#include "SqlHighlighter.h"

static const wchar_t *keywords[] = {
	L"as", L"alter", L"all", L"and", L"any", L"by", L"char", L"column", L"create", L"database", L"date", L"from", L"full", L"group", L"having",
	L"in", L"inner", L"int", L"join", L"left", L"not", L"numeric", L"or", L"order", L"outer", L"right", L"select", L"smallint", L"table", L"time",
	L"timestamp", L"timestamptz", L"varchar", L"where"
};

static const wchar_t *operators[] = {
	L"+", L"-", L"*", L"/", L"<", L">", L"<=", L">=", L"<>", L"!=", L"~"
};


//static auto types = R"-(bigint|boolean|char|character varying|date|int[248]|integer|numeric|smallint|time|timestamp(?:tz)?|timestamp(?:\s+with\s+timezone)?|varchar)-";
//static auto err = R"-(left|right|inner|outer)-";

//	static_assert(sizeof(keywords)/4 == 25,
//					  "sizeof keywords");


SqlHighlighter::SqlHighlighter(QTextDocument *parent)
	: QSyntaxHighlighter(parent)
{
//	{
//		static auto keywords = R"-(as|alter|all|and|any|by|column|create|database|from|group|having|in|not|or|order|select|table|where|(?:(?:inner|(?:left|right|full)(\s+outer)?)\s+)?join)-";
//		static auto types = R"-(bigint|boolean|char|character varying|date|int[248]|integer|numeric|smallint|time|timestamp(?:tz)?|timestamp(?:\s+with\s+timezone)?|varchar)-";
//		static auto err = R"-(left|right|inner|outer)-";

//		QTextCharFormat errFormat;
//		errFormat.setForeground(QColor(255, 128, 128));
//		errFormat.setFontWeight(QFont::Bold);
//		highlightingRules.emplace_back(QRegExp(err, Qt::CaseInsensitive), errFormat);

//		QTextCharFormat keywordFormat;
//		keywordFormat.setForeground(QColor(128, 128, 255));
//		keywordFormat.setFontWeight(QFont::Bold);
//		highlightingRules.emplace_back(QRegExp(keywords, Qt::CaseInsensitive), keywordFormat);

//		QTextCharFormat typesFormat;
//		typesFormat.setForeground(QColor(128, 255, 128));
//		typesFormat.setFontWeight(QFont::Bold);
//		highlightingRules.emplace_back(QRegExp(types, Qt::CaseInsensitive), typesFormat);

//	}
}

namespace {

	// Advances ofs to first whitespace or end of string, returns false at end of string
	void skipWhiteSpace(const QString &in, int &ofs)
	{
		const int l = in.length();
		while (ofs < l && in.at(ofs).isSpace())	++ofs;
	}

	enum class BasicTokenType {
		None,
		End, // End of input
		Symbol, // can be many things, keyword, object name, operator, ..
		Comment,
		QuotedString,
		DollarQuotedString,
		QuotedIdentifier
	};

	/**
	 * @brief NextBasicToken
	 * @param in
	 * @param ofs
	 * @param start
	 * @param length
	 * @return false when input seems invalid, it will return what it did recognize but something wasn't right, parser should try to recover
	 */
	bool NextBasicToken(const QString &in, int ofs, int &start, int &length, BasicTokenType &tokentype)
	{
		// Basically chops based on white space
		// it does also recognize comments and quoted strings/identifiers
		bool result = false;

		skipWhiteSpace(in, ofs);
		const int len = in.length();
		while (ofs < len) {
			if (ofs+1 < len && in.at(ofs) == L'-' && in.at(ofs+1) == L'-') {
				// Start of comment, end of line is end of comment

			}
			else if (in.at(ofs) == L'\'') {
				// Start of quoted string

			}
			else if (in.at(ofs) == L'"') {
				// Start of quoted identifier

			}
			else if (in.at(ofs) == L'/' && ofs+1 < len && in.at(ofs+1) == L'*') {
				// Start of C style comment, scan for end
			}

		}
		return result;
	}

}

void SqlHighlighter::highlightBlock(const QString &text)
{
//	foreach (const HighlightingRule &rule, highlightingRules) {
//		QRegExp expression(rule.pattern);
//		int index = expression.indexIn(text);
//		while (index >= 0) {
//			int length = expression.matchedLength();
//			setFormat(index, length, rule.format);
//			index = expression.indexIn(text, index + length);
//		}
//	}
	setCurrentBlockState(0);
}