/*
 * Copyright (C) 2016-2022 Apple Inc. All rights reserved.
 * Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "ExceptionHelpers.h"
#include "HashMapHelper.h"
#include "JSObject.h"
#include <wtf/MallocPtr.h>

WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN

namespace JSC {

enum class HashTableType {
    Key,
    KeyValue
};

struct WeakMapBucketDataKey {
    static const HashTableType Type = HashTableType::Key;
    WriteBarrier<JSCell> key;
};
static_assert(sizeof(WeakMapBucketDataKey) == sizeof(void*));

struct WeakMapBucketDataKeyValue {
    static const HashTableType Type = HashTableType::KeyValue;
    WriteBarrier<JSCell> key;
#if USE(JSVALUE32_64)
    uint32_t padding;
#endif
    WriteBarrier<Unknown> value;
};
static_assert(sizeof(WeakMapBucketDataKeyValue) == 16);

ALWAYS_INLINE uint32_t jsWeakMapHash(JSCell* key);
ALWAYS_INLINE uint32_t nextCapacityAfterBatchRemoval(uint32_t capacity, uint32_t keyCount);

template <typename Data>
class WeakMapBucket {
public:
    ALWAYS_INLINE void setKey(VM& vm, JSCell* owner, JSCell* key)
    {
        m_data.key.set(vm, owner, key);
    }

    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type setValue(VM& vm, JSCell* owner, JSValue value)
    {
        m_data.value.set(vm, owner, value);
    }
    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type setValue(VM&, JSCell*, JSValue) { }

    ALWAYS_INLINE JSCell* key() const { return m_data.key.get(); }

    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, JSValue>::type value() const
    {
        return m_data.value.get();
    }
    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value, JSValue>::type value() const { return JSValue(); }

    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type copyFrom(const WeakMapBucket& from)
    {
        m_data.key.copyFrom(from.m_data.key);
        m_data.value.setWithoutWriteBarrier(from.m_data.value.get());
    }
    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type copyFrom(const WeakMapBucket& from)
    {
        m_data.key.copyFrom(from.m_data.key);
    }

    static constexpr ptrdiff_t offsetOfKey()
    {
        return OBJECT_OFFSETOF(WeakMapBucket, m_data) + OBJECT_OFFSETOF(Data, key);
    }

    template <typename T = Data>
    static typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, ptrdiff_t>::type offsetOfValue()
    {
        return OBJECT_OFFSETOF(WeakMapBucket, m_data) + OBJECT_OFFSETOF(Data, value);
    }

    template <typename T = Data>
    ALWAYS_INLINE static typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value, JSValue>::type extractValue(const WeakMapBucket& bucket)
    {
        return bucket.value();
    }

    template <typename T = Data>
    ALWAYS_INLINE static typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value, JSValue>::type extractValue(const WeakMapBucket&)
    {
        return JSValue();
    }

    bool isEmpty()
    {
        return !m_data.key.unvalidatedGet();
    }

    static JSCell* deletedKey()
    {
        return std::bit_cast<JSCell*>(static_cast<uintptr_t>(-3));
    }

    bool isDeleted()
    {
        return m_data.key.unvalidatedGet() == deletedKey();
    }

    void makeDeleted()
    {
        m_data.key.setWithoutWriteBarrier(deletedKey());
        clearValue();
    }

    template <typename T = Data, typename Visitor>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type visitAggregate(Visitor& visitor)
    {
        visitor.append(m_data.value);
    }

private:
    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKeyValue>::value>::type clearValue()
    {
        m_data.value.clear();
    }
    template <typename T = Data>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucketDataKey>::value>::type clearValue() { }

    Data m_data;
};

template <typename BucketType>
class WeakMapBuffer {
public:
    WeakMapBuffer() = delete;

    static size_t allocationSize(Checked<size_t> capacity)
    {
        return capacity * sizeof(BucketType);
    }

    ALWAYS_INLINE BucketType* buffer() const
    {
        return std::bit_cast<BucketType*>(this);
    }

    static MallocPtr<WeakMapBuffer> create(uint32_t capacity)
    {
        size_t allocationSize = WeakMapBuffer::allocationSize(capacity);
        auto buffer = MallocPtr<WeakMapBuffer>::malloc(allocationSize);
        buffer->reset(capacity);
        return buffer;
    }

