hyperion.ng/include/utils/jsonschema/QJsonSchemaChecker.h

#pragma once

#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonValue>
#include <QJsonArray>
#include <QStringList>

/// JsonSchemaChecker is a very basic implementation of json schema.
/// The json schema definition draft can be found at
/// http://tools.ietf.org/html/draft-zyp-json-schema-03
///
/// The following keywords are supported:
/// - type
/// - required
/// - properties
/// - items
/// - enum
/// - minimum
/// - maximum
/// - addtionalProperties
/// - minItems
/// - maxItems

class QJsonSchemaChecker
{
public:
	QJsonSchemaChecker();
	virtual ~QJsonSchemaChecker();

	///
	/// @param schema The schema to use
	/// @return true upon succes
	///
	bool setSchema(const QJsonObject & schema);
	
	///
	/// @brief Validate a JSON structure
	/// @param value The JSON value to check
	/// @return true when the arguments is valid according to the schema
	///
	bool validate(const QJsonObject & value, bool ignoreRequired = false);

	///
	/// @return A list of error messages
	///
	const QStringList & getMessages() const;

private:
	///
	/// Validates a json-value against a given schema. Results are stored in the members of this
	/// class (_error & _messages)
	///
	/// @param[in] value The value to validate
	/// @param[in] schema The schema against which the value is validated
	///
	void validate(const QJsonValue &value, const QJsonObject & schema);

	///
	/// Adds the given message to the message-queue (with reference to current line-number)
	///
	/// @param[in] message The message to add to the queue
	///
	void setMessage(const QString & message);

private:
	// attribute check functions
	///
	/// Checks if the given value is of the specified type. If the type does not match _error is set
	/// to true and an error-message is added to the message-queue
	///
	/// @param[in] value The given value
	/// @param[in] schema The specified type (as json-value)
	///
	void checkType(const QJsonValue & value, const QJsonValue & schema);
	
	///
	/// Checks is required properties of an json-object exist and if all properties are of the
	/// correct format. If this is not the case _error is set to true and an error-message is added
	/// to the message-queue.
	///
	/// @param[in] value The given json-object
	/// @param[in] schema The schema of the json-object
	///
	void checkProperties(const QJsonObject & value, const QJsonObject & schema);

	///
	/// Verifies the additional configured properties of an json-object. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param value The given json-object
	/// @param schema The schema for the json-object
	/// @param ignoredProperties The properties that were ignored
	///
	void checkAdditionalProperties(const QJsonObject & value, const QJsonValue & schema, const QStringList & ignoredProperties);

	///
	/// Checks if the given value is larger or equal to the specified value. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param[in] value The given value
	/// @param[in] schema The minimum value (as json-value)
	///
	void checkMinimum(const QJsonValue & value, const QJsonValue & schema);

	///
	/// Checks if the given value is smaller or equal to the specified value. If this is not the
	/// case _error is set to true and an error-message is added to the message-queue.
	///
	/// @param[in] value The given value
	/// @param[in] schema The maximum value (as json-value)
	///
	void checkMaximum(const QJsonValue & value, const QJsonValue & schema);

	///
	/// Validates all the items of an array.
	///
	/// @param value The json-array
	/// @param schema The schema for the items in the array
	///
	void checkItems(const QJsonValue & value, const QJsonObject & schema);

	///
	/// Checks if a given array has at least a minimum number of items. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param value The json-array
	/// @param schema The minimum size specification (as json-value)
	///
	void checkMinItems(const QJsonValue & value, const QJsonValue & schema);

	///
	/// Checks if a given array has at most a maximum number of items. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param value The json-array
	/// @param schema The maximum size specification (as json-value)
	///
	void checkMaxItems(const QJsonValue & value, const QJsonValue & schema);

	///
	/// Checks if a given array contains only unique items. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param value The json-array
	/// @param schema Bool to enable the check (as json-value)
	///
	void checkUniqueItems(const QJsonValue & value, const QJsonValue & schema);

	///
	/// Checks if an enum value is actually a valid value for that enum. If this is not the case
	/// _error is set to true and an error-message is added to the message-queue.
	///
	/// @param value The enum value
	/// @param schema The enum schema definition
	///
	void checkEnum(const QJsonValue & value, const QJsonValue & schema);

private:
	/// The schema of the entire json-configuration
	QJsonObject _qSchema;
	/// ignore the required value in json schema
	bool _ignoreRequired;
	/// The current location into a json-configuration structure being checked
	QStringList _currentPath;
	/// The result messages collected during the schema verification
	QStringList _messages;
	/// Flag indicating an error occured during validation
	bool _error;
};