Qt: Allow rebinding keyboard controls (#779)

* Initial input UI draft

Co-Authored-By: Paris Oplopoios <parisoplop@gmail.com>

* More keybinding work

Co-Authored-By: Paris Oplopoios <parisoplop@gmail.com>

* Nit

Co-Authored-By: Paris Oplopoios <parisoplop@gmail.com>

* More nits

Co-Authored-By: Paris Oplopoios <parisoplop@gmail.com>

---------

Co-authored-by: Paris Oplopoios <parisoplop@gmail.com>

include/input_mappings.hpp

@@ -1,5 +1,10 @@
 #pragma once
 
+#include <filesystem>
+#include <fstream>
+#include <map>
+#include <optional>
+#include <toml.hpp>
 #include <unordered_map>
 
 #include "helpers.hpp"
@@ -15,8 +20,108 @@ struct InputMappings {
 	}
 
 	void setMapping(Scancode scancode, u32 key) { container[scancode] = key; }
+
+	template <typename ScancodeToString>
+	void serialize(const std::filesystem::path& path, const std::string& frontend, ScancodeToString scancodeToString) const {
+		toml::basic_value<toml::preserve_comments, std::map> data;
+
+		std::error_code error;
+		if (std::filesystem::exists(path, error)) {
+			try {
+				data = toml::parse<toml::preserve_comments, std::map>(path);
+			} catch (const std::exception& ex) {
+				Helpers::warn("Exception trying to parse mappings file. Exception: %s\n", ex.what());
+				return;
+			}
+		} else {
+			if (error) {
+				Helpers::warn("Filesystem error accessing %s (error: %s)\n", path.string().c_str(), error.message().c_str());
+			}
+			printf("Saving new mappings file %s\n", path.string().c_str());
+		}
+
+		data["Metadata"]["Name"] = name.empty() ? "Unnamed Mappings" : name;
+		data["Metadata"]["Device"] = device.empty() ? "Unknown Device" : device;
+		data["Metadata"]["Frontend"] = frontend;
+
+		data["Mappings"] = toml::table{};
+
+		for (const auto& [scancode, key] : container) {
+			const std::string& keyName = HID::Keys::keyToName(key);
+			if (!data["Mappings"].contains(keyName)) {
+				data["Mappings"][keyName] = toml::array{};
+			}
+			data["Mappings"][keyName].push_back(scancodeToString(scancode));
+		}
+
+		std::ofstream file(path, std::ios::out);
+		file << data;
+	}
+
+	template <typename ScancodeFromString>
+	static std::optional<InputMappings> deserialize(
+		const std::filesystem::path& path, const std::string& wantFrontend, ScancodeFromString stringToScancode
+	) {
+		toml::basic_value<toml::preserve_comments, std::map> data;
+		std::error_code error;
+
+		if (!std::filesystem::exists(path, error)) {
+			if (error) {
+				Helpers::warn("Filesystem error accessing %s (error: %s)\n", path.string().c_str(), error.message().c_str());
+			}
+
+			return std::nullopt;
+		}
+
+		InputMappings mappings;
+
+		try {
+			data = toml::parse<toml::preserve_comments, std::map>(path);
+
+			const auto metadata = toml::find(data, "Metadata");
+			mappings.name = toml::find_or<std::string>(metadata, "Name", "Unnamed Mappings");
+			mappings.device = toml::find_or<std::string>(metadata, "Device", "Unknown Device");
+
+			std::string haveFrontend = toml::find_or<std::string>(metadata, "Frontend", "Unknown Frontend");
+
+			bool equal = std::equal(haveFrontend.begin(), haveFrontend.end(), wantFrontend.begin(), wantFrontend.end(), [](char a, char b) {
+				return std::tolower(a) == std::tolower(b);
+			});
+
+			if (!equal) {
+				Helpers::warn(
+					"Mappings file %s was created for frontend %s, but we are using frontend %s\n", path.string().c_str(), haveFrontend.c_str(),
+					wantFrontend.c_str()
+				);
+
+				return std::nullopt;
+			}
+		} catch (const std::exception& ex) {
+			Helpers::warn("Exception trying to parse config file. Exception: %s\n", ex.what());
+			return std::nullopt;
+		}
+
+		const auto& mappingsTable = toml::find_or<toml::table>(data, "Mappings", toml::table{});
+		for (const auto& [keyName, scancodes] : mappingsTable) {
+			for (const auto& scancodeVal : scancodes.as_array()) {
+				std::string scancodeStr = scancodeVal.as_string();
+				mappings.setMapping(stringToScancode(scancodeStr), HID::Keys::nameToKey(keyName));
+			}
+		}
+
+		return mappings;
+	}
+
 	static InputMappings defaultKeyboardMappings();
 
+	auto begin() { return container.begin(); }
+	auto end() { return container.end(); }
+
+	auto begin() const { return container.begin(); }
+	auto end() const { return container.end(); }
+
   private:
 	Container container;
+	std::string name;
+	std::string device;
 };