    ALWAYS_INLINE void reset(uint32_t capacity)
    {
        memset(this, 0, allocationSize(capacity));
    }
};

template <typename WeakMapBucketType>
class WeakMapImpl : public JSNonFinalObject {
    using Base = JSNonFinalObject;
    using WeakMapBufferType = WeakMapBuffer<WeakMapBucketType>;

public:
    using BucketType = WeakMapBucketType;

    static constexpr DestructionMode needsDestruction = NeedsDestruction;
    static void destroy(JSCell*);

    DECLARE_VISIT_CHILDREN;

    static size_t estimatedSize(JSCell*, VM&);

    static constexpr uint32_t initialCapacity = 4;

    WeakMapImpl(VM& vm, Structure* structure)
        : Base(vm, structure)
    {
        ASSERT_WITH_MESSAGE(WeakMapBucket<WeakMapBucketDataKey>::offsetOfKey() == WeakMapBucket<WeakMapBucketDataKeyValue>::offsetOfKey(), "We assume this to be true in the DFG and FTL JIT.");
        makeAndSetNewBuffer(initialCapacity);
    }

    // WeakMap operations must not cause GC. We model operations in DFG based on this guarantee.
    // This guarantee is ensured by AssertNoGC.

    template <typename T = WeakMapBucketType>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucket<WeakMapBucketDataKeyValue>>::value, JSValue>::type get(JSCell* key)
    {
        AssertNoGC assertNoGC;
        if (WeakMapBucketType* bucket = findBucket(key))
            return bucket->value();
        return jsUndefined();
    }

    template <typename T = WeakMapBucketType>
    ALWAYS_INLINE typename std::enable_if<std::is_same<T, WeakMapBucket<WeakMapBucketDataKeyValue>>::value, JSValue>::type getBucket(JSCell* key, uint32_t hash, size_t index)
    {
        UNUSED_PARAM(key);
        UNUSED_PARAM(hash);
        ASSERT(jsWeakMapHash(key) == hash);

        WeakMapBucketType* bucket = buffer() + index;
        ASSERT(bucket);
        ASSERT(findBucket(key, hash) == bucket);

        return bucket->value();
    }

    ALWAYS_INLINE std::pair<size_t, bool> findBucketIndex(JSCell* key, uint32_t hash)
    {
        return findBucketIndexAlreadyHashed(key, hash);
    }

    ALWAYS_INLINE WeakMapBucketType* findBucket(JSCell* key, uint32_t hash)
    {
        if (auto [index, exists] = findBucketIndexAlreadyHashed(key, hash); exists)
            return buffer() + index;
        return nullptr;
    }

    ALWAYS_INLINE bool has(JSCell* key)
    {
        AssertNoGC assertNoGC;
        return !!findBucket(key);
    }

    ALWAYS_INLINE void add(VM&, JSCell* key, JSValue = JSValue());
    ALWAYS_INLINE void add(VM&, JSCell* key, JSValue, uint32_t hash);
    ALWAYS_INLINE void addBucket(VM&, JSCell* key, JSValue, uint32_t hash, size_t index);

    ALWAYS_INLINE bool remove(JSCell* key)
    {
        AssertNoGC assertNoGC;
        WeakMapBucketType* bucket = findBucket(key);
        if (!bucket)
            return false;

        bucket->makeDeleted();

        ++m_deleteCount;
        RELEASE_ASSERT(m_keyCount > 0);
        --m_keyCount;

        if (shouldShrink())
            rehash();

        return true;
    }

    ALWAYS_INLINE uint32_t size() const
    {
        return m_keyCount;
    }

    void takeSnapshot(MarkedArgumentBuffer&, unsigned limit = 0);

    static constexpr ptrdiff_t offsetOfBuffer()
    {
        return OBJECT_OFFSETOF(WeakMapImpl<WeakMapBucketType>, m_buffer);
    }

    static constexpr ptrdiff_t offsetOfCapacity()
    {
        return OBJECT_OFFSETOF(WeakMapImpl<WeakMapBucketType>, m_capacity);
    }

    static constexpr bool isWeakMap()
    {
        return std::is_same<WeakMapBucketType, JSC::WeakMapBucket<WeakMapBucketDataKeyValue>>::value;
    }

    static constexpr bool isWeakSet()
    {
        return std::is_same<WeakMapBucketType, JSC::WeakMapBucket<WeakMapBucketDataKey>>::value;
    }

    template<typename CellType, SubspaceAccess mode>
    static GCClient::IsoSubspace* subspaceFor(VM& vm)
    {
        if constexpr (isWeakMap())
            return vm.weakMapSpace<mode>();
        return vm.weakSetSpace<mode>();
    }

    template<typename Visitor> static void visitOutputConstraints(JSCell*, Visitor&);
    void finalizeUnconditionally(VM&, CollectionScope);

private:
    template<typename Visitor>
    ALWAYS_INLINE static void visitOutputConstraintsForDataKeyValue(JSCell*, Visitor&);

