#include "pocketpy/pocketpy.h"

#include "pocketpy/common/utils.h"
#include "pocketpy/common/sstream.h"
#include "pocketpy/objects/object.h"
#include "pocketpy/interpreter/vm.h"

#define PK_DICT_MAX_COLLISION 3

typedef struct {
    py_i64 hash;
    py_TValue key;
    py_TValue val;
} DictEntry;

typedef struct {
    int _[PK_DICT_MAX_COLLISION];
} DictIndex;

typedef struct {
    int length;
    int capacity;
    DictIndex* indices;
    c11_vector /*T=DictEntry*/ entries;
} Dict;

typedef struct {
    DictEntry* curr;
    DictEntry* end;
} DictIterator;

static void Dict__ctor(Dict* self, int capacity) {
    self->length = 0;
    self->capacity = capacity;
    self->indices = malloc(self->capacity * sizeof(DictIndex));
    memset(self->indices, -1, self->capacity * sizeof(DictIndex));
    c11_vector__ctor(&self->entries, sizeof(DictEntry));
}

static void Dict__dtor(Dict* self) {
    self->length = 0;
    self->capacity = 0;
    free(self->indices);
    c11_vector__dtor(&self->entries);
}

static bool Dict__try_get(Dict* self, py_TValue* key, DictEntry** out) {
    py_i64 hash;
    if(!py_hash(key, &hash)) return false;
    int idx = hash & (self->capacity - 1);
    for(int i = 0; i < PK_DICT_MAX_COLLISION; i++) {
        int idx2 = self->indices[idx]._[i];
        if(idx2 == -1) continue;
        DictEntry* entry = c11__at(DictEntry, &self->entries, idx2);
        int res = py_eq(&entry->key, key);
        if(res == 1) {
            *out = entry;
            return true;
        }
        if(res == -1) return false;  // error
    }
    *out = NULL;
    return true;
}

static void Dict__clear(Dict* self) {
    memset(self->indices, -1, self->capacity * sizeof(DictIndex));
    c11_vector__clear(&self->entries);
    self->length = 0;
}

static void Dict__rehash_2x(Dict* self) {
    Dict old_dict = *self;

    int new_capacity = self->capacity * 2;
    assert(new_capacity <= 1073741824);

    do {
        Dict__ctor(self, new_capacity);

        for(int i = 0; i < old_dict.entries.count; i++) {
            DictEntry* entry = c11__at(DictEntry, &old_dict.entries, i);
            if(py_isnil(&entry->key)) continue;
            int idx = entry->hash & (new_capacity - 1);
            bool success = false;
            for(int i = 0; i < PK_DICT_MAX_COLLISION; i++) {
                int idx2 = self->indices[idx]._[i];
                if(idx2 == -1) {
                    // insert new entry (empty slot)
                    c11_vector__push(DictEntry, &self->entries, *entry);
                    self->indices[idx]._[i] = self->entries.count - 1;
                    self->length++;
                    success = true;
                    break;
                }
            }
            if(!success) {
                Dict__dtor(self);
                new_capacity *= 2;
                continue;
            }
        }
        // resize complete
        Dict__dtor(&old_dict);
        return;
    } while(1);
}

static void Dict__compact_entries(Dict* self) {
    int* mappings = malloc(self->entries.count * sizeof(int));

    int n = 0;
    for(int i = 0; i < self->entries.count; i++) {
        DictEntry* entry = c11__at(DictEntry, &self->entries, i);
        if(py_isnil(&entry->key)) continue;
        mappings[i] = n;
        if(i != n) {
            DictEntry* new_entry = c11__at(DictEntry, &self->entries, n);
            *new_entry = *entry;
        }
        n++;
    }
    self->entries.count = n;
    // update indices
    for(int i = 0; i < self->capacity; i++) {
        for(int j = 0; j < PK_DICT_MAX_COLLISION; j++) {
            int idx = self->indices[i]._[j];
            if(idx == -1) continue;
            self->indices[i]._[j] = mappings[idx];
        }
    }
    free(mappings);
}

static bool Dict__set(Dict* self, py_TValue* key, py_TValue* val) {
    py_i64 hash;
    if(!py_hash(key, &hash)) return false;
    int idx = hash & (self->capacity - 1);
    for(int i = 0; i < PK_DICT_MAX_COLLISION; i++) {
        int idx2 = self->indices[idx]._[i];
        if(idx2 == -1) {
            // insert new entry
            DictEntry* new_entry = c11_vector__emplace(&self->entries);
            new_entry->hash = hash;
            new_entry->key = *key;
            new_entry->val = *val;
            self->indices[idx]._[i] = self->entries.count - 1;
            self->length++;
            return true;
        }
        // update existing entry
        DictEntry* entry = c11__at(DictEntry, &self->entries, idx2);
        int res = py_eq(&entry->key, key);
        if(res == 1) {
            entry->val = *val;
            return true;
        }
        if(res == -1) return false;  // error
    }
    // no empty slot found
    Dict__rehash_2x(self);
    return Dict__set(self, key, val);
}

