// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <zircon/assert.h>

#include <algorithm>
#include <limits>
#include <memory>
#include <utility>

#include <wlan/mlme/packet.h>

namespace wlan {

Packet::Packet(std::unique_ptr<Buffer> buffer, size_t len) : buffer_(std::move(buffer)), len_(len) {
  ZX_ASSERT(buffer_.get());
  ZX_DEBUG_ASSERT(len <= buffer_->capacity());
}

zx_status_t Packet::CopyFrom(const void* src, size_t len, size_t offset) {
  if (offset + len > buffer_->capacity()) {
    return ZX_ERR_BUFFER_TOO_SMALL;
  }
  std::memcpy(buffer_->data() + offset, src, len);
  len_ = std::max(len_, offset + len);
  return ZX_OK;
}

wlan_tx_packet_t Packet::AsWlanTxPacket() {
  ZX_DEBUG_ASSERT(len() <= std::numeric_limits<uint16_t>::max());
  wlan_tx_packet_t tx_pkt = {};
  tx_pkt.packet_head.data_buffer = data();
  tx_pkt.packet_head.data_size = static_cast<uint16_t>(len());
  if (has_ext_data()) {
    tx_pkt.packet_tail_list = ext_data()->operation();
    tx_pkt.tail_offset = ext_offset();
  }
  if (has_ctrl_data<wlan_tx_info_t>()) {
    std::memcpy(&tx_pkt.info, ctrl_data<wlan_tx_info_t>(), sizeof(tx_pkt.info));
  }
  return tx_pkt;
}

bool IsBodyAligned(const Packet& pkt) {
  auto rx = pkt.ctrl_data<wlan_rx_info_t>();
  return rx != nullptr && rx->rx_flags & WLAN_RX_INFO_FLAGS_FRAME_BODY_PADDING_4;
}

mlme_in_buf_t IntoRustInBuf(std::unique_ptr<Packet> packet) {
  auto* pkt = packet.release();
  return mlme_in_buf_t{
      .free_buffer = [](void* raw) { std::unique_ptr<Packet>(static_cast<Packet*>(raw)).reset(); },
      .raw = pkt,
      .data = pkt->data(),
      .len = pkt->len(),
  };
}

std::unique_ptr<Packet> FromRustOutBuf(mlme_out_buf_t buf) {
  if (!buf.raw) {
    return {};
  }
  auto pkt = std::unique_ptr<Packet>(static_cast<Packet*>(buf.raw));
  pkt->set_len(buf.written_bytes);
  return pkt;
}

void LogAllocationFail(Buffer::Size size) {
  BufferDebugger<SmallBufferAllocator, LargeBufferAllocator, HugeBufferAllocator,
                 kBufferDebugEnabled>::Fail(size);
}

std::unique_ptr<Buffer> GetBuffer(size_t len) {
  std::unique_ptr<Buffer> buffer;

  if (len <= kSmallBufferSize) {
    buffer = SmallBufferAllocator::New();
    if (buffer != nullptr) {
      return buffer;
    } else {
      LogAllocationFail(Buffer::Size::kSmall);
    }
  }

  if (len <= kLargeBufferSize) {
    buffer = LargeBufferAllocator::New();
    if (buffer != nullptr) {
      return buffer;
    } else {
      LogAllocationFail(Buffer::Size::kLarge);
    }
  }

  if (len <= kHugeBufferSize) {
    buffer = HugeBufferAllocator::New();
    if (buffer != nullptr) {
      return buffer;
    } else {
      LogAllocationFail(Buffer::Size::kHuge);
    }
  }

  return nullptr;
}

std::unique_ptr<Packet> GetPacket(size_t len, Packet::Peer peer) {
  auto buffer = GetBuffer(len);
  if (buffer == nullptr) {
    return nullptr;
  }
  auto packet = std::make_unique<Packet>(std::move(buffer), len);
  packet->set_peer(peer);
  return packet;
}

std::unique_ptr<Packet> GetEthPacket(size_t len) { return GetPacket(len, Packet::Peer::kEthernet); }

std::unique_ptr<Packet> GetWlanPacket(size_t len) { return GetPacket(len, Packet::Peer::kWlan); }

std::unique_ptr<Packet> GetSvcPacket(size_t len) { return GetPacket(len, Packet::Peer::kService); }

mlme_buffer_provider_ops_t rust_buffer_provider{
    .get_buffer = [](size_t min_len) -> mlme_in_buf_t {
      // Note: Once Rust MLME supports more than sending WLAN frames this needs
      // to change.
      auto pkt = GetWlanPacket(min_len);
      ZX_DEBUG_ASSERT(pkt != nullptr);
      return IntoRustInBuf(std::move(pkt));
    },
};

}  // namespace wlan

// Definition of static slab allocators.
// TODO(tkilbourn): tune how many slabs we are willing to grow up to. Reasonably
// large limits chosen for now.
DECLARE_STATIC_SLAB_ALLOCATOR_STORAGE(::wlan::HugeBufferTraits, ::wlan::kHugeSlabs, true);
DECLARE_STATIC_SLAB_ALLOCATOR_STORAGE(::wlan::LargeBufferTraits, ::wlan::kLargeSlabs, true);
DECLARE_STATIC_SLAB_ALLOCATOR_STORAGE(::wlan::SmallBufferTraits, ::wlan::kSmallSlabs, true);