    ALWAYS_INLINE WeakMapBucketType* findBucket(JSCell* key)
    {
        return findBucket(key, jsWeakMapHash(key));
    }

    ALWAYS_INLINE WeakMapBucketType* buffer() const
    {
        return m_buffer->buffer();
    }

    enum class IterationState { Continue, Stop };
    template<typename Functor>
    void forEach(Functor functor)
    {
        auto* buffer = this->buffer();
        for (uint32_t index = 0; index < m_capacity; ++index) {
            auto* bucket = buffer + index;
            if (bucket->isEmpty() || bucket->isDeleted())
                continue;
            if (functor(bucket->key(), bucket->value()) == IterationState::Stop)
                return;
        }
    }

    ALWAYS_INLINE uint32_t shouldRehashAfterAdd() const;

    ALWAYS_INLINE uint32_t shouldShrink() const
    {
        return JSC::shouldShrink(m_capacity, m_keyCount);
    }

    ALWAYS_INLINE static bool canUseBucket(WeakMapBucketType* bucket, JSCell* key)
    {
        return !bucket->isDeleted() && key == bucket->key();
    }

    ALWAYS_INLINE void addInternal(VM& vm, JSCell* key, JSValue value, uint32_t hash)
    {
        const uint32_t mask = m_capacity - 1;
        uint32_t index = hash & mask;
        WeakMapBucketType* buffer = this->buffer();
        WeakMapBucketType* bucket = buffer + index;
        while (!bucket->isEmpty()) {
            if (canUseBucket(bucket, key)) {
                ASSERT(!bucket->isDeleted());
                bucket->setValue(vm, this, value);
                return;
            }
            index = (index + 1) & mask;
            bucket = buffer + index;
        }

        auto* newEntry = buffer + index;
        newEntry->setKey(vm, this, key);
        newEntry->setValue(vm, this, value);
        ++m_keyCount;
    }

    ALWAYS_INLINE std::pair<size_t, bool> findBucketIndexAlreadyHashed(JSCell* key, uint32_t hash)
    {
        const uint32_t mask = m_capacity - 1;
        uint32_t index = hash & mask;
        WeakMapBucketType* buffer = this->buffer();
        WeakMapBucketType* bucket = buffer + index;

        while (!bucket->isEmpty()) {
            if (canUseBucket(bucket, key)) {
                ASSERT(!bucket->isDeleted());
                return { index, true };
            }
            index = (index + 1) & mask;
            bucket = buffer + index;
        }
        return { index, false };
    }

    enum class RehashMode { Normal, RemoveBatching };
    void rehash(RehashMode = RehashMode::Normal);

    ALWAYS_INLINE void checkConsistency() const
    {
        if (ASSERT_ENABLED) {
            uint32_t size = 0;
            auto* buffer = this->buffer();
            for (uint32_t index = 0; index < m_capacity; ++index) {
                auto* bucket = buffer + index;
                if (bucket->isEmpty() || bucket->isDeleted())
                    continue;
                ++size;
            }
            ASSERT_UNUSED(size, size == m_keyCount);
        }
    }

    void makeAndSetNewBuffer(uint32_t capacity)
    {
        ASSERT(!(capacity & (capacity - 1)));

        m_buffer = WeakMapBufferType::create(capacity);
        m_capacity = capacity;
        ASSERT(m_buffer);
        assertBufferIsEmpty();
    }

    ALWAYS_INLINE void assertBufferIsEmpty() const
    {
        if (ASSERT_ENABLED) {
            for (unsigned i = 0; i < m_capacity; i++)
                ASSERT((buffer() + i)->isEmpty());
        }
    }

    template<typename Appender>
    void takeSnapshotInternal(unsigned limit, Appender);

    MallocPtr<WeakMapBufferType> m_buffer;
    uint32_t m_capacity { 0 };
    uint32_t m_keyCount { 0 };
    uint32_t m_deleteCount { 0 };
};

} // namespace JSC

WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