/// Delete an entry from the dict.
/// If the key is found, `py_retval()` is set to the value.
/// If the key is not found, `py_retval()` is set to `nil`.
/// Returns false on error.
static bool Dict__pop(Dict* self, py_Ref key) {
    py_i64 hash;
    if(!py_hash(key, &hash)) return false;
    int idx = hash & (self->capacity - 1);
    for(int i = 0; i < PK_DICT_MAX_COLLISION; i++) {
        int idx2 = self->indices[idx]._[i];
        if(idx2 == -1) continue;
        DictEntry* entry = c11__at(DictEntry, &self->entries, idx2);
        int res = py_eq(&entry->key, key);
        if(res == 1) {
            *py_retval() = entry->val;
            py_newnil(&entry->key);
            self->indices[idx]._[i] = -1;
            self->length--;
            if(self->length < self->entries.count / 2) Dict__compact_entries(self);
            return true;
        }
        if(res == -1) return false;  // error
    }
    py_newnil(py_retval());
    return true;
}

static void DictIterator__ctor(DictIterator* self, Dict* dict) {
    self->curr = dict->entries.data;
    self->end = self->curr + dict->entries.count;
}

static DictEntry* DictIterator__next(DictIterator* self) {
    DictEntry* retval;
    do {
        if(self->curr == self->end) return NULL;
        retval = self->curr++;
    } while(py_isnil(&retval->key));
    return retval;
}

///////////////////////////////
static bool _py_dict__new__(int argc, py_Ref argv) {
    py_newdict(py_retval());
    return true;
}

static bool _py_dict__init__(int argc, py_Ref argv) {
    if(argc > 2) return TypeError("dict.__init__() takes at most 2 arguments (%d given)", argc);
    if(argc == 1) return true;
    assert(argc == 2);
    PY_CHECK_ARG_TYPE(1, tp_list);
    Dict* self = py_touserdata(argv);
    py_Ref list = py_arg(1);
    for(int i = 0; i < py_list__len(list); i++) {
        py_Ref tuple = py_list__getitem(list, i);
        if(!py_istuple(tuple) || py_tuple__len(tuple) != 2) {
            return TypeError("dict.__init__() argument must be a list of tuple-2");
        }
        py_Ref key = py_tuple__getitem(tuple, 0);
        py_Ref val = py_tuple__getitem(tuple, 1);
        if(!Dict__set(self, key, val)) return false;
    }
    return true;
}

static bool _py_dict__getitem__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(2);
    Dict* self = py_touserdata(argv);
    DictEntry* entry;
    if(!Dict__try_get(self, py_arg(1), &entry)) return false;
    if(entry) {
        *py_retval() = entry->val;
        return true;
    }
    return KeyError(py_arg(1));
}

static bool _py_dict__setitem__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(3);
    Dict* self = py_touserdata(argv);
    return Dict__set(self, py_arg(1), py_arg(2));
}

static bool _py_dict__delitem__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(2);
    Dict* self = py_touserdata(argv);
    if(!Dict__pop(self, py_arg(1))) return false;
    return true;
}

static bool _py_dict__contains__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(2);
    Dict* self = py_touserdata(argv);
    DictEntry* entry;
    if(!Dict__try_get(self, py_arg(1), &entry)) return false;
    py_newbool(py_retval(), entry != NULL);
    return true;
}

static bool _py_dict__len__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    py_newint(py_retval(), self->length);
    return true;
}

static bool _py_dict__repr__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    c11_sbuf buf;
    c11_sbuf__ctor(&buf);
    c11_sbuf__write_char(&buf, '{');
    bool is_first = true;
    for(int i = 0; i < self->entries.count; i++) {
        DictEntry* entry = c11__at(DictEntry, &self->entries, i);
        if(py_isnil(&entry->key)) continue;
        if(!is_first) c11_sbuf__write_cstr(&buf, ", ");
        if(!py_repr(&entry->key)) return false;
        c11_sbuf__write_sv(&buf, py_tosv(py_retval()));
        c11_sbuf__write_cstr(&buf, ": ");
        if(!py_repr(&entry->val)) return false;
        c11_sbuf__write_sv(&buf, py_tosv(py_retval()));
        is_first = false;
    }
    c11_sbuf__write_char(&buf, '}');
    c11_string* res = c11_sbuf__submit(&buf);
    py_newstrn(py_retval(), res->data, res->size);
    c11_string__delete(res);
    return true;
}

