#pragma once

#include "kernel.h"

namespace pybind11 {
class handle;
class object;
class attr_accessor;
class item_accessor;
class iterator;
class str;
class bytes;
class iterable;
class tuple;
class dict;
class list;
class set;
class function;
class module;
class type;
class bool_;
class int_;
class float_;
class str;
class bytes;

template <typename T>
T& _builtin_cast(const handle& obj);

template <typename T>
T reinterpret_borrow(const handle& h);

template <typename T>
T reinterpret_steal(const handle& h);

class handle {
protected:
    pkpy::PyVar m_ptr = nullptr;
    mutable int* ref_count = nullptr;

public:
    handle() = default;
    handle(const handle& h) = default;
    handle& operator= (const handle& other) = default;

    handle(pkpy::PyVar ptr) : m_ptr(ptr) {}

    pkpy::PyVar ptr() const { return m_ptr; }

    int reference_count() const { return ref_count == nullptr ? 0 : *ref_count; }

    const handle& inc_ref() const {
        assert(m_ptr != nullptr);
        if(ref_count == nullptr) {
            auto iter = _ref_counts_map->find(m_ptr);
            if(iter == _ref_counts_map->end()) {
                ref_count = ::new int(1);
                _ref_counts_map->insert({m_ptr, ref_count});
            } else {
                ref_count = iter->second;
                *ref_count += 1;
            }
        } else {
            *ref_count += 1;
        }
        return *this;
    }

    const handle& dec_ref() const {
        assert(m_ptr != nullptr);
        assert(ref_count != nullptr);

        *ref_count -= 1;
        try {
            if(*ref_count == 0) {
                _ref_counts_map->erase(m_ptr);
                ::delete ref_count;
                ref_count = nullptr;
            }
        } catch(std::exception& e) { std::cerr << "Error: " << e.what() << std::endl; }

        return *this;
    }

public:
    template <typename T>
    T cast() const;

    explicit operator bool () const { return m_ptr.operator bool (); }

    bool is(const handle& other) const { return m_ptr == other.m_ptr; }

    bool is_none() const { return m_ptr == vm->None; }

    bool in(const handle& other) const {
        return pkpy::py_cast<bool>(vm, vm->call(vm->py_op("contains"), other.m_ptr, m_ptr));
    }

    bool contains(const handle& other) const {
        return pkpy::py_cast<bool>(vm, vm->call(vm->py_op("contains"), m_ptr, other.m_ptr));
    }

    iterator begin() const;
    iterator end() const;

    str doc() const;

    attr_accessor attr(const char* name) const;
    attr_accessor attr(const handle& name) const;
    attr_accessor attr(object&& name) const;

    item_accessor operator[] (int64_t key) const;
    item_accessor operator[] (const char* key) const;
    item_accessor operator[] (const handle& key) const;
    item_accessor operator[] (object&& key) const;

    object operator- () const;
    object operator~() const;

    template <return_value_policy policy = return_value_policy::automatic, typename... Args>
    object operator() (Args&&... args) const;

private:
    friend object operator+ (const handle& lhs, const handle& rhs);
    friend object operator- (const handle& lhs, const handle& rhs);
    friend object operator* (const handle& lhs, const handle& rhs);
    friend object operator% (const handle& lhs, const handle& rhs);
    friend object operator/ (const handle& lhs, const handle& rhs);
    friend object operator| (const handle& lhs, const handle& rhs);
    friend object operator& (const handle& lhs, const handle& rhs);
    friend object operator^ (const handle& lhs, const handle& rhs);
    friend object operator<< (const handle& lhs, const handle& rhs);
    friend object operator>> (const handle& lhs, const handle& rhs);

    friend object operator+= (const handle& lhs, const handle& rhs);
    friend object operator-= (const handle& lhs, const handle& rhs);
    friend object operator*= (const handle& lhs, const handle& rhs);
    friend object operator/= (const handle& lhs, const handle& rhs);
    friend object operator%= (const handle& lhs, const handle& rhs);
    friend object operator|= (const handle& lhs, const handle& rhs);
    friend object operator&= (const handle& lhs, const handle& rhs);
    friend object operator^= (const handle& lhs, const handle& rhs);
    friend object operator<<= (const handle& lhs, const handle& rhs);
    friend object operator>>= (const handle& lhs, const handle& rhs);

