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

#pragma once

// stl includes
#include <string>
#include <list>

// jsoncpp includes
#include <json/json.h>


/// 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
///
/// And the non-standard:
/// - dependencies
class JsonSchemaChecker
{
public:
	JsonSchemaChecker();
	virtual ~JsonSchemaChecker();

	///
	/// @param schema The schema to use
	/// @return true upon succes
	///
	bool setSchema(const Json::Value & 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 Json::Value & value);

	///
	/// @return A list of error messages
	///
	const std::list<std::string> & 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 Json::Value &value, const Json::Value & 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 std::string & message);

	///
	/// Retrieves all references from the json-value as specified by the schema
	///
	/// @param[in] value The json-value
	/// @param[in] schema The schema
	///
	void collectDependencies(const Json::Value & value, const Json::Value &schema);

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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & schema, const Json::Value::Members & ignoredProperties);

	///
	/// Checks if references are configued and used correctly. 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 schemaLink The schema of the json-object
	///
	void checkDependencies(const Json::Value & value, const Json::Value & schemaLink);

	///
	/// 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & 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 Json::Value & value, const Json::Value & schema);

private:
	/// The schema of the entire json-configuration
	Json::Value _schema;

	/// The current location into a json-configuration structure being checked
	std::list<std::string> _currentPath;
	/// The result messages collected during the schema verification
	std::list<std::string> _messages;
	/// Flag indicating an error occured during validation
	bool _error;

	/// A list with references (string => json-value)
	std::map<std::string, const Json::Value *> _references; // ref 2 value
};