[fractal] room-history: Fix parsing of matrix.to URIs that are not percent-encoded

[Kévin Commaille <kcommaille src gnome org>]

commit 23691dbf87fec516f3db2989b7230b339e40bbc6
Author: Kévin Commaille <zecakeh tedomum fr>
Date:   Tue Sep 27 20:02:03 2022 +0200

    room-history: Fix parsing of matrix.to URIs that are not percent-encoded

 .../content/room_history/message_row/text.rs       |  8 +--
 src/utils.rs                                       | 78 +++++++++++++++++++++-
 2 files changed, 80 insertions(+), 6 deletions(-)
---
diff --git a/src/session/content/room_history/message_row/text.rs 
b/src/session/content/room_history/message_row/text.rs
index c94c8bb24..879862093 100644
--- a/src/session/content/room_history/message_row/text.rs
+++ b/src/session/content/room_history/message_row/text.rs
@@ -10,7 +10,7 @@ use log::warn;
 use matrix_sdk::ruma::{
     events::room::message::{FormattedBody, MessageFormat},
     matrix_uri::MatrixId,
-    MatrixToUri, MatrixUri,
+    MatrixUri,
 };
 use sourceview::prelude::*;
 
@@ -18,7 +18,7 @@ use super::ContentFormat;
 use crate::{
     components::{LabelWithWidgets, Pill, DEFAULT_PLACEHOLDER},
     session::{room::Member, Room, UserExt},
-    utils::EMOJI_REGEX,
+    utils::{parse_matrix_to_uri, EMOJI_REGEX},
 };
 
 enum WithMentions<'a> {
@@ -375,8 +375,8 @@ fn extract_mentions(s: &str, room: &Room) -> (String, Vec<Pill>) {
 
         let id = if let Ok(mx_uri) = MatrixUri::parse(uri) {
             mx_uri.id().to_owned()
-        } else if let Ok(mx_to_uri) = MatrixToUri::parse(uri) {
-            mx_to_uri.id().to_owned()
+        } else if let Ok((id, _)) = parse_matrix_to_uri(uri) {
+            id
         } else {
             continue;
         };
diff --git a/src/utils.rs b/src/utils.rs
index 8b33a623e..b765bdbcd 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -166,7 +166,7 @@ macro_rules! _add_toast {
     }};
 }
 
-use std::{path::PathBuf, str::FromStr};
+use std::{collections::HashMap, convert::TryInto, path::PathBuf, str::FromStr};
 
 use gettextrs::gettext;
 use gtk::{
@@ -174,7 +174,10 @@ use gtk::{
     glib::{self, closure, Object},
 };
 use matrix_sdk::ruma::{
-    events::room::MediaSource, EventId, OwnedEventId, OwnedTransactionId, TransactionId, UInt,
+    events::room::MediaSource, exports::percent_encoding::percent_decode_str, matrix_uri::MatrixId,
+    serde::urlencoded, EventId, IdParseError, MatrixIdError, MatrixToError, OwnedEventId,
+    OwnedServerName, OwnedTransactionId, RoomAliasId, RoomId, ServerName, TransactionId, UInt,
+    UserId,
 };
 use mime::Mime;
 use once_cell::sync::Lazy;
@@ -478,3 +481,74 @@ pub static EMOJI_REGEX: Lazy<Regex> = Lazy::new(|| {
     )
     .unwrap()
 });
+
+const MATRIX_TO_BASE_URL: &str = "https://matrix.to/#/";;
+
+/// Parse a matrix.to URI.
+///
+/// Ruma's parsing fails with non-percent-encoded identifiers, which is the
+/// format of permalinks provided by Element Web.
+pub fn parse_matrix_to_uri(uri: &str) -> Result<(MatrixId, Vec<OwnedServerName>), IdParseError> {
+    let s = uri
+        .strip_prefix(MATRIX_TO_BASE_URL)
+        .ok_or(MatrixToError::WrongBaseUrl)?;
+    let s = s.strip_suffix('/').unwrap_or(s);
+
+    let mut parts = s.split('?');
+    let ids_part = parts.next().ok_or(MatrixIdError::NoIdentifier)?;
+    let mut ids = ids_part.split('/');
+
+    let first = ids.next().ok_or(MatrixIdError::NoIdentifier)?;
+    let first_id = percent_decode_str(first).decode_utf8()?;
+
+    let id: MatrixId = match first_id.as_bytes()[0] {
+        b'!' => {
+            let room_id = RoomId::parse(&first_id)?;
+
+            if let Some(second) = ids.next() {
+                let second_id = percent_decode_str(second).decode_utf8()?;
+                let event_id = EventId::parse(&second_id)?;
+                (room_id, event_id).into()
+            } else {
+                room_id.into()
+            }
+        }
+        b'#' => {
+            let room_id = RoomAliasId::parse(&first_id)?;
+
+            if let Some(second) = ids.next() {
+                let second_id = percent_decode_str(second).decode_utf8()?;
+                let event_id = EventId::parse(&second_id)?;
+                (room_id, event_id).into()
+            } else {
+                room_id.into()
+            }
+        }
+        b'@' => UserId::parse(&first_id)?.into(),
+        b'$' => return Err(MatrixIdError::MissingRoom.into()),
+        _ => return Err(MatrixIdError::UnknownIdentifier.into()),
+    };
+
+    if ids.next().is_some() {
+        return Err(MatrixIdError::TooManyIdentifiers.into());
+    }
+
+    let via = parts
+        .next()
+        .map(|query| {
+            let query_parts = urlencoded::from_str::<HashMap<String, String>>(query)
+                .or(Err(MatrixToError::InvalidUrl))?;
+            query_parts
+                .into_iter()
+                .filter_map(|(key, value)| (key == "via").then(|| ServerName::parse(&value)))
+                .collect::<Result<Vec<_>, _>>()
+        })
+        .transpose()?
+        .unwrap_or_default();
+
+    if parts.next().is_some() {
+        return Err(MatrixToError::InvalidUrl.into());
+    }
+
+    Ok((id, via))
+}