From 6bc74795a009a35a0c1a27426b619b9f20a2db8e Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Wed, 30 Dec 2020 15:06:30 +0200
Subject: feat: allow restoring latest generation

---
 obnam.md            | 23 +++++++++++++++++++++++
 src/cmd/restore.rs  | 10 +++++++++-
 src/lib.rs          |  1 +
 subplot/client.py   | 12 ++++++++++--
 subplot/client.yaml |  3 +++
 5 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/obnam.md b/obnam.md
index 6706fb7..c3b03a8 100644
--- a/obnam.md
+++ b/obnam.md
@@ -896,6 +896,29 @@ given a manifest of the directory live restored in rest in rest.yaml
 then files live.yaml and rest.yaml match
 ~~~
 
+## Restore latest generation
+
+This scenario verifies that the latest backup generation can be
+specified with literal string "latest". It makes two backups, which
+are different.
+
+~~~scenario
+given an installed obnam
+and a running chunk server
+and a client config based on metadata.yaml
+
+given a file live/data.dat containing some random data
+when I run obnam --config metadata.yaml backup
+
+given a file live/more.dat containing some random data
+and a manifest of the directory live in second.yaml
+when I run obnam --config metadata.yaml backup
+
+when I invoke obnam --config metadata.yaml restore latest rest
+given a manifest of the directory live restored in rest in rest.yaml
+then files second.yaml and rest.yaml match
+~~~
+
 
 
 
diff --git a/src/cmd/restore.rs b/src/cmd/restore.rs
index dd7ed41..9e137f2 100644
--- a/src/cmd/restore.rs
+++ b/src/cmd/restore.rs
@@ -1,5 +1,6 @@
 use crate::client::BackupClient;
 use crate::client::ClientConfig;
+use crate::error::ObnamError;
 use crate::fsentry::{FilesystemEntry, FilesystemKind};
 use crate::generation::NascentGeneration;
 use indicatif::{ProgressBar, ProgressStyle};
@@ -14,7 +15,7 @@ use std::path::{Path, PathBuf};
 use structopt::StructOpt;
 use tempfile::NamedTempFile;
 
-pub fn restore(config: &ClientConfig, gen_id: &str, to: &Path) -> anyhow::Result<()> {
+pub fn restore(config: &ClientConfig, gen_ref: &str, to: &Path) -> anyhow::Result<()> {
     // Create a named temporary file. We don't meed the open file
     // handle, so we discard that.
     let dbname = {
@@ -24,6 +25,13 @@ pub fn restore(config: &ClientConfig, gen_id: &str, to: &Path) -> anyhow::Result
     };
 
     let client = BackupClient::new(&config.server_url)?;
+
+    let genlist = client.list_generations()?;
+    let gen_id: String = match genlist.resolve(gen_ref) {
+        None => return Err(ObnamError::UnknownGeneration(gen_ref.to_string()).into()),
+        Some(id) => id,
+    };
+
     let gen_chunk = client.fetch_generation(&gen_id)?;
     debug!("gen: {:?}", gen_chunk);
 
diff --git a/src/lib.rs b/src/lib.rs
index 1880758..a06d396 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,7 @@ pub mod chunkid;
 pub mod chunkmeta;
 pub mod client;
 pub mod cmd;
+pub mod error;
 pub mod fsentry;
 pub mod fsiter;
 pub mod generation;
diff --git a/subplot/client.py b/subplot/client.py
index 1dcbe8c..0a09d31 100644
--- a/subplot/client.py
+++ b/subplot/client.py
@@ -24,9 +24,17 @@ def configure_client(ctx, filename=None):
 
 
 def run_obnam_restore(ctx, filename=None, genid=None, todir=None):
+    genid = ctx["vars"][genid]
+    run_obnam_restore_with_genref(ctx, filename=filename, genref=genid, todir=todir)
+
+
+def run_obnam_restore_latest(ctx, filename=None, todir=None):
+    run_obnam_restore_with_genref(ctx, filename=filename, genref="latest", todir=todir)
+
+
+def run_obnam_restore_with_genref(ctx, filename=None, genref=None, todir=None):
     runcmd_run = globals()["runcmd_run"]
 
-    genid = ctx["vars"][genid]
     runcmd_run(
         ctx,
         [
@@ -36,7 +44,7 @@ def run_obnam_restore(ctx, filename=None, genid=None, todir=None):
             "--config",
             filename,
             "restore",
-            genid,
+            genref,
             todir,
         ],
     )
diff --git a/subplot/client.yaml b/subplot/client.yaml
index f8e89b6..e526304 100644
--- a/subplot/client.yaml
+++ b/subplot/client.yaml
@@ -7,6 +7,9 @@
 - when: "I invoke obnam --config {filename} restore <{genid}> {todir}"
   function: run_obnam_restore
 
+- when: "I invoke obnam --config {filename} restore latest {todir}"
+  function: run_obnam_restore_latest
+
 - then: "backup generation is {varname}"
   function: capture_generation_id
 
-- 
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