From 9bbcff7cf549718151fb91c5a22370cfb2551715 Mon Sep 17 00:00:00 2001
From: Stepland <16676308+Stepland@users.noreply.github.com>
Date: Tue, 18 Feb 2020 01:44:21 +0100
Subject: [PATCH] Density Graph WIP again

---
 meson.build                                 |  41 +++---
 src/Data/Chart.cpp                          |  16 ++-
 src/Data/Chart.hpp                          |   4 +-
 src/Data/Note.hpp                           |   6 +-
 src/Data/Song.cpp                           | 133 +++++++++++++++++
 src/Data/{SongList.hpp => Song.hpp}         |  35 +++--
 src/Data/SongList.cpp                       | 152 --------------------
 src/Main.cpp                                |   2 +-
 src/Screens/MusicSelect/DensityGraph.cpp    |  49 +++++++
 src/Screens/MusicSelect/DensityGraph.hpp    |  41 ++++++
 src/Screens/MusicSelect/MusicSelect.hpp     |   2 +-
 src/Screens/MusicSelect/Panel.cpp           |  26 ++--
 src/Screens/MusicSelect/Panel.hpp           |   8 +-
 src/Screens/MusicSelect/Ribbon.cpp          |  31 ++--
 src/Screens/MusicSelect/Ribbon.hpp          |   3 +-
 src/Screens/MusicSelect/SharedResources.cpp |   8 +-
 src/Screens/MusicSelect/SharedResources.hpp |  10 +-
 src/Screens/MusicSelect/SongInfo.cpp        |  33 ++---
 18 files changed, 343 insertions(+), 257 deletions(-)
 create mode 100644 src/Data/Song.cpp
 rename src/Data/{SongList.hpp => Song.hpp} (62%)
 delete mode 100644 src/Data/SongList.cpp
 create mode 100644 src/Screens/MusicSelect/DensityGraph.cpp
 create mode 100644 src/Screens/MusicSelect/DensityGraph.hpp

diff --git a/meson.build b/meson.build
index ce80515..7f9fd3a 100644
--- a/meson.build
+++ b/meson.build
@@ -24,40 +24,40 @@ sources = [
     'include/imgui/imgui_draw.cpp',
     'include/imgui/imgui_widgets.cpp',
     'include/imgui-sfml/imgui-SFML.cpp',
-    'src/Main.cpp',
     'src/Data/Buttons.hpp',
     'src/Data/Buttons.cpp',
+    'src/Data/Chart.cpp',
     'src/Data/Chart.hpp',
     'src/Data/KeyMapping.hpp',
     'src/Data/KeyMapping.cpp',
     'src/Data/Note.hpp',
     'src/Data/Preferences.hpp',
     'src/Data/Score.hpp',
-    'src/Data/SongList.hpp',
-    'src/Data/SongList.cpp',
-    # 'src/Screens/Gameplay.hpp',
-    'src/Screens/MusicSelect/ButtonHighlight.hpp',
-    'src/Screens/MusicSelect/ButtonHighlight.cpp',
-    # 'src/Screens/MusicSelect/DensityGraph.hpp',
-    # 'src/Screens/MusicSelect/DensityGraph.cpp',
-    'src/Screens/MusicSelect/MusicSelect.hpp',
-    'src/Screens/MusicSelect/MusicSelect.cpp',
-    'src/Screens/MusicSelect/Panel.hpp',
-    'src/Screens/MusicSelect/Panel.cpp',
-    'src/Screens/MusicSelect/SharedResources.hpp',
-    'src/Screens/MusicSelect/SharedResources.cpp',
-    'src/Screens/MusicSelect/SongInfo.hpp',
-    'src/Screens/MusicSelect/SongInfo.cpp',
-    'src/Screens/MusicSelect/Ribbon.hpp',
-    'src/Screens/MusicSelect/Ribbon.cpp',
-    # 'src/Screens/Result.hpp',
+    'src/Data/Song.hpp',
+    'src/Data/Song.cpp',
     'src/Resources/TextureCache.cpp',
     'src/Resources/TextureCache.hpp',
     # 'src/Resources/CoverAtlas.hpp',
     # 'src/Resources/CoverAtlas.cpp',
+    # 'src/Screens/Gameplay.hpp',
+    'src/Screens/MusicSelect/ButtonHighlight.hpp',
+    'src/Screens/MusicSelect/ButtonHighlight.cpp',
+    'src/Screens/MusicSelect/DensityGraph.hpp',
+    'src/Screens/MusicSelect/DensityGraph.cpp',
+    'src/Screens/MusicSelect/MusicSelect.hpp',
+    'src/Screens/MusicSelect/MusicSelect.cpp',
+    'src/Screens/MusicSelect/Panel.hpp',
+    'src/Screens/MusicSelect/Panel.cpp',
+    'src/Screens/MusicSelect/Ribbon.hpp',
+    'src/Screens/MusicSelect/Ribbon.cpp',
+    'src/Screens/MusicSelect/SharedResources.hpp',
+    'src/Screens/MusicSelect/SharedResources.cpp',
+    'src/Screens/MusicSelect/SongInfo.hpp',
+    'src/Screens/MusicSelect/SongInfo.cpp',
+    # 'src/Screens/Result.hpp',
     'src/Toolkit/AffineTransform.hpp',
-    'src/Toolkit/Debuggable.hpp',
     'src/Toolkit/Cache.hpp',
+    'src/Toolkit/Debuggable.hpp',
     'src/Toolkit/EasingFunctions.hpp',
     'src/Toolkit/EasingFunctions.cpp',
     'src/Toolkit/HSL.hpp',
@@ -65,6 +65,7 @@ sources = [
     'src/Toolkit/NormalizedOrigin.hpp',
     'src/Toolkit/QuickRNG.hpp',
     'src/Toolkit/QuickRNG.cpp',
+    'src/Main.cpp',
 ]
 
