/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            cachemanager.h
 *
 *  Fri Apr 10 10:39:24 CEST 2015
 *  Copyright 2015 Jonas Suhr Christensen
 *  jsc@umbraculum.org
 ****************************************************************************/

/*
 *  This file is part of DrumGizmo.
 *
 *  DrumGizmo 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.
 *
 *  DrumGizmo 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 DrumGizmo; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#pragma once

#include <string>
#include <list>
#include <vector>

#include "thread.h"
#include "semaphore.h"
#include "mutex.h"

#include "audiotypes.h"
#include "audiofile.h"
#include "cacheaudiofile.h"

#define CACHE_DUMMYID -2
#define CACHE_NOID -1

#define CHUNK_MULTIPLIER 16

class AudioFile;
class CacheAudioFile;
class CacheAudioFiles;

typedef int cacheid_t;

class CacheChannel {
public:
	size_t channel;
	sample_t* samples;
	size_t num_samples;
	volatile bool* ready;
};

class CacheChannels : public std::list<CacheChannel> {};

//TODO:
// 1: Move nodata initialisation to init method.
// 2: Make semaphore in thread to block init call until thread has been started.

//// next
// Pre: preloaded contains 2 x framesize. chunk size is framesize.
// allocate 2 chunks and copy initial_samples_needed to first buffer from
// preloaded data and enough to fill up the second buffer from preloaded
// returns the first buffer and its size in &size.
// get id from "free stack" and store pointers to buffers in id vector.
// event: open sndfile handle (if not already open) and increase refcount

//// next
// Return which ever buffer is the front, swap them and add event to load the
// next chunk.

//// close
// decrement file handle refcounter and close file if it is 0.
// free the 2 buffers
// (do not erase from the id vector), push index to
// "free stack" for reuse.

class CacheManager : public Thread {
public:
	/**
	 * Empty constructor...
	 */
	CacheManager();

	/**
	 * Destroy object and stop thread if needed.
	 */
	~CacheManager();

	/**
	 * Initialise cache manager and allocate needed resources
	 * This method starts the cache manager thread.
	 * This method blocks until the thread has been started.
	 * @param poolsize The maximum number of parellel events supported.
	 */
	void init(size_t poolsize, bool threaded);

	/**
	 * Stop thread and clean up resources.
	 * This method blocks until the thread has stopped.
	 */
	void deinit();

	/**
	 * Register new cache entry.
	 * Prepares an entry in the cache manager for future disk streaming.
	 * @param file A pointer to the file which is to be streamed from.
	 * @param initial_samples_needed The number of samples needed in the first
	 *  read that is not nessecarily of framesize. This is the number of samples
	 *  from the input event offset to the end of the frame in which it resides.
	 *  initial_samples_needed <= framesize.
	 * @param channel The channel to which the cache id will be bound.
	 * @param [out] new_id The newly created cache id.
	 * @return A pointer to the first buffer containing the
	 *  'initial_samples_needed' number of samples.
	 */
	sample_t *open(AudioFile *file, size_t initial_samples_needed, int channel,
	               cacheid_t &new_id);

	/**
	 * Get next buffer.
	 * Returns the next buffer for reading based on cache id.
	 * This function will (if needed) schedule a new disk read to make sure that
	 * data is available in the next call to this method.
	 * @param id The cache id to read from.
	 * @param [out] size The size of the returned buffer.
	 * @return A pointer to the buffer.
	 */
	sample_t *next(cacheid_t id, size_t &size);

	/**
	 * Unregister cache entry.
	 * Close associated file handles and free associated buffers.
	 * @param id The cache id to close.
	 */
	void close(cacheid_t id);

	/**
	 * Set internal framesize used when iterating through cache buffers.
	 */
	void setFrameSize(size_t framesize);

	/**
	 * Control reader thread.
	 * Set to true to make reading happen threaded, false to do all reading sync.
	 */
	void setAsyncMode(bool async);

private:
	///! Internal thread main method
	void thread_main();

	size_t framesize;
	sample_t *nodata;

	typedef struct {
		CacheAudioFile* afile;
		size_t channel;
		size_t pos; //< File possition
		volatile bool ready;
		sample_t *front;
		sample_t *back;
		size_t localpos; //< Intra buffer (front) position.

		sample_t* preloaded_samples; // NULL means not active.
		size_t preloaded_samples_size;

	} cache_t;

	typedef enum {
		LOADNEXT = 0,
		CLOSE = 1
	} cmd_t;

	typedef struct {
		cmd_t cmd;

		// For close event:
		cacheid_t id;

		// For load next event:
		size_t pos;
		CacheAudioFile* afile;
		CacheChannels channels;
	} cevent_t;

	cevent_t createLoadNextEvent(CacheAudioFile* afile, size_t channel,
	                             size_t pos, sample_t* buffer,
	                             volatile bool* ready);
	cevent_t createCloseEvent(cacheid_t id);

	void handleLoadNextEvent(cevent_t& e);
	void handleCloseEvent(cevent_t& e);
	void handleCloseCache(cacheid_t& cacheid);

	void handleEvent(cevent_t& e);
	void pushEvent(cevent_t& e);

	std::vector<cache_t> id2cache;

	// Protected by mutex:
	std::list<cevent_t> eventqueue;
	std::list<cacheid_t> availableids;

	Mutex m_events;
	Mutex m_ids;

	bool threaded; // Indicates if we are running in thread mode or offline mode.
	Semaphore sem;
	Semaphore sem_run;
	bool running;

	CacheAudioFiles files;
	//std::map<std::string, CacheAudioFile*> files;
};