diff --git a/src/main.rs b/src/main.rs
index afdf455..98fe9f1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,65 +1,64 @@
-use serde::{Deserialize, Serialize};
-use serde_json::Value;
 use std::{env, fs, path::Path, process};
 
+use crate::utils::save_library;
+
+mod structs;
+mod utils;
+
 fn main() {
     let mut args = env::args();
     let _binary = args.next();
-
-    while let Some(arg) = args.next() {
-        match arg.as_str() {
-            "add" => add(&mut args),
-            _other => println!("needs parameters"),
+    let mut library = match utils::deserialize_state_file() {
+        Ok(library) => library,
+        Err(e) => {
+            eprintln!("Error creating library: {}", e);
+            process::exit(1)
         }
+    };
+
+    if let Some(arg) = args.next() {
+        match arg.as_str() {
+            "add" => add_file(&mut args, &mut library),
+            "ls" => list_library(&mut library),
+            &_ => println!("no command"),
+        }
+    } else {
+        println!("no parameters")
     }
-    return;
+    dbg!(&library);
+    save_library(library);
+    process::exit(0);
 }
 
-fn deserialize_var() -> Library {
-    let key = "HOME";
-    let content: Library = match env::var(key) {
-        Ok(val) => match serde_json::from_str(&val) {
-            Ok(library) => library,
-            Err(..) => initialize_library(),
-        },
-        Err(..) => initialize_library(),
-    };
-    return content;
+fn list_library(library: &mut structs::Library) {
+    let current_shelf_index =
+        utils::get_shelf_index(&library.shelves, &library.current_shelf).unwrap_or(0);
+    let current_shelf = &library.shelves[current_shelf_index];
+    println!("Shelves: {}", library.shelves.len());
+    println!("Current Shelf: {}", &current_shelf.name);
+    println!("Content: ");
+    for path in &current_shelf.content {
+        println!()
+    }
 }
 
-fn initialize_library() -> Library {
-    let default_shelf: Shelf = Shelf {
-        id: 0,
-        name: "default".to_string(),
-        content: Vec::new(),
-    };
-
-    let mut shelf_vec: Vec<Shelf> = Vec::new();
-    shelf_vec.push(default_shelf);
-    let default_library: Library = Library {
-        current_shelf: 0,
-        shelves: shelf_vec,
-    };
-    return default_library;
-}
-
-fn add(args: &mut env::Args) {
+fn add_file(args: &mut env::Args, library: &mut structs::Library) {
     for file in args {
         println!("Adding {}", &file);
         let file_path = Path::new(&file);
+        let absolute_path = Path::canonicalize(&file_path).expect("No Such File");
+
+        println!("Current path: {}", absolute_path.to_str().unwrap());
+
+        let shelves = &library.shelves;
+        let current_shelf = &library.current_shelf;
+        let shelf_index = utils::get_shelf_index(shelves, current_shelf).unwrap_or(0);
+
+        let current_shelf = &mut library.shelves[*&shelf_index];
+        current_shelf
+            .content
+            .push(absolute_path.to_str().unwrap().to_string())
     }
-    process::exit(0)
-}
-
-#[derive(Default, Deserialize, Serialize)]
-struct Library {
-    current_shelf: u16,
-    shelves: Vec<Shelf>,
-}
-
-#[derive(Deserialize, Serialize)]
-struct Shelf {
-    id: u64,
-    name: String,
-    content: Vec<String>,
+    // process::exit(0)
+    return;
 }
diff --git a/src/structs.rs b/src/structs.rs
new file mode 100644
index 0000000..3204c03
--- /dev/null
+++ b/src/structs.rs
@@ -0,0 +1,14 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Default, Deserialize, Serialize, Debug)]
+pub struct Library {
+    pub current_shelf: u8,
+    pub shelves: Vec<Shelf>,
+}
+
+#[derive(Deserialize, Serialize, Debug)]
+pub struct Shelf {
+    pub id: u8,
+    pub name: String,
+    pub content: Vec<String>,
+}
diff --git a/src/utils.rs b/src/utils.rs
new file mode 100644
index 0000000..efd6fe9
--- /dev/null
+++ b/src/utils.rs
@@ -0,0 +1,60 @@
+use crate::structs::{Library, Shelf};
+use std::{env, fs, io, io::Read};
+use xdg::BaseDirectories;
+
+pub fn get_shelf_index(shelves: &Vec<Shelf>, id: &u8) -> Option<usize> {
+    shelves.iter().position(|shelf| shelf.id == *id)
+}
+
+pub fn deserialize_state_file() -> io::Result<Library> {
+    let xdg_dirs = get_xdg();
+    let state_file_path = xdg_dirs.place_state_file("shelf-state.json")?;
+
+    let state_file_content = match fs::read_to_string(state_file_path) {
+        Ok(content) => content,
+        Err(e) => {
+            eprintln!("Could not read state file: {}", e);
+            return Ok(initialize_library());
+        }
+    };
+
+    let state_file_decoded: Library = serde_json::from_str(&state_file_content)?;
+
+    Ok(state_file_decoded)
+}
+
+pub fn get_xdg() -> BaseDirectories {
+    let xdg_dirs = xdg::BaseDirectories::with_prefix("shelf");
+    return xdg_dirs;
+}
+
+pub fn get_state_file() -> io::Result<std::path::PathBuf> {
+    let xdg_dirs = get_xdg();
+    let state_file_path = xdg_dirs.place_state_file("shelf-state.json")?;
+    Ok(state_file_path)
+}
+
+pub fn save_library(library: Library) -> io::Result<()> {
+    let seralized_library = serde_json::to_string(&library).unwrap_or_default();
+    let state_file = get_state_file()?;
+
+    fs::write(state_file, seralized_library)?;
+
+    Ok(())
+}
+
+pub fn initialize_library() -> Library {
+    let default_shelf: Shelf = Shelf {
+        id: 0,
+        name: "default".to_string(),
+        content: Vec::new(),
+    };
+
+    let mut shelf_vec: Vec<Shelf> = Vec::new();
+    shelf_vec.push(default_shelf);
+    let default_library: Library = Library {
+        current_shelf: 0,
+        shelves: shelf_vec,
+    };
+    return default_library;
+}