#include <QStack>
#include <QRegularExpression>
#include <QSqlQuery>
#include <QSqlError>
#include <QDebug>
#include "sqlitesearch.h"
#include "qssgeneralexception.h"

SqliteSearch::SqliteSearch(QSqlDatabase &db)
{
	this->db = &db;
}

QVector<SqliteSearch::Token> SqliteSearch::tokenize(QString expression)
{
	if(!checkParanthesis(expression))
	{
		throw QSSGeneralException("Invalid paranthesis");
	}
	// TODO: merge lonewords
	QVector<SqliteSearch::Token> result;
	QRegularExpression rx("((?<filtername>(\\.|\\w)+):(?<args>\\((?<innerargs>[^\\)]+)\\)|(\\w)+)|(?<boolean>AND|OR|!)|"
						  "(?<bracket>\\(|\\))|(?<loneword>\\w+))");
	QRegularExpressionMatchIterator i = rx.globalMatch(expression);
	bool wasbool = true;
	while(i.hasNext())
	{
		QRegularExpressionMatch m = i.next();
		QString boolean = m.captured("boolean");
		QString filtername = m.captured("filtername");
		QString bracket = m.captured("bracket");
		QString loneword = m.captured("loneword");

		if(boolean != "")
		{
			wasbool = true;
			result.append(Token(boolean));
		}

		if(bracket != "")
		{
			if(!wasbool)
			{
				if(bracket == "(")
				{
					result.append(Token("AND"));
				}
			}
			result.append(Token(bracket));
		}

		if(loneword != "")
		{
			if(!wasbool)
			{
				result.append(Token("AND"));
			}
			wasbool = false;
			result.append(Token("path.contains", loneword));
		}

		if(filtername != "")
		{
			if(!wasbool)
			{
				result.append(Token("AND"));
			}
			wasbool = false;
			QString value = m.captured("innerargs");
			if(value == "")
			{
				value = m.captured("args");
			}
			result.append(Token(filtername, value));
		}
	}
	return result;
}

QString SqliteSearch::createSql(const SqliteSearch::Token &token)
{
	QString key = token.key;
	QString value = token.value;
	value = value.replace("'", "\\'");
	if(key == "AND" || key == "OR" || key == "(" || key == ")")
	{
		return " " + key + " ";
	}
	if(key == "!")
	{
		return " NOT ";
	}
	if(key == "path.starts")
	{
		return " file.path LIKE '" + value + "%' ";
	}
	if(key == "path.ends")
	{
		return " file.path LIKE '%" + value + "' ";
	}
	if(key == "path.contains" || key == "inpath")
	{
		return " file.path LIKE '%" + value + "%' ";
	}
	if(key == "page")
	{
		return " content.page = " + value;
	}
	if(key == "contains" || key == "c")
	{
		return " content.id IN (SELECT content_fts.ROWID FROM content_fts WHERE content_fts.content MATCH '" + value +
			   "' )";
	}
	throw QSSGeneralException("Unknown token: " + key);
}

QString SqliteSearch::makeSql(const QVector<SqliteSearch::Token> &tokens)
{
	QString result;
	for(const Token &c : tokens)
	{
		result += createSql(c);
	}
	return result;
}

QVector<SearchResult> SqliteSearch::search(const QString &query)
{
	QVector<SearchResult> results;
	QString whereSql = makeSql(tokenize(query));
	QString prep;
	// TODO: hack, as we don't wanna look into content and get redundant results, when we don't even care about content
	if(whereSql.contains("content."))
	{
		prep = "SELECT file.path AS path, content.page AS page, file.mtime AS mtime, file.size AS size, file.filetype "
			   "AS filetype FROM file INNER JOIN content ON file.id = content.fileid WHERE 1=1 AND " +
			   whereSql + " ORDER By file.mtime DESC, content.page ASC";
	}
	else
	{
		prep = "SELECT file.path AS path, 0 as page,  file.mtime AS mtime, file.size AS size, file.filetype AS "
			   "filetype FROM file WHERE " +
			   whereSql + " ORDER by file.mtime DESC";
	}
	QSqlQuery dbquery(*db);
	dbquery.prepare(prep);
	bool success = dbquery.exec();
	if(!success)
	{
		qDebug() << "prepped: " << prep;
		qDebug() << dbquery.lastError();
		throw QSSGeneralException("SQL Error: " + dbquery.lastError().text());
	}

	while(dbquery.next())
	{
		SearchResult result;
		result.fileData.absPath = dbquery.value("path").toString();
		result.fileData.mtime = dbquery.value("mtime").toUInt();
		result.fileData.size = dbquery.value("size").toUInt();
		result.fileData.filetype = dbquery.value("filetype").toChar();
		result.page = dbquery.value("page").toUInt();
		results.append(result);
	}
	return results;
}

bool SqliteSearch::checkParanthesis(QString expression)
{
	QStack<QChar> open;
	QStack<QChar> close;

	for(QChar &c : expression)
	{
		if(c == '(')
		{
			open.push(c);
		}
		if(c == ')')
		{
			close.push(c);
		}
	}
	if(open.size() != close.size())
	{
		return false;
	}
	while(!open.empty() && !close.empty())
	{
		QChar o = open.pop();
		QChar c = close.pop();
		if(o != '(' && c != ')')
		{
			return false;
		}
	}
	return true;
}