static bool _py_dict__eq__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(2);
    Dict* self = py_touserdata(py_arg(0));
    if(!py_isdict(py_arg(1))) {
        py_newnotimplemented(py_retval());
        return true;
    }
    Dict* other = py_touserdata(py_arg(1));
    if(self->length != other->length) {
        py_newbool(py_retval(), false);
        return true;
    }
    DictIterator iter;
    DictIterator__ctor(&iter, self);
    // for each self key
    while(1) {
        DictEntry* entry = DictIterator__next(&iter);
        if(!entry) break;
        DictEntry* other_entry;
        if(!Dict__try_get(other, &entry->key, &other_entry)) return false;
        if(!other_entry) {
            py_newbool(py_retval(), false);
            return true;
        }
        int res = py_eq(&entry->val, &other_entry->val);
        if(res == -1) return false;
        if(!res) {
            py_newbool(py_retval(), false);
            return true;
        }
    }
    return true;
}

static bool _py_dict__ne__(int argc, py_Ref argv) {
    if(!_py_dict__eq__(argc, argv)) return false;
    if(py_isbool(py_retval())) {
        bool res = py_tobool(py_retval());
        py_newbool(py_retval(), !res);
    }
    return true;
}

static bool _py_dict__clear(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    Dict__clear(self);
    return true;
}

static bool _py_dict__copy(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    Dict* new_dict = py_newobject(py_retval(), tp_dict, 0, sizeof(Dict));
    new_dict->capacity = self->capacity;
    new_dict->length = self->length;
    new_dict->entries = c11_vector__copy(&self->entries);
    // copy indices
    new_dict->indices = malloc(new_dict->capacity * sizeof(DictIndex));
    memcpy(new_dict->indices, self->indices, new_dict->capacity * sizeof(DictIndex));
    return true;
}

static bool _py_dict__update(int argc, py_Ref argv) {
    PY_CHECK_ARGC(2);
    PY_CHECK_ARG_TYPE(1, tp_dict);
    Dict* self = py_touserdata(argv);
    Dict* other = py_touserdata(py_arg(1));
    for(int i = 0; i < other->entries.count; i++) {
        DictEntry* entry = c11__at(DictEntry, &other->entries, i);
        if(py_isnil(&entry->key)) continue;
        if(!Dict__set(self, &entry->key, &entry->val)) return false;
    }
    return true;
}

static bool _py_dict__get(int argc, py_Ref argv) {
    Dict* self = py_touserdata(argv);
    if(argc > 3) return TypeError("get() takes at most 3 arguments (%d given)", argc);
    py_Ref default_val = argc == 3 ? py_arg(2) : py_None;
    DictEntry* entry;
    if(!Dict__try_get(self, py_arg(1), &entry)) return false;
    *py_retval() = entry ? entry->val : *default_val;
    return true;
}

static bool _py_dict__pop(int argc, py_Ref argv) {
    Dict* self = py_touserdata(argv);
    if(argc < 2 || argc > 3) return TypeError("pop() takes 2 or 3 arguments (%d given)", argc);
    py_Ref default_val = argc == 3 ? py_arg(2) : py_None;
    if(!Dict__pop(self, py_arg(1))) return false;
    if(py_isnil(py_retval())) *py_retval() = *default_val;
    return true;
}

static bool _py_dict__items(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    DictIterator* ud = py_newobject(py_retval(), tp_dict_items, 1, sizeof(DictIterator));
    DictIterator__ctor(ud, self);
    py_setslot(py_retval(), 0, argv);  // keep a reference to the dict
    return true;
}

static bool _py_dict__keys(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    py_newtuple(py_retval(), self->length);
    DictIterator iter;
    DictIterator__ctor(&iter, self);
    int i = 0;
    while(1) {
        DictEntry* entry = DictIterator__next(&iter);
        if(!entry) break;
        py_tuple__setitem(py_retval(), i++, &entry->key);
    }
    assert(i == self->length);
    return true;
}

