Move settings file to app config folder and add commands to modify

Cargo.toml

@@ -35,6 +35,8 @@ derive_more = {version = "2.0", features = ["add", "display"]}
 petgraph = "0.8.2"
 strum = {version = "0.27.2", features = ["derive"]}
 documented = "0.9.2"
+dirs = "6.0.0"
+edit = "0.1.5"
 
 [dev-dependencies]
 current_dir = "0.1.2"

docs/user_guide.md

@@ -5,10 +5,22 @@
 Once you have installed MUSE 2.0, you should be able to run it via the `muse2` command-line program.
 For details of the command-line interface, [see here](./command_line_help.md).
 
-You can also configure the behaviour of MUSE 2.0 by creating a `settings.toml` file. For more
-information, see [the documentation for this file][settings.toml-docs].
+## Modifying the program settings
 
-[settings.toml-docs]: https://energysystemsmodellinglab.github.io/MUSE_2.0/file_formats/program_settings.html
+You can configure the behaviour of MUSE 2.0 with a `settings.toml` file. To edit this file, run:
+
+```sh
+muse2 settings edit
+```
+
+There are also some more commands for working with the settings file; for details, run: `muse2
+settings help`.
+
+For information about the available settings, see [the documentation for the `settings.toml`
+file][settings.toml-docs].
+
+[settings.toml-docs]:
+https://energysystemsmodellinglab.github.io/MUSE_2.0/file_formats/program_settings.html
 
 ## Setting the log level
 

src/cli.rs

@@ -11,6 +11,9 @@ use std::path::{Path, PathBuf};
 pub mod example;
 use example::ExampleSubcommands;
 
+pub mod settings;
+use settings::SettingsSubcommands;
+
 /// The command line interface for the simulation.
 #[derive(Parser)]
 #[command(version, about)]
@@ -59,21 +62,23 @@ enum Commands {
         /// The path to the model directory.
         model_dir: PathBuf,
     },
-    /// Print default settings file.
-    DumpDefaultSettings,
+    /// Manage settings file.
+    Settings {
+        /// The subcommands for managing the settings file.
+        #[command(subcommand)]
+        subcommand: SettingsSubcommands,
+    },
 }
 
 impl Commands {
     /// Execute the supplied CLI command
     fn execute(self) -> Result<()> {
         match self {
-            Self::Run { model_dir, opts } => handle_run_command(&model_dir, &opts, None)?,
-            Self::Example { subcommand } => subcommand.execute()?,
-            Self::Validate { model_dir } => handle_validate_command(&model_dir, None)?,
-            Self::DumpDefaultSettings => handle_dump_default_settings(),
+            Self::Run { model_dir, opts } => handle_run_command(&model_dir, &opts, None),
+            Self::Example { subcommand } => subcommand.execute(),
+            Self::Validate { model_dir } => handle_validate_command(&model_dir, None),
+            Self::Settings { subcommand } => subcommand.execute(),
         }
-
-        Ok(())
     }
 }
 
@@ -173,8 +178,3 @@ pub fn handle_validate_command(model_path: &Path, settings: Option<Settings>) ->
 
     Ok(())
 }
-
-/// Handle the `dump-default-settings` command
-fn handle_dump_default_settings() {
-    print!("{}", Settings::default_file_contents());
-}