// Copyright 2021 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#include "pw_router/static_router.h"

#include "gtest/gtest.h"
#include "pw_assert/check.h"
#include "pw_router/egress_function.h"

namespace pw::router {
namespace {

struct BasicPacket {
  static constexpr uint32_t kMagic = 0x8badf00d;

  constexpr BasicPacket(uint32_t addr, uint64_t data)
      : magic(kMagic), address(addr), priority(0), payload(data) {}

  constexpr BasicPacket(uint32_t addr, uint32_t prio, uint64_t data)
      : magic(kMagic), address(addr), priority(prio), payload(data) {}

  ConstByteSpan data() const { return std::as_bytes(std::span(this, 1)); }

  uint32_t magic;
  uint32_t address;
  uint32_t priority;
  uint64_t payload;
};

class BasicPacketParser : public PacketParser {
 public:
  constexpr BasicPacketParser() : packet_(nullptr) {}

  bool Parse(pw::ConstByteSpan packet) final {
    packet_ = reinterpret_cast<const BasicPacket*>(packet.data());
    return packet_->magic == BasicPacket::kMagic;
  }

  std::optional<uint32_t> GetDestinationAddress() const final {
    PW_DCHECK_NOTNULL(packet_);
    return packet_->address;
  }

  std::optional<uint32_t> GetPriority() const final {
    PW_DCHECK_NOTNULL(packet_);
    return packet_->priority;
  };

 private:
  const BasicPacket* packet_;
};

EgressFunction GoodEgress(+[](ConstByteSpan, const PacketMetadata&) {
  return OkStatus();
});
EgressFunction BadEgress(+[](ConstByteSpan, const PacketMetadata&) {
  return Status::ResourceExhausted();
});

TEST(StaticRouter, RoutePacket_RoutesToAnEgress) {
  BasicPacketParser parser;
  constexpr StaticRouter::Route routes[] = {{1, GoodEgress}, {2, BadEgress}};
  StaticRouter router(parser, std::span(routes));

  EXPECT_EQ(router.RoutePacket(BasicPacket(1, 0xdddd).data()), OkStatus());
  EXPECT_EQ(router.RoutePacket(BasicPacket(2, 0xdddd).data()),
            Status::Unavailable());
}

TEST(StaticRouter, RoutePacket_ForwardsPacketMetadata) {
  PacketMetadata metadata = {};
  EgressFunction metadata_egress(
      [&metadata](ConstByteSpan, const PacketMetadata& md) {
        metadata = md;
        return OkStatus();
      });

  BasicPacketParser parser;
  StaticRouter::Route routes[] = {{1, metadata_egress}};
  StaticRouter router(parser, std::span(routes));

  EXPECT_EQ(router.RoutePacket(BasicPacket(1, 71, 0xdddd).data()), OkStatus());
  ASSERT_TRUE(metadata.priority.has_value());
  EXPECT_EQ(metadata.priority.value(), 71u);
}

TEST(StaticRouter, RoutePacket_ReturnsParserError) {
  BasicPacketParser parser;
  constexpr StaticRouter::Route routes[] = {{1, GoodEgress}, {2, BadEgress}};
  StaticRouter router(parser, std::span(routes));

  BasicPacket bad_magic(1, 0xdddd);
  bad_magic.magic = 0x1badda7a;
  EXPECT_EQ(router.RoutePacket(bad_magic.data()), Status::DataLoss());
}

TEST(StaticRouter, RoutePacket_ReturnsNotFoundOnInvalidRoute) {
  BasicPacketParser parser;
  constexpr StaticRouter::Route routes[] = {{1, GoodEgress}, {2, BadEgress}};
  StaticRouter router(parser, std::span(routes));

  EXPECT_EQ(router.RoutePacket(BasicPacket(42, 0xdddd).data()),
            Status::NotFound());
}

TEST(StaticRouter, RoutePacket_TracksNumberOfDrops) {
  BasicPacketParser parser;
  constexpr StaticRouter::Route routes[] = {{1, GoodEgress}, {2, BadEgress}};
  StaticRouter router(parser, std::span(routes));

  // Good
  EXPECT_EQ(router.RoutePacket(BasicPacket(1, 0xdddd).data()), OkStatus());

  // Egress error
  EXPECT_EQ(router.RoutePacket(BasicPacket(2, 0xdddd).data()),
            Status::Unavailable());

  // Parser error
  BasicPacket bad_magic(1, 0xdddd);
  bad_magic.magic = 0x1badda7a;
  EXPECT_EQ(router.RoutePacket(bad_magic.data()), Status::DataLoss());

  // Good
  EXPECT_EQ(router.RoutePacket(BasicPacket(1, 0xdddd).data()), OkStatus());

  // Bad route
  EXPECT_EQ(router.RoutePacket(BasicPacket(42, 0xdddd).data()),
            Status::NotFound());

  EXPECT_EQ(router.dropped_packets(), 3u);
}

}  // namespace
}  // namespace pw::router