/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com

Copyright(c) 2021 John Wellbelove

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
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to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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******************************************************************************/

#include "unit_test_framework.h"

#include <chrono>
#include <iostream>
#include <random>
#include <thread>
#include <vector>

#include "etl/bip_buffer_spsc_atomic.h"

#include "data.h"

#if ETL_HAS_ATOMIC

  #if defined(ETL_TARGET_OS_WINDOWS)
    #include <Windows.h>
  #endif

  #define REALTIME_TEST 0

namespace
{
  SUITE(test_bip_buffer_spsc_atomic)
  {
    //*************************************************************************
    TEST(test_constructor)
    {
      etl::bip_buffer_spsc_atomic<int, 5> stream;

      CHECK_EQUAL(5U, stream.max_size());
      CHECK_EQUAL(5U, stream.capacity());
    }

    //*************************************************************************
    TEST(test_size_write_read)
    {
      etl::bip_buffer_spsc_atomic<int, 5> stream;
      etl::ibip_buffer_spsc_atomic<int>&  istream = stream;

      // Verify empty buffer
      CHECK_EQUAL(0U, stream.size());
      CHECK(stream.empty());
      CHECK((stream.max_size() / 2U) <= stream.available());
      CHECK(stream.available() <= stream.max_size());

      auto reader = istream.read_reserve(1U);
      CHECK_EQUAL(0U, reader.size());

      // Write partially
      auto writer = istream.write_reserve(1U);
      CHECK_EQUAL(1U, writer.size());
      writer[0] = 1;

      CHECK(stream.empty());

      istream.write_commit(writer); // 1 * * * *
      CHECK_EQUAL(1U, stream.size());

      writer = istream.write_reserve(1U);
      CHECK_EQUAL(1U, writer.size());
      writer[0] = 2;

      istream.write_commit(writer); // 1 2 * * *
      CHECK_EQUAL(2U, stream.size());

      // Write to capacity
      writer = istream.write_reserve(istream.available());
      CHECK_EQUAL(3U, writer.size());
      writer[0] = 3;
      writer[1] = 4;
      writer[2] = 5;

      istream.write_commit(writer); // 1 2 3 4 5

      // Verify full buffer
      CHECK_EQUAL(0U, stream.available());
      CHECK(stream.full());
      CHECK((stream.max_size() - 1) <= stream.size());
      CHECK(stream.size() <= stream.max_size());

      writer = istream.write_reserve(1U);
      CHECK_EQUAL(0U, writer.size());

      // Read partially
      reader = istream.read_reserve(1U);
      CHECK_EQUAL(1U, reader.size());
      CHECK_EQUAL(1, reader[0]);
      CHECK_EQUAL(5U, stream.size());

      istream.read_commit(reader); // * 2 3 4 5
      CHECK_EQUAL(4U, stream.size());

      reader = istream.read_reserve(1U);
      CHECK_EQUAL(1U, reader.size());
      CHECK_EQUAL(2, reader[0]);
      CHECK_EQUAL(4U, stream.size());

      istream.read_commit(reader); // * * 3 4 5
      CHECK_EQUAL(3U, stream.size());

      // Write to wraparound area (one element remains reserved)
      writer = istream.write_reserve(istream.available());
      CHECK_EQUAL(1U, writer.size());
      CHECK_EQUAL(1U, stream.available());
      writer[0] = 6;

      istream.write_commit(writer); // 6 * 3 4 5

      // Verify full buffer
      CHECK_EQUAL(0U, stream.available());
      CHECK(stream.full());
      CHECK((stream.max_size() - 1) <= stream.size());
      CHECK(stream.size() <= stream.max_size());

      writer = istream.write_reserve(1U);
      CHECK_EQUAL(0U, writer.size());

      // Read to capacity
      reader = istream.read_reserve();
      CHECK_EQUAL(3U, reader.size());
      CHECK_EQUAL(3, reader[0]);
      CHECK_EQUAL(4, reader[1]);
      CHECK_EQUAL(5, reader[2]);
      CHECK_EQUAL(4U, stream.size());

      istream.read_commit(reader); // * 2 * * *
      CHECK_EQUAL(1U, stream.size());

      reader = istream.read_reserve();
      CHECK_EQUAL(1U, reader.size());
      CHECK_EQUAL(6, reader[0]);
      CHECK_EQUAL(1U, stream.size());

      istream.read_commit(reader); // * * * * *

      // Verify empty buffer
      CHECK_EQUAL(0U, stream.size());
      CHECK(stream.empty());
      CHECK((stream.max_size() / 2U) <= stream.available());
      CHECK(stream.available() <= stream.max_size());
    }

