diff --git a/sample.ts b/sample.ts
new file mode 100644
index 0000000..14c6a46
--- /dev/null
+++ b/sample.ts
@@ -0,0 +1,29 @@
+function add(foo: any, bar: any): any { // todo@types
+    return foo + bar;
+}
+
+function subtract(foo: any, bar: any): any { // todo@types add types
+    return foo - bar;
+}
+
+function hello() {
+    // console.log("Hello world!"); // todo000
+}
+
+function hello_world() {
+    // todo00 add return typehint
+    console.log("Hello world!");
+}
+
+function greet(name: any) {
+    // todo0 add name typehint
+    console.log(`Hello ${name}`);
+}
+
+function greet2(name: string) { // todo1 add return typehint
+    console.log(`Hello ${name}`);
+}
+
+function echo(str: string) { // todo2 add return typehint
+    console.log(str);
+}
diff --git a/src/main.rs b/src/main.rs
index e7a11a9..8350a92 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,399 @@
-fn main() {
-    println!("Hello, world!");
+use std::{io, fs};
+use std::path::{Path, PathBuf};
+
+#[derive(Debug, PartialEq)]
+struct Location {
+    file: PathBuf,
+    line: usize,
+}
+
+#[derive(Debug, PartialEq)]
+struct PriorityEntry {
+    text: String,
+    priority: isize,
+    location: Location,
+}
+
+#[derive(Debug, PartialEq)]
+struct CategoryEntry {
+    text: String,
+    category: String,
+    location: Location,
+}
+
+#[derive(Debug, PartialEq)]
+struct GenericEntry {
+    text: String,
+    location: Location,
+}
+
+#[derive(Debug, PartialEq)]
+enum Entry {
+    Priority(PriorityEntry),
+    Category(CategoryEntry),
+    Generic(GenericEntry),
+}
+
+fn scan_string(str: String, filename: PathBuf, entries: &mut Vec<Entry>) {
+    for (line_num, line) in str.lines().enumerate() {
+        if ! line.to_lowercase().contains("todo") {
+            continue;
+        }
+
+        for word in line.split(" ") {
+            if ! word.to_lowercase().starts_with("todo") {
+                continue;
+            }
+
+            // Handles: `todo`, `TODO`, `todo:`, `TODO:`
+            // todo `replace` isnt ideal, it should only replace *after* the todo, to avoid merging eg `to:do`
+            if word.to_lowercase().replace(':', "") == "todo" {
+                let text_dirty = line.split(word).nth(1).unwrap().replace("*/", "");
+                let text = text_dirty.trim();
+
+                entries.push(Entry::Generic(GenericEntry {
+                    text: text.to_string(),
+                    location: Location {
+                        file: filename.clone(),
+                        line: line_num + 1,
+                    }
+                }));
+
+                break;
+            }
+
+            if word.contains('@') {
+                let category = word.split('@').nth(1).unwrap();
+                let text_dirty = line.split(word).nth(1).unwrap().replace("*/", "");
+                let text = text_dirty.trim();
+
+                entries.push(Entry::Category(CategoryEntry {
+                    text: text.to_string(),
+                    category: category.to_string(),
+                    location: Location {
+                        file: filename.clone(),
+                        line: line_num + 1,
+                    },
+                }));
+
+                break;
+            }
+
+            // [0, 1, ..., 9]
+            let priority_chars: Vec<char> = (0..10).map(|int| char::from_digit(int, 10).unwrap()).collect();
+
+            if word.chars().any(|ch| priority_chars.contains(&ch)) {
+                let cleaned_word = word.to_lowercase();
+                let priority_chars = cleaned_word.split("todo").nth(1).unwrap();
+
+                let priority: isize;
+
+                if priority_chars.len() == 1 {
+                    priority = priority_chars.to_string().parse::<isize>().unwrap();
+                } else if priority_chars.chars().all(|ch| ch == '0') {
+                    // todo0: 1 - 1 = 0
+                    // todo00: 1 - 2 = -1
+                    priority = 1 - priority_chars.len() as isize;
+                } else {
+                    break; // incorrect syntax like todo11
+                }
+
+                let text_dirty = line.split(word).nth(1).unwrap().replace("*/", "");
+                let text = text_dirty.trim();
+
+                entries.push(Entry::Priority(PriorityEntry {
+                    text: text.to_string(),
+                    priority: priority,
+                    location: Location {
+                        file: filename.clone(),
+                        line: line_num + 1,
+                    }
+                }));
+            }
+        }
+    }
+}
+
+fn scan_file(path: &Path, entries: &mut Vec<Entry>) -> io::Result<()> {
+    match std::fs::read_to_string(path) {
+        Ok(str) => scan_string(str, path.to_path_buf(), entries),
+        Err(_) => (),
+    };
+
+    Ok(())
+}
+
+fn scan_dir(path: &Path, entries: &mut Vec<Entry>) -> io::Result<()> {
+    for entry in fs::read_dir(path)? {
+        let entry = entry?;
+        let path = entry.path();
+
+        if path.is_dir() {
+            scan_dir(path.as_path(), entries)?
+        } else {
+            scan_file(path.as_path(), entries)?
