#ifndef CAMELLYA_VM_H
#define CAMELLYA_VM_H

#include "chunk.h"
#include "value.h"
#include "exceptions.h"
#include <vector>
#include <map>
#include <memory>

namespace camellya {

// Call frame for function calls
struct CallFrame {
    std::shared_ptr<Chunk> chunk;
    size_t ip;  // Instruction pointer
    size_t stack_offset;  // Where this frame's locals start on the stack
    
    CallFrame(std::shared_ptr<Chunk> chunk, size_t stack_offset)
        : chunk(std::move(chunk)), ip(0), stack_offset(stack_offset) {}
};

// Virtual Machine - stack-based bytecode interpreter
class VM {
public:
    VM();
    
    // Execute a chunk of bytecode
    bool execute(std::shared_ptr<Chunk> chunk);
    
    // Get the last error message
    const std::string& get_error() const { return error_message; }
    
    // Register native functions
    void register_native_function(const std::string& name, NativeFunction func);
    
    // Register built-in classes for types (like list, map)
    void register_builtin_class(const std::string& type_name, std::shared_ptr<ClassValue> klass);
    
    // Global variable access
    void set_global(const std::string& name, ValuePtr value);
    ValuePtr get_global(const std::string& name);
    
    // Stack operations (for C++ API)
    void push(ValuePtr value);
    ValuePtr pop();
    ValuePtr peek(int distance = 0);
    
private:
    std::vector<ValuePtr> stack;
    std::vector<CallFrame> frames;
    CallFrame* current_frame;
    std::map<std::string, ValuePtr> globals;
    std::map<std::string, std::shared_ptr<ClassValue>> builtin_classes;
    std::string error_message;
    
    // Main execution loop
    bool run();
    
    // Helper methods
    uint8_t read_byte();
    uint16_t read_short();
    ValuePtr read_constant();
    std::string read_string();
    
    // Stack operations
    void runtime_error(const std::string& message);
    bool is_falsey(ValuePtr value);
    
    // Binary operations
    bool binary_op(OpCode op);
    
    // Built-in functions
    void register_builtin_functions();
};

} // namespace camellya

#endif // CAMELLYA_VM_H