show transition information when new version runs for first time

crates/main/main.rs

@@ -17,9 +17,10 @@ Main program for `pacdef`. All internal logic happens in [`pacdef_core`].
 
 use std::process::{ExitCode, Termination};
 
-use anyhow::{bail, Context, Result};
+use anyhow::{Context, Result};
 
-use pacdef_core::{get_args, get_config_path, get_group_dir, Config, Group, Pacdef};
+use pacdef_core::path::{get_config_path, get_config_path_old_version, get_group_dir};
+use pacdef_core::{get_args, Config, Group, Pacdef};
 
 fn main() -> ExitCode {
     handle_final_result(main_inner())
@@ -45,7 +46,17 @@ fn main_inner() -> Result<()> {
     let args = get_args();
 
     let config_file = get_config_path().context("getting config file")?;
-    let config = load_config(config_file)?;
+
+    let config = Config::load(&config_file)
+        .or_else(|_| {
+            get_config_path_old_version()?
+                .exists()
+                .then(show_transition_link);
+            let default = Config::default();
+            default.save(&config_file)?;
+            Ok::<Config, anyhow::Error>(default)
+        })
+        .context("loading config")?;
 
     let group_dir = get_group_dir().context("resolving group dir")?;
     let groups = Group::load(&group_dir, config.warn_not_symlinks)
@@ -55,18 +66,11 @@ fn main_inner() -> Result<()> {
     pacdef.run_action_from_arg().context("running action")
 }
 
-fn load_config(config_file: std::path::PathBuf) -> Result<Config> {
-    let config = match Config::load(&config_file)
-        .with_context(|| format!("loading config file {}", config_file.to_string_lossy()))
-    {
-        Ok(config) => config,
-        Err(e) => {
-            let e = e.root_cause().downcast_ref::<pacdef_core::Error>();
-            match e {
-                Some(pacdef_core::Error::ConfigFileNotFound) => Config::default(),
-                _ => bail!("huh"),
-            }
-        }
-    };
-    Ok(config)
+fn show_transition_link() {
+    println!("VERSION UPGRADE");
+    println!("You seem to have used version 0.x of pacdef before.");
+    println!("Version 1.x changes the syntax of the config files and the command line arguments.");
+    println!("Check out https://github.com/steven-omaha/pacdef for new syntax information.");
+    println!("This message will not appear again.");
+    println!("------");
 }

crates/pacdef_core/src/config.rs

@@ -38,10 +38,13 @@ impl Config {
         serde_yaml::from_str(&content).context("parsing yaml config")
     }
 
-    fn use_default_and_save_to(file: &Path) -> Result<Self> {
-        let result = Self::default();
-
-        let content = serde_yaml::to_string(&result).context("converting Config to yaml")?;
+    /// Save the instance of [`Config`] to disk.
+    ///
+    /// # Errors
+    ///
+    /// This function will return an error if the config file cannot be saved to disk.
+    pub fn save(&self, file: &Path) -> Result<()> {
+        let content = serde_yaml::to_string(&self).context("converting Config to yaml")?;
 
         let parent = file.parent().context("getting parent of config dir")?;
         if !parent.is_dir() {
@@ -52,7 +55,7 @@ impl Config {
         let mut output = File::create(file).context("creating default config file")?;
         write!(output, "{content}").context("writing default config")?;
 
-        Ok(result)
+        Ok(())
     }
 }
 

crates/pacdef_core/src/lib.rs

@@ -30,7 +30,7 @@ mod core;
 mod env;
 mod errors;
 mod grouping;
-mod path;
+pub mod path;
 mod review;
 mod search;
 mod ui;
@@ -41,6 +41,5 @@ pub use crate::core::Pacdef;
 pub use crate::errors::Error;
 pub use crate::grouping::Group;
 pub(crate) use crate::grouping::Package;
-pub use crate::path::{get_config_path, get_group_dir};
 
 extern crate pacdef_macros;

crates/pacdef_core/src/path.rs

@@ -1,9 +1,14 @@
+/*!
+All functions related to `pacdef`'s internal paths.
+*/
+
 use std::env;
 use std::path::PathBuf;
 
 use anyhow::{Context, Result};
 
 const CONFIG_FILE_NAME: &str = "pacdef.yaml";
+const CONFIG_FILE_NAME_OLD: &str = "pacdef.conf";
 
 /// Get the group directory where all group files are located. This is
 /// `$XDG_CONFIG_HOME/pacdef/groups`, which defaults to `$HOME/.config/pacdef/groups`.
@@ -17,7 +22,7 @@ pub fn get_group_dir() -> Result<PathBuf> {
     Ok(result)
 }
 
-pub fn get_pacdef_base_dir() -> Result<PathBuf> {
+pub(crate) fn get_pacdef_base_dir() -> Result<PathBuf> {
     let mut dir = get_xdg_config_home().context("getting XDG_CONFIG_HOME")?;
     dir.push("pacdef");
     Ok(dir)
@@ -33,7 +38,7 @@ fn get_xdg_config_home() -> Result<PathBuf> {
     }
 }
 
-pub fn get_home_dir() -> Result<PathBuf> {
+pub(crate) fn get_home_dir() -> Result<PathBuf> {
     Ok(env::var("HOME").context("getting $HOME variable")?.into())
 }
 
@@ -47,3 +52,14 @@ pub fn get_config_path() -> Result<PathBuf> {
     file.push(CONFIG_FILE_NAME);
     Ok(file)
 }
+
+/// Get the path to the pacdef config file. This is `$XDG_CONFIG_HOME/pacdef/pacdef.yaml`.
+///
+/// # Errors
+///
+/// This function returns an error if both `$XDG_CONFIG_HOME` and `$HOME` are undefined.
+pub fn get_config_path_old_version() -> Result<PathBuf> {
+    let mut file = get_pacdef_base_dir().context("getting pacdef base dir for config file")?;
+    file.push(CONFIG_FILE_NAME_OLD);
+    Ok(file)
+}