1 files changed, 80 insertions, 0 deletions
diff --git a/src/imap/index.rs b/src/imap/index.rs
new file mode 100644
index 0000000..347222c
--- /dev/null
+++ b/src/imap/index.rs
@@ -0,0 +1,80 @@
+use std::num::NonZeroU32;
+
+use anyhow::{anyhow, bail, Result};
+use imap_codec::imap_types::sequence::{self, SequenceSet};
+
+use crate::mail::uidindex::{ImapUid, UidIndex};
+use crate::mail::unique_ident::UniqueIdent;
+
+pub struct Index<'a>(pub &'a UidIndex);
+impl<'a> Index<'a> {
+    pub fn fetch(self: &Index<'a>, sequence_set: &SequenceSet, by_uid: bool) -> Result<Vec<MailIndex<'a>>> {
+        let mail_vec = self
+            .0
+            .idx_by_uid
+            .iter()
+            .map(|(uid, uuid)| (*uid, *uuid))
+            .collect::<Vec<_>>();
+
+        let mut mails = vec![];
+
+        if by_uid {
+            if mail_vec.is_empty() {
+                return Ok(vec![]);
+            }
+            let iter_strat = sequence::Strategy::Naive {
+                largest: mail_vec.last().unwrap().0,
+            };
+
+            let mut i = 0;
+            for uid in sequence_set.iter(iter_strat) {
+                while mail_vec.get(i).map(|mail| mail.0 < uid).unwrap_or(false) {
+                    i += 1;
+                }
+                if let Some(mail) = mail_vec.get(i) {
+                    if mail.0 == uid {
+                        mails.push(MailIndex {
+                            i: NonZeroU32::try_from(i as u32 + 1).unwrap(),
+                            uid: mail.0,
+                            uuid: mail.1,
+                            flags: self.0.table.get(&mail.1).ok_or(anyhow!("mail is missing from index"))?.1.as_ref(),
+                        });
+                    }
+                } else {
+                    break;
+                }
+            }
+        } else {
+            if mail_vec.is_empty() {
+                bail!("No such message (mailbox is empty)");
+            }
+
+            let iter_strat = sequence::Strategy::Naive {
+                largest: NonZeroU32::try_from((mail_vec.len()) as u32).unwrap(),
+            };
+
+            for i in sequence_set.iter(iter_strat) {
+                if let Some(mail) = mail_vec.get(i.get() as usize - 1) {
+                    mails.push(MailIndex {
+                        i,
+                        uid: mail.0,
+                        uuid: mail.1,
+                        flags: self.0.table.get(&mail.1).ok_or(anyhow!("mail is missing from index"))?.1.as_ref(),
+                    });
+                } else {
+                    bail!("No such mail: {}", i);
+                }
+            }
+        }
+
+        Ok(mails)
+
+    }
+}
+
+pub struct MailIndex<'a> {
+    pub i: NonZeroU32,
+    pub uid: ImapUid,
+    pub uuid: UniqueIdent,
+    pub flags: &'a Vec<String>
+}