feat(App): introduce a central manager

The multiple components in the proposed MVVM architecture require a
central manager to orchestrate event handling, controlling and
orchestration. Introduce an `App` to be the central manager with draft
implementations for methods.

Signed-off-by: Ivin Joel Abraham <[email protected]>

Author: ivinjabraham

src/app.rs

@@ -0,0 +1,68 @@
+use crate::viewmodels::ViewModel;
+use std::collections::HashMap;
+
+use color_eyre::eyre::Result;
+use ratatui::crossterm::event::{self, Event, KeyEventKind};
+
+use crate::model::{screens::View, Model};
+
+#[allow(dead_code)]
+pub struct App {
+    model: Model,
+    current_view: View,
+    viewmodels: HashMap<View, Box<dyn ViewModel>>,
+}
+
+impl App {
+    #[allow(dead_code)]
+    pub fn new(model: Model) -> color_eyre::Result<Self> {
+        Ok(App {
+            model,
+            current_view: View::MailingListSelection,
+            viewmodels: HashMap::new(),
+        })
+    }
+
+    #[allow(dead_code)]
+    pub fn get_current_view(&self) -> View {
+        self.current_view
+    }
+
+    #[allow(dead_code)]
+    pub fn get_current_viewmodel(&mut self) -> &mut Box<dyn ViewModel> {
+        self.viewmodels
+            .entry(self.current_view)
+            .or_insert_with(|| match self.current_view {
+                View::MailingListSelection => {
+                    todo!()
+                }
+                View::BookmarkedPatchsets => {
+                    todo!()
+                }
+                View::LatestPatchsets => {
+                    todo!()
+                }
+                View::PatchsetDetails => {
+                    todo!()
+                }
+                View::EditConfig => {
+                    todo!()
+                }
+            })
+    }
+
+    #[allow(dead_code)]
+    pub fn run(&mut self) -> Result<()> {
+        loop {
+            self.get_current_view().draw_screen();
+
+            if let Event::Key(key) = event::read()? {
+                if key.kind == KeyEventKind::Release {
+                    continue;
+                }
+
+                self.get_current_viewmodel().handle_key(key);
+            }
+        }
+    }
+}

src/main.rs

@@ -1,10 +1,12 @@
+mod app;
 mod cli;
 mod handler;
 mod infrastructure;
 mod lore;
 mod macros;
 mod model;
 mod ui;
+mod viewmodels;
 
 use clap::Parser;
 use cli::Cli;

src/viewmodels/mod.rs

@@ -1,5 +1,3 @@
-mod mailing_list_viewmodel;
-
 use ratatui::crossterm::event::KeyEvent;
 #[allow(dead_code)]
 pub trait ViewModel {