// Copyright (c) 2010, Amar Takhar <verm@aegisub.org>
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
// $Id$

/// @file mru.cpp
/// @brief Most Recently Used (MRU) Lists
/// @ingroup libaegisub

#include "libaegisub/cajun/writer.h"

#include "libaegisub/access.h"
#include "libaegisub/io.h"
#include "libaegisub/json.h"
#include "libaegisub/log.h"
#include "libaegisub/mru.h"

namespace agi {

MRUManager::MRUManager(const std::string &config, const std::string &default_config): config_name(config) {
	LOG_D("agi/mru") << "Loading MRU List";

	json::UnknownElement root = json_util::file(config, default_config);
	const json::Object& root_new = (json::Object)root;

	json::Object::const_iterator index_object(root_new.Begin()), index_objectEnd(root_new.End());

	for (; index_object != index_objectEnd; ++index_object) {
		const json::Object::Member& member = *index_object;
		const std::string &member_name = member.name;
		const json::UnknownElement& element = member.element;

		Load(member_name, (json::Array)element);
	}
}


MRUManager::~MRUManager() {
}

MRUManager::MRUListMap &MRUManager::Find(std::string const& key) {
	MRUMap::iterator index = mru.find(key);
	if (index == mru.end())
		throw MRUErrorInvalidKey("Invalid key value");
	return index->second;
}


void MRUManager::Add(const std::string &key, const std::string &entry) {
	MRUListMap &map = Find(key);
	map.remove(entry);
	map.push_front(entry);
	Prune(map);

	Flush();
}


void MRUManager::Remove(const std::string &key, const std::string &entry) {
	Find(key).remove(entry);

	Flush();
}


const MRUManager::MRUListMap* MRUManager::Get(const std::string &key) {
	return &Find(key);
}

std::string const& MRUManager::GetEntry(const std::string &key, size_t entry) {
	const MRUManager::MRUListMap *map = Get(key);

	if (entry > map->size())
		throw MRUErrorIndexOutOfRange("Requested element index is out of range.");

	MRUListMap::const_iterator index = map->begin();
	advance(index, entry);
	return *index;
}


void MRUManager::Flush() {
	json::Object out;

	for (MRUMap::const_iterator i = mru.begin(); i != mru.end(); ++i) {
		json::Array &array = out[i->first];
		const MRUListMap &map_list = i->second;

		for (MRUListMap::const_iterator i_lst = map_list.begin(); i_lst != map_list.end(); ++i_lst) {
			array.Insert(json::String(*i_lst));
		}
	}

	json::Writer::Write(out, io::Save(config_name).Get());
}


/// @brief Prune MRUListMap to the desired length.
/// This uses the user-set values for MRU list length.
inline void MRUManager::Prune(MRUListMap& map) {
	map.resize(std::min<size_t>(16, map.size()));
}

static json::String cast_str(json::UnknownElement const& e) {
	return static_cast<json::String>(e);
}

/// @brief Load MRU Lists.
/// @param key List name.
/// @param array json::Array of values.
void MRUManager::Load(const std::string &key, const json::Array& array) {
	transform(array.Begin(), array.End(), back_inserter(mru[key]), cast_str);
	Prune(mru[key]);
}

}