static bool _py_dict__values(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    Dict* self = py_touserdata(argv);
    py_newtuple(py_retval(), self->length);
    DictIterator iter;
    DictIterator__ctor(&iter, self);
    int i = 0;
    while(1) {
        DictEntry* entry = DictIterator__next(&iter);
        if(!entry) break;
        py_tuple__setitem(py_retval(), i++, &entry->val);
    }
    assert(i == self->length);
    return true;
}

py_Type pk_dict__register() {
    py_Type type = pk_newtype("dict", tp_object, NULL, (void (*)(void*))Dict__dtor, false, false);

    py_bindmagic(type, __new__, _py_dict__new__);
    py_bindmagic(type, __init__, _py_dict__init__);
    py_bindmagic(type, __getitem__, _py_dict__getitem__);
    py_bindmagic(type, __setitem__, _py_dict__setitem__);
    py_bindmagic(type, __delitem__, _py_dict__delitem__);
    py_bindmagic(type, __contains__, _py_dict__contains__);
    py_bindmagic(type, __len__, _py_dict__len__);
    py_bindmagic(type, __repr__, _py_dict__repr__);
    py_bindmagic(type, __eq__, _py_dict__eq__);
    py_bindmagic(type, __ne__, _py_dict__ne__);

    py_bindmethod(type, "clear", _py_dict__clear);
    py_bindmethod(type, "copy", _py_dict__copy);
    py_bindmethod(type, "update", _py_dict__update);
    py_bindmethod(type, "get", _py_dict__get);
    py_bindmethod(type, "pop", _py_dict__pop);
    py_bindmethod(type, "items", _py_dict__items);
    py_bindmethod(type, "keys", _py_dict__keys);
    py_bindmethod(type, "values", _py_dict__values);

    py_setdict(py_tpobject(type), __hash__, py_None);
    return type;
}

//////////////////////////
static bool _py_dict_items__iter__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    *py_retval() = *argv;
    return true;
}

static bool _py_dict_items__next__(int argc, py_Ref argv) {
    PY_CHECK_ARGC(1);
    DictIterator* iter = py_touserdata(py_arg(0));
    DictEntry* entry = (DictIterator__next(iter));
    if(entry) {
        py_newtuple(py_retval(), 2);
        py_tuple__setitem(py_retval(), 0, &entry->key);
        py_tuple__setitem(py_retval(), 1, &entry->val);
        return true;
    }
    return StopIteration();
}

py_Type pk_dict_items__register() {
    py_Type type = pk_newtype("dict_items", tp_object, NULL, NULL, false, true);
    py_bindmagic(type, __iter__, _py_dict_items__iter__);
    py_bindmagic(type, __next__, _py_dict_items__next__);
    return type;
}

//////////////////////////

void py_newdict(py_Ref out) {
    Dict* ud = py_newobject(out, tp_dict, 0, sizeof(Dict));
    Dict__ctor(ud, 8);
}

py_Ref py_dict__getitem(const py_Ref self, const py_Ref key) {
    assert(py_isdict(self));
    Dict* ud = py_touserdata(self);
    DictEntry* entry;
    if(!Dict__try_get(ud, key, &entry)) return NULL;
    if(entry) return &entry->val;
    return NULL;
}

void py_dict__setitem(py_Ref self, const py_Ref key, const py_Ref val) {
    assert(py_isdict(self));
    Dict* ud = py_touserdata(self);
    Dict__set(ud, key, val);
}

bool py_dict__contains(const py_Ref self, const py_Ref key) {
    assert(py_isdict(self));
    Dict* ud = py_touserdata(self);
    DictEntry* entry;
    bool ok = Dict__try_get(ud, key, &entry);
    return ok && entry != NULL;
}

int py_dict__len(const py_Ref self) {
    assert(py_isdict(self));
    Dict* ud = py_touserdata(self);
    return ud->length;
}

bool py_dict__apply(const py_Ref self, bool (*f)(const py_Ref, const py_Ref, void *), void *ctx){
    Dict* ud = py_touserdata(self);
    for(int i = 0; i < ud->entries.count; i++) {
        DictEntry* entry = c11__at(DictEntry, &ud->entries, i);
        if(py_isnil(&entry->key)) continue;
        if(!f(&entry->key, &entry->val, ctx)) return false;
    }
    return true;
}

void pk_dict__mark(void* ud, void (*marker)(py_TValue*)) {
    Dict* self = ud;
    for(int i = 0; i < self->entries.count; i++) {
        DictEntry* entry = c11__at(DictEntry, &self->entries, i);
        if(py_isnil(&entry->key)) continue;
        marker(&entry->key);
        marker(&entry->val);
    }
}