    //*************************************************************************
    TEST(test_optimal_write)
    {
      etl::bip_buffer_spsc_atomic<int, 5> stream;
      etl::ibip_buffer_spsc_atomic<int>&  istream = stream;

      // Prepare buffer for bipartite split
      auto writer = istream.write_reserve_optimal();
      CHECK_EQUAL(5U, writer.size());
      writer[0] = 1;
      writer[1] = 2;
      writer[2] = 3;
      writer[3] = 4;
      istream.write_commit(writer.subspan(0U, 4U)); // 1 2 3 4 *

      auto reader = istream.read_reserve(3U);
      istream.read_commit(reader); // * * * 4 *
      CHECK_EQUAL(1U, stream.size());
      CHECK_EQUAL(2U, stream.available());

      // Write to remaining linear area
      writer = istream.write_reserve_optimal();
      CHECK_EQUAL(1U, writer.size());
      writer[0] = 5;

      istream.write_commit(writer); // * * * 4 5

      // Read to capacity
      reader = istream.read_reserve();
      CHECK_EQUAL(2U, reader.size());
      CHECK_EQUAL(4, reader[0]);
      CHECK_EQUAL(5, reader[1]);

      istream.read_commit(reader); // * * * * *

      // Verify empty buffer
      CHECK_EQUAL(0U, stream.size());
      CHECK(stream.empty());
      CHECK((stream.max_size() / 2U) <= stream.available());
      CHECK(stream.available() <= stream.max_size());
    }

    //*************************************************************************
    TEST(test_clear)
    {
      etl::bip_buffer_spsc_atomic<int, 5> stream;
      etl::ibip_buffer_spsc_atomic<int>&  istream = stream;

      CHECK(stream.empty());

      // Write the whole buffer
      auto writer = istream.write_reserve(istream.capacity());
      // data is committed without set to valid value (it won't be read anyway)
      istream.write_commit(writer);
      CHECK(stream.full());

      istream.clear();
      CHECK(stream.empty());

      // Repeat to see that clear() resets the internal state completely and
      // correctly
      writer = istream.write_reserve(istream.capacity());
      // data is committed without set to valid value (it won't be read anyway)
      istream.write_commit(writer);
      CHECK(stream.full());

      istream.clear();
      CHECK(stream.empty());
    }

    //*************************************************************************
    TEST(test_partial_commits)
    {
      etl::bip_buffer_spsc_atomic<int, 5> stream;
      etl::ibip_buffer_spsc_atomic<int>&  istream = stream;

      // Write reserve available
      auto writer_1 = istream.write_reserve(istream.capacity());
      CHECK_EQUAL(5U, stream.available());
      CHECK_EQUAL(5U, writer_1.size());

      // Write and commit partially
      writer_1[0] = 1;
      writer_1[1] = 2;
      writer_1[2] = 3;
      writer_1[3] = 4;

      // Cannot commit subspans with offset
      CHECK_THROW(istream.write_commit(writer_1.subspan(1U, 3U)), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.write_commit(writer_1.subspan(2U, 2U)), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.write_commit(writer_1.subspan(3U, 1U)), etl::bip_buffer_reserve_invalid);

      CHECK_NO_THROW(istream.write_commit(writer_1.subspan(0U, 4U))); // 1 2 3 4 *
      CHECK_EQUAL(4U, stream.size());

      // Can only commit once for each reserve (provided they don't cover a
      // valid area)
      CHECK_THROW(istream.write_commit(writer_1), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.write_commit(writer_1.subspan(0U, 4U)), etl::bip_buffer_reserve_invalid);

      // Read reserve available
      auto reader_1 = istream.read_reserve(istream.capacity());
      CHECK_EQUAL(4U, reader_1.size());

      // Read and commit partially
      CHECK_EQUAL(1, reader_1[0]);
      CHECK_EQUAL(2, reader_1[1]);
      CHECK_EQUAL(3, reader_1[2]);

      // Cannot commit subspans with offset
      CHECK_THROW(istream.read_commit(reader_1.subspan(1U, 2U)), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.read_commit(reader_1.subspan(2U, 1U)), etl::bip_buffer_reserve_invalid);

