// SPDX-License-Identifier: Apache-2.0

// SPDX-FileCopyrightText: Copyright The WasmEdge Authors

//===-- wasmedge/runtime/instance/table.h - Table Instance definition -----===//

//

// Part of the WasmEdge Project.

//

//===----------------------------------------------------------------------===//

///

/// \file

/// This file contains the table instance definition in store manager.

///

//===----------------------------------------------------------------------===//

#pragma once

#include "ast/segment.h"

#include "ast/type.h"

#include "common/errcode.h"

#include "common/errinfo.h"

#include "common/spdlog.h"

#include <algorithm>

#include <cstdint>

#include <vector>

namespace WasmEdge {

namespace Runtime {

namespace Instance {

class TableInstance {

public:

  TableInstance() = delete;

  TableInstance(const AST::TableType &TType) noexcept

      : TabType(TType),

        Refs(TType.getLimit().getMin(), RefVariant(TType.getRefType())),

        InitValue(RefVariant(TType.getRefType())) {

    // The reference type should be nullable because there is no initial ref.

    // This constructor only handles abstract heap types correctly for null

    // refs. For concrete type indices, the caller should use the two-arg

    // constructor with a properly initialized RefVariant.

    assuming(TType.getRefType().isNullableRefType());

    assuming(TType.getRefType().isAbsHeapType());

  }

  TableInstance(const AST::TableType &TType, const RefVariant &InitVal) noexcept

      : TabType(TType), Refs(TType.getLimit().getMin(), InitVal),

        InitValue(InitVal) {

    // If the reference type is not nullable, the initial reference is required.

    assuming(TType.getRefType().isNullableRefType() || !InitVal.isNull());

  }

  /// Get size of table.refs

  uint64_t getSize() const noexcept {

    // The table size is bound to the limit in the table type.

    return TabType.getLimit().getMin();

  }

  /// Getter for table type.

  const AST::TableType &getTableType() const noexcept { return TabType; }

  /// Check whether access is out of bounds.

  bool checkAccessBound(const uint64_t Offset,

                        const uint64_t Length) const noexcept {

    // Due to applying the Memory64 proposal, we should avoid the overflow issue

    // of the following code:

    //   return Offset + Length <= Limit;

    const uint64_t Limit = TabType.getLimit().getMin();

    return std::numeric_limits<uint64_t>::max() - Offset >= Length &&

           Offset + Length <= Limit;

  }

  /// Grow table with initialization value.

  bool growTable(const uint64_t Count, const RefVariant &Val) noexcept {

    if (Count == 0) {

      return true;

    }

    uint64_t MaxSizeCaped = getMaxAddress(TabType.getLimit().getAddrType());

    const uint64_t Min = TabType.getLimit().getMin();

    assuming(MaxSizeCaped >= Min);

    if (TabType.getLimit().hasMax()) {

      const uint64_t Max = TabType.getLimit().getMax();

      MaxSizeCaped = std::min(Max, MaxSizeCaped);

    }

    if (Count > MaxSizeCaped - Min) {

      return false;

    }

    Refs.resize(Refs.size() + Count);

    std::fill_n(Refs.end() - static_cast<std::ptrdiff_t>(Count), Count, Val);

    TabType.getLimit().setMin(Min + Count);

    return true;

  }

  bool growTable(const uint64_t Count) noexcept {

    return growTable(Count, InitValue);

  }

  /// Get slice of Refs[Offset : Offset + Length - 1]

  Expect<Span<const RefVariant>> getRefs(const uint64_t Offset,

                                         const uint64_t Length) const noexcept {

    // Check the accessing boundary.

    if (!checkAccessBound(Offset, Length)) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Offset, Length, getSize()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    return Span<const RefVariant>(

        Refs.begin() + static_cast<std::ptrdiff_t>(Offset), Length);

  }

  /// Replace the Refs[Dst :] by Slice[Src : Src + Length)

  Expect<void> setRefs(Span<const RefVariant> Slice, const uint64_t Dst,

                       const uint64_t Src, const uint64_t Length) noexcept {

    // Check the accessing boundary.

    if (!checkAccessBound(Dst, Length)) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Dst, Length, getSize()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    // Check the input data validation.

    if (std::numeric_limits<uint64_t>::max() - Src < Length ||

        Src + Length > Slice.size()) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Src, Length, Slice.size()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    // Copy the references.

    if (Dst <= Src) {

      std::copy(Slice.begin() + Src, Slice.begin() + Src + Length,

                Refs.begin() + static_cast<std::ptrdiff_t>(Dst));

    } else {

      std::copy(std::make_reverse_iterator(Slice.begin() + Src + Length),

                std::make_reverse_iterator(Slice.begin() + Src),

                std::make_reverse_iterator(

                    Refs.begin() + static_cast<std::ptrdiff_t>(Dst + Length)));

    }

    return {};

  }

  /// Fill the Refs[Offset : Offset + Length - 1] by Val.

  Expect<void> fillRefs(const RefVariant &Val, const uint64_t Offset,

                        const uint64_t Length) noexcept {

    // Check the accessing boundary.

    if (!checkAccessBound(Offset, Length)) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Offset, Length, getSize()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    // Fill the references.

    std::fill_n(Refs.begin() + static_cast<std::ptrdiff_t>(Offset), Length,

                Val);

    return {};

  }

  /// Get the elem address.

  Expect<RefVariant> getRefAddr(const uint64_t Idx) const noexcept {

    if (Idx >= Refs.size()) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Idx, 1, getSize()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    return Refs[Idx];

  }

  /// Set the elem address.

  Expect<void> setRefAddr(const uint64_t Idx, const RefVariant &Val) {

    if (Idx >= Refs.size()) {

      spdlog::error(ErrCode::Value::TableOutOfBounds);

      spdlog::error(ErrInfo::InfoBoundary(Idx, 1, getSize()));

      return Unexpect(ErrCode::Value::TableOutOfBounds);

    }

    Refs[Idx] = Val;

    return {};

  }

private:

  /// \name Data of table instance.

  /// @{

  AST::TableType TabType;

  std::vector<RefVariant> Refs;

  RefVariant InitValue;

  /// @}

};

} // namespace Instance

} // namespace Runtime

} // namespace WasmEdge