#include <QStack>
#include <QRegularExpression>
#include <QSqlQuery>
#include <QSqlError>
#include <QStringList>
#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::fieldToColumn(QString field)
{
	if(field == "mtime" || field == "file.mtime")
	{
		return "file.mtime";
	}
	else if(field == "page" || field == "content.page")
	{
		return "content.page";
	}
	else if(field == "path" || field == "file.path")
	{
		return "file.path";
	}
	else if(field == "size" || field == "file.size")
	{
		return "file.size";
	}
	return "";
}

QString SqliteSearch::createSortSql(const SqliteSearch::Token &token)
{
	// sort:(mtime desc, page asc)
	if(token.key == "sort")
	{
		QString sortsql = " ORDER BY ";
		QStringList splitted_inner = token.value.split(",");
		for(int i = 0; i < splitted_inner.length(); i++)
		{
			QStringList splitted = splitted_inner[i].split(" ");
			if(splitted.length() == 2)
			{
				QString field = splitted[0];
				QString order = splitted[1];
				if(order.compare("asc", Qt::CaseInsensitive))
				{
					order = "ASC";
				}
				else if(order.compare("desc", Qt::CaseInsensitive))
				{
					order = "DESC";
				}
				else
				{
					throw QSSGeneralException("Unknown order specifier: " + order);
				}

				field = fieldToColumn(field);
				if(field == "")
				{
					throw QSSGeneralException("Unknown field:" + field);
				}

				sortsql += field + " " + order;
				if(splitted_inner.length() - i > 1)
				{
					sortsql += ", ";
				}
			}
			else if(splitted.length() == 1)
			{
				sortsql += splitted[0] + " ASC ";
			}
			else
			{
				throw QSSGeneralException("sort specifier must have format [field] (asc|desc)");
			}
		}
		return sortsql;
	}
	return "";
}

QPair<QString, QVector<QString>> SqliteSearch::createSql(const SqliteSearch::Token &token)
{
	QPair<QString, QVector<QString>> result;

	QString key = token.key;
	QString value = token.value;
	value = value.replace("'", "\\'");
	if(key == "AND" || key == "OR" || key == "(" || key == ")")
	{
		return {" " + key + " ", QVector<QString>()};
	}
	if(key == "!")
	{
		return {" NOT ", QVector<QString>()};
	}
	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);
}

QSqlQuery SqliteSearch::makeSqlQuery(const QVector<SqliteSearch::Token> &tokens)
{
	QString whereSql;
	QString sortSql;
	QString limitSql;
	QVector<QString> bindValues;
	bool isContentSearch = false;
	for(const Token &c : tokens)
	{
		if(c.key == "sort")
		{
			if(sortSql != "")
			{
				throw QSSGeneralException("Invalid input: Two seperate sort statements are invalid");
			}
			sortSql = createSortSql(c);
		}
		else
		{
			if(c.key == "c" || c.key == "contains")
			{
				isContentSearch = true;
			}
			auto sql = createSql(c);
			whereSql += sql.first;
			bindValues.append(sql.second);
		}
	}

	QString prepSql;
	if(isContentSearch)
	{
		prepSql =
			"SELECT file.path AS path, group_concat(content.page) AS pages, 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 + " " + sortSql + " GROUP BY file.path";
	}
	else
	{
		prepSql = "SELECT file.path AS path, '0' as pages,  file.mtime AS mtime, file.size AS size, file.filetype AS "
				  "filetype FROM file WHERE  1=1 AND " +
				  whereSql + " " + sortSql;
	}

	QSqlQuery dbquery(*db);
	dbquery.prepare(prepSql);

	for(const QString &value : bindValues)
	{
		if(value != "")
		{
			dbquery.addBindValue(value);
		}
	}
	return dbquery;
}

QVector<SearchResult> SqliteSearch::search(const QString &query)
{
	QVector<SearchResult> results;
	QSqlQuery dbQuery = makeSqlQuery(tokenize(query));
	bool success = dbQuery.exec();
	if(!success)
	{

		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();
		QString pages = dbQuery.value("pages").toString();
		QStringList pagesList = pages.split(",");
		for(QString &page : pagesList)
		{
			if(page != "")
			{
				result.pages.append(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;
}