#include "pocketpy.h"
#include "pocketpy_c.h"

using namespace pkpy;

struct LuaStack: public ValueStackImpl<32>{
    PyObject*& at(int i) {
        if(i < 0 || i >= size()){
            throw std::runtime_error("lua stack index out of range");
        }
        return _begin[i];
    }
    PyObject* const& at(int i) const {
        if(i < 0 || i >= size()){
            throw std::runtime_error("lua stack index out of range");
        }
        return _begin[i];
    }

    void safe_push(PyObject* obj){
        if(size() >= max_size()) throw std::runtime_error("lua stack overflow");
        push(obj);
    }

    void safe_pop(){
        if(size() == 0) throw std::runtime_error("lua stack is empty");
        pop();
    }

    PyObject*& safe_top(){
        if(size() == 0) throw std::runtime_error("lua stack is empty");
        return top();
    }
};

#define ERRHANDLER_OPEN \
    if (vm->c_data->size() > 0 && vm->c_data->top() == nullptr) \
        return false; \
    try {

#define ERRHANDLER_CLOSE \
    } catch(Exception& e ) { \
        vm->c_data->push(py_var(vm, e)); \
        vm->c_data->push(NULL); \
        return false; \
    } catch(const std::exception& re){ \
        auto e = Exception("std::exception", re.what()); \
        vm->c_data->push(py_var(vm, e)); \
        vm->c_data->push(NULL); \
        return false; \
    }


class CVM : public VM {
    public :

    LuaStack* c_data;
    CVM(bool enable_os=true) : VM(enable_os) {
        c_data = new LuaStack();
    }

    ~CVM() {
        c_data->clear();
        delete c_data;
    }

    struct TempStack{
        CVM* cvm;
        LuaStack* prev;
        TempStack(CVM* cvm, LuaStack* new_data) : cvm(cvm) {
            prev = cvm->c_data;
            cvm->c_data = new_data;
        }

        ~TempStack() { restore(); }

        void restore(){
            if(prev == nullptr) return;
            cvm->c_data = prev;
            prev = nullptr;
        }
    };
};


//for now I will unpack a tuple automatically, we may not want to handle
//it this way, not sure
//it is more lua like, but maybe not python like
static void unpack_return(CVM* vm, PyObject* ret) {
    if (is_type(ret, vm->tp_tuple)) {
        Tuple& t = _py_cast<Tuple&>(vm, ret);
        for (int i = 0; i < t.size(); i++) 
            vm->c_data->push(t[i]);
    } else if (ret == vm->None) {
        //do nothing here
        //having to pop the stack after every call that returns none is annoying
        //lua does not do this
        //
        //so for now we will not push none on the stack when it is the sole thing returned
        //if this becomes a problem we can change it
        //
        //you can still check if it returned none by comparing stack size before
        //and after if you have to
    } else 
        vm->c_data->push(ret);

}


bool pkpy_clear_error(pkpy_vm* vm_handle, char** message) {
    CVM* vm = (CVM*) vm_handle;
    if (vm->c_data->size() == 0 || vm->c_data->top() != nullptr) 
        return false;

    vm->c_data->pop();
    Exception& e = py_cast<Exception&>(vm, vm->c_data->top());
    if (message != nullptr) 
        *message = e.summary().c_str_dup();
    else
        std::cerr << "ERROR: " << e.summary() << "\n";

    vm->c_data->clear();
    vm->callstack.clear();
    vm->s_data.clear(); 
    return true;
}

void gc_marker_ex(CVM* vm) {
    for(PyObject* obj: *vm->c_data) if(obj!=nullptr) OBJ_MARK(obj);
}

static OutputHandler stdout_handler = nullptr;
static OutputHandler stderr_handler = nullptr;

void pkpy_set_output_handlers(pkpy_vm*, OutputHandler stdout_handler, OutputHandler stderr_handler){
    ::stdout_handler = stdout_handler;
    ::stderr_handler = stderr_handler;
}

pkpy_vm* pkpy_vm_create(bool use_stdio, bool enable_os) {

    CVM* vm = new CVM(enable_os);
    vm->c_data = new LuaStack();
    vm->heap._gc_marker_ex = (void (*)(VM*)) gc_marker_ex;

    if (!use_stdio) {
        vm->_stdout = [](VM* vm, const Str& s){
            std::string str = s.str();
            if (stdout_handler != nullptr) stdout_handler((pkpy_vm*)vm, str.c_str());
        };
        vm->_stderr = [](VM* vm, const Str& s){
            std::string str = s.str();
            if (stderr_handler != nullptr) stderr_handler((pkpy_vm*)vm, str.c_str());
        };
    }

    return (pkpy_vm*) vm;
}

bool pkpy_vm_run(pkpy_vm* vm_handle, const char* source) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    CodeObject_ code = vm->compile(source, "<c-bound>", EXEC_MODE);
    vm->_exec(code, vm->_main);
    ERRHANDLER_CLOSE

