Now have a simple color palette system.

palette.cpp

@@ -0,0 +1,40 @@
+#include <fmt/core.h>
+#include "palette.hpp"
+#include "config.hpp"
+#include "dbc.hpp"
+
+namespace palette {
+  using std::string;
+  using nlohmann::json;
+
+  struct PaletteMgr {
+    std::unordered_map<string, sf::Color> palettes;
+  };
+
+  static PaletteMgr COLOR;
+
+  void init(const string &json_file) {
+    Config config(json_file);
+    json& colors = config.json();
+
+    for(auto [key, value_specs] : colors.items()) {
+      const string& base_key = key;
+
+      for(auto [value, rgba] : value_specs.items()) {
+        auto color_path = base_key + ":" + value;
+        dbc::check(!COLOR.palettes.contains(color_path),
+            fmt::format("PALLETES already has a color path {}", color_path));
+
+        uint8_t alpha = rgba.size() == 3 ? 255 : (uint8_t)rgba[3];
+
+        sf::Color color{rgba[0], rgba[1], rgba[2], alpha};
+
+        COLOR.palettes.try_emplace(color_path, color);
+      }
+    }
+  }
+
+  sf::Color get(const string& key) {
+    return COLOR.palettes.at(key);
+  }
+}