moved cursor into own file

moved click tracking as a new State struct to input::mouse
made cursor field of text_input state private
brought back cursor type(Index, Selection) representation with a state enum
cleaned out some stuff (but not enough/all)
TODO: Documentation (sigh)
TODO: Editor struct
TODO: some (hopefully) small improvements here and there

native/src/input/mouse.rs

@@ -2,5 +2,69 @@
 mod button;
 mod event;
 
+use crate::Point;
 pub use button::Button;
 pub use event::{Event, ScrollDelta};
+use std::time::{Duration, SystemTime};
+
+/// enum to track the type of the last click
+#[derive(Debug, Copy, Clone)]
+pub enum Interaction {
+    /// Last Click was a single click
+    Click(Point),
+    /// Last Click was a double click
+    DoubleClick(Point),
+    /// Last Click was a triple click
+    TripleClick(Point),
+}
+
+/// Compiler bully
+#[derive(Debug, Copy, Clone)]
+pub struct State {
+    last_click: Option<Interaction>,
+    last_click_timestamp: Option<SystemTime>,
+}
+
+impl Default for State {
+    fn default() -> Self {
+        State {
+            last_click: None,
+            last_click_timestamp: None,
+        }
+    }
+}
+
+impl State {
+    /// processes left click to check for double/triple clicks
+    /// return amount of repetitive mouse clicks
+    /// (1 -> double click, 2 -> triple click)
+    pub fn update(&mut self, position: Point) -> Interaction {
+        self.last_click_timestamp = Some(SystemTime::now());
+        self.last_click = match self.last_click {
+            None => Some(Interaction::Click(position)),
+            Some(x) => match x {
+                Interaction::Click(p) if self.process_click(p, position) => {
+                    Some(Interaction::DoubleClick(position))
+                }
+                Interaction::DoubleClick(p)
+                    if self.process_click(p, position) =>
+                {
+                    Some(Interaction::TripleClick(position))
+                }
+                _ => Some(Interaction::Click(position)),
+            },
+        };
+        self.last_click.unwrap_or(Interaction::Click(position))
+    }
+
+    fn process_click(&self, old_position: Point, new_position: Point) -> bool {
+        old_position == new_position
+            && SystemTime::now()
+                .duration_since(
+                    self.last_click_timestamp.unwrap_or(SystemTime::UNIX_EPOCH),
+                )
+                .unwrap_or(Duration::from_secs(1))
+                .as_millis()
+                <= 500
+    }
+}