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

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

QString SqliteSearch::fieldToColumn(QueryField field)
{
	if(field == FILE_MTIME)
	{
		return "file.mtime";
	}
	else if(field == FILE_PATH)
	{
		return "file.path";
	}
	else if(field == FILE_SIZE)
	{
		return "file.size";
	}
	else if(field == CONTENT_TEXT_PAGE)
	{
		return "content.page";
	}
	else if(field == CONTENT_TEXT)
	{
		return "content.text";
	}
	return "";
}

QString SqliteSearch::createSortSql(const QVector<SortCondition> sortConditions)
{
	QString sortsql;
	for(const SortCondition &sc : sortConditions)
	{
		QString order;
		QString field = fieldToColumn(sc.field);
		if(field == "")
		{
			throw LooqsGeneralException("Unknown sort field supplied");
		}
		if(sc.order == DESC)
		{
			order = "DESC";
		}
		else
		{
			order = "ASC";
		}
		sortsql += field + " " + order + ", ";
	}
	sortsql.chop(2);
	if(!sortsql.isEmpty())
	{
		return " ORDER BY " + sortsql;
	}
	return "";
}

QString SqliteSearch::escapeFtsArgument(QString ftsArg)
{
	QString result;
	static QRegularExpression extractor(R"#("([^"]*)"|([^\s]+))#");
	QRegularExpressionMatchIterator i = extractor.globalMatch(ftsArg);
	while(i.hasNext())
	{
		QRegularExpressionMatch m = i.next();
		QString value = m.captured(1);
		if(value.isEmpty())
		{
			value = m.captured(2);
			if(value.endsWith('*'))
			{
				value = value.mid(0, value.size() - 1);
			}
			result += "\"" + value + "\"* ";
		}
		else
		{
			result += "\"" + value + "\" ";
		}
	}
	return result;
}

QPair<QString, QVector<QString>> createNonArgPair(QString key)
{
	return {" " + key + " ", QVector<QString>()};
}

QPair<QString, QVector<QString>> SqliteSearch::createSql(const Token &token)
{
	QPair<QString, QVector<QString>> result;
	QString value = token.value;
	value = value.replace("'", "\\'");

	if(token.type == BOOL_AND)
	{
		return createNonArgPair("AND");
	}
	if(token.type == BOOL_OR)
	{
		return createNonArgPair("OR");
	}
	if(token.type == NEGATION)
	{
		return createNonArgPair("NOT");
	}
	if(token.type == BRACKET_OPEN)
	{
		return createNonArgPair("(");
	}
	if(token.type == BRACKET_CLOSE)
	{
		return createNonArgPair(")");
	}
	if(token.type == FILTER_PATH_STARTS)
	{
		return {" file.path LIKE ? || '%' ", {value}};
	}
	if(token.type == FILTER_PATH_ENDS)
	{
		return {" file.path LIKE '%' || ? ", {value}};
	}
	if(token.type == FILTER_PATH_CONTAINS)
	{
		return {" file.path LIKE '%' || ? || '%' ", {value}};
	}
	if(token.type == FILTER_CONTENT_PAGE)
	{
		return {" content.page = ?", {value}};
	}
	if(token.type == FILTER_CONTENT_CONTAINS)
	{
		return {" fts MATCH ? ", {escapeFtsArgument(value)}};
	}
	if(token.type == FILTER_TAG_ASSIGNED)
	{
		return {" file.id IN (SELECT fileid FROM filetag WHERE tagid = (SELECT id FROM tag WHERE name = ?)) ",
				{value.toLower()}};
	}
	throw LooqsGeneralException("Unknown token passed (should not happen)");
}

QSqlQuery SqliteSearch::makeSqlQuery(const LooqsQuery &query)
{
	QString whereSql;
	QVector<QString> bindValues;
	bool isContentSearch = (query.getTokensMask() & FILTER_CONTENT) == FILTER_CONTENT;
	if(query.getTokens().isEmpty())
	{
		throw LooqsGeneralException("Nothing to search for supplied");
	}

	auto tokens = query.getTokens();
	for(const Token &token : tokens)
	{
		auto sql = createSql(token);
		whereSql += sql.first;
		bindValues.append(sql.second);
	}

	QString prepSql;
	QString sortSql = createSortSql(query.getSortConditions());
	int bindIterations = 1;
	if(isContentSearch)
	{
		if(sortSql.isEmpty())
		{
			if(std::find_if(tokens.begin(), tokens.end(),
							[](const Token &t) -> bool { return t.type == FILTER_CONTENT_CONTAINS; }) != tokens.end())
			{
				sortSql = "ORDER BY prio, rank";
			}
		}
		QString whereSqlTrigram = whereSql;
		whereSqlTrigram.replace("fts MATCH", "fts_trigram MATCH"); // A bit dirty...
		prepSql = "SELECT DISTINCT path, page, mtime, size, filetype FROM ("
				  "SELECT file.path AS path,  content.page AS page, file.mtime AS mtime, file.size AS size, "
				  "file.filetype AS filetype, 0 AS prio, fts.rank AS rank FROM file INNER JOIN content ON file.id = "
				  "content.fileid "
				  "INNER JOIN fts ON content.ftsid = fts.ROWID WHERE 1=1 AND " +
				  whereSql +
				  "UNION ALL SELECT file.path AS path,  content.page AS page, file.mtime AS mtime, file.size AS size, "
				  "file.filetype AS filetype, 1 as prio, fts_trigram.rank AS rank FROM file INNER JOIN content ON "
				  "file.id = "
				  "content.fileid " +
				  "INNER JOIN fts_trigram ON content.fts_trigramid = fts_trigram.ROWID WHERE 1=1 AND " +
				  whereSqlTrigram + " ) " + sortSql;
		++bindIterations;
	}
	else
	{
		if(sortSql.isEmpty())
		{
			sortSql = "ORDER BY file.mtime DESC";
		}
		prepSql = "SELECT file.path AS path, '0' as page,  file.mtime AS mtime, file.size AS size, file.filetype AS "
				  "filetype FROM file WHERE  1=1 AND " +
				  whereSql + " " + sortSql;
	}

	if(query.getLimit() > 0)
	{
		prepSql += " LIMIT " + QString::number(query.getLimit());
	}

	QSqlQuery dbquery(*db);
	dbquery.prepare(prepSql);
	for(int i = 0; i < bindIterations; i++)
	{
		for(const QString &value : bindValues)
		{
			if(value != "")
			{
				dbquery.addBindValue(value);
			}
		}
	}
	return dbquery;
}

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

		qDebug() << dbQuery.lastError();
		qDebug() << dbQuery.executedQuery();
		throw LooqsGeneralException("SQL Error: " + dbQuery.lastError().text());
	}

	bool contentSearch = query.hasContentSearch();
	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();
		result.wasContentSearch = contentSearch;
		results.append(result);
	}
	return results;
}