      CHECK_NO_THROW(istream.read_commit(reader_1.subspan(0U, 3U))); // * * * 4 *
      CHECK_EQUAL(1U, stream.size());

      // Can only commit once for each reserve (provided they don't cover a
      // valid area)
      CHECK_THROW(istream.read_commit(reader_1), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.read_commit(reader_1.subspan(0U, 3U)), etl::bip_buffer_reserve_invalid);

      // Write reserve available
      auto writer_2 = istream.write_reserve(istream.capacity());
      CHECK_EQUAL(2U, stream.available());
      CHECK_EQUAL(2U, writer_2.size());

      // Write and commit partially
      writer_2[0] = 5;
      CHECK_NO_THROW(istream.write_commit(writer_2.subspan(0U, 1U))); // 5 * * 4 *
      CHECK_EQUAL(2U, stream.size());
      // Even though the second committed span could have fit at the end,
      // the reservation asked for the largest consecutive block,
      // which resulted in a wraparound span to be allocated

      // Can only commit once for each reserve (provided they don't cover a
      // valid area)
      CHECK_THROW(istream.write_commit(writer_1), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.write_commit(writer_2), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.write_commit(writer_2.subspan(0U, 1U)), etl::bip_buffer_reserve_invalid);

      // Read reserve available
      auto reader_2 = istream.read_reserve(istream.capacity());
      CHECK_EQUAL(1U, reader_2.size());

      // Read and commit
      CHECK_EQUAL(4, reader_2[0]);
      CHECK_NO_THROW(istream.read_commit(reader_2)); // 5 * * * *
      CHECK_EQUAL(1U, stream.size());

      // Can only commit once for each reserve (provided they don't cover a
      // valid area)
      CHECK_THROW(istream.read_commit(reader_1), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.read_commit(reader_2), etl::bip_buffer_reserve_invalid);

      // Read reserve available
      auto reader_3 = istream.read_reserve(istream.capacity());
      CHECK_EQUAL(1U, reader_3.size());

      // Read and commit
      CHECK_EQUAL(5, reader_3[0]);
      CHECK_NO_THROW(istream.read_commit(reader_3)); // * * * * *
      CHECK_EQUAL(0U, stream.size());

      // Can only commit once for each reserve (provided they don't cover a
      // valid area)
      CHECK_THROW(istream.read_commit(reader_1), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.read_commit(reader_2), etl::bip_buffer_reserve_invalid);
      CHECK_THROW(istream.read_commit(reader_3), etl::bip_buffer_reserve_invalid);

      CHECK(stream.empty());
    }

    //*************************************************************************
    TEST(test_optimal_write_issue_1276)
    {
      etl::bip_buffer_spsc_atomic<char, 5> stream;
      etl::ibip_buffer_spsc_atomic<char>&  istream = stream;

      // 1. Make all `read`, `write` and `last` in the end of the buffer.
      {
        const auto writer = istream.write_reserve_optimal(5);
        CHECK_EQUAL(5U, writer.size());
        writer[0] = '0';
        writer[1] = '1';
        writer[2] = '2';
        writer[3] = '3';
        writer[4] = '4';
        CHECK_NO_THROW(istream.write_commit(writer)); // [0 1 2 3 4]
        const auto reader = istream.read_reserve();
        CHECK_EQUAL(5U, reader.size());
        CHECK_NO_THROW(istream.read_commit(reader)); //  * * * * *[]
      }
      // 2. Write & read 4 bytes.
      {
        const auto writer = istream.write_reserve_optimal(4);
        CHECK_EQUAL(4U, writer.size());
        writer[0] = '5';
        writer[1] = '6';
        writer[2] = '7';
        writer[3] = '8';
        CHECK_NO_THROW(istream.write_commit(writer.subspan(0U, 4U))); // 5 6 7 8] *[

        const auto reader = istream.read_reserve();
        CHECK_EQUAL(4U, reader.size());
        CHECK_EQUAL('5', reader[0]);
        CHECK_EQUAL('6', reader[1]);
        CHECK_EQUAL('7', reader[2]);
        CHECK_EQUAL('8', reader[3]);
        CHECK_NO_THROW(istream.read_commit(reader)); // * * * *[]*
      }
      // 3. Write and read 2 bytes.
      {
        const auto writer = istream.write_reserve_optimal(2);
        CHECK_EQUAL(3U, writer.size());
        writer[0] = '9';
        writer[1] = 'A';
        CHECK_NO_THROW(istream.write_commit(writer.subspan(0, 2))); // 9 A]* *[*

        const auto reader = istream.read_reserve();
        CHECK_EQUAL(2U, reader.size());
        CHECK_EQUAL('9', reader[0]);
        CHECK_EQUAL('A', reader[1]);
      }
    }

