list: thread tree listing

Cargo.lock

@@ -194,6 +194,12 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7360491ce676a36bf9bb3c56c1aa791658183a54d2744120f27285738d90465a"
 
+[[package]]
+name = "fixedbitset"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37ab347416e802de484e4d03c7316c48f1ecb56574dfd4a46a80f173ce1de04d"
+
 [[package]]
 name = "fs2"
 version = "0.4.3"
@@ -281,12 +287,23 @@ dependencies = [
  "mailproc",
  "mime2ext",
  "moins",
+ "petgraph",
  "rusqlite",
  "rustls-connector",
  "rustyline",
  "subprocess",
 ]
 
+[[package]]
+name = "indexmap"
+version = "1.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "824845a0bf897a9042383849b02c1bc219c2383772efcd5c6f9766fa4b81aef3"
+dependencies = [
+ "autocfg",
+ "hashbrown",
+]
+
 [[package]]
 name = "itertools"
 version = "0.10.0"
@@ -493,6 +510,16 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77af24da69f9d9341038eba93a073b1fdaaa1b788221b00a69bce9e762cb32de"
 
+[[package]]
+name = "petgraph"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "467d164a6de56270bd7c4d070df81d07beace25012d5103ced4e9ff08d6afdb7"
+dependencies = [
+ "fixedbitset",
+ "indexmap",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.19"

Cargo.toml

@@ -23,3 +23,4 @@ anyhow = "1.0.40"
 mailproc = { git = "https://github.com/FliegendeWurst/mailproc.git", branch = "master" }
 subprocess = "0.2.6"
 mime2ext = "0.1.2"
+petgraph = "0.5.1"

src/bin/list.rs

@@ -1,9 +1,10 @@
-use std::{array::IntoIter, collections::HashSet, env, fs};
+use std::{array::IntoIter, cell::RefCell, cmp, collections::{HashMap, HashSet}, env, fs};
 
 use ascii_table::{Align, AsciiTable, Column};
 use inboxid::*;
 use itertools::Itertools;
 use mailparse::ParsedMail;
+use petgraph::{EdgeDirection, dot::Dot, graph::{DiGraph, NodeIndex}, visit::{Dfs, IntoNodeReferences, Walker}};
 use rustyline::{Editor, error::ReadlineError};
 
 fn main() -> Result<()> {
@@ -43,6 +44,87 @@ fn show_listing(mailbox: &str) -> Result<()> {
 		rows.push(IntoIter::new([(mails.len() - i).to_string(), flags_display, mail.from.clone(), mail.subject.clone(), mail.date_iso.clone()]));
 	}
 
+	let mut mails_by_id = HashMap::new();
+	let mut threads: HashMap<_, Vec<_>> = HashMap::new();
+	for mail in &mails {
+		let mid = mail.get_header("Message-ID");
+		threads.entry(mid.clone()).or_default().push(mail);
+		if mails_by_id.insert(mid, mail).is_some() {
+			println!("error: missing/duplicate Message-ID");
+			return Ok(());
+		}
+		for value in mail.get_header_values("References") {
+			for mid in value.split(' ').map(ToOwned::to_owned) {
+				threads.entry(mid).or_default().push(mail);
+			}
+		}
+		for value in mail.get_header_values("In-Reply-To") {
+			for mid in value.split(' ').map(ToOwned::to_owned) {
+				threads.entry(mid).or_default().push(mail);
+			}
+		}
+	}
+	let mut threads = threads.into_iter().collect_vec();
+	threads.sort_unstable_by_key(|(_, mails)| mails.len());
+	threads.reverse();
+	let mut graph = DiGraph::new();
+	let mut nodes = HashMap::new();
+	let mut nodes_inv = HashMap::new();
+	for mail in &mails {
+		let node = graph.add_node(mail);
+		nodes.insert(mail, node);
+		nodes_inv.insert(node, mail);
+	}
+	for mail in &mails {
+		for value in mail.get_header_values("In-Reply-To") {
+			for mid in value.split(' ').map(ToOwned::to_owned) {
+				if let Some(other_mail) = mails_by_id.get(&mid) {
+					graph.add_edge(nodes[other_mail], nodes[mail], ());
+				} else {
+					let pseudomail = Box::leak(Box::new(EasyMail::new_pseudo(mid.clone())));
+					let node = graph.add_node(pseudomail);
+					nodes.insert(pseudomail, node);
+					nodes_inv.insert(node, pseudomail);
+					graph.add_edge(node, nodes[mail], ());
+					mails_by_id.insert(mid, pseudomail);
+				}
+			}
+		}
+	}
+	let mut roots = graph.node_references().filter(|x| graph.neighbors_directed(x.0, EdgeDirection::Incoming).count() == 0).collect_vec();
+	roots.sort_unstable_by_key(|x| x.1.date);
+	let mails_printed = RefCell::new(HashSet::new());
+
+	struct PrintThread<'a> {
+		f: &'a dyn Fn(&PrintThread, NodeIndex, usize)
+	}
+	let print_thread = |this: &PrintThread, node, depth| {
+		let mail = nodes_inv[&node];
+		if mails_printed.borrow().contains(mail) && depth == 0 {
+			return;
+		}
+		println!("{}{}", "   ".repeat(depth), mail.subject);
+		mails_printed.borrow_mut().insert(mail);
+		let mut replies = graph.neighbors_directed(node, EdgeDirection::Outgoing).collect_vec();
+		replies.sort_unstable_by_key(|&idx| {
+			let mut maximum = &nodes_inv[&idx].date;
+			let mut dfs = Dfs::new(&graph, idx);
+			while let Some(idx) = dfs.next(&graph) {
+				let other = nodes_inv[&idx];
+				maximum = cmp::max(maximum, &other.date);
+			}
+			maximum
+		});
+		for r in replies {
+			(this.f)(this, r, depth + 1);
+		}
+	};
+	let print_thread = PrintThread { f: &print_thread };
+
+	for root in roots {
+		(print_thread.f)(&print_thread, root.0, 0);
+	}
+
 	let mut ascii_table = AsciiTable::default();
 	ascii_table.draw_lines = false;
 	ascii_table.max_width = usize::MAX;