 executable(
diff --git a/src/Data/Chart.cpp b/src/Data/Chart.cpp
index d271926..498bc1d 100644
--- a/src/Data/Chart.cpp
+++ b/src/Data/Chart.cpp
@@ -5,24 +5,28 @@
 #include "Buttons.hpp"
 
 namespace Data {
-    Chart::Chart(const stepland::memon& memon, const std::string& chart_name) {
-        auto it = memon.charts.find(chart_name);
+    Chart::Chart(const stepland::memon& memon, const std::string& difficulty) {
+        auto it = memon.charts.find(difficulty);
         if (it == memon.charts.end()) {
-            throw std::invalid_argument("Memon file has no "+chart_name+" chart");
+            throw std::invalid_argument("Memon file has no "+difficulty+" chart");
         }
         auto [_, chart] = *it;
-        level = static_cast<unsigned int>(chart.level);
+        level = chart.level;
         resolution = static_cast<std::size_t>(chart.resolution);
         Toolkit::AffineTransform<float> memon_timing_to_300Hz(
             0.f, static_cast<float>(chart.resolution),
             -memon.offset*300.f, (-memon.offset+60.f/memon.BPM)*300.f
         );
+        Toolkit::AffineTransform<float> memon_timing_to_300Hz_proportional(
+            0.f, static_cast<float>(chart.resolution),
+            0.f, (60.f/memon.BPM)*300.f
+        );
         for (auto &&note : chart.notes) {
             auto timing = static_cast<std::size_t>(memon_timing_to_300Hz.transform(note.get_timing()));
             auto position = static_cast<Button>(note.get_pos());
-            auto length = static_cast<std::size_t>(note.get_length());
+            auto length = static_cast<std::size_t>(memon_timing_to_300Hz_proportional.transform(note.get_length()));
             auto tail = convert_memon_tail(position, note.get_tail_pos());
-            notes.emplace(timing, position, length, tail);
+            notes.insert({timing, position, length, tail});
         }
     }
 
diff --git a/src/Data/Chart.hpp b/src/Data/Chart.hpp
index 46aac1b..7dbb669 100644
--- a/src/Data/Chart.hpp
+++ b/src/Data/Chart.hpp
@@ -10,8 +10,8 @@
 
 namespace Data {
     struct Chart {
-        explicit Chart(const stepland::memon& memon, const std::string& chart);
-        unsigned int level;
+        Chart(const stepland::memon& memon, const std::string& difficulty);
+        int level;
         std::set<Note> notes;
         std::size_t resolution;
     };
diff --git a/src/Data/Note.hpp b/src/Data/Note.hpp
index 13a0186..308227b 100644
--- a/src/Data/Note.hpp
+++ b/src/Data/Note.hpp
@@ -4,10 +4,10 @@
 
 namespace Data {
     struct Note {
-        // Timing is stored as ticks on a 300Hz clock
-        std::size_t timing;
+        // Timing is stored as ticks on a 300Hz clock starting at the begging of the audio
+        long int timing;
         Button position;
-        // zero is standard note
+        // zero length means it's a standard note
         std::size_t length;
         Button tail;
 
