvalidParamException;
use yii\base\Arrayable;
use yii\web\JsExpression;

/**
 * BaseJson provides concrete implementation for [[Json]].
 *
 * Do not use BaseJson. Use [[Json]] instead.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class BaseJson
{
    /**
     * Encodes the given value into a JSON string.
     * The method enhances `json_encode()` by supporting JavaScript expressions.
     * In particular, the method will not encode a JavaScript expression that is
     * represented in terms of a [[JsExpression]] object.
     * @param mixed $value the data to be encoded
     * @param integer $options the encoding options. For more details please refer to
     * <http://www.php.net/manual/en/function.json-encode.php>.
     * @return string the encoding result
     */
    public static function encode($value, $options = 0)
    {
        $expressions = [];
        $value = static::processData($value, $expressions, uniqid());
        $json = json_encode($value, $options);

        return empty($expressions) ? $json : strtr($json, $expressions);
    }

    /**
     * Decodes the given JSON string into a PHP data structure.
     * @param string $json the JSON string to be decoded
     * @param boolean $asArray whether to return objects in terms of associative arrays.
     * @return mixed the PHP data
     * @throws InvalidParamException if there is any decoding error
     */
    public static function decode($json, $asArray = true)
    {
        if (is_array($json)) {
            throw new InvalidParamException('Invalid JSON data.');
        }
        $decode = json_decode((string) $json, $asArray);
        switch (json_last_error()) {
            case JSON_ERROR_NONE:
                break;
            case JSON_ERROR_DEPTH:
                throw new InvalidParamException('The maximum stack depth has been exceeded.');
            case JSON_ERROR_CTRL_CHAR:
                throw new InvalidParamException('Control character error, possibly incorrectly encoded.');
            case JSON_ERROR_SYNTAX:
                throw new InvalidParamException('Syntax error.');
            case JSON_ERROR_STATE_MISMATCH:
                throw new InvalidParamException('Invalid or malformed JSON.');
            case JSON_ERROR_UTF8:
                throw new InvalidParamException('Malformed UTF-8 characters, possibly incorrectly encoded.');
            default:
                throw new InvalidParamException('Unknown JSON decoding error.');
        }

        return $decode;
    }

    /**
     * Pre-processes the data before sending it to `json_encode()`.
     * @param mixed $data the data to be processed
     * @param array $expressions collection of JavaScript expressions
     * @param string $expPrefix a prefix internally used to handle JS expressions
     * @return mixed the processed data
     */
    protected static function processData($data, &$expressions, $expPrefix)
    {
        if (is_object($data)) {
            if ($data instanceof JsExpression) {
                $token = "!{[$expPrefix=" . count($expressions) . ']}!';
                $expressions['"' . $token . '"'] = $data->expression;

                return $token;
            } elseif ($data instanceof \JsonSerializable) {
                $data = $data->jsonSerialize();
            } elseif ($data instanceof Arrayable) {
                $data = $data->toArray();
            } else {
                $result = [];
                foreach ($data as $name => $value) {
                    $result[$name] = $value;
                }
                $data = $result;
            }

            if ($data === []) {
                return new \stdClass();
            }
        }

        if (is_array($data)) {
            foreach ($data as $key => $value) {
                if (is_array($value) || is_object($value)) {
                    $data[$key] = static::processData($value, $expressions, $expPrefix);
                }
            }
        }

        return $data;
    }
}
