/*
 * CFilesystemLoader.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#pragma once

#include "ISimpleResourceLoader.h"
#include "ResourceID.h"

VCMI_LIB_NAMESPACE_BEGIN

class CInputStream;

/**
 * A class which can scan and load files of directories.
 */
class DLL_LINKAGE CFilesystemLoader : public ISimpleResourceLoader
{
public:
	/**
	 * Ctor.
	 *
	 * @param baseDirectory Specifies the base directory and their sub-directories which should be indexed.
	 * @param depth - recursion depth of subdirectories search. 0 = no recursion
	 *
	 * @throws std::runtime_error if the base directory is not a directory or if it is not available
	 */
	explicit CFilesystemLoader(std::string mountPoint, boost::filesystem::path baseDirectory, size_t depth = 16, bool initial = false);

	/// Interface implementation
	/// @see ISimpleResourceLoader
	std::unique_ptr<CInputStream> load(const ResourceID & resourceName) const override;
	bool existsResource(const ResourceID & resourceName) const override;
	std::string getMountPoint() const override;
	bool createResource(std::string filename, bool update = false) override;
	std::optional<boost::filesystem::path> getResourceName(const ResourceID & resourceName) const override;
	void updateFilteredFiles(std::function<bool(const std::string &)> filter) const override;
	std::unordered_set<ResourceID> getFilteredFiles(std::function<bool(const ResourceID &)> filter) const override;

private:
	/** The base directory which is scanned and indexed. */
	boost::filesystem::path baseDirectory;

	std::string mountPoint;
	
	size_t recursiveDepth;

	/** A list of files in the directory
	 * key = ResourceID for resource loader
	 * value = name that can be used to access file
	*/
	mutable std::unordered_map<ResourceID, boost::filesystem::path> fileList;

	/**
	 * Returns a list of pathnames denoting the files in the directory denoted by this pathname.
	 *
	 * If the pathname of this directory is absolute, then the file info pathnames are absolute as well. If the pathname of this directory is relative
	 * then the file info pathnames are relative to the basedir as well.
	 *
	 * @return a list of pathnames denoting the files and directories in the directory denoted by this pathname
	 * The array will be empty if the directory is empty. Ptr is null if the directory doesn't exist or if it isn't a directory.
	 */
	std::unordered_map<ResourceID, boost::filesystem::path> listFiles(const std::string &mountPoint, size_t depth, bool initial) const;
};

VCMI_LIB_NAMESPACE_END