/*]  Copyright (c) 2009-2010, Charles McGarvey  [**************************
**]  All rights reserved.
*
* vi:ts=4 sw=4 tw=75
*
* Distributable under the terms and conditions of the 2-clause BSD license;
* see the file COPYING for a complete text of the license.
*
**************************************************************************/

#ifndef _MOOF_RESOURCE_HH_
#define _MOOF_RESOURCE_HH_

/**
 * \file resource.hh
 * Interface for textures, sounds, and other types of resources.
 */

#include "../config.h"

#include <cstdio>
#include <map>
#include <stdexcept>
#include <string>
#include <vector>

#include <boost/shared_ptr.hpp>
#include <boost/function.hpp>

#include <moof/debug.hh>


namespace moof {


class resource;
typedef boost::shared_ptr<resource> resource_ptr;


/**
 * Generic resource class capable of containing any type of resource,
 * providing a type-safe interface.
 */
class resource
{
public:

	// FIXME: this won't be necessary once the existing code is modified to
	// use the resource handles
	resource() {}

	/**
	 * Add a directory to search when looking for resource files.
	 * \param paths A colon-separated list of directory paths.
	 */
	static void add_search_paths(const std::string& paths);


	/**
	 * Get the path to a resource of a given name.
	 * \param path The name of the resource to find.  Upon successful
	 * return, this is changed to an absolute path to the resource.
	 * \return True if a path to a resource was found, false otherwise.
	 */
	static bool find(const std::string& file);

	/**
	 * Get the path to a resource of a given name and open it if a resource
	 * was found.
	 * \param path The name of the resource to find.  Upon successful
	 * return, this is changed to an absolute path to the resource.
	 * \param mode The open mode.
	 * \return The FILE* if the resource was found, 0 otherwise.
	 */
	static FILE* open_file(const std::string& path,
						   const std::string& mode = "rb");


	/**
	 * Register a type with the extension of files which this type can
	 * load.  If any type has already been registered with the given file
	 * extension, it will be replaced.
	 * \param extension The file extension.
	 */
	template <class T>
	static void register_type(const std::string& extension)
	{
		if (!type_lookup_) type_lookup_ = type_lookup_ptr(new type_lookup);
		loader_ptr loader(new specific_loader<T>);
		(*type_lookup_)[extension] = loader;
	}

	/**
	 * Unregister the type associated with a file extension.  Resources of
	 * this type will no longer be loadable, although resources which are
	 * already loaded will remain loaded.
	 * \param extension The file extension
	 */
	static void unregister_type(const std::string& extension)
	{
		type_lookup_->erase(extension);
	}


	static resource_ptr load(const std::string& path);

	static resource_ptr reload(std::string& path);


	/**
	 * Construct a resource container.
	 * \param ptr A pointer to the underlying resource data.
	 */
	template <class T>
	explicit resource(T* ptr) :
		resource_(ptr),
		typeinfo_(const_cast<std::type_info*>(&typeid(T))),
		unloader_(new specific_unloader<T>(ptr)) {}

	/**
	 * Deconstruct a resource container.
	 */
	virtual ~resource();


	/**
	 * Reload the resource data.  This will cause the resource file to be
	 * reread, and the underlying resource data will change.
	 */
	void reload();


	/**
	 * Get whether or not the type of the underlying resource data matches
	 * an expected type.
	 * \return True if the types match, false otherwise.
	 */
	template <class T>
	bool check() const
	{
		return *typeinfo_ == typeid(T);
	}

	/**
	 * Get a pointer to the underlying resource data as long as the type of
	 * the resource data matches the expected type.
	 * \return The resource data, or null if there is a type mismatch.
	 */
	template <class T>
	T* get() const
	{
		if (check<T>()) return (T*)resource_;
		return 0;
	}


	/**
	 * Reloads some resources which have been modified on disk since they
	 * were loaded.  Hotloading must have been enabled at compile-time.
	 * \return The number of resources reloaded.
	 */
	static int reload_as_needed();


private:

	class loader
	{
	public:

		virtual ~loader() {}

		virtual resource* load(const std::string& path)
		{
			return 0;
		}
	};

	typedef boost::shared_ptr<loader> loader_ptr;

	template <class T>
	class specific_loader : public loader
	{
	public:

		virtual resource* load(const std::string& path)
		{
			return new resource(new T(path));
		}
	};


	class unloader
	{
	public:

		virtual ~unloader() {};
	};

	typedef boost::shared_ptr<unloader> unloader_ptr;

	template <class T>
	class specific_unloader : public unloader
	{
	public:

		specific_unloader(T* object = 0) :
			object_(object) {}

		virtual ~specific_unloader()
		{
			log_warning("unloading resource of type ", typeid(T).name());
			delete object_;
		}


	private:

		T* object_;
	};


	void set_loader(const std::string& path, loader_ptr loader)
	{
		path_ = path;
		loader_ = loader;
	}


	void*			resource_;
	std::type_info*	typeinfo_;
	unloader_ptr	unloader_;

	std::string		path_;
	loader_ptr		loader_;

	typedef std::map<std::string,loader_ptr> type_lookup;
	typedef boost::shared_ptr<type_lookup> type_lookup_ptr;
	static type_lookup_ptr type_lookup_;

#ifdef USE_HOTLOADING
	int wd_;

	void set_watch_descriptor(int wd)
	{
		wd_ = wd;
	}
#endif
};


/**
 * The resource handle class provides a nicer way to work with resources.
 * It allows you to work with a resource pointer as if you already know the
 * type of the resource.
 */
template <class T>
class resource_handle
{
public:

	/**
	 * Construct a null resource handle.
	 */
	resource_handle() {}

	/**
	 * Construct a resource handle.
	 * \param ptr The resource pointer to reference.
	 */
	resource_handle(resource_ptr ptr) :
		resource_(ptr) {}


	/**
	 * Get whether or not the handle is dereferenceable to the type of this
	 * handle.  A resource handle is dereferenceable if it is not a null
	 * handle and if its underlying resource is in fact the same type as is
	 * expected by the handle.
	 * \return True if the handle is dereferenceable, false otherwise.
	 */
	operator bool () const
	{
		if (!resource_) return false;
		return resource_->check<T>();
	}


	/**
	 * Get a pointer to the underlying resource.
	 * \return The pointer, or null if this handle is not dereferenceable.
	 */
	T* get() const
	{
		if (!*this) return 0;
		return resource_->get<T>();
	}

	/**
	 * Dereference the handle all the way to the underlying resource.
	 * \return A reference to the resource.
	 * \throws std::runtime_error If this is a null handle.
	 */
	T& get_reference() const
	{
		if (!*this) throw std::runtime_error("dereference null handle");
		return *(resource_->get<T>());
	}


	/**
	 * Same as get() for getting a pointer to the underlying resources.
	 * \return The pointer, or null if this handle is not dereferenceable.
	 */
	T* operator -> () const
	{
		return get();
	}

	/**
	 * Same a get_reference() for dereferencing the handle.
	 * \return A reference to the resource.
	 * \throws std::runtime_error If this is a null handle.
	 */
	T& operator * () const
	{
		return get_reference();
	}


private:

	resource_ptr resource_;
};


} // namespace moof

#endif // _MOOF_RESOURCE_HH_