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#ifndef QV4BYTECODEGENERATOR_P_H
#define QV4BYTECODEGENERATOR_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <private/qv4instr_moth_p.h>

QT_BEGIN_NAMESPACE

namespace QQmlJS {
namespace AST {
class SourceLocation;
}
}

namespace QV4 {
namespace Moth {

class BytecodeGenerator {
public:

    struct Label {
        enum LinkMode {
            LinkNow,
            LinkLater
        };
        Label() = default;
        Label(BytecodeGenerator *generator, LinkMode mode = LinkNow)
            : generator(generator),
              index(generator->labels.size()) {
            generator->labels.append(mode == LinkNow ? generator->instructions.size() : -1);
        }
        static Label returnLabel() {
            Label l;
            l.index = INT_MAX;
            return l;
        }
        bool isReturn() const {
            return index == INT_MAX;
        }

        void link() {
            Q_ASSERT(index >= 0);
            Q_ASSERT(generator->labels[index] == -1);
            generator->labels[index] = generator->instructions.size();
        }

        BytecodeGenerator *generator = 0;
        int index = -1;
    };

    struct Jump {
        Jump(BytecodeGenerator *generator, int instruction, int offset)
            : generator(generator),
              index(generator->jumps.size()) {
            generator->jumps.append({ instruction, offset, -1 });
        }
        ~Jump() {
            Q_ASSERT(generator->jumps[index].linkedLabel != -1);
        }


        BytecodeGenerator *generator;
        int index;

        void link() {
            link(generator->label());
        }
        void link(Label l) {
            Q_ASSERT(l.index >= 0);
            Q_ASSERT(generator->jumps[index].linkedLabel == -1);
            generator->jumps[index].linkedLabel = l.index;
        }
    };

    struct ExceptionHandler : public Label {
        ExceptionHandler(BytecodeGenerator *generator)
            : Label(generator, LinkLater)
        {
        }
        ~ExceptionHandler()
        {
            Q_ASSERT(generator->currentExceptionHandler != this);
        }
    };

    Label label() {
        return Label(this, Label::LinkNow);
    }

    Label newLabel() {
        return Label(this, Label::LinkLater);
    }

    ExceptionHandler newExceptionHandler() {
        return ExceptionHandler(this);
    }

    template<int InstrT>
    void addInstruction(const InstrData<InstrT> &data)
    {
        Instr genericInstr;
        genericInstr.common.instructionType = static_cast<Instr::Type>(InstrT);
        InstrMeta<InstrT>::setDataNoCommon(genericInstr, data);
        addInstructionHelper(InstrMeta<InstrT>::Size, genericInstr);
    }

    Q_REQUIRED_RESULT Jump jump()
    {
        Instruction::Jump data;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpEq()
    {
        Instruction::JumpEq data;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpNe()
    {
        Instruction::JumpNe data;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpStrictEqual(const StackSlot &lhs)
    {
        Instruction::JumpStrictEqual data;
        data.lhs = lhs;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpStrictNotEqual(const StackSlot &lhs)
    {
        Instruction::JumpStrictNotEqual data;
        data.lhs = lhs;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpStrictEqualStackSlotInt(const StackSlot &lhs, int rhs)
    {
        Instruction::JumpStrictEqualStackSlotInt data;
        data.lhs = lhs;
        data.rhs = rhs;
        return addJumpInstruction(data);
    }

    Q_REQUIRED_RESULT Jump jumpStrictNotEqualStackSlotInt(const StackSlot &lhs, int rhs)
    {
        Instruction::JumpStrictNotEqualStackSlotInt data;
        data.lhs = lhs;
        data.rhs = rhs;
        return addJumpInstruction(data);
    }

    void setExceptionHandler(ExceptionHandler *handler)
    {
        currentExceptionHandler = handler;
        Instruction::SetExceptionHandler data;
        data.offset = 0;
        if (!handler)
            addInstruction(data);
        else
            addJumpInstruction(data).link(*handler);
    }

    void setLocation(const QQmlJS::AST::SourceLocation &loc);

    ExceptionHandler *exceptionHandler() const {
        return currentExceptionHandler;
    }

    int newRegister();
    int newRegisterArray(int n);
    int registerCount() const { return regCount; }

    QByteArray finalize();

    template<int InstrT>
    Jump addJumpInstruction(const InstrData<InstrT> &data)
    {
        Instr genericInstr;
        genericInstr.common.instructionType = static_cast<Instr::Type>(InstrT);
        InstrMeta<InstrT>::setDataNoCommon(genericInstr, data);
        return Jump(this, addInstructionHelper(InstrMeta<InstrT>::Size, genericInstr), offsetof(InstrData<InstrT>, offset));
    }

private:
    friend struct Jump;
    friend struct Label;
    friend struct ExceptionHandler;

    int addInstructionHelper(uint size, const Instr &i) {
        int pos = instructions.size();
        instructions.append({size, i});
        return pos;
    }

    struct JumpData {
        int instructionIndex;
        int offset;
        int linkedLabel;
    };

    struct I {
        uint size;
        Instr instr;
    };

    QVector<I> instructions;
    QVector<int> labels;
    QVector<JumpData> jumps;
    ExceptionHandler *currentExceptionHandler;
    int regCount = 0;
public:
    int currentReg = 0;
private:
    int currentLine = -1;
};

}
}

QT_END_NAMESPACE

#endif