/** Configuration file parsing.
 *
 * @file
 * @author Steffen Vogel <post@steffenvogel.de>
 * @copyright 2014-2022, Institute for Automation of Complex Power Systems, EONERC
 * @license Apache 2.0
 *********************************************************************************/

#pragma once

#include <cstdio>
#include <unistd.h>
#include <jansson.h>

#include <functional>
#include <regex>

#include <villas/node/config.hpp>
#include <villas/log.hpp>

#ifdef WITH_CONFIG
  #include <libconfig.h>
#endif

namespace villas {
namespace node {

class Config {

protected:
	using str_walk_fcn_t = std::function<json_t *(json_t *)>;

	Logger logger;

	std::list<std::string> includeDirectories;

	/** Check if file exists on local system. */
	static bool isLocalFile(const std::string &uri)
	{
		return access(uri.c_str(), F_OK) != -1;
	}

	/** Decode configuration file. */
	json_t * decode(FILE *f);

#ifdef WITH_CONFIG
	/** Convert libconfig .conf file to libjansson .json file. */
	json_t * libconfigDecode(FILE *f);

	static const char ** includeFuncStub(config_t *cfg, const char *include_dir, const char *path, const char **error);

	const char ** includeFunc(config_t *cfg, const char *include_dir, const char *path, const char **error);
#endif /* WITH_CONFIG */

	/** Load configuration from standard input (stdim). */
	FILE * loadFromStdio();

	/** Load configuration from local file. */
	FILE * loadFromLocalFile(const std::string &u);

	std::list<std::string> resolveIncludes(const std::string &name);

	void resolveEnvVars(std::string &text);

	/** Resolve custom include directives. */
	json_t * expandIncludes(json_t *in);

	/** To shell-like subsitution of environment variables in strings. */
	json_t * expandEnvVars(json_t *in);

	/** Run a callback function for each string in the config */
	json_t * walkStrings(json_t *in, str_walk_fcn_t cb);

	/** Get the include dirs */
	std::list<std::string> getIncludeDirectories(FILE *f) const;

public:
	json_t *root;

	Config();
	Config(const std::string &u);

	~Config();

	json_t * load(std::FILE *f, bool resolveIncludes = true, bool resolveEnvVars = true);

	json_t * load(const std::string &u, bool resolveIncludes = true, bool resolveEnvVars = true);
};

} // namespace node
} // namespace villas