src/lib.rs

@@ -1,4 +1,4 @@
-use std::{borrow::Cow, convert::{TryFrom, TryInto}, env, fs, io, net::TcpStream, ops::Deref};
+use std::{borrow::Cow, convert::{TryFrom, TryInto}, env, fmt::Debug, fs, hash::Hash, io, net::TcpStream, ops::Deref};
 
 use anyhow::Context;
 use chrono::{DateTime, Local, NaiveDateTime, TimeZone};
@@ -52,7 +52,7 @@ pub fn gen_id(uid_validity: u32, uid: u32) -> String {
 	format!("{}_{}", uid_validity, uid)
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct MaildirID {
 	uid_validity: u32,
 	pub uid: u32,
@@ -92,7 +92,7 @@ impl MaildirID {
 }
 
 pub struct EasyMail<'a> {
-	pub mail: ParsedMail<'a>,
+	mail: Option<ParsedMail<'a>>,
 	pub id: MaildirID,
 	pub flags: String,
 	pub from: String,
@@ -101,11 +101,55 @@ pub struct EasyMail<'a> {
 	pub date_iso: String,
 }
 
+impl EasyMail<'_> {
+	pub fn new_pseudo(subject: String) -> Self {
+		Self {
+		    mail: None,
+		    id: MaildirID::new(0, 0),
+			flags: "S".to_owned(),
+			from: String::new(),
+		    subject,
+			date: Local.from_utc_datetime(&NaiveDateTime::from_timestamp(0, 0)),
+			date_iso: "????-??-??".to_owned()
+		}
+	}
+
+	pub fn get_header(&self, header: &str) -> String {
+		self.get_headers().get_all_values(header).join(" ")
+	}
+
+	pub fn get_header_values(&self, header: &str) -> Vec<String> {
+		self.get_headers().get_all_values(header)
+	}
+}
+
+impl Debug for EasyMail<'_> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Mail[ID={},Subject={:?}]", self.id.uid, self.subject)
+    }
+}
+
+impl PartialEq for EasyMail<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.id == other.id && self.from == other.from && self.subject == other.subject
+    }
+}
+
+impl Eq for EasyMail<'_> {}
+
+impl Hash for EasyMail<'_> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.id.hash(state);
+		self.from.hash(state);
+		self.subject.hash(state);
+    }
+}
+
 impl<'a> Deref for EasyMail<'a> {
 	type Target = ParsedMail<'a>;
 
 	fn deref(&self) -> &Self::Target {
-		&self.mail
+		&self.mail.as_ref().unwrap()
 	}
 }
 
@@ -169,7 +213,7 @@ impl MaildirExtension for Maildir {
 				Local.from_utc_datetime(&NaiveDateTime::from_timestamp(x, 0))
 			)?;
 			mails.push(EasyMail {
-				mail,
+				mail: Some(mail),
 				flags,
 				id,
 				from,