#ifndef TGRAMMAR_INCLUDED
#define TGRAMMAR_INCLUDED

#include <memory>

// TnzCore includes
#include "tcommon.h"

// TnzBase includes
#include "ttokenizer.h"

#undef DVAPI
#undef DVVAR
#ifdef TNZBASE_EXPORTS
#define DVAPI DV_EXPORT_API
#define DVVAR DV_EXPORT_VAR
#else
#define DVAPI DV_IMPORT_API
#define DVVAR DV_IMPORT_VAR
#endif

//==============================================

//    Forward declarations

class TDoubleParam;
class TUnit;

namespace TSyntax
{
class Token;
class Calculator;
}

//==============================================

//-------------------------------------------------------------------
// Calculator & calculator nodes
//-------------------------------------------------------------------

namespace TSyntax
{

class DVAPI CalculatorNodeVisitor
{
public:
	CalculatorNodeVisitor() {}
	virtual ~CalculatorNodeVisitor() {}
};

//-------------------------------------------------------------------

class DVAPI CalculatorNode
{
	Calculator *m_calculator;

public:
	CalculatorNode(Calculator *calculator) : m_calculator(calculator) {}
	virtual ~CalculatorNode() {}

	Calculator *getCalculator() const { return m_calculator; }

	enum { T,
		   FRAME,
		   RFRAME };
	virtual double compute(double vars[3]) const = 0;

	virtual void accept(CalculatorNodeVisitor &visitor) = 0;

private:
	// Non-copyable
	CalculatorNode(const CalculatorNode &);
	CalculatorNode &operator=(const CalculatorNode &);
};

//-------------------------------------------------------------------

class DVAPI Calculator
{
	CalculatorNode *m_rootNode; //!< (owned) Root calculator node

	TDoubleParam *m_param; //!< (not owned) Owner of the calculator object
	const TUnit *m_unit;   //!< (not owned)

public:
	Calculator();
	virtual ~Calculator();

	void setRootNode(CalculatorNode *node);

	double compute(double t, double frame, double rframe)
	{
		double vars[3];
		vars[0] = t, vars[1] = frame, vars[2] = rframe;
		return m_rootNode->compute(vars);
	}

	void accept(CalculatorNodeVisitor &visitor) { m_rootNode->accept(visitor); }

	typedef double Calculator::*Variable;

	void setOwnerParameter(TDoubleParam *param) { m_param = param; }
	TDoubleParam *getOwnerParameter() const { return m_param; }

	const TUnit *getUnit() const { return m_unit; }
	void setUnit(const TUnit *unit) { m_unit = unit; }

private:
	// not copyable
	Calculator(const Calculator &);
	Calculator &operator=(const Calculator &);
};

//-------------------------------------------------------------------

class DVAPI NumberNode : public CalculatorNode
{
	double m_value;

public:
	NumberNode(Calculator *calc, double value) : CalculatorNode(calc), m_value(value) {}

	double compute(double vars[3]) const { return m_value; }

	void accept(CalculatorNodeVisitor &visitor) {}
};

//-------------------------------------------------------------------

class DVAPI VariableNode : public CalculatorNode
{
	int m_varIdx;

public:
	VariableNode(Calculator *calc, int varIdx)
		: CalculatorNode(calc), m_varIdx(varIdx) {}

	double compute(double vars[3]) const { return vars[m_varIdx]; }

	void accept(CalculatorNodeVisitor &visitor) {}
};

//-------------------------------------------------------------------
// Pattern
//-------------------------------------------------------------------

enum TokenType {
	Unknown = 0,

	Number,
	Constant,
	Variable,
	Operator,
	Parenthesis,
	Function,
	Comma,

	UnexpectedToken = -100,
	Eos,
	Mismatch,

	InternalError = -200
};

//-------------------------------------------------------------------

class DVAPI Pattern
{
	std::string m_description;

public:
	Pattern() {}
	virtual ~Pattern() {}

	virtual std::string getFirstKeyword() const { return ""; }
	virtual void getAcceptableKeywords(std::vector<std::string> &keywords) const {}
	virtual int getPriority() const { return 0; }
	virtual bool expressionExpected(const std::vector<Token> &previousTokens) const { return false; }
	virtual bool matchToken(const std::vector<Token> &previousTokens, const Token &token) const = 0;
	virtual bool isFinished(const std::vector<Token> &previousTokens, const Token &token) const = 0;
	virtual bool isComplete(const std::vector<Token> &previousTokens, const Token &token) const { return isFinished(previousTokens, token); }
	virtual TokenType getTokenType(const std::vector<Token> &previousTokens, const Token &token) const = 0; // see also SyntaxToken in tparser.h

	virtual void createNode(
		Calculator *calc,
		std::vector<CalculatorNode *> &stack,
		const std::vector<Token> &tokens) const = 0;

	std::string getDescription() const { return m_description; }
	void setDescription(std::string description) { m_description = description; }

	// helper methods
	CalculatorNode *popNode(std::vector<CalculatorNode *> &stack) const;
};

//-------------------------------------------------------------------

class DVAPI Grammar
{
	class Imp;
	std::unique_ptr<Imp> m_imp;

public:
	Grammar();
	~Grammar();

	void addPattern(Pattern *pattern); // take ownership

	enum Position { ExpressionStart,
					ExpressionEnd };

	// note: returns a matching pattern (or 0 if no pattern matches)
	const Pattern *getPattern(Position position, const Token &token) const;

	// returns matching <keywords, comment>
	typedef std::vector<std::pair<std::string, std::string>> Suggestions;
	void getSuggestions(Suggestions &suggetsions, Position position) const;

private:
	// not implemented
	Grammar(const Grammar &);
	Grammar &operator=(const Grammar &);
};

} // namespace TSyntax

#endif // TGRAMMAR_INCLUDED