    //*************************************************************************
    TEST(test_write_random_back_pressure)
    {
      // Deliberately seeded with fixed number, so that if it fails then always
      // in the same way.
      std::mt19937 mte(123);

      constexpr size_t                    N = 256;
      etl::bip_buffer_spsc_atomic<int, N> stream;
      etl::ibip_buffer_spsc_atomic<int>&  istream = stream;

      auto makeRandomNumber = [&mte](const size_t n) -> size_t
      {
        return mte() % n;
      };

      auto verifyIota = [&](const etl::span<int>& seq)
      {
        if (!seq.empty())
        {
          auto prev = seq[0];
          for (auto i = 1U; i < seq.size(); ++i)
          {
            const auto curr = seq[i];
            if (prev > curr)
            {
              CHECK(prev <= curr);
              std::cerr << "prev(" << prev << ") should not be bigger than curr(" << curr << ")!\n";
            }
            prev = curr;
          }
        }
      };

      const auto all = istream.write_reserve(N);
      CHECK_EQUAL(N, all.size());
      std::fill_n(all.begin(), all.size(), 0);

      int iota = 0;
      // Loop writing a bit more than reading.
      // 10K iterations is enough to detect 2 failures.
      for (int i = 0; i < 10000; ++i)
      {
        // Write [0...N/16] chunks - on average N/32.
        {
          const size_t toWrite = makeRandomNumber(N / 16 + 1);
          const auto   reserve = istream.write_reserve(toWrite);
          if (reserve.size() >= toWrite)
          {
            ++iota;
            const auto written = makeRandomNumber(toWrite + 1);
            std::fill_n(reserve.begin(), written, iota);
            istream.write_commit(reserve.first(written));
            verifyIota(reserve.first(written));
          }
        }

        // Read a bit less [0...N/17] chunks - on average N/34.
        if (const size_t toRead = makeRandomNumber(N / 17 + 1))
        {
          const auto reserve = istream.read_reserve(toRead);
          verifyIota(reserve);
          const auto read = makeRandomNumber(reserve.size() + 1);
          istream.read_commit(reserve.first(read));
        }
      }
    }

    //*************************************************************************
  #if REALTIME_TEST && defined(ETL_COMPILER_MICROSOFT)
    #if defined(ETL_TARGET_OS_WINDOWS) // Only Windows priority is currently
                                       // supported
      #define FIX_PROCESSOR_AFFINITY1 SetThreadAffinityMask(GetCurrentThread(), 1);
      #define FIX_PROCESSOR_AFFINITY2 SetThreadAffinityMask(GetCurrentThread(), 2);
    #else
      #error No thread priority modifier defined
    #endif

    etl::bip_buffer_spsc_atomic<int, 100> stream;

    const size_t LENGTH = 100UL;

    void timer_event()
    {
      FIX_PROCESSOR_AFFINITY1;

      const size_t write_chunk_size = 7UL;
      size_t       tick             = 0UL;

      while (tick < LENGTH)
      {
        auto writer = stream.write_reserve(min(write_chunk_size, LENGTH - tick));
        for (auto& item : writer)
        {
          item = tick++;
        }
        stream.write_commit(writer);
      }
    }

    TEST(bip_buffer_threads)
    {
      FIX_PROCESSOR_AFFINITY2;

      const size_t read_chunk_size = stream.capacity();

      std::vector<int> tick_list;
      tick_list.reserve(LENGTH);

      std::thread t1(timer_event);

      while (tick_list.size() < LENGTH)
      {
        etl::span<int> reader = stream.read_reserve(read_chunk_size);
        tick_list.insert(tick_list.end(), reader.begin(), reader.end());
        stream.read_commit(reader);
      }

      // Join the thread with the main thread
      t1.join();

      CHECK_EQUAL(LENGTH, tick_list.size());

      for (size_t i = 0UL; i < LENGTH; i++)
      {
        CHECK_EQUAL(i, tick_list[i]);
      }
    }
  #endif
  }
} // namespace

#endif // ETL_HAS_ATOMIC