Add MailIterator for iterating over entries that are mails

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

2 files changed, 84 insertions, 0 deletions

diff --git a/lib/domain/libimagmail/src/iter.rs b/lib/domain/libimagmail/src/iter.rs
new file mode 100644
index 00000000..bba6b690
--- /dev/null
+++ b/lib/domain/libimagmail/src/iter.rs
@@ -0,0 +1,83 @@
+//
+// imag - the personal information management suite for the commandline
+// Copyright (C) 2015-2020 Matthias Beyer <mail@beyermatthias.de> and contributors
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; version
+// 2.1 of the License.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+//
+
+use failure::Fallible as Result;
+use failure::ResultExt;
+use failure::Error;
+use failure::err_msg;
+
+use libimagstore::iter::get::StoreGetIterator;
+use libimagstore::store::FileLockEntry;
+
+use crate::mail::Mail;
+
+pub struct MailIterator<'a> {
+    inner: StoreGetIterator<'a>,
+    ignore_ungetable: bool,
+}
+
+impl<'a> MailIterator<'a> {
+    pub fn new(sgi: StoreGetIterator<'a>) -> Self {
+        MailIterator { inner: sgi, ignore_ungetable: true }
+    }
+
+    pub fn ignore_ungetable(mut self, b: bool) -> Self {
+        self.ignore_ungetable = b;
+        self
+    }
+}
+
+pub trait IntoMailIterator<'a> {
+    fn into_mail_iterator(self) -> MailIterator<'a>;
+}
+
+impl<'a> IntoMailIterator<'a> for StoreGetIterator<'a> {
+    fn into_mail_iterator(self) -> MailIterator<'a> {
+        MailIterator::new(self)
+    }
+}
+
+impl<'a> Iterator for MailIterator<'a> {
+    type Item = Result<FileLockEntry<'a>>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        while let Some(n) = self.inner.next() {
+            match n {
+                Ok(Some(fle)) => {
+                    match fle.is_mail().context("Checking whether entry is a Mail").map_err(Error::from) {
+                        Err(e)    => return Some(Err(e)),
+                        Ok(true)  => return Some(Ok(fle)),
+                        Ok(false) => continue,
+                    }
+                },
+
+                Ok(None) => if self.ignore_ungetable {
+                    continue
+                } else {
+                    return Some(Err(err_msg("Failed to get one entry")))
+                },
+
+                Err(e) => return Some(Err(e)),
+            }
+        }
+
+        None
+    }
+}
+
diff --git a/lib/domain/libimagmail/src/lib.rs b/lib/domain/libimagmail/src/lib.rs
index b3d5785b..32f1da64 100644
--- a/lib/domain/libimagmail/src/lib.rs
+++ b/lib/domain/libimagmail/src/lib.rs
@@ -55,6 +55,7 @@ module_entry_path_mod!("mail");
 
 pub mod config;
 pub mod hasher;
+pub mod iter;
 pub mod mail;
 pub mod mid;
 pub mod store;