feat: check if the dependencies are present before running patch-hub

Check if the depedencies are present, log any issues and if hard
dependencies are not present do not run the app.

[Maintainer edits]
- Squash test commit aggainst commit that introduces the unit (this)
- Change var name `ok` in `binary_exists` to `can_run_app`

Signed-off-by: OJarrisonn <[email protected]>
Reviewed-by: David Tadokoro <[email protected]>
Signed-off-by: David Tadokoro <[email protected]>

Author: OJarrisonn

Cargo.lock

@@ -19,6 +19,7 @@ thiserror = "1.0.37"
 clap = { version = "4.5.13", features = ["derive"] }
 chrono = "0.4.38"
 ansi-to-tui = "6.0.0"
+which = "6.0.3"
 
 # The profile that 'cargo dist' will build with
 [profile.dist]

Cargo.toml

@@ -3,6 +3,7 @@ use color_eyre::eyre::bail;
 use config::Config;
 use logging::Logger;
 use patch_hub::{lore_api_client::BlockingLoreAPIClient, lore_session, patch::Patch};
+use patch_renderer::PatchRenderer;
 use screens::{
     bookmarked::BookmarkedPatchsetsState,
     details_actions::{PatchsetAction, PatchsetDetailsAndActionsState},
@@ -13,6 +14,8 @@ use screens::{
 };
 use std::collections::HashMap;
 
+use crate::utils;
+
 mod config;
 pub mod logging;
 pub mod patch_renderer;
@@ -250,4 +253,46 @@ impl App {
     pub fn set_current_screen(&mut self, new_current_screen: CurrentScreen) {
         self.current_screen = new_current_screen;
     }
+
+    /// Check if the external dependencies are installed
+    ///
+    /// If soft dependencies are missing, the application can still run and
+    /// their absence will only be logged
+    pub fn check_external_deps(&self) -> bool {
+        let mut app_can_run = true;
+
+        if !utils::binary_exists("b4") {
+            Logger::error("b4 is not installed, patchsets cannot be downloaded");
+            app_can_run = false;
+        }
+
+        if !utils::binary_exists("git") {
+            Logger::warn("git is not installed, send-email won't work");
+        }
+
+        match self.config.patch_renderer() {
+            PatchRenderer::Bat => {
+                if !utils::binary_exists("bat") {
+                    Logger::warn("bat is not installed, patch rendering will fallback to default");
+                }
+            }
+            PatchRenderer::Delta => {
+                if !utils::binary_exists("delta") {
+                    Logger::warn(
+                        "delta is not installed, patch rendering will fallback to default",
+                    );
+                }
+            }
+            PatchRenderer::DiffSoFancy => {
+                if !utils::binary_exists("diff-so-fancy") {
+                    Logger::warn(
+                        "diff-so-fancy is not installed, patch rendering will fallback to default",
+                    );
+                }
+            }
+            _ => {}
+        }
+
+        app_can_run
+    }
 }

src/app.rs

@@ -10,12 +10,13 @@ use std::{
 };
 
 use crate::{
-    app::{screens::CurrentScreen, App},
+    app::{logging::Logger, screens::CurrentScreen, App},
     loading_screen,
     ui::draw_ui,
 };
 
 use bookmarked::handle_bookmarked_patchsets;
+use color_eyre::eyre::bail;
 use details_actions::handle_patchset_details;
 use edit_config::handle_edit_config;
 use latest::handle_latest_patchsets;
@@ -101,6 +102,11 @@ pub fn run_app<B>(mut terminal: Terminal<B>, mut app: App) -> color_eyre::Result
 where
     B: Backend + Send + 'static,
 {
+    if !app.check_external_deps() {
+        Logger::error("patch-hub cannot be executed because some dependencies are missing");
+        bail!("patch-hub cannot be executed because some dependencies are missing, check logs for more information");
+    }
+
     loop {
         terminal.draw(|f| draw_ui(f, &app))?;
 

src/handler.rs

@@ -71,6 +71,12 @@ pub fn teardown_user_io<B: Backend>(terminal: &mut Terminal<B>) -> color_eyre::R
     Ok(())
 }
 
+#[inline]
+/// Simply calls `which` to check if a binary exists
+pub fn binary_exists(binary: &str) -> bool {
+    which::which(binary).is_ok()
+}
+
 #[macro_export]
 /// Macro that encapsulates a piece of code that takes long to run and displays a loading screen while it runs.
 ///
@@ -111,3 +117,13 @@ macro_rules! loading_screen {
         }
     };
 }
+
+mod tests {
+    #[test]
+    fn test_binary_exists() {
+        // cargo should always exist since we are running the tests with `cargo test`
+        assert!(super::binary_exists("cargo"));
+        // there is no way this binary exists
+        assert!(!super::binary_exists("there_is_no_way_this_binary_exists"));
+    }
+}