/*
    Ousía
    Copyright (C) 2014, 2015  Benjamin Paaßen, Andreas Stöckel

    This program 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 3 of the License, or
    (at your option) any later version.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file FileLocator.hpp
 *
 * Contains the FileLocator class which is used to locate resources and to
 * canonicalize file system paths.
 *
 * @author Benjamin Paaßen (bpassen@techfak.uni-bielefeld.de)
 */

#ifndef _OUSIA_FILE_LOCATOR_HPP_
#define _OUSIA_FILE_LOCATOR_HPP_

#include <core/resource/Resource.hpp>
#include <core/resource/ResourceLocator.hpp>

#include <map>
#include <set>
#include <vector>

namespace ousia {

/**
 * The FileLocator class is an implementation of the abstract ResourceLocator
 * interface used to locate resources in the filesystem.
 */
class FileLocator : public ResourceLocator {
public:
	/**
	 * Type alias representing the internal search path list.
	 */
	using SearchPaths = std::map<ResourceType, std::vector<std::string>>;

private:
	/**
	 * Internal variable containing all stored search paths.
	 */
	SearchPaths searchPaths;

	/**
	 * Internally used to add a search path to the given vector without
	 * duplications.
	 *
	 * @parm path is the path that should be added to the vector (must be
	 * canonicalized).
	 * @parm paths is the list to which the path should be added.
	 */
	void addPath(const std::string &path, std::vector<std::string> &paths);

	/**
	 * Internally used to add the default search paths for various resource
	 * types relative to a certain parent directory.
	 *
	 * @param relativeTo is the base directory relative to which the search
	 * paths ought to be setup.
	 */
	void addDefaultSearchPaths(const std::string &relativeTo);

protected:
	bool doLocate(Resource &resource, const std::string &path,
	              const ResourceType type,
	              const std::string &relativeTo) const override;

	std::vector<std::string> doAutocomplete(
	    const std::string &path, const ResourceType type,
	    const std::string &relativeTo) const override;

	std::unique_ptr<std::istream> doStream(
	    const std::string &location) const override;

public:
	FileLocator() : searchPaths() {}

	/**
	 * Adds a search paths for the given types.
	 *
	 * @param path is a fully qualified/canonical path to a directory.
	 * @param types is a set of Resource Types. The FileLocator will look for
	 *              resources of the specified types at the given path in the
	 *              future.
	 */
	void addSearchPath(const std::string &path, std::set<ResourceType> types);

	/**
	 * Adds a search path. Implicitly adds the search path for the "unknown"
	 *
	 * @param path is a fully qualified/canonical path to a directory.
	 * @param type is a single type for which the path should be added.
	 */
	void addSearchPath(const std::string &path,
	                   ResourceType type = ResourceType::UNKNOWN);

	/**
	 * Adds platform-specific default search paths. These include
	 * (in order of their precedence):
	 * <ul>
	 *   <li>The user application data directory (~/.local/share/ousia/ on
	 *       UNIX)</li>
	 *   <li>The global application data directory used for make install
	 *       (default is /usr/local/share on UNIX)</li>
	 * </ul>
	 * Resource type specific subdirectories (ontology, typesytem, etc.)
	 * are automatically added to the aforementioned paths.
	 */
	void addDefaultSearchPaths();

	/**
	 * Adds a search path for a unit test. This function should not be used
	 * outside the code in the "test" folder.
	 *
	 * @param subdir is the subdirectory in the "testdata" directory that should
	 * be added.
	 * @param type is a single type for which the path should be added.
	 */
	void addUnittestSearchPath(const std::string &subdir,
	                           ResourceType type = ResourceType::UNKNOWN);

	/**
	 * Returns the backing map containing all search paths for a given type.
	 * This is read-only.
	 */
	const SearchPaths &getSearchPaths() const { return searchPaths; }
};
}

#endif /* _OUSIA_FILE_LOCATOR_HPP_ */