Port changes from -x repo (#3)

* Port config support from -x repo

* Port changes from -x repo

src/config_io.rs

@@ -0,0 +1,71 @@
+use log::error;
+use once_cell::sync::Lazy;
+use std::{
+    fs::{self, create_dir},
+    path::PathBuf,
+};
+
+const FALLBACK_CONFIG_PATH: &str = "/tmp/wlxoverlay";
+
+pub static CONFIG_ROOT_PATH: Lazy<PathBuf> = Lazy::new(|| {
+    if let Ok(xdg_dirs) = xdg::BaseDirectories::new() {
+        let mut dir = xdg_dirs.get_config_home();
+        dir.push("wlxoverlay");
+        return dir;
+    }
+    //Return fallback config path
+    error!(
+        "Err: Failed to find config path, using {}",
+        FALLBACK_CONFIG_PATH
+    );
+    PathBuf::from(FALLBACK_CONFIG_PATH)
+});
+
+pub fn get_conf_d_path() -> PathBuf {
+    let mut config_root = CONFIG_ROOT_PATH.clone();
+    config_root.push("conf.d");
+    config_root
+}
+
+// Make sure config directory is present and return root config path
+pub fn ensure_config_root() -> PathBuf {
+    let path = CONFIG_ROOT_PATH.clone();
+    let _ = create_dir(&path);
+
+    let path_conf_d = get_conf_d_path();
+    let _ = create_dir(path_conf_d);
+    path
+}
+
+fn get_config_file_path(filename: &str) -> PathBuf {
+    let mut config_root = CONFIG_ROOT_PATH.clone();
+    config_root.push(filename);
+    config_root
+}
+
+pub fn load(filename: &str) -> Option<String> {
+    let path = get_config_file_path(filename);
+    println!("Loading config {}", path.to_string_lossy());
+
+    if let Ok(data) = fs::read_to_string(path) {
+        Some(data)
+    } else {
+        None
+    }
+}
+
+#[macro_export]
+macro_rules! load_with_fallback {
+    ($filename: expr,  $fallback: expr) => {
+        if let Some(data) = config_io::load($filename) {
+            data
+        } else {
+            println!(
+                "Config {}/{} does not exist, using internal fallback",
+                config_io::CONFIG_ROOT_PATH.to_string_lossy(),
+                $filename
+            );
+            include_str!($fallback).to_string()
+        }
+    };
+}