From 96265648e93910242d593a9e4b91b9dd3b9b4901 Mon Sep 17 00:00:00 2001
From: "Dr. Matthias Ratajczak" <m.ratajczak@hzdr.de>
Date: Tue, 10 Jan 2023 18:17:12 +0100
Subject: [PATCH] rework backend internals

---
 src/backend/mod.rs    |  4 ++--
 src/backend/pacman.rs | 53 +++++++++++++++++++++++--------------------
 src/backend/rust.rs   | 14 ++++--------
 3 files changed, 35 insertions(+), 36 deletions(-)

diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 7e62f79..248abf5 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -13,8 +13,8 @@ use crate::{Group, Package};
 
 pub(crate) use todo_per_backend::ToDoPerBackend;
 
-pub use pacman::Pacman;
-pub use rust::Rust;
+pub(crate) use pacman::Pacman;
+pub(crate) use rust::Rust;
 pub(in crate::backend) type Switches = &'static [&'static str];
 pub(in crate::backend) type Text = &'static str;
 
diff --git a/src/backend/pacman.rs b/src/backend/pacman.rs
index 519c680..ccd2986 100644
--- a/src/backend/pacman.rs
+++ b/src/backend/pacman.rs
@@ -2,13 +2,13 @@ use std::collections::HashSet;
 
 use alpm::Alpm;
 use alpm::PackageReason::Explicit;
-use anyhow::Result;
+use anyhow::{Context, Result};
 
 use super::{Backend, Switches, Text};
 use crate::{impl_backend_constants, Group, Package};
 
-pub struct Pacman {
-    pub packages: HashSet<Package>,
+pub(crate) struct Pacman {
+    pub(crate) packages: HashSet<Package>,
 }
 
 const BINARY: Text = "paru";
@@ -20,51 +20,56 @@ impl Backend for Pacman {
     impl_backend_constants!();
 
     fn get_all_installed_packages(&self) -> Result<HashSet<Package>> {
-        Ok(convert_to_pacdef_packages(
-            get_all_installed_packages_from_alpm(),
-        ))
+        let alpm_packages = get_all_installed_packages_from_alpm()
+            .context("getting all installed packages from alpm")?;
+
+        let result = convert_to_pacdef_packages(alpm_packages);
+        Ok(result)
     }
 
     fn get_explicitly_installed_packages(&self) -> Result<HashSet<Package>> {
-        Ok(convert_to_pacdef_packages(
-            get_explicitly_installed_packages_from_alpm(),
-        ))
+        let alpm_packages = get_explicitly_installed_packages_from_alpm()
+            .context("getting all installed packages from alpm")?;
+        let result = convert_to_pacdef_packages(alpm_packages);
+        Ok(result)
     }
 }
 
-fn get_all_installed_packages_from_alpm() -> HashSet<String> {
-    let db = Alpm::new("/", "/var/lib/pacman").unwrap();
-    db.localdb()
+fn get_all_installed_packages_from_alpm() -> Result<HashSet<String>> {
+    let db = get_db_handle().context("getting DB handle")?;
+    let result = db
+        .localdb()
         .pkgs()
         .iter()
         .map(|p| p.name().to_string())
-        .collect()
+        .collect();
+    Ok(result)
 }
 
-fn get_explicitly_installed_packages_from_alpm() -> HashSet<String> {
-    let db = Alpm::new("/", "/var/lib/pacman").unwrap();
-    db.localdb()
+fn get_explicitly_installed_packages_from_alpm() -> Result<HashSet<String>> {
+    let db = get_db_handle().context("getting DB handle")?;
+    let result = db
+        .localdb()
         .pkgs()
         .iter()
         .filter(|p| p.reason() == Explicit)
         .map(|p| p.name().to_string())
-        .collect()
+        .collect();
+    Ok(result)
 }
 
 fn convert_to_pacdef_packages(packages: HashSet<String>) -> HashSet<Package> {
     packages.into_iter().map(Package::from).collect()
 }
 
+fn get_db_handle() -> Result<Alpm> {
+    Alpm::new("/", "/var/lib/pacman").context("connecting to DB using expected default values")
+}
+
 impl Pacman {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         Self {
             packages: HashSet::new(),
         }
     }
 }
-
-impl Default for Pacman {
-    fn default() -> Self {
-        Self::new()
-    }
-}
diff --git a/src/backend/rust.rs b/src/backend/rust.rs
index ef00356..12d3aae 100644
--- a/src/backend/rust.rs
+++ b/src/backend/rust.rs
@@ -8,8 +8,8 @@ use serde_json::Value;
 use super::{Backend, Switches, Text};
 use crate::{impl_backend_constants, Group, Package};
 
-pub struct Rust {
-    pub packages: HashSet<Package>,
+pub(crate) struct Rust {
+    pub(crate) packages: HashSet<Package>,
 }
 
 const BINARY: Text = "cargo";
@@ -52,21 +52,15 @@ fn extract_packages(json: Value) -> Result<HashSet<Package>> {
 }
 
 impl Rust {
-    pub fn new() -> Self {
+    pub(crate) fn new() -> Self {
         Self {
             packages: HashSet::new(),
         }
     }
 }
 
-impl Default for Rust {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 fn get_crates_file() -> Result<PathBuf> {
-    let mut result = crate::path::get_home_dir()?;
+    let mut result = crate::path::get_home_dir().context("getting home dir")?;
     result.push(".cargo");
     result.push(".crates2.json");
     Ok(result)