    //unpack_return(w, result);
    //NOTE: it seems like vm->_exec should return whatever the last command it
    //ran returned but instead it seems to pretty much always return None
    //so I guess uncomment this line if that every changes

    return true;
}

void pkpy_vm_destroy(pkpy_vm* vm_handle) {
    CVM* vm = (CVM*) vm_handle;
    delete vm;
}

PyObject* c_function_wrapper(VM* vm, ArgsView args) {
    LuaStyleFuncC f;
    if(args[-1] != PY_NULL){
        f = _py_cast<NativeFunc&>(vm, args[-1])._lua_f;
    } else {
        f = _py_cast<NativeFunc&>(vm, args[-2])._lua_f;
    }
    CVM* cvm = (CVM*) vm;

    //setup c stack
    LuaStack local_stack;

    for (int i = 0; i < args.size(); i++)
        local_stack.safe_push(args[i]);
    
    // tmp is controlled by RAII
    auto tmp = CVM::TempStack(cvm, &local_stack);
    int retc = f(cvm);

    // propagate_if_errored
    if (!cvm->c_data->empty() && cvm->c_data->top() == nullptr){
        cvm->c_data->pop();     // pop nullptr
        Exception& e = _py_cast<Exception&>(vm, cvm->c_data->popx());
        tmp.restore();
        // throw e;
        vm->_error(e);
    }
    tmp.restore();

    PyObject* ret = cvm->None;

    if (retc == 1) 
        ret = local_stack.safe_top();
    else if (retc > 1) {
        Tuple t(retc);

        for (int i = 0; i < retc; i++)  {
            int stack_index = (local_stack.size() - retc) + i;
            t[i] = local_stack.at(stack_index);
        }

        ret = py_var(cvm, t);
    }

    return ret;
}

bool pkpy_push_function(pkpy_vm* vm_handle, pkpy_function f, int argc) {
    CVM* vm = (CVM*) vm_handle;
    NativeFunc nf = NativeFunc(c_function_wrapper, argc, false);
    nf._lua_f = (LuaStyleFuncC) f;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, nf));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_int(pkpy_vm* vm_handle, int value) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, value));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_float(pkpy_vm* vm_handle, double value) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, value));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_bool(pkpy_vm* vm_handle, bool value) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, value));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_string(pkpy_vm* vm_handle, const char* value) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, value));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_stringn(pkpy_vm* vm_handle, const char* value, int length) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, Str(value, length)));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_voidp(pkpy_vm* vm_handle, void* value) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(py_var(vm, value));
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_push_none(pkpy_vm* vm_handle) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->c_data->safe_push(vm->None);
    ERRHANDLER_CLOSE
    return true;
}



bool pkpy_set_global(pkpy_vm* vm_handle, const char* name) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    vm->_main->attr().set(name, vm->c_data->safe_top());
    vm->c_data->safe_pop();
    ERRHANDLER_CLOSE
    return true;
}

//get global will also get bulitins
bool pkpy_get_global(pkpy_vm* vm_handle, const char* name) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    PyObject* o = vm->_main->attr().try_get(name);
    if (o == nullptr) {
        o = vm->builtins->attr().try_get(name);
        if (o == nullptr)
            throw Exception("NameError", name);
    }
    vm->c_data->safe_push(o);
    ERRHANDLER_CLOSE
    return true;
}


bool pkpy_call(pkpy_vm* vm_handle, int argc) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN

    int callable_index = vm->c_data->size() - argc  - 1;

    PyObject* callable = vm->c_data->begin()[callable_index];

    vm->s_data.push(callable);
    vm->s_data.push(PY_NULL);

    for (int i = 0; i < argc; i++) 
        vm->s_data.push(vm->c_data->at(callable_index + i + 1));

    PyObject* o = vm->vectorcall(argc);

    vm->c_data->shrink(argc + 1);

    unpack_return(vm, o);
    ERRHANDLER_CLOSE

    return true;
}

bool pkpy_call_method(pkpy_vm* vm_handle, const char* name, int argc) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN

    int self_index = vm->c_data->size() - argc  - 1;
    PyObject* self = vm->c_data->begin()[self_index];

    PyObject* callable = vm->get_unbound_method(self, name, &self);

    vm->s_data.push(callable);
    vm->s_data.push(self);

    for (int i = 0; i < argc; i++) 
        vm->s_data.push(vm->c_data->at(self_index + i + 1));

    PyObject* o = vm->vectorcall(argc);

    vm->c_data->shrink(argc + 1);

    unpack_return(vm, o);

    return true;
    ERRHANDLER_CLOSE
}



static int lua_to_cstack_index(int index, int size) {
    if (index < 0) index = size + index;
    return index;
}

bool pkpy_to_int(pkpy_vm* vm_handle, int index, int* ret) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN

    index = lua_to_cstack_index(index, vm->c_data->size());