+        }
+    }
+
+    Ok(())
+}
+
+fn main() {
+    let root_dir: PathBuf = std::env::current_dir().unwrap(); // todo@CLI make the root dir configurable
+
+    let mut entries: Vec<Entry> = vec![];
+
+    scan_dir(root_dir.as_path(), &mut entries).unwrap();
+
+    dbg!(entries);
+}
+
+#[test]
+fn generic_test() {
+    let str = r#"
+        1
+        2
+        // todo foo
+        /* TODO: bar */
+        /*
+
+        * TODO baz
+        TODO baz2
+        TODO baz2 todo
+        */
+    "#;
+
+    let mut entries: Vec<Entry> = vec![];
+    let mut path = PathBuf::new();
+    path.push("foo.txt");
+
+    scan_string(str.to_string(), path.clone(), &mut entries);
+
+    assert_eq!(5, entries.len());
+
+    assert_eq!(Entry::Generic(GenericEntry {
+        text: String::from("foo"),
+        location: Location {
+            file: path.clone(),
+            line: 4,
+        }
+    }), entries[0]);
+
+    assert_eq!(Entry::Generic(GenericEntry {
+        text: String::from("bar"),
+        location: Location {
+            file: path.clone(),
+            line: 5,
+        }
+    }), entries[1]);
+
+    assert_eq!(Entry::Generic(GenericEntry {
+        text: String::from("baz"),
+        location: Location {
+            file: path.clone(),
+            line: 8,
+        }
+    }), entries[2]);
+
+    assert_eq!(Entry::Generic(GenericEntry {
+        text: String::from("baz2"),
+        location: Location {
+            file: path.clone(),
+            line: 9,
+        }
+    }), entries[3]);
+
+    assert_eq!(Entry::Generic(GenericEntry {
+        text: String::from("baz2 todo"),
+        location: Location {
+            file: path.clone(),
+            line: 10,
+        }
+    }), entries[4]);
+}
+
+#[test]
+fn category_test() {
+    let str = r#"
+        1
+        2
+        todo@foo
+        todo@bar abc def
+        3
+        todo@baz x y
+        4
+        // TODO@baz2 a
+        /* TODO@baz3 */
+        // TODO@baz3 b
+    "#;
+
+    let mut entries: Vec<Entry> = vec![];
+    let mut path = PathBuf::new();
+    path.push("foo.txt");
+
+    scan_string(str.to_string(), path.clone(), &mut entries);
+
+    assert_eq!(6, entries.len());
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("foo"),
+        text: String::from(""),
+        location: Location {
+            file: path.clone(),
+            line: 4,
+        }
+    }), entries[0]);
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("bar"),
+        text: String::from("abc def"),
+        location: Location {
+            file: path.clone(),
+            line: 5,
+        }
+    }), entries[1]);
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("baz"),
+        text: String::from("x y"),
+        location: Location {
+            file: path.clone(),
+            line: 7,
+        }
+    }), entries[2]);
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("baz2"),
+        text: String::from("a"),
+        location: Location {
+            file: path.clone(),
+            line: 9,
+        }
+    }), entries[3]);
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("baz3"),
+        text: String::from(""),
+        location: Location {
+            file: path.clone(),
+            line: 10,
+        }
+    }), entries[4]);
+
+    assert_eq!(Entry::Category(CategoryEntry {
+        category: String::from("baz3"),
+        text: String::from("b"),
+        location: Location {
+            file: path.clone(),
+            line: 11,
+        }
+    }), entries[5]);
+}
+
+#[test]
+fn priority_test() {
+    let str = r#"
+        1
+        2
+        todo00
+        todo000 abc
+        todo0 abc def
+        todo1 foo
+        3
+        todo1 x y
+        4
+        // todo0 bar
+        // TODO1 a
+        /* TODO2 */
+        // TODO3 b
+    "#;
+
+    let mut entries: Vec<Entry> = vec![];
+    let mut path = PathBuf::new();
+    path.push("foo.txt");
+
+    scan_string(str.to_string(), path.clone(), &mut entries);
+
+    assert_eq!(9, entries.len());
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: -1,
+        text: String::from(""),
+        location: Location {
+            file: path.clone(),
+            line: 4,
+        }
+    }), entries[0]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: -2,
+        text: String::from("abc"),
+        location: Location {
+            file: path.clone(),
+            line: 5,
+        }
+    }), entries[1]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 0,
+        text: String::from("abc def"),
+        location: Location {
+            file: path.clone(),
+            line: 6,
+        }
+    }), entries[2]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 1,
+        text: String::from("foo"),
+        location: Location {
+            file: path.clone(),
+            line: 7,
+        }
+    }), entries[3]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 1,
+        text: String::from("x y"),
+        location: Location {
+            file: path.clone(),
+            line: 9,
+        }
+    }), entries[4]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 0,
+        text: String::from("bar"),
+        location: Location {
+            file: path.clone(),
+            line: 11,
+        }
+    }), entries[5]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 1,
+        text: String::from("a"),
+        location: Location {
+            file: path.clone(),
+            line: 12,
+        }
+    }), entries[6]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 2,
+        text: String::from(""),
+        location: Location {
+            file: path.clone(),
+            line: 13,
+        }
+    }), entries[7]);
+
+    assert_eq!(Entry::Priority(PriorityEntry {
+        priority: 3,
+        text: String::from("b"),
+        location: Location {
+            file: path.clone(),
+            line: 14,
+        }
+    }), entries[8]);
 }
diff --git a/todo.md b/todo.md
new file mode 100644
index 0000000..2968d6e
--- /dev/null
+++ b/todo.md
@@ -0,0 +1,6 @@
+## CLI
+
+- README.md
+- todo.md
+- Output format?
+- termcolor + --no-ansi