    friend object operator== (const handle& lhs, const handle& rhs);
    friend object operator!= (const handle& lhs, const handle& rhs);
    friend object operator< (const handle& lhs, const handle& rhs);
    friend object operator> (const handle& lhs, const handle& rhs);
    friend object operator<= (const handle& lhs, const handle& rhs);
    friend object operator>= (const handle& lhs, const handle& rhs);

    template <typename T>
    friend T& _builtin_cast(const handle& obj) {
        // FIXME: 2.0 does not use Py_<T> anymore
        static_assert(!std::is_reference_v<T>, "T must not be a reference type.");
        return obj.ptr().obj_get<T>();
    }
};

static_assert(std::is_trivially_copyable_v<handle>);

class object : public handle {
public:
    object(const object& other) : handle(other) { inc_ref(); }

    object(object&& other) noexcept : handle(other) {
        other.m_ptr = nullptr;
        other.ref_count = nullptr;
    }

    object& operator= (const object& other) {
        if(this != &other) {
            dec_ref();
            m_ptr = other.m_ptr;
            ref_count = other.ref_count;
            inc_ref();
        }
        return *this;
    }

    object& operator= (object&& other) noexcept {
        if(this != &other) {
            dec_ref();
            m_ptr = other.m_ptr;
            ref_count = other.ref_count;
            other.m_ptr = nullptr;
            other.ref_count = nullptr;
        }
        return *this;
    }

    ~object() {
        if(m_ptr != nullptr) { dec_ref(); }
    }

protected:
    object(const handle& h, bool borrow) : handle(h) {
        if(borrow) { inc_ref(); }
    }

    template <typename T>
    friend T reinterpret_borrow(const handle& h) {
        return {h, true};
    }

    template <typename T>
    friend T reinterpret_steal(const handle& h) {
        return {h, false};
    }
};

inline void setattr(const handle& obj, const handle& name, const handle& value);
inline void setitem(const handle& obj, const handle& key, const handle& value);

#define PYBIND11_BINARY_OPERATOR(OP, NAME)                                                                             \
    inline object operator OP (const handle& lhs, const handle& rhs) {                                                 \
        return reinterpret_borrow<object>(vm->call(vm->py_op(NAME), lhs.m_ptr, rhs.m_ptr));                            \
    }

PYBIND11_BINARY_OPERATOR(+, "add");
PYBIND11_BINARY_OPERATOR(-, "sub");
PYBIND11_BINARY_OPERATOR(*, "mul");
PYBIND11_BINARY_OPERATOR(/, "truediv");
PYBIND11_BINARY_OPERATOR(%, "mod");
PYBIND11_BINARY_OPERATOR(|, "or_");
PYBIND11_BINARY_OPERATOR(&, "and_");
PYBIND11_BINARY_OPERATOR(^, "xor");
PYBIND11_BINARY_OPERATOR(<<, "lshift");
PYBIND11_BINARY_OPERATOR(>>, "rshift");

PYBIND11_BINARY_OPERATOR(+=, "iadd");
PYBIND11_BINARY_OPERATOR(-=, "isub");
PYBIND11_BINARY_OPERATOR(*=, "imul");
PYBIND11_BINARY_OPERATOR(/=, "itruediv");
PYBIND11_BINARY_OPERATOR(%=, "imod");
PYBIND11_BINARY_OPERATOR(|=, "ior");
PYBIND11_BINARY_OPERATOR(&=, "iand");
PYBIND11_BINARY_OPERATOR(^=, "ixor");
PYBIND11_BINARY_OPERATOR(<<=, "ilshift");
PYBIND11_BINARY_OPERATOR(>>=, "irshift");

PYBIND11_BINARY_OPERATOR(==, "eq");
PYBIND11_BINARY_OPERATOR(!=, "ne");
PYBIND11_BINARY_OPERATOR(<, "lt");
PYBIND11_BINARY_OPERATOR(>, "gt");
PYBIND11_BINARY_OPERATOR(<=, "le");
PYBIND11_BINARY_OPERATOR(>=, "ge");

#undef PYBIND11_BINARY_OPERATOR

}  // namespace pybind11