    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) *ret = py_cast<int>(vm, o);

    return true;
    ERRHANDLER_CLOSE
}

bool pkpy_to_float(pkpy_vm* vm_handle, int index, double* ret) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) *ret = py_cast<double>(vm, o);
    return true;
    ERRHANDLER_CLOSE
}

bool pkpy_to_bool(pkpy_vm* vm_handle, int index, bool* ret) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) *ret = py_cast<bool>(vm, o);
    return true;
    ERRHANDLER_CLOSE
}

bool pkpy_to_voidp(pkpy_vm* vm_handle, int index, void** ret) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) *ret = py_cast<void*>(vm, o);
    return true;
    ERRHANDLER_CLOSE
}

bool pkpy_to_string(pkpy_vm* vm_handle, int index, char** ret) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) {
        *ret = py_cast<Str&>(vm, o).c_str_dup();
    }
    return true;
    ERRHANDLER_CLOSE
}

bool pkpy_to_stringn(pkpy_vm* vm_handle, int index, const char** ret, int* size) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if (ret != nullptr) {
        std::string_view sv = py_cast<Str&>(vm, o).sv();
        *ret = sv.data();
        *size = sv.size();
    }
    return true;
    ERRHANDLER_CLOSE
}


bool pkpy_is_int(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return is_type(o, vm->tp_int);
}
bool pkpy_is_float(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return is_type(o, vm->tp_float);
}
bool pkpy_is_bool(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return is_type(o, vm->tp_bool);
}
bool pkpy_is_string(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return is_type(o, vm->tp_str);
}
bool pkpy_is_voidp(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return is_type(o, VoidP::_type(vm));
}

bool pkpy_is_none(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    return o == vm->None;
}

bool pkpy_check_global(pkpy_vm* vm_handle, const char* name) {
    CVM* vm = (CVM*) vm_handle;
    PyObject* o = vm->_main->attr().try_get(name);
    if (o == nullptr) {
        o = vm->builtins->attr().try_get(name);
        if (o == nullptr)
            return false;
    }
    return true;
}

bool pkpy_check_error(pkpy_vm* vm_handle) {
    CVM* vm = (CVM*) vm_handle;
    if (vm->c_data->size() > 0 && vm->c_data->top() == nullptr) 
        return true; 
    return false;
}


bool pkpy_check_stack(pkpy_vm* vm_handle, int free) {
    CVM* vm = (CVM*) vm_handle;
    return free + vm->c_data->size() <= LuaStack::max_size();
}

int pkpy_stack_size(pkpy_vm* vm_handle) {
    CVM* vm = (CVM*) vm_handle;
    return vm->c_data->size();
}

bool pkpy_pop(pkpy_vm* vm_handle, int n) {
    CVM* vm = (CVM*) vm_handle;
    vm->c_data->shrink(n);
    return true;
}


bool pkpy_push(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    vm->c_data->safe_push(vm->c_data->at(index));
    return true;
}


bool pkpy_error(pkpy_vm* vm_handle, const char* name, const char* message) {
    CVM* vm = (CVM*) vm_handle;
    // already in error state
    if (vm->c_data->size() > 0 && vm->c_data->top() == nullptr) {
        return false;
    }
    vm->c_data->safe_push(py_var(vm, Exception(name, message)));
    vm->c_data->safe_push(NULL);
    return false;
}

bool pkpy_getattr(pkpy_vm* vm_handle, const char* name) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    PyObject* o = vm->c_data->safe_top();
    PyObject* ret = vm->getattr(o, name, false);
    if(ret == nullptr) return false;
    vm->c_data->top() = ret;
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_setattr(pkpy_vm* vm_handle, const char* name) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    if(vm->c_data->size() < 2){
        throw std::runtime_error("not enough arguments");
    }
    PyObject* a = vm->c_data->top();
    PyObject* val = vm->c_data->second();
    vm->setattr(a, name, val);
    vm->c_data->shrink(2);
    ERRHANDLER_CLOSE
    return true;
}

bool pkpy_eval(pkpy_vm* vm_handle, const char* code) {
    CVM* vm = (CVM*) vm_handle;
    ERRHANDLER_OPEN
    CodeObject_ co = vm->compile(code, "<eval>", EVAL_MODE);
    PyObject* ret = vm->_exec(co, vm->_main);
    vm->c_data->safe_push(ret);
    ERRHANDLER_CLOSE
    return true;
}

void* pkpy_get_id(pkpy_vm* vm_handle, int index) {
    CVM* vm = (CVM*) vm_handle;
    index = lua_to_cstack_index(index, vm->c_data->size());
    PyObject* o = vm->c_data->at(index);
    if(is_tagged(o)) return nullptr;
    return (void*) o;
}