use std::num::{NonZeroU32, NonZeroU64};
use anyhow::{anyhow, Result};
use imap_codec::imap_types::sequence::{SeqOrUid, Sequence, SequenceSet};
use aero_collections::mail::uidindex::{ImapUid, ModSeq, UidIndex};
use aero_collections::unique_ident::UniqueIdent;
pub struct Index<'a> {
pub imap_index: Vec<MailIndex<'a>>,
pub internal: &'a UidIndex,
}
impl<'a> Index<'a> {
pub fn new(internal: &'a UidIndex) -> Result<Self> {
let imap_index = internal
.idx_by_uid
.iter()
.enumerate()
.map(|(i_enum, (&uid, &uuid))| {
let (_, modseq, flags) = internal
.table
.get(&uuid)
.ok_or(anyhow!("mail is missing from index"))?;
let i_int: u32 = (i_enum + 1).try_into()?;
let i: NonZeroU32 = i_int.try_into()?;
Ok(MailIndex {
i,
uid,
uuid,
modseq: *modseq,
flags,
})
})
.collect::<Result<Vec<_>>>()?;
Ok(Self {
imap_index,
internal,
})
}
pub fn last(&'a self) -> Option<&'a MailIndex<'a>> {
self.imap_index.last()
}
/// Fetch mail descriptors based on a sequence of UID
///
/// Complexity analysis:
/// - Sort is O(n * log n) where n is the number of uid generated by the sequence
/// - Finding the starting point in the index O(log m) where m is the size of the mailbox
/// While n =< m, it's not clear if the difference is big or not.
///
/// For now, the algorithm tries to be fast for small values of n,
/// as it is what is expected by clients.
///
/// So we assume for our implementation that : n << m.
/// It's not true for full mailbox searches for example...
pub fn fetch_on_uid(&'a self, sequence_set: &SequenceSet) -> Vec<&'a MailIndex<'a>> {
if self.imap_index.is_empty() {
return vec![];
}
let largest = self.last().expect("The mailbox is not empty").uid;
let mut unroll_seq = sequence_set.iter(largest).collect::<Vec<_>>();
unroll_seq.sort();
let start_seq = match unroll_seq.iter().next() {
Some(elem) => elem,
None => return vec![],
};
// Quickly jump to the right point in the mailbox vector O(log m) instead
// of iterating one by one O(m). Works only because both unroll_seq & imap_index are sorted per uid.
let mut imap_idx = {
let start_idx = self
.imap_index
.partition_point(|mail_idx| &mail_idx.uid < start_seq);
&self.imap_index[start_idx..]
};
let mut acc = vec![];
for wanted_uid in unroll_seq.iter() {
// Slide the window forward as long as its first element is lower than our wanted uid.
let start_idx = match imap_idx.iter().position(|midx| &midx.uid >= wanted_uid) {
Some(v) => v,
None => break,
};
imap_idx = &imap_idx[start_idx..];
// If the beginning of our new window is the uid we want, we collect it
if &imap_idx[0].uid == wanted_uid {
acc.push(&imap_idx[0]);
}
}
acc
}
pub fn fetch_on_id(&'a self, sequence_set: &SequenceSet) -> Result<Vec<&'a MailIndex<'a>>> {
if self.imap_index.is_empty() {
return Ok(vec![]);
}
let largest = NonZeroU32::try_from(self.imap_index.len() as u32)?;
let mut acc = sequence_set
.iter(largest)
.map(|wanted_id| {
self.imap_index
.get((wanted_id.get() as usize) - 1)
.ok_or(anyhow!("Mail not found"))
})
.collect::<Result<Vec<_>>>()?;
// Sort the result to be consistent with UID
acc.sort_by(|a, b| a.i.cmp(&b.i));
Ok(acc)
}
pub fn fetch(
self: &'a Index<'a>,
sequence_set: &SequenceSet,
by_uid: bool,
) -> Result<Vec<&'a MailIndex<'a>>> {
match by_uid {
true => Ok(self.fetch_on_uid(sequence_set)),
_ => self.fetch_on_id(sequence_set),
}
}
pub fn fetch_changed_since(
self: &'a Index<'a>,
sequence_set: &SequenceSet,
maybe_modseq: Option<NonZeroU64>,
by_uid: bool,
) -> Result<Vec<&'a MailIndex<'a>>> {
let raw = self.fetch(sequence_set, by_uid)?;
let res = match maybe_modseq {
Some(pit) => raw.into_iter().filter(|midx| midx.modseq > pit).collect(),
None => raw,
};
Ok(res)
}
pub fn fetch_unchanged_since(
self: &'a Index<'a>,
sequence_set: &SequenceSet,
maybe_modseq: Option<NonZeroU64>,
by_uid: bool,
) -> Result<(Vec<&'a MailIndex<'a>>, Vec<&'a MailIndex<'a>>)> {
let raw = self.fetch(sequence_set, by_uid)?;
let res = match maybe_modseq {
Some(pit) => raw.into_iter().partition(|midx| midx.modseq <= pit),
None => (raw, vec![]),
};
Ok(res)
}
}
#[derive(Clone, Debug)]
pub struct MailIndex<'a> {
pub i: NonZeroU32,
pub uid: ImapUid,
pub uuid: UniqueIdent,
pub modseq: ModSeq,
pub flags: &'a Vec<String>,
}
impl<'a> MailIndex<'a> {
// The following functions are used to implement the SEARCH command
pub fn is_in_sequence_i(&self, seq: &Sequence) -> bool {
match seq {
Sequence::Single(SeqOrUid::Asterisk) => true,
Sequence::Single(SeqOrUid::Value(target)) => target == &self.i,
Sequence::Range(SeqOrUid::Asterisk, SeqOrUid::Value(x))
| Sequence::Range(SeqOrUid::Value(x), SeqOrUid::Asterisk) => x <= &self.i,
Sequence::Range(SeqOrUid::Value(x1), SeqOrUid::Value(x2)) => {
if x1 < x2 {
x1 <= &self.i && &self.i <= x2
} else {
x1 >= &self.i && &self.i >= x2
}
}
Sequence::Range(SeqOrUid::Asterisk, SeqOrUid::Asterisk) => true,
}
}
pub fn is_in_sequence_uid(&self, seq: &Sequence) -> bool {
match seq {
Sequence::Single(SeqOrUid::Asterisk) => true,
Sequence::Single(SeqOrUid::Value(target)) => target == &self.uid,
Sequence::Range(SeqOrUid::Asterisk, SeqOrUid::Value(x))
| Sequence::Range(SeqOrUid::Value(x), SeqOrUid::Asterisk) => x <= &self.uid,
Sequence::Range(SeqOrUid::Value(x1), SeqOrUid::Value(x2)) => {
if x1 < x2 {
x1 <= &self.uid && &self.uid <= x2
} else {
x1 >= &self.uid && &self.uid >= x2
}
}
Sequence::Range(SeqOrUid::Asterisk, SeqOrUid::Asterisk) => true,
}
}
pub fn is_flag_set(&self, flag: &str) -> bool {
self.flags
.iter()
.any(|candidate| candidate.as_str() == flag)
}
}