diff --git a/src/Data/Song.cpp b/src/Data/Song.cpp
new file mode 100644
index 0000000..61bdbdd
--- /dev/null
+++ b/src/Data/Song.cpp
@@ -0,0 +1,133 @@
+#include "Song.hpp"
+
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <list>
+
+#include <memon.hpp>
+
+namespace fs = ghc::filesystem;
+
+namespace Data {
+
+    bool cmp_dif_name::operator()(const std::string &a, const std::string &b) const {
+        if (dif_names.find(a) != dif_names.end()) {
+            if (dif_names.find(b) != dif_names.end()) {
+                return dif_names.find(a)->second < dif_names.find(b)->second;
+            } else {
+                return true;
+            }
+        } else {
+            if (dif_names.find(b) != dif_names.end()) {
+                return false;
+            } else {
+                return a < b;
+            }
+        }
+    }
+
+    std::optional<fs::path> Song::full_cover_path() const {
+        if (cover) {
+            return folder/cover.value();
+        } else {
+            return {};
+        } 
+    }
+
+    std::optional<fs::path> Song::full_audio_path() const {
+        if (audio) {
+            return folder/audio.value();
+        } else {
+            return {};
+        } 
+    }
+
+    SongList::SongList() :
+        songs()
+    {
+        fs::path song_folder = "songs/";
+
+        if (fs::exists(song_folder) and fs::is_directory(song_folder)) {
+            for (const auto& dir_item : fs::directory_iterator("songs/")) {
+                if (dir_item.is_directory()) {
+                    songs.splice(songs.end(), recursiveSongSearch(dir_item.path()));
+                }
+            }
+        }
+        std::cout << "Loaded Data::SongList, found " << songs.size() << " songs" << std::endl;
+    }
+
+    std::list<std::shared_ptr<Song>> recursiveSongSearch(fs::path song_or_pack) {
+        std::list<std::shared_ptr<Song>> res;
+
+        // First try : any .memo file in the folder ?
+        fs::directory_iterator folder_memo{song_or_pack};
+        if (
+            std::any_of(
+                fs::begin(folder_memo),
+                fs::end(folder_memo),
+                [](const fs::directory_entry& de) {return de.path().extension() == ".memo";}
+            )
+        ) {
+            throw std::invalid_argument("jujube does not support .memo files for now ...");
+        }
+
+        // Second try : any .memon file in the folder ?
+        // if yes get the first one
+        fs::directory_iterator folder_memon{song_or_pack};
+        auto memon_path = std::find_if(
+            fs::begin(folder_memon),
+            fs::end(folder_memon),
+            [](const fs::directory_entry& de) {return de.path().extension() == ".memon";}
+        );
+        if (memon_path != fs::end(folder_memon)) {
+            res.push_back(std::make_shared<MemonSong>(memon_path->path()));
+            return res;
+        }
+        // Nothing found : recurse in subfolders
+        for (auto& p : fs::directory_iterator(song_or_pack)) {
+            if (p.is_directory()) {
+                res.splice(res.end(), recursiveSongSearch(p));
+            }
+        }
+        return res;
+    }
+
+    MemonSong::MemonSong(const fs::path& t_memon_path) :
+        memon_path(t_memon_path)
+    {
+        auto song_folder = t_memon_path.parent_path();
+        folder = song_folder;
+        stepland::memon m;
+        {
+            std::ifstream file(t_memon_path);
+            file >> m;
+        }
+        this->title = m.song_title;
+        this->artist = m.artist;
+        if (not m.album_cover_path.empty()) {
+            this->cover.emplace(m.album_cover_path);
+        }
+        if (not m.music_path.empty()) {
+            this->audio.emplace(m.music_path);
+        }
+        for (const auto& [difficulty, chart] : m.charts) {
+            this->chart_levels[difficulty] = chart.level;
+        }
+    }
+
+    std::optional<Chart> MemonSong::get_chart(const std::string& difficulty) const {
+        stepland::memon m;
+        {
+            std::ifstream file(memon_path);
+            file >> m;
+        }
+        auto chart = m.charts.find(difficulty);
+        if (chart == m.charts.end()) {
+            return {};
+        } else {
+            return Chart(m, difficulty);
+        }
+    }
+}
diff --git a/src/Data/SongList.hpp b/src/Data/Song.hpp
similarity index 62%
rename from src/Data/SongList.hpp
rename to src/Data/Song.hpp
index 303ce09..d5815a4 100644
--- a/src/Data/SongList.hpp
+++ b/src/Data/Song.hpp
@@ -4,9 +4,13 @@
 #include <iterator>
 #include <list>
 #include <map>
+#include <memory>
 #include <optional>
 #include <string>
-#include <vector>
+#include <variant>
+#include <unordered_map>
+
+#include "Chart.hpp"
 
 namespace fs = ghc::filesystem;
 
@@ -22,8 +26,6 @@ namespace Data {
 
     // Basic metadata about a song
     struct Song {
-        Song() = default;
-        explicit Song(fs::path song_folder);
         fs::path folder;
         std::string title;
         std::string artist;
@@ -35,24 +37,39 @@ namespace Data {
         std::map<std::string, unsigned int, cmp_dif_name> chart_levels;
 
         std::optional<fs::path> full_cover_path() const;
+        std::optional<fs::path> full_audio_path() const;
+
+        virtual std::optional<Chart> get_chart(const std::string& difficulty) const = 0;
 
         static bool sort_by_title(const Data::Song& a, const Data::Song& b) {
             return a.title < b.title;
         }
+        virtual ~Song() = default;
     };
 
+    struct MemonSong : public Song {
+        explicit MemonSong(const fs::path& memon_path);
+        std::optional<Chart> get_chart(const std::string& difficulty) const;
+    private:
+        fs::path memon_path;
+    };
+
+    /*
+    struct MemoSong : public Song {
+        explicit MemoSong(const std::unordered_map<std::string, fs::path>& memo_paths);
+    private:
+        std::unordered_map<std::string, fs::path> memo_paths;
+    };
+    */
+
     // Class holding all the necessary song data to run the Music Select screen
     class SongList {
     public:
         SongList();
-        std::vector<Song> songs;
+        std::list<std::shared_ptr<Song>> songs;
     };
 
