#include <Poco/File.h>

#include <DB/Common/escapeForFileName.h>
#include <DB/IO/ReadBufferFromFile.h>
#include <DB/IO/WriteBufferFromString.h>
#include <DB/IO/copyData.h>
#include <DB/Parsers/ASTCreateQuery.h>
#include <DB/Parsers/ParserCreateQuery.h>
#include <DB/Interpreters/Context.h>


namespace DB
{

String Context::getPath() const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	return shared->path;
}


void Context::setPath(const String & path)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	shared->path = path;
}


bool Context::isTableExist(const String & database_name, const String & table_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	Databases::const_iterator it;
	return shared->databases.end() != (it = shared->databases.find(db))
		&& it->second.end() != it->second.find(table_name);
}


bool Context::isDatabaseExist(const String & database_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	String db = database_name.empty() ? current_database : database_name;
	return shared->databases.end() != shared->databases.find(db);
}


void Context::assertTableExists(const String & database_name, const String & table_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;
		
	Databases::const_iterator it;
	if (shared->databases.end() == (it = shared->databases.find(db)))
		throw Exception("Database " + db + " doesn't exist", ErrorCodes::UNKNOWN_DATABASE);

	if (it->second.end() == it->second.find(table_name))
		throw Exception("Table " + db + "." + table_name + " doesn't exist.", ErrorCodes::UNKNOWN_TABLE);
}


void Context::assertTableDoesntExist(const String & database_name, const String & table_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	Databases::const_iterator it;
	if (shared->databases.end() != (it = shared->databases.find(db))
		&& it->second.end() != it->second.find(table_name))
		throw Exception("Table " + db + "." + table_name + " already exists.", ErrorCodes::TABLE_ALREADY_EXISTS);
}


void Context::assertDatabaseExists(const String & database_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	if (shared->databases.end() == shared->databases.find(db))
		throw Exception("Database " + db + " doesn't exist", ErrorCodes::UNKNOWN_DATABASE);
}


void Context::assertDatabaseDoesntExist(const String & database_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	if (shared->databases.end() != shared->databases.find(db))
		throw Exception("Database " + db + " already exists.", ErrorCodes::DATABASE_ALREADY_EXISTS);
}


StoragePtr Context::getTable(const String & database_name, const String & table_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	Databases::const_iterator it;
	if (shared->databases.end() == (it = shared->databases.find(db)))
		throw Exception("Database " + db + " doesn't exist", ErrorCodes::UNKNOWN_DATABASE);

	Tables::const_iterator jt;
	if (it->second.end() == (jt = it->second.find(table_name)))
		throw Exception("Table " + db + "." + table_name + " doesn't exist.", ErrorCodes::UNKNOWN_TABLE);

	return jt->second;
}


void Context::addTable(const String & database_name, const String & table_name, StoragePtr table)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	
	String db = database_name.empty() ? current_database : database_name;

	assertDatabaseExists(db);
	assertTableDoesntExist(db, table_name);
	shared->databases[db][table_name] = table;
}


void Context::addDatabase(const String & database_name)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	assertDatabaseDoesntExist(db);
	shared->databases[db];
}


void Context::detachTable(const String & database_name, const String & table_name)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	assertTableExists(db, table_name);
	shared->databases[db].erase(shared->databases[db].find(table_name));
}


void Context::detachDatabase(const String & database_name)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	assertDatabaseExists(db);
	shared->databases.erase(shared->databases.find(db));
}


ASTPtr Context::getCreateQuery(const String & database_name, const String & table_name) const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);

	String db = database_name.empty() ? current_database : database_name;

	assertDatabaseExists(db);
	assertTableExists(db, table_name);

	/// Здесь хранится определение таблицы
	String metadata_path = shared->path + "metadata/" + escapeForFileName(db) + "/" + escapeForFileName(table_name) + ".sql";
	if (!Poco::File(metadata_path).exists())
		throw Exception("Metadata file " + metadata_path + " for table " + db + "." + table_name + " doesn't exist.",
			ErrorCodes::TABLE_METADATA_DOESNT_EXIST);

	String query;
	{
		ReadBufferFromFile in(metadata_path);
		WriteBufferFromString out(query);
		copyData(in, out);
	}

	const char * begin = query.data();
	const char * end = begin + query.size();
	const char * pos = begin;

	ParserCreateQuery parser;
	ASTPtr ast;
	String expected;
	bool parse_res = parser.parse(pos, end, ast, expected);

	/// Распарсенный запрос должен заканчиваться на конец входных данных или на точку с запятой.
	if (!parse_res || (pos != end && *pos != ';'))
		throw DB::Exception("Syntax error while parsing query from file " + metadata_path + ": failed at position "
			+ Poco::NumberFormatter::format(pos - begin) + ": "
			+ std::string(pos, std::min(SHOW_CHARS_ON_SYNTAX_ERROR, end - pos))
			+ ", expected " + (parse_res ? "end of query" : expected) + ".",
			DB::ErrorCodes::SYNTAX_ERROR);

	ASTCreateQuery & ast_create_query = dynamic_cast<ASTCreateQuery &>(*ast);
	ast_create_query.attach = false;
	ast_create_query.database = db;

	return ast;
}


Settings Context::getSettings() const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	return settings;
}


void Context::setSettings(const Settings & settings_)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	settings = settings_;
}


void Context::setSetting(const String & name, const Field & value)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	settings.set(name, value);
}


String Context::getCurrentDatabase() const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	return current_database;
}


void Context::setCurrentDatabase(const String & name)
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	assertDatabaseExists(name);
	current_database = name;
}


Context & Context::getSessionContext()
{
	if (!session_context)
		throw Exception("There is no session", ErrorCodes::THERE_IS_NO_SESSION);
	return *session_context;
}


Context & Context::getGlobalContext()
{
	if (!global_context)
		throw Exception("Logical error: there is no global context", ErrorCodes::LOGICAL_ERROR);
	return *global_context;
}


const Dictionaries & Context::getDictionaries() const
{
	Poco::ScopedLock<Poco::Mutex> lock(shared->mutex);
	
	if (!shared->dictionaries)
		shared->dictionaries = new Dictionaries;
	
	return *shared->dictionaries;
}

}