Allow user to set theme with flag (#481)

closes #480 

4 files changed, 41 insertions, 23 deletions

diff --git a/THEMES.md b/THEMES.md
index 99726144..ac486429 100644
--- a/THEMES.md
+++ b/THEMES.md
@@ -3,11 +3,13 @@
 default on light terminal:
 ![](assets/light-theme.png)
 
-to change the colors of the program you have to modify `theme.ron` file
+to change the colors of the default theme you have to modify `theme.ron` file
 [Ron format](https://github.com/ron-rs/ron) located at config path. The path differs depending on the operating system:
 
 * `$HOME/Library/Application Support/gitui/theme.ron` (mac)
 * `$XDG_CONFIG_HOME/gitui/theme.ron` (linux using XDG)
 * `$HOME/.config/gitui/theme.ron` (linux)
 
+Alternatively you may make a theme in the same directory mentioned above with and select with the `-t` flag followed by the name of the file in the directory. E.g. If you are on linux calling `gitui -t arc.ron` wil use `$XDG_CONFIG_HOME/gitui/arc.ron` or `$HOME/.config/gitui/arc.ron`
+
 Valid colors can be found in tui-rs' [Color](https://docs.rs/tui/0.12.0/tui/style/enum.Color.html) struct. note that rgb colors might not be supported in every terminal.
diff --git a/src/app.rs b/src/app.rs
index 5045cf2f..2ce3b6be 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -22,7 +22,7 @@ use crossbeam_channel::Sender;
 use crossterm::event::{Event, KeyEvent};
 use std::{
     cell::{Cell, RefCell},
-    path::Path,
+    path::{Path, PathBuf},
     rc::Rc,
 };
 use tui::{
@@ -70,10 +70,11 @@ impl App {
     pub fn new(
         sender: &Sender<AsyncNotification>,
         input: Input,
+        theme_path: PathBuf,
     ) -> Self {
         let queue = Queue::default();
 
-        let theme = Rc::new(Theme::init());
+        let theme = Rc::new(Theme::init(theme_path));
         let key_config = Rc::new(KeyConfig::init());
 
         Self {
diff --git a/src/main.rs b/src/main.rs
index 560d52ee..e1e45ec0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -73,8 +73,12 @@ pub enum QueueEvent {
     InputEvent(InputEvent),
 }
 
+struct CliArgs {
+    theme: PathBuf,
+}
+
 fn main() -> Result<()> {
-    process_cmdline()?;
+    let cliargs = process_cmdline()?;
 
     let _profiler = Profiler::new();
 
@@ -100,7 +104,7 @@ fn main() -> Result<()> {
     let ticker = tick(TICK_INTERVAL);
     let spinner_ticker = tick(SPINNER_INTERVAL);
 
-    let mut app = App::new(&tx_git, input);
+    let mut app = App::new(&tx_git, input, cliargs.theme);
 
     let mut spinner = Spinner::default();
     let mut first_update = true;
@@ -261,12 +265,20 @@ fn setup_logging() -> Result<()> {
     Ok(())
 }
 
-fn process_cmdline() -> Result<()> {
+fn process_cmdline() -> Result<CliArgs> {
     let app = ClapApp::new(crate_name!())
         .author(crate_authors!())
         .version(crate_version!())
         .about(crate_description!())
         .arg(
+            Arg::with_name("theme")
+                .help("Set the color theme (defaults to theme.ron)")
+                .short("t")
+                .long("theme")
+                .value_name("THEME")
+                .takes_value(true),
+        )
+        .arg(
             Arg::with_name("logging")
                 .help("Stores logging output into a cache directory")
                 .short("l")
@@ -290,8 +302,17 @@ fn process_cmdline() -> Result<()> {
             arg_matches.value_of("directory").unwrap_or(".");
         env::set_current_dir(directory)?;
     }
-
-    Ok(())
+    let arg_theme =
+        arg_matches.value_of("theme").unwrap_or("theme.ron");
+    if get_app_config_path()?.join(arg_theme).is_file() {
+        Ok(CliArgs {
+            theme: get_app_config_path()?.join(arg_theme),
+        })
+    } else {
+        Ok(CliArgs {
+            theme: get_app_config_path()?.join("theme.ron"),
+        })
+    }
 }
 
 fn set_panic_handlers() -> Result<()> {
diff --git a/src/ui/style.rs b/src/ui/style.rs
index a1e59f8d..50b81b21 100644
--- a/src/ui/style.rs
+++ b/src/ui/style.rs
@@ -1,4 +1,3 @@
-use crate::get_app_config_path;
 use anyhow::Result;
 use asyncgit::{DiffLineType, StatusItemType};
 use ron::{
@@ -230,19 +229,14 @@ impl Theme {
             .bg(self.push_gauge_bg)
     }
 
-    fn save(&self) -> Result<()> {
-        let theme_file = Self::get_theme_file()?;
+    // This will only be called when theme.ron doesn't already exists
+    fn save(&self, theme_file: PathBuf) -> Result<()> {
         let mut file = File::create(theme_file)?;
         let data = to_string_pretty(self, PrettyConfig::default())?;
         file.write_all(data.as_bytes())?;
         Ok(())
     }
 
-    fn get_theme_file() -> Result<PathBuf> {
-        let app_home = get_app_config_path()?;
-        Ok(app_home.join("theme.ron"))
-    }
-
     fn read_file(theme_file: PathBuf) -> Result<Self> {
         let mut f = File::open(theme_file)?;
         let mut buffer = Vec::new();
@@ -250,21 +244,21 @@ impl Theme {
         Ok(from_bytes(&buffer)?)
     }
 
-    fn init_internal() -> Result<Self> {
-        let file = Self::get_theme_file()?;
-        if file.exists() {
-            Ok(Self::read_file(file)?)
+    fn init_internal(theme: PathBuf) -> Result<Self> {
+        if theme.exists() {
+            Ok(Self::read_file(theme)?)
         } else {
+            // This will only be called when theme.ron doesn't already exists
             let def = Self::default();
-            if def.save().is_err() {
+            if def.save(theme).is_err() {
                 log::warn!("failed to store default theme to disk.")
             }
             Ok(def)
         }
     }
 
-    pub fn init() -> Self {
-        Self::init_internal().unwrap_or_default()
+    pub fn init(theme_path: PathBuf) -> Self {
+        Self::init_internal(theme_path).unwrap_or_default()
     }
 }