     // Returns the folders conscidered to contain a valid song
     // classic memo files should have the .memo extension
-    // .memon files also accepted
-    const std::vector<fs::path> getSongFolders();
-    std::list<fs::path> recursiveSongSearch(fs::path song_or_pack);
-    const std::vector<fs::path> getMemoFiles(fs::path song_folder);
-    const std::vector<fs::path> getMemonFiles(fs::path song_folder);
+    std::list<std::shared_ptr<Song>> recursiveSongSearch(fs::path song_or_pack);
 }
diff --git a/src/Data/SongList.cpp b/src/Data/SongList.cpp
deleted file mode 100644
index 3e982d7..0000000
--- a/src/Data/SongList.cpp
+++ /dev/null
@@ -1,152 +0,0 @@
-#include "SongList.hpp"
-
-#include <algorithm>
-#include <fstream>
-#include <iostream>
-#include <list>
-
-#include <memon.hpp>
-
-namespace fs = ghc::filesystem;
-
-namespace Data {
-
-    bool cmp_dif_name::operator()(const std::string &a, const std::string &b) const {
-        if (dif_names.find(a) != dif_names.end()) {
-            if (dif_names.find(b) != dif_names.end()) {
-                return dif_names.find(a)->second < dif_names.find(b)->second;
-            } else {
-                return true;
-            }
-        } else {
-            if (dif_names.find(b) != dif_names.end()) {
-                return false;
-            } else {
-                return a < b;
-            }
-        }
-    }
-
-    std::optional<fs::path> Song::full_cover_path() const {
-        if (cover) {
-            return folder/cover.value();
-        } else {
-            return {};
-        } 
-    }
-
-    SongList::SongList::SongList() {
-
-        // Loading all song metadata
-        for (const auto& folder : getSongFolders()) {
-            try {
-                songs.emplace_back(folder);
-            } catch (const std::exception& e) {
-                std::cerr << "Exception while parsing song folder "
-                << folder.string() << " : " << e.what() << '\n';
-                continue;
-            }
-        }
-    }
-
-
-    const std::vector<fs::path> getSongFolders() {
-
-        std::vector<fs::path> potential_song_folders;
-        fs::path song_folder = "songs/";
-
-        if (fs::exists(song_folder) and fs::is_directory(song_folder)) {
-            for (const auto& dir_item : fs::directory_iterator("songs/")) {
-                if (dir_item.is_directory()) {
-                    for (auto& path : recursiveSongSearch(dir_item.path())) {
-                        potential_song_folders.push_back(path);
-                    }
-                }
-            }
-        }
-
-        return potential_song_folders;
-    }
-
-    std::list<fs::path> recursiveSongSearch(fs::path song_or_pack) {
-        std::list<fs::path> res;
-        fs::directory_iterator folder{song_or_pack};
-        if (
-            std::any_of(
-                fs::begin(folder),
-                fs::end(folder),
-                [](const fs::directory_entry& de) {
-                    return de.path().extension() == ".memo" or
-                    de.path().extension() == ".memon";
-                }
-            )
-        ) {
-            res.push_back(song_or_pack);
-            return res;
-        } else {
-            for (auto& p : fs::directory_iterator(song_or_pack)) {
-                if (p.is_directory()) {
-                    res.splice(res.end(), recursiveSongSearch(p));
-                }
-            }
-            return res;
-        }
-    }
-
-    Song::Song(fs::path song_folder) :
-        folder(song_folder)
-    {
-        
-        // .memon ?
-        auto memon_files = getMemonFiles(song_folder);
-        if (not memon_files.empty()) {
-            if (memon_files.size() > 1) {
-                throw std::invalid_argument("Multiple .memon files");
-            } else {
-                stepland::memon m;
-                std::ifstream file(memon_files.back());
-                file >> m;
-                this->title = m.song_title;
-                this->artist = m.artist;
-                if (not m.album_cover_path.empty()) {
-                    this->cover.emplace(m.album_cover_path);
-                }
-                if (not m.music_path.empty()) {
-                    this->audio.emplace(m.music_path);
-                }
-                for (const auto& [difficulty, chart] : m.charts) {
-                    this->chart_levels[difficulty] = chart.level;
-                }
-            }
-        } else {
-            // .memo ?
-            auto memo_files = getMemoFiles(song_folder);
-            if (not memo_files.empty()) {
-                throw std::invalid_argument("jujube does not support .memo files for now ...");
-            } else {
-                throw std::invalid_argument("No valid file found in song folder");
-            }
-        }
-    }
-
-    const std::vector<fs::path> getMemoFiles(fs::path song_folder) {
-        std::vector<fs::path> res;
-        for (const auto& p : fs::directory_iterator(song_folder)) {
-            if (p.path().extension() == ".memo") {
-                res.push_back(p.path());
-            }
-        }
-        return res;
-    }
-
-    const std::vector<fs::path> getMemonFiles(fs::path song_folder) {
-        std::vector<fs::path> res;
-        for (const auto& p : fs::directory_iterator(song_folder)) {
-            if (p.path().extension() == ".memon") {
-                res.push_back(p.path());
-            }
-        }
-        return res;
-    }
-
-}
diff --git a/src/Main.cpp b/src/Main.cpp
index 1da828f..96b691a 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -4,7 +4,7 @@
 #include <SFML/Graphics.hpp>
 #include <cereal/archives/json.hpp>
 
