#include "pocketpy/objects/dict.hpp"

namespace pkpy {

Dict::Dict() :
    _capacity(__Capacity), _mask(__Capacity - 1), _size(0), _critical_size(__Capacity * __LoadFactor + 0.5f),
    _head_idx(-1), _tail_idx(-1) {
    __alloc_items();
}

void Dict::__alloc_items() {
    _items = (Item*)std::malloc(_capacity * sizeof(Item));
    for(int i = 0; i < _capacity; i++) {
        _items[i].first = nullptr;
        _items[i].second = nullptr;
        _items[i].prev = -1;
        _items[i].next = -1;
    }
}

Dict::Dict(Dict&& other) {
    _capacity = other._capacity;
    _mask = other._mask;
    _size = other._size;
    _critical_size = other._critical_size;
    _head_idx = other._head_idx;
    _tail_idx = other._tail_idx;
    _items = other._items;
    other._items = nullptr;
}

Dict::Dict(const Dict& other) {
    _capacity = other._capacity;
    _mask = other._mask;
    _size = other._size;
    _critical_size = other._critical_size;
    _head_idx = other._head_idx;
    _tail_idx = other._tail_idx;
    // copy items
    _items = (Item*)std::malloc(_capacity * sizeof(Item));
    std::memcpy(_items, other._items, _capacity * sizeof(Item));
}

void Dict::set(VM* vm, PyVar key, PyVar val) {
    // do possible rehash
    if(_size + 1 > _critical_size) _rehash(vm);
    bool ok;
    int i;
    _probe_1(vm, key, ok, i);
    if(!ok) {
        _size++;
        _items[i].first = key;

        // append to tail
        if(_size == 0 + 1) {
            _head_idx = i;
            _tail_idx = i;
        } else {
            _items[i].prev = _tail_idx;
            _items[_tail_idx].next = i;
            _tail_idx = i;
        }
    }
    _items[i].second = val;
}

void Dict::_rehash(VM* vm) {
    Item* old_items = _items;
    int old_head_idx = _head_idx;

    _capacity *= 4;
    _mask = _capacity - 1;
    _size = 0;
    _critical_size = _capacity * __LoadFactor + 0.5f;
    _head_idx = -1;
    _tail_idx = -1;

    __alloc_items();

    // copy old items to new dict
    int i = old_head_idx;
    while(i != -1) {
        set(vm, old_items[i].first, old_items[i].second);
        i = old_items[i].next;
    }

    std::free(old_items);
}

PyVar Dict::try_get(VM* vm, PyVar key) const {
    bool ok;
    int i;
    _probe_0(vm, key, ok, i);
    if(!ok) return nullptr;
    return _items[i].second;
}

bool Dict::contains(VM* vm, PyVar key) const {
    bool ok;
    int i;
    _probe_0(vm, key, ok, i);
    return ok;
}

bool Dict::del(VM* vm, PyVar key) {
    bool ok;
    int i;
    _probe_0(vm, key, ok, i);
    if(!ok) return false;
    _items[i].first = nullptr;
    // _items[i].second = PY_DELETED_SLOT;  // do not change .second if it is not NULL, it means the slot is occupied by
    // a deleted item
    _size--;

    if(_size == 0) {
        _head_idx = -1;
        _tail_idx = -1;
    } else {
        if(_head_idx == i) {
            _head_idx = _items[i].next;
            _items[_head_idx].prev = -1;
        } else if(_tail_idx == i) {
            _tail_idx = _items[i].prev;
            _items[_tail_idx].next = -1;
        } else {
            _items[_items[i].prev].next = _items[i].next;
            _items[_items[i].next].prev = _items[i].prev;
        }
    }
    _items[i].prev = -1;
    _items[i].next = -1;
    return true;
}

void Dict::update(VM* vm, const Dict& other) {
    other.apply([&](PyVar k, PyVar v) {
        set(vm, k, v);
    });
}

Tuple Dict::keys() const {
    Tuple t(_size);
    int i = _head_idx;
    int j = 0;
    while(i != -1) {
        t[j++] = _items[i].first;
        i = _items[i].next;
    }
    assert(j == _size);
    return t;
}

Tuple Dict::values() const {
    Tuple t(_size);
    int i = _head_idx;
    int j = 0;
    while(i != -1) {
        t[j++] = _items[i].second;
        i = _items[i].next;
    }
    assert(j == _size);
    return t;
}

void Dict::clear() {
    _size = 0;
    _head_idx = -1;
    _tail_idx = -1;
    for(int i = 0; i < _capacity; i++) {
        _items[i].first = nullptr;
        _items[i].second = nullptr;
        _items[i].prev = -1;
        _items[i].next = -1;
    }
}

Dict::~Dict() {
    if(_items) std::free(_items);
}
}  // namespace pkpy