refactor: dedicated class for torrent queue (#7332)

* Revert "feat: save queue order between sessions (#6753)"

This reverts commit 4db50dae10.

* refactor: new torrent queue class

* refactor: replace queue code with new class

* test: new tests for new class

* feat: store and load queue order across sessions

* build: xcode

* refactor: use set_difference instead of unordered_set

* code review: use `tr_torrent_id_t` as key

* fix: don't overflow when moving up/down

---------

Co-authored-by: Dzmitry Neviadomski <nevack.d@gmail.com>

tests/libtransmission/CMakeLists.txt

@@ -49,6 +49,7 @@ target_sources(libtransmission-test
         torrent-files-test.cc
         torrent-magnet-test.cc
         torrent-metainfo-test.cc
+        torrent-queue-test.cc
         torrents-test.cc
         tr-peer-info-test.cc
         utils-test.cc

tests/libtransmission/torrent-queue-test.cc

@@ -0,0 +1,167 @@
+// This file Copyright © Mnemosyne LLC.
+// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
+// or any future license endorsed by Mnemosyne LLC.
+// License text can be found in the licenses/ folder.
+
+#include <fstream>
+#include <map>
+#include <memory>
+#include <string_view>
+#include <vector>
+
+#include <libtransmission/torrent-queue.h>
+#include <libtransmission/torrent.h>
+
+#include "gtest/gtest.h"
+#include "test-fixtures.h"
+
+using namespace std::literals;
+
+struct TorrentQueueTest : public libtransmission::test::SandboxedTest
+{
+    class MockMediator final : public tr_torrent_queue::Mediator
+    {
+    public:
+        explicit MockMediator(TorrentQueueTest const& test)
+            : test_{ test }
+        {
+        }
+
+        [[nodiscard]] std::string config_dir() const override
+        {
+            return test_.sandboxDir();
+        }
+
+        [[nodiscard]] std::string store_filename(tr_torrent_id_t id) const override
+        {
+            if (auto it = test_.torrents_.find(id); it != std::end(test_.torrents_))
+            {
+                return it->second.store_filename();
+            }
+            return {};
+        }
+
+    private:
+        TorrentQueueTest const& test_;
+    };
+
+    std::map<tr_torrent_id_t, tr_torrent const&> torrents_;
+
+    MockMediator mediator_{ *this };
+
+    static auto constexpr TorFilenames = std::array{
+        "Android-x86 8.1 r6 iso.torrent"sv,
+        "debian-11.2.0-amd64-DVD-1.iso.torrent"sv,
+        "ubuntu-18.04.6-desktop-amd64.iso.torrent"sv,
+        "ubuntu-20.04.4-desktop-amd64.iso.torrent"sv,
+    };
+};
+
+TEST_F(TorrentQueueTest, addRemoveToFromQueue)
+{
+    auto queue = tr_torrent_queue{ mediator_ };
+
+    auto owned = std::vector<std::unique_ptr<tr_torrent>>{};
+    for (auto const& name : TorFilenames)
+    {
+        auto const path = tr_pathbuf{ LIBTRANSMISSION_TEST_ASSETS_DIR, '/', name };
+        auto tm = tr_torrent_metainfo{};
+        EXPECT_TRUE(tm.parse_torrent_file(path));
+
+        auto& tor = owned.emplace_back(std::make_unique<tr_torrent>(std::move(tm)));
+        tor->init_id(std::size(owned));
+        torrents_.try_emplace(tor->id(), *tor);
+        queue.add(tor->id());
+    }
+
+    for (size_t i = 0; i < std::size(owned); ++i)
+    {
+        EXPECT_EQ(i, queue.get_pos(owned[i]->id()));
+    }
+
+    queue.remove(owned[1]->id());
+    queue.remove(owned[2]->id());
+    owned.erase(std::begin(owned) + 1, std::begin(owned) + 3);
+    for (size_t i = 0; i < std::size(owned); ++i)
+    {
+        EXPECT_EQ(i, queue.get_pos(owned[i]->id()));
+    }
+}
+
+TEST_F(TorrentQueueTest, setQueuePos)
+{
+    static auto constexpr QueuePos = std::array{ 1U, 3U, 0U, 2U };
+
+    auto queue = tr_torrent_queue{ mediator_ };
+
+    auto owned = std::vector<std::unique_ptr<tr_torrent>>{};
+    for (auto const& name : TorFilenames)
+    {
+        auto const path = tr_pathbuf{ LIBTRANSMISSION_TEST_ASSETS_DIR, '/', name };
+        auto tm = tr_torrent_metainfo{};
+        EXPECT_TRUE(tm.parse_torrent_file(path));
+
+        auto& tor = owned.emplace_back(std::make_unique<tr_torrent>(std::move(tm)));
+        tor->init_id(std::size(owned));
+        torrents_.try_emplace(tor->id(), *tor);
+        queue.add(tor->id());
+    }
+
+    for (size_t i = 0; i < std::size(owned); ++i)
+    {
+        EXPECT_EQ(i, queue.get_pos(owned[i]->id()));
+    }
+
+    for (size_t i = 0; i < std::size(owned); ++i)
+    {
+        auto const id = owned[i]->id();
+        auto const pos = QueuePos[i];
+        queue.set_pos(id, pos);
+        EXPECT_EQ(queue.get_pos(id), pos);
+    }
+
+    for (size_t i = 0; i < std::size(owned); ++i)
+    {
+        EXPECT_EQ(queue.get_pos(owned[i]->id()), QueuePos[i]);
+    }
+}
+
+TEST_F(TorrentQueueTest, toFromFile)
+{
+    static auto constexpr ExpectedContents =
+        "[\n"
+        "    \"70341e8e1fe8778af23f6318ca75a22f8b1f1c05.torrent\",\n"
+        "    \"c9a337562cb0360fd6f5ab40fd2b1b81d5325dbd.torrent\",\n"
+        "    \"bc26c6bc83d0ca1a7bf9875df1ffc3fed81ff555.torrent\",\n"
+        "    \"f09c8d0884590088f4004e010a928f8b6178c2fd.torrent\"\n"
+        "]"sv;
+
+    auto queue = tr_torrent_queue{ mediator_ };
+
+    auto owned = std::vector<std::unique_ptr<tr_torrent>>{};
+    for (auto const& name : TorFilenames)
+    {
+        auto const path = tr_pathbuf{ LIBTRANSMISSION_TEST_ASSETS_DIR, '/', name };
+        auto tm = tr_torrent_metainfo{};
+        EXPECT_TRUE(tm.parse_torrent_file(path));
+
+        auto& tor = owned.emplace_back(std::make_unique<tr_torrent>(std::move(tm)));
+        tor->init_id(std::size(owned));
+        torrents_.try_emplace(tor->id(), *tor);
+        queue.add(tor->id());
+    }
+
+    queue.to_file();
+
+    auto f = std::ifstream{ sandboxDir() + "/queue.json" };
+    auto const contents = std::string{ std::istreambuf_iterator{ f }, std::istreambuf_iterator<decltype(f)::char_type>{} };
+    EXPECT_EQ(contents, ExpectedContents);
+    f.close();
+
+    auto const filenames = queue.from_file();
+    ASSERT_EQ(std::size(filenames), std::size(owned));
+    for (size_t i = 0; i < std::size(filenames); ++i)
+    {
+        EXPECT_EQ(filenames[i], owned[i]->store_filename());
+    }
+}