-#include "Data/SongList.hpp"
+#include "Data/Song.hpp"
 #include "Data/Preferences.hpp"
 // #include "Data/Chart.hpp"
 // #include "Data/Score.hpp"
diff --git a/src/Screens/MusicSelect/DensityGraph.cpp b/src/Screens/MusicSelect/DensityGraph.cpp
new file mode 100644
index 0000000..8e3db2a
--- /dev/null
+++ b/src/Screens/MusicSelect/DensityGraph.cpp
@@ -0,0 +1,49 @@
+#include "DensityGraph.hpp"
+
+#include <algorithm>
+#include <functional>
+
+#include <SFML/Audio.hpp>
+
+namespace Data {
+
+    DensityGraph compute_density_graph_1(const SongDifficulty& sd) {
+        return compute_density_graph_2(sd.song, sd.difficulty);
+    }
+
+    DensityGraph compute_density_graph_2(const Song& song, const std::string& difficulty) {
+        auto c = song.get_chart(difficulty);
+        if (not c.has_value()) {
+            throw std::invalid_argument("Song "+song.title+" has no "+difficulty+" chart");
+        }
+        if (not song.audio.has_value()) {
+            return compute_density_graph_3(*c, c->notes.begin()->timing, c->notes.rbegin()->timing);
+        }
+        sf::Music m;
+        if (not m.openFromFile(*song.full_audio_path())) {
+            return compute_density_graph_3(*c, c->notes.begin()->timing, c->notes.rbegin()->timing);
+        }
+        return compute_density_graph_3(
+            *c,
+            std::min(0L, c->notes.begin()->timing),
+            std::max(c->notes.rbegin()->timing, static_cast<long>(m.getDuration().asMilliseconds()*3/10))
+        );
+    }
+
+    DensityGraph compute_density_graph_3(const Chart& chart, long start, long end) {
+        DensityGraph d{};
+        if (start != end) {
+            for (auto &&note : chart.notes) {
+                auto index = (note.timing-start)*115/(end-start);
+                d.at(index) += 1;
+            }
+            std::replace_if(
+                d.begin(),
+                d.end(),
+                std::bind(std::greater<unsigned int>(), std::placeholders::_1, 8),
+                8
+            );
+        }
+        return d;
+    }
+}
diff --git a/src/Screens/MusicSelect/DensityGraph.hpp b/src/Screens/MusicSelect/DensityGraph.hpp
new file mode 100644
index 0000000..0b4810d
--- /dev/null
+++ b/src/Screens/MusicSelect/DensityGraph.hpp
@@ -0,0 +1,41 @@
+#pragma once
+
+#include <array>
+#include <tuple>
+
+#include "../../Data/Chart.hpp"
+#include "../../Data/Song.hpp"
+#include "../../Toolkit/Cache.hpp"
+
+namespace Data {
+    using DensityGraph = std::array<unsigned int, 115>;
+
+    struct SongDifficulty {
+        const Song& song;
+        const std::string& difficulty;
+
+        bool operator==(const SongDifficulty &other) const {
+            return (
+                song.folder == other.song.folder and
+                difficulty == other.difficulty
+            );
+        }
+    };
+
+    DensityGraph compute_density_graph_1(const SongDifficulty& sd);
+    DensityGraph compute_density_graph_2(const Song& song, const std::string& difficulty);
+    DensityGraph compute_density_graph_3(const Chart& chart, long start, long end);
+
+    using DensityGraphCache = Toolkit::Cache<SongDifficulty, DensityGraph, &compute_density_graph_1>;
+}
+
+namespace std {
+    template <>
+    struct hash<Data::SongDifficulty> {
+        std::size_t operator()(const Data::SongDifficulty& sd) const {
+            auto song_hash = std::hash<std::string>()(sd.song.folder.string());
+            song_hash ^= std::hash<std::string>()(sd.difficulty) + 0x9e3779b9 + (song_hash<<6) + (song_hash>>2);
+            return song_hash;
+        }
+    };
+}
\ No newline at end of file
diff --git a/src/Screens/MusicSelect/MusicSelect.hpp b/src/Screens/MusicSelect/MusicSelect.hpp
index 3fa11ef..54190ca 100644
--- a/src/Screens/MusicSelect/MusicSelect.hpp
+++ b/src/Screens/MusicSelect/MusicSelect.hpp
@@ -4,7 +4,7 @@
 
