Implement --replace|-r mode for pkg-fetch

1 files changed, 67 insertions, 18 deletions

diff --git a/bpkg/pkg-fetch.cxx b/bpkg/pkg-fetch.cxx
index daa2d5e..c8b8543 100644
--- a/bpkg/pkg-fetch.cxx
+++ b/bpkg/pkg-fetch.cxx
@@ -15,6 +15,7 @@
 #include <bpkg/diagnostics>
 #include <bpkg/manifest-utility>
 
+#include <bpkg/pkg-purge>
 #include <bpkg/pkg-verify>
 
 using namespace std;
@@ -38,6 +39,35 @@ namespace bpkg
     auto_rm arm;
     bool purge;
     repository_location rl;
+    shared_ptr<selected_package> sp;
+
+    // Check if the package already exists in this configuration and
+    // diagnose all the illegal cases. We want to do this as soon as
+    // the package name is known which happens at different times
+    // depending on whether we are dealing with an existing archive
+    // or fetching one.
+    //
+    auto check = [&o, &c, &db] (const string& n)
+      -> shared_ptr<selected_package>
+    {
+      shared_ptr<selected_package> p (db.find<selected_package> (n));
+
+      if (p == nullptr ||
+          (p->state == package_state::fetched && o.replace ()))
+        return p;
+
+      {
+        diag_record dr (error);
+
+        dr << "package " << n << " already exists in configuration " << c <<
+          info << "version: " << p->version << ", state: " << p->state;
+
+        if (p->state == package_state::fetched)
+          dr << info << "use 'pkg-fetch --replace|-r' to replace its archive";
+      }
+
+      throw failed ();
+    };
 
     if (o.existing ())
     {
@@ -71,6 +101,10 @@ namespace bpkg
         fail << "package version expected" <<
           info << "run 'bpkg help pkg-fetch' for more information";
 
+      // Check/diagnose an already existing package.
+      //
+      sp = check (n);
+
       if (db.query_value<repository_count> () == 0)
         fail << "configuration " << c << " has no repositories" <<
           info << "use 'bpkg rep-add' to add a repository";
@@ -79,18 +113,18 @@ namespace bpkg
         fail << "configuration " << c << " has no available packages" <<
           info << "use 'bpkg rep-fetch' to fetch available packages list";
 
-      shared_ptr<available_package> p (
+      shared_ptr<available_package> ap (
         db.find<available_package> (available_package_id (n, v)));
 
-      if (p == nullptr)
+      if (ap == nullptr)
         fail << "package " << n << " " << v << " is not available";
 
-      // Pick a repository. Preferring local ones over the remote seems
+      // Pick a repository. Preferring a local one over the remotes seems
       // like a sensible thing to do.
       //
-      const package_location* pl (&p->locations.front ());
+      const package_location* pl (&ap->locations.front ());
 
-      for (const package_location& l: p->locations)
+      for (const package_location& l: ap->locations)
       {
         if (!l.repository.load ()->location.remote ())
         {
@@ -116,13 +150,10 @@ namespace bpkg
     package_manifest m (pkg_verify (o, a));
     level4 ([&]{trace << m.name << " " << m.version;});
 
-    const auto& n (m.name);
-
-    // See if this package already exists in this configuration.
+    // Check/diagnose an already existing package.
     //
-    if (shared_ptr<selected_package> p = db.find<selected_package> (n))
-      fail << "package " << n << " already exists in configuration " << c <<
-        info << "version: " << p->version << ", state: " << p->state;
+    if (o.existing ())
+      sp = check (m.name);
 
     // Make the archive and configuration paths absolute and normalized.
     // If the archive is inside the configuration, use the relative path.
@@ -134,9 +165,27 @@ namespace bpkg
     if (a.sub (c))
       a = a.leaf (c);
 
-    // Add the package to the configuration.
-    //
-    shared_ptr<selected_package> p (new selected_package {
+    if (sp != nullptr)
+    {
+      // Clean up the archive we are replacing. Once this is done, there
+      // is no going back. If things go badly, we can't simply abort the
+      // transaction.
+      //
+      if (sp->purge_archive)
+        pkg_purge_archive (c, t, sp);
+
+      sp->version = move (m.version);
+      sp->repository = move (rl);
+      sp->archive = move (a);
+      sp->purge_archive = purge;
+
+      db.update (sp);
+    }
+    else
+    {
+      // Add the package to the configuration.
+      //
+      sp.reset (new selected_package {
         move (m.name),
         move (m.version),
         package_state::fetched,
@@ -146,15 +195,15 @@ namespace bpkg
         nullopt, // No source directory yet.
         false,
         nullopt, // No output directory yet.
-        {}       // No prerequisites captured yet.
-     });
+        {}});    // No prerequisites captured yet.
 
-    db.persist (p);
+      db.persist (sp);
+    }
 
     t.commit ();
     arm.cancel ();
 
     if (verb)
-      text << "fetched " << p->name << " " << p->version;
+      text << "fetched " << sp->name << " " << sp->version;
   }
 }