refactor: have fun with rust's functional stuff

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://git.rustybever.be/Chewing_Bever/alex/src/branch/dev)
 
+### Added
+
+* Export command to export any backup as a new full backup
+
 ## [0.3.0](https://git.rustybever.be/Chewing_Bever/alex/src/tag/0.3.0)
 
 ### Added

src/backup/manager/mod.rs

@@ -4,7 +4,7 @@ mod meta;
 pub use config::ManagerConfig;
 pub use meta::MetaManager;
 
-use super::{Backup, Delta, State};
+use super::{Backup, BackupType, Delta, State};
 use crate::other;
 use chrono::SubsecRound;
 use chrono::Utc;
@@ -162,6 +162,25 @@ where
         chrono::offset::Utc::now()
     }
 
+    /// Search for a chain containing a backup with the specified start time.
+    ///
+    /// # Returns
+    ///
+    /// A tuple (chain, index) with index being the index of the found backup in the returned
+    /// chain.
+    fn find(&self, start_time: chrono::DateTime<Utc>) -> Option<(&Vec<Backup<T>>, usize)> {
+        for chain in &self.chains {
+            if let Some(index) = chain
+                .iter()
+                .position(|b| b.start_time.trunc_subsecs(0) == start_time)
+            {
+                return Some((chain, index));
+            }
+        }
+
+        None
+    }
+
     /// Restore the backup with the given start time by restoring its chain up to and including the
     /// backup, in order.
     pub fn restore_backup(
@@ -169,62 +188,57 @@ where
         start_time: chrono::DateTime<Utc>,
         dirs: &Vec<(PathBuf, PathBuf)>,
     ) -> io::Result<()> {
-        // Iterate over each chain, skipping elements until the element with the given start time
-        // is possibly found.
-        for chain in &self.chains {
-            // If we find the element in the chain, restore the entire chain up to and including
-            // the element
-            if let Some(index) = chain
-                .iter()
-                .position(|b| b.start_time.trunc_subsecs(0) == start_time)
-            {
+        self.find(start_time)
+            .ok_or_else(|| other("Unknown layer."))
+            .and_then(|(chain, index)| {
                 for backup in chain.iter().take(index + 1) {
                     backup.restore(&self.backup_dir, dirs)?;
                 }
 
-                return Ok(());
-            }
-        }
-
-        Err(other("Unknown backup."))
+                Ok(())
+            })
     }
 
+    /// Export the backup with the given start time as a new full archive.
     pub fn export_backup<P: AsRef<Path>>(
         &self,
         start_time: chrono::DateTime<Utc>,
         output_path: P,
     ) -> io::Result<()> {
-        // Iterate over each chain, skipping elements until the element with the given start time
-        // is possibly found.
-        for chain in &self.chains {
-            // If we find the element in the chain, restore the entire chain up to and including
-            // the element
-            if let Some(index) = chain
-                .iter()
-                .position(|b| b.start_time.trunc_subsecs(0) == start_time)
-            {
-                let contributions =
-                    Delta::contributions(chain.iter().take(index + 1).map(|b| &b.delta).rev());
+        self.find(start_time)
+            .ok_or_else(|| other("Unknown layer."))
+            .and_then(|(chain, index)| {
+                match chain[index].type_ {
+                    // A full backup is simply copied to the output path
+                    BackupType::Full => std::fs::copy(
+                        Backup::path(&self.backup_dir, chain[index].start_time),
+                        output_path,
+                    )
+                    .map(|_| ()),
+                    // Incremental backups are exported one by one according to their contribution
+                    BackupType::Incremental => {
+                        let contributions = Delta::contributions(
+                            chain.iter().take(index + 1).map(|b| &b.delta).rev(),
+                        );
 
-                let tar_gz = OpenOptions::new()
-                    .write(true)
-                    .create(true)
-                    .open(output_path.as_ref())?;
-                let enc = GzEncoder::new(tar_gz, Compression::default());
-                let mut ar = tar::Builder::new(enc);
+                        let tar_gz = OpenOptions::new()
+                            .write(true)
+                            .create(true)
+                            .open(output_path.as_ref())?;
+                        let enc = GzEncoder::new(tar_gz, Compression::default());
+                        let mut ar = tar::Builder::new(enc);
 
-                for (contribution, backup) in
-                    contributions.iter().rev().zip(chain.iter().take(index + 1))
-                {
-                    backup.append(&self.backup_dir, contribution, &mut ar)?;
+                        for (contribution, backup) in
+                            contributions.iter().rev().zip(chain.iter().take(index + 1))
+                        {
+                            backup.append(&self.backup_dir, contribution, &mut ar)?;
+                        }
+
+                        let mut enc = ar.into_inner()?;
+                        enc.try_finish()
+                    }
                 }
-
-                let mut enc = ar.into_inner()?;
-                return enc.try_finish();
-            }
-        }
-
-        Err(other("Unknown backup."))
+            })
     }
 
     /// Get a reference to the underlying chains

src/backup/path.rs

@@ -129,16 +129,15 @@ pub trait PathExt {
 
 impl PathExt for Path {
     fn not_modified_since(&self, timestamp: chrono::DateTime<Utc>) -> bool {
-        if let Ok(metadata) = self.metadata() {
-            if let Ok(last_modified) = metadata.modified() {
+        self.metadata()
+            .and_then(|m| m.modified())
+            .map(|last_modified| {
                 let t: chrono::DateTime<Utc> = last_modified.into();
                 let t = t.with_timezone(&Local);
 
-                return t < timestamp;
-            }
-        }
-
-        false
+                t < timestamp
+            })
+            .unwrap_or(false)
     }
 
     fn read_dir_recursive(&self) -> io::Result<ReadDirRecursive> {