 #include <SFML/Window.hpp>
 
-#include "../../Data/SongList.hpp"
+#include "../../Data/Song.hpp"
 #include "../../Data/Chart.hpp"
 #include "../../Data/KeyMapping.hpp"
 #include "../../Toolkit/AffineTransform.hpp"
diff --git a/src/Screens/MusicSelect/Panel.cpp b/src/Screens/MusicSelect/Panel.cpp
index 7c38883..b1e1585 100644
--- a/src/Screens/MusicSelect/Panel.cpp
+++ b/src/Screens/MusicSelect/Panel.cpp
@@ -69,22 +69,22 @@ namespace MusicSelect {
     void SongPanel::click(Ribbon& ribbon, std::size_t from_button_index) {
         if (selected_chart.has_value()) {
             // The song was already selected : look for the next chart in order
-            auto it = m_song.chart_levels.upper_bound(*selected_chart);
-            if (it != m_song.chart_levels.cend()) {
+            auto it = m_song->chart_levels.upper_bound(*selected_chart);
+            if (it != m_song->chart_levels.cend()) {
                 selected_chart = it->first;
             } else {
-                selected_chart = m_song.chart_levels.cbegin()->first;
+                selected_chart = m_song->chart_levels.cbegin()->first;
             }
             m_resources.selected_panel->last_click.restart();
             m_resources.selected_panel->is_first_click = false;
         } else {
             // Look for the first chart with dif greater or equal to the last select one
             // or else select the first chart
-            auto it = m_song.chart_levels.lower_bound(m_resources.get_last_selected_chart());
-            if (it != m_song.chart_levels.cend()) {
+            auto it = m_song->chart_levels.lower_bound(m_resources.get_last_selected_difficulty());
+            if (it != m_song->chart_levels.cend()) {
                 selected_chart = it->first;
             } else {
-                selected_chart = m_song.chart_levels.cbegin()->first;
+                selected_chart = m_song->chart_levels.cbegin()->first;
             }
             // The song was not selected before : first unselect the last one
             if (m_resources.selected_panel.has_value()) {
@@ -100,7 +100,7 @@ namespace MusicSelect {
 
     std::optional<ChartSelection> SongPanel::get_selected_chart() const {
         if (selected_chart) {
-            return ChartSelection{m_song, *selected_chart};
+            return ChartSelection{*m_song, *selected_chart};
         } else {
             return {};
         }
@@ -108,11 +108,11 @@ namespace MusicSelect {
 
     void SongPanel::draw(sf::RenderTarget& target, sf::RenderStates states) const {
         states.transform *= getTransform();
-        auto last_selected_chart = m_resources.get_last_selected_chart();
+        auto last_selected_chart = m_resources.get_last_selected_difficulty();
         // We should gray out the panel if the currently selected difficulty doesn't exist for this song
-        bool should_be_grayed_out = m_song.chart_levels.find(last_selected_chart) == m_song.chart_levels.end();
-        if (m_song.cover) {
-            auto loaded_texture = m_resources.covers.async_get(m_song.folder/m_song.cover.value());
+        bool should_be_grayed_out = m_song->chart_levels.find(last_selected_chart) == m_song->chart_levels.end();
+        if (m_song->cover) {
+            auto loaded_texture = m_resources.covers.async_get(m_song->folder/m_song->cover.value());
             if (loaded_texture) {
                 sf::Sprite cover{*(loaded_texture->texture)};
                 auto alpha = static_cast<std::uint8_t>(
@@ -140,7 +140,7 @@ namespace MusicSelect {
         }
         target.draw(chart_dif_badge, states);
         if (not should_be_grayed_out) {
-            auto dif = m_song.chart_levels.at(last_selected_chart);
+            auto dif = m_song->chart_levels.at(last_selected_chart);
             sf::Text dif_label{
                 std::to_string(dif),
                 m_resources.noto_sans_medium,
@@ -153,7 +153,7 @@ namespace MusicSelect {
         }
         sf::Text song_title;
         song_title.setFont(m_resources.noto_sans_medium);
-        song_title.setString(m_song.title);
+        song_title.setString(m_song->title);
         song_title.setCharacterSize(static_cast<unsigned int>(0.06875f*get_size()));
         song_title.setFillColor(sf::Color::White);
         auto song_title_bounds = song_title.getLocalBounds();
diff --git a/src/Screens/MusicSelect/Panel.hpp b/src/Screens/MusicSelect/Panel.hpp
index 449bd08..eddbe0a 100644
--- a/src/Screens/MusicSelect/Panel.hpp
+++ b/src/Screens/MusicSelect/Panel.hpp
@@ -6,7 +6,7 @@
 #include <SFML/Graphics.hpp>
 #include <SFML/Window.hpp>
 
-#include "../../Data/SongList.hpp"
+#include "../../Data/Song.hpp"
 #include "../../Toolkit/AffineTransform.hpp"
 #include "SharedResources.hpp"
 
@@ -64,7 +64,7 @@ namespace MusicSelect {
 
     struct ChartSelection {
         const Data::Song& song;
-        const std::string& chart;
+        const std::string& difficulty;
     };
 
     class SelectablePanel : public Panel {
@@ -77,13 +77,13 @@ namespace MusicSelect {
 
     class SongPanel final : public SelectablePanel {
     public:
-        explicit SongPanel(SharedResources& resources, const Data::Song& t_song) : SelectablePanel(resources), m_song(t_song) {};
+        explicit SongPanel(SharedResources& resources, const std::shared_ptr<const Data::Song>& t_song) : SelectablePanel(resources), m_song(t_song) {};
         void click(Ribbon& ribbon, std::size_t from_button_index) override;
         void unselect() override;
         std::optional<ChartSelection> get_selected_chart() const override;
     private:
         void draw(sf::RenderTarget& target, sf::RenderStates states) const override;
-        const Data::Song& m_song;
+        std::shared_ptr<const Data::Song> m_song;
         const Toolkit::AffineTransform<float> m_seconds_to_alpha{0.0f, 0.15f, 0.f, 255.f};
         std::optional<std::string> selected_chart;
     };
diff --git a/src/Screens/MusicSelect/Ribbon.cpp b/src/Screens/MusicSelect/Ribbon.cpp
index 36c094d..49958ad 100644
--- a/src/Screens/MusicSelect/Ribbon.cpp
+++ b/src/Screens/MusicSelect/Ribbon.cpp
@@ -10,7 +10,7 @@
 #include <vector>
 
