/* Copyright (C) 2018 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
	CConfigDB - Load, access and store configuration variables

	TDD		:	http://www.wildfiregames.com/forum/index.php?showtopic=1125
	OVERVIEW:

	JavaScript: Check this documentation: http://trac.wildfiregames.com/wiki/Exposed_ConfigDB_Functions
*/

#ifndef INCLUDED_CONFIGDB
#define INCLUDED_CONFIGDB

#include "lib/file/vfs/vfs_path.h"
#include "ps/CStr.h"
#include "ps/Singleton.h"

// Namespace priorities: User supersedes mod supersedes system.
//						 Command-line arguments override everything.

enum EConfigNamespace
{
	CFG_DEFAULT,
	CFG_SYSTEM,
	CFG_MOD,
	CFG_USER,
	CFG_COMMAND,
	CFG_LAST
};

typedef std::vector<CStr> CConfigValueSet;

#define g_ConfigDB CConfigDB::GetSingleton()

class CConfigDB: public Singleton<CConfigDB>
{
	static std::map<CStr, CConfigValueSet> m_Map[];
	static VfsPath m_ConfigFile[];
	static bool m_HasChanges[];

public:
	CConfigDB();

	/**
	 * Attempt to retrieve the value of a config variable with the given name;
	 * will search CFG_COMMAND first, and then all namespaces from the specified
	 * namespace down.
	 */
	void GetValue(EConfigNamespace ns, const CStr& name, bool& value);
	///@copydoc CConfigDB::GetValue
	void GetValue(EConfigNamespace ns, const CStr& name, int& value);
	///@copydoc CConfigDB::GetValue
	void GetValue(EConfigNamespace ns, const CStr& name, u32& value);
	///@copydoc CConfigDB::GetValue
	void GetValue(EConfigNamespace ns, const CStr& name, float& value);
	///@copydoc CConfigDB::GetValue
	void GetValue(EConfigNamespace ns, const CStr& name, double& value);
	///@copydoc CConfigDB::GetValue
	void GetValue(EConfigNamespace ns, const CStr& name, std::string& value);

	/**
	 * Returns true if changed with respect to last write on file
	 */
	bool HasChanges(EConfigNamespace ns) const;

	void SetChanges(EConfigNamespace ns, bool value);

	/**
	 * Attempt to retrieve a vector of values corresponding to the given setting;
	 * will search CFG_COMMAND first, and then all namespaces from the specified
	 * namespace down.
	 */
	void GetValues(EConfigNamespace ns, const CStr& name, CConfigValueSet& values) const;

	/**
	 * Returns the namespace that the value returned by GetValues was defined in,
	 * or CFG_LAST if it wasn't defined at all.
	 */
	EConfigNamespace GetValueNamespace(EConfigNamespace ns, const CStr& name) const;

	/**
	 * Retrieve a map of values corresponding to settings whose names begin
	 * with the given prefix;
	 * will search all namespaces from default up to the specified namespace.
	 */
	std::map<CStr, CConfigValueSet> GetValuesWithPrefix(EConfigNamespace ns, const CStr& prefix) const;

	/**
	 * Save a config value in the specified namespace. If the config variable
	 * existed the value is replaced.
	 */
	void SetValueString(EConfigNamespace ns, const CStr& name, const CStr& value);

	void SetValueBool(EConfigNamespace ns, const CStr& name, const bool value);

	/**
	 * Remove a config value in the specified namespace.
	 */
	void RemoveValue(EConfigNamespace ns, const CStr& name);

	/**
	 * Set the path to the config file used to populate the specified namespace
	 * Note that this function does not actually load the config file. Use
	 * the Reload() method if you want to read the config file at the same time.
	 *
	 * 'path': The path to the config file.
	 */
	void SetConfigFile(EConfigNamespace ns, const VfsPath& path);

	/**
	 * Reload the config file associated with the specified config namespace
	 * (the last config file path set with SetConfigFile)
	 *
	 * Returns:
	 *	true:	if the reload succeeded,
	 *	false:	if the reload failed
	 */
	bool Reload(EConfigNamespace);

	/**
	 * Write the current state of the specified config namespace to the file
	 * specified by 'path'
	 *
	 * Returns:
	 *	true:	if the config namespace was successfully written to the file
	 *	false:	if an error occurred
	 */
	bool WriteFile(EConfigNamespace ns, const VfsPath& path) const;

	/**
	 * Write the current state of the specified config namespace to the file
	 * it was originally loaded from.
	 *
	 * Returns:
	 *	true:	if the config namespace was successfully written to the file
	 *	false:	if an error occurred
	 */
	bool WriteFile(EConfigNamespace ns) const;

	/**
	 * Write a config value to the file specified by 'path'
	 *
	 * Returns:
	 *	true:	if the config value was successfully saved and written to the file
	 *	false:	if an error occurred
	 */
	bool WriteValueToFile(EConfigNamespace ns, const CStr& name, const CStr& value, const VfsPath& path);

	bool WriteValueToFile(EConfigNamespace ns, const CStr& name, const CStr& value);
};


// stores the value of the given key into <destination>. this quasi-template
// convenience wrapper on top of GetValue simplifies user code
#define CFG_GET_VAL(name, destination)\
	g_ConfigDB.GetValue(CFG_USER, name, destination)

#endif // INCLUDED_CONFIGDB