#include <gtest/gtest.h>
#include <web_server/src/H264_Encoder.hpp>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <vector>

namespace aethera::web {
namespace {
std::vector<std::byte> test_pattern(std::uint32_t width,
                                    std::uint32_t height) {
    std::vector<std::byte> result(
        static_cast<std::size_t>(width) * height * 4U);
    for (std::uint32_t y = 0; y < height; ++y) {
        for (std::uint32_t x = 0; x < width; ++x) {
            const auto offset =
                (static_cast<std::size_t>(y) * width + x) * 4U;
            result[offset] = std::byte{static_cast<std::uint8_t>(x)};
            result[offset + 1U] = std::byte{static_cast<std::uint8_t>(y)};
            result[offset + 2U] =
                std::byte{static_cast<std::uint8_t>(x ^ y)};
            result[offset + 3U] = std::byte{255};
        }
    }
    return result;
}
}

TEST(H264_Encoder, Rejects_Invalid_Input_Before_FFmpeg) {
    H264_Encoder encoder(100.0);
    const auto pixels = test_pattern(320, 192);
    EXPECT_THROW(static_cast<void>(encoder.encode(
                     pixels, 319, 192, Video_Pixel_Layout::rgba,
                     1, std::chrono::microseconds{10'000})),
                 std::invalid_argument);
    EXPECT_THROW(static_cast<void>(encoder.encode(
                     std::span<const std::byte>{pixels}.first(pixels.size() - 1U),
                     320, 192, Video_Pixel_Layout::rgba, 1,
                     std::chrono::microseconds{10'000})),
                 std::invalid_argument);
}

TEST(H264_Encoder, Hardware_Backend_Produces_Annex_B_At_One_Hundred_Fps) {
    constexpr std::uint32_t width{1'920};
    constexpr std::uint32_t height{768};
    H264_Encoder encoder(100.0);
    auto pixels = test_pattern(width, height);
    std::optional<Encoded_Video_Frame> first;
    for (std::uint64_t sequence = 1; sequence <= 4 && !first; ++sequence) {
        first = encoder.encode(
            pixels, width, height, Video_Pixel_Layout::rgba, sequence,
            std::chrono::microseconds{static_cast<std::int64_t>(sequence * 10'000)});
    }
    ASSERT_TRUE(first);
    ASSERT_FALSE(first->annex_b.empty());
    EXPECT_TRUE(first->key_frame);
    ASSERT_GE(first->annex_b.size(), 4U);
    EXPECT_EQ(first->annex_b[0], std::byte{0});
    EXPECT_EQ(first->annex_b[1], std::byte{0});
    EXPECT_TRUE((first->annex_b[2] == std::byte{1}) ||
                (first->annex_b[2] == std::byte{0} &&
                first->annex_b[3] == std::byte{1}));
    EXPECT_NE(video_encoder_backend_name(first->backend), "unknown");
    EXPECT_EQ(h264_profile_level_id(), "640033");
}

TEST(H264_Encoder, Hardware_Pipeline_Drains_A_Continuous_Frame_Sequence) {
    constexpr std::uint32_t width{1'920};
    constexpr std::uint32_t height{768};
    H264_Encoder encoder(100.0);
    auto pixels = test_pattern(width, height);
    std::uint64_t produced{};
    std::uint64_t latest_sequence{};
    std::optional<Video_Encoder_Backend> backend;
    const auto started = std::chrono::steady_clock::now();
    for (std::uint64_t sequence = 1; sequence <= 120; ++sequence) {
        pixels[0] = std::byte{static_cast<std::uint8_t>(sequence)};
        const auto frame = encoder.encode(
            pixels, width, height, Video_Pixel_Layout::rgba, sequence,
            std::chrono::microseconds{
                static_cast<std::int64_t>(sequence * 10'000)});
        if (!frame) continue;
        ++produced;
        EXPECT_GT(frame->sequence, latest_sequence);
        latest_sequence = frame->sequence;
        EXPECT_FALSE(frame->annex_b.empty());
        if (!backend) backend = frame->backend;
        EXPECT_EQ(frame->backend, *backend);
    }
    const auto elapsed = std::chrono::steady_clock::now() - started;
    EXPECT_GE(produced, 115U);
    EXPECT_GE(latest_sequence, 115U);
    EXPECT_LE(elapsed, std::chrono::milliseconds{1'200});
}
}