 #include "Panel.hpp"
-#include "../../Data/SongList.hpp"
+#include "../../Data/Song.hpp"
 #include "../../Toolkit/QuickRNG.hpp"
 
 
@@ -69,15 +69,19 @@ namespace MusicSelect {
     }
 
     void Ribbon::title_sort(const Data::SongList &song_list) {
-        std::vector<std::reference_wrapper<const Data::Song>> songs;
+        std::vector<std::shared_ptr<const Data::Song>> songs;
         for (auto &&song : song_list.songs) {
-            songs.push_back(std::cref(song));
+            songs.push_back(song);
         }
-        std::sort(songs.begin(), songs.end(), Data::Song::sort_by_title);
+        std::sort(
+            songs.begin(),
+            songs.end(),
+            [](std::shared_ptr<const Data::Song> a, std::shared_ptr<const Data::Song> b){return Data::Song::sort_by_title(*a, *b);}
+        );
         std::map<std::string, std::vector<std::shared_ptr<Panel>>> categories;
         for (const auto &song : songs) {
-            if (song.get().title.size() > 0) {
-                char letter = song.get().title[0];
+            if (song->title.size() > 0) {
+                char letter = song->title[0];
                 if ('A' <= letter and letter <= 'Z') {
                     categories
                     [std::string(1, letter)]
@@ -140,21 +144,6 @@ namespace MusicSelect {
         layout_from_category_map(categories);
     }
 
-    void Ribbon::test_song_cover_sort() {
-        std::string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
-        std::map<std::string, std::vector<std::shared_ptr<Panel>>> categories;
-        Toolkit::UniformIntRNG category_size_generator{1, 10};
-        for (auto &&letter : alphabet) {
-            auto category_size = category_size_generator.generate();
-            for (int i = 0; i < category_size; i++) {
-                categories[std::string(1, letter)].push_back(
-                    std::make_shared<SongPanel>(m_resources, this->empty_song)
-                );
-            }
-        }
-        layout_from_category_map(categories);
-    }
-
 
     std::size_t Ribbon::get_layout_column(const std::size_t& button_index) const {
         return (m_position + (button_index % 4)) % m_layout.size();
diff --git a/src/Screens/MusicSelect/Ribbon.hpp b/src/Screens/MusicSelect/Ribbon.hpp
index 5cd8471..afdda35 100644
--- a/src/Screens/MusicSelect/Ribbon.hpp
+++ b/src/Screens/MusicSelect/Ribbon.hpp
@@ -6,7 +6,7 @@
 #include <SFML/Graphics/Transformable.hpp>
 
 #include "../../Data/Preferences.hpp"
-#include "../../Data/SongList.hpp"
+#include "../../Data/Song.hpp"
 #include "../../Toolkit/AffineTransform.hpp"
 #include "../../Toolkit/Debuggable.hpp"
 #include "../../Toolkit/EasingFunctions.hpp"
@@ -59,6 +59,5 @@ namespace MusicSelect {
         std::size_t m_position = 0;
         mutable std::optional<MoveAnimation> m_move_animation;
         float m_time_factor = 1.f;
-        Data::Song empty_song;
     };
 }
\ No newline at end of file
diff --git a/src/Screens/MusicSelect/SharedResources.cpp b/src/Screens/MusicSelect/SharedResources.cpp
index 09b4264..e786843 100644
--- a/src/Screens/MusicSelect/SharedResources.cpp
+++ b/src/Screens/MusicSelect/SharedResources.cpp
@@ -22,11 +22,11 @@ namespace MusicSelect {
         std::cout << "Loaded MusicSelect::SharedResources" << std::endl;
     }
 
-    std::string SharedResources::get_last_selected_chart() {
-        return get_selected_chart().value_or("BSC");
+    std::string SharedResources::get_last_selected_difficulty() {
+        return get_selected_difficulty().value_or("BSC");
     }
 
-    std::optional<std::string> SharedResources::get_selected_chart() {
+    std::optional<std::string> SharedResources::get_selected_difficulty() {
         if (not selected_panel.has_value()) {
             return {};
         }
@@ -34,7 +34,7 @@ namespace MusicSelect {
         if (not chart_selection.has_value()) {
             return {};
         }
-        return chart_selection->chart;
+        return chart_selection->difficulty;
     }
 
     std::optional<std::reference_wrapper<const Data::Song>> MusicSelect::SharedResources::get_selected_song() {
diff --git a/src/Screens/MusicSelect/SharedResources.hpp b/src/Screens/MusicSelect/SharedResources.hpp
index 42a03d2..2e2c45c 100644
--- a/src/Screens/MusicSelect/SharedResources.hpp
+++ b/src/Screens/MusicSelect/SharedResources.hpp
@@ -8,7 +8,9 @@
 
 #include "../../Resources/TextureCache.hpp"
 #include "../../Data/Preferences.hpp"
-#include "../../Data/SongList.hpp"
+#include "../../Data/Song.hpp"
+
+#include "DensityGraph.hpp"
 
 namespace MusicSelect {
 
@@ -31,10 +33,12 @@ namespace MusicSelect {
         sf::Texture fallback_cover;
         
         sf::Font noto_sans_medium;
+
+        Data::DensityGraphCache density_graphs;
         
         std::optional<TimedSelectedPanel> selected_panel;
-        std::string get_last_selected_chart();
-        std::optional<std::string> get_selected_chart();
+        std::string get_last_selected_difficulty();
+        std::optional<std::string> get_selected_difficulty();
         std::optional<std::reference_wrapper<const Data::Song>> get_selected_song();
 
         sf::Color BSC_color = sf::Color{34,216,92};
diff --git a/src/Screens/MusicSelect/SongInfo.cpp b/src/Screens/MusicSelect/SongInfo.cpp
index 913b5f3..ed259f8 100644
--- a/src/Screens/MusicSelect/SongInfo.cpp
+++ b/src/Screens/MusicSelect/SongInfo.cpp
@@ -52,9 +52,10 @@ namespace MusicSelect {
         target.draw(cover, states);
     }
 
-    SongInfo::SongInfo(SharedResources& resources) : HoldsSharedResources(resources), m_big_cover(resources) {
-
-    }
+    SongInfo::SongInfo(SharedResources& resources) :
+        HoldsSharedResources(resources),
+        m_big_cover(resources)
+    {}
 
     void SongInfo::draw(sf::RenderTarget& target, sf::RenderStates states) const {
         states.transform *= getTransform();
@@ -142,7 +143,7 @@ namespace MusicSelect {
         target.draw(level_label, states);
         
         sf::Text level_number_label{
-            std::to_string(selected_chart->song.chart_levels.at(selected_chart->chart)),
+            std::to_string(selected_chart->song.chart_levels.at(selected_chart->difficulty)),
             m_resources.noto_sans_medium,
             static_cast<unsigned int>(130.f/768.f*get_screen_width())
         };
@@ -151,23 +152,23 @@ namespace MusicSelect {
         level_number_label.setFillColor(sf::Color::White);
         target.draw(level_number_label, states);
 
-        std::string full_chart_name = selected_chart->chart;
-        if (selected_chart->chart == "BSC") {
-            full_chart_name = "BASIC";
-        } else if (selected_chart->chart == "ADV") {
-            full_chart_name = "ADVANCED";
-        } else if (selected_chart->chart == "EXT") {
-            full_chart_name = "EXTREME";
+        std::string full_difficulty = selected_chart->difficulty;
+        if (selected_chart->difficulty == "BSC") {
+            full_difficulty = "BASIC";
+        } else if (selected_chart->difficulty == "ADV") {
+            full_difficulty = "ADVANCED";
+        } else if (selected_chart->difficulty == "EXT") {
+            full_difficulty = "EXTREME";
         }
 
         sf::Text chart_label{
-            full_chart_name,
+            full_difficulty,
             m_resources.noto_sans_medium,
             static_cast<unsigned int>(20.f/768.f*get_screen_width())
         };
         Toolkit::set_origin_normalized_no_position(chart_label, 0.5f, 0.f);
         chart_label.setPosition(get_big_level_x(), get_big_level_y()+(145.f/768.f*get_screen_width()));
-        chart_label.setFillColor(m_resources.get_chart_color(selected_chart->chart));
+        chart_label.setFillColor(m_resources.get_chart_color(selected_chart->difficulty));
         target.draw(chart_label, states);
     }
 
@@ -185,13 +186,13 @@ namespace MusicSelect {
         auto dif_badge_y = 40.f/768.f*get_screen_width();
         auto dif_badge_step = 3.f*dif_badge_radius;
         std::size_t dif_index = 0;
-        for (auto &&[chart_name, level] : selected_chart->song.chart_levels) {
+        for (auto &&[difficulty, level] : selected_chart->song.chart_levels) {
             sf::CircleShape dif_badge{dif_badge_radius};
             Toolkit::set_origin_normalized(dif_badge, 0.5f, 0.5f);
-            dif_badge.setFillColor(m_resources.get_chart_color(chart_name));
+            dif_badge.setFillColor(m_resources.get_chart_color(difficulty));
             dif_badge.setPosition(dif_badge_x+dif_index*dif_badge_step, dif_badge_y);
             target.draw(dif_badge, states);
-            if (chart_name == selected_chart->chart) {
+            if (difficulty == selected_chart->difficulty) {
                 sf::CircleShape select_triangle(dif_badge_radius, 3);
                 Toolkit::set_origin_normalized(select_triangle, 0.5f, 0.5f);
                 select_triangle.rotate(180.f);