feat(pkgs/back): Rewrite the `git-bug` interface code

The previous code was more or less reverse engineered, whilst this code
is based on the actually git-bug source code. This improves the whole
issue and operation handling immensely and also makes the code better
maintainable. Furthermore, it also adds support for the operations that
had not already used in `vhack.eu/nixos-server.git`.

6 files changed, 239 insertions, 646 deletions

diff --git a/pkgs/by-name/ba/back/src/web/format/mod.rs b/pkgs/by-name/ba/back/src/web/format/mod.rs
deleted file mode 100644
index f78d3b3..0000000
--- a/pkgs/by-name/ba/back/src/web/format/mod.rs
+++ /dev/null
@@ -1,88 +0,0 @@
-// Back - An extremely simple git issue tracking system. Inspired by tvix's
-// panettone
-//
-// Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This file is part of Back.
-//
-// You should have received a copy of the License along with this program.
-// If not, see <https://www.gnu.org/licenses/agpl.txt>.
-
-use std::fmt::Display;
-
-use markdown::to_html;
-
-#[derive(Debug, Default, Clone)]
-pub struct Markdown {
-    value: String,
-}
-
-impl From<String> for Markdown {
-    fn from(value: String) -> Self {
-        Self { value }
-    }
-}
-impl Display for Markdown {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(to_html(&self.value).as_str())
-    }
-}
-
-#[derive(Debug, Default)]
-pub struct BackString {
-    value: String,
-}
-
-impl From<Markdown> for BackString {
-    fn from(value: Markdown) -> Self {
-        Self { value: value.value }
-    }
-}
-
-impl From<String> for BackString {
-    fn from(value: String) -> Self {
-        Self { value }
-    }
-}
-impl Display for BackString {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.write_str(escape_html(&self.value).as_str())
-    }
-}
-
-// From `tera::escape_html`
-/// Escape HTML following [OWASP](https://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet)
-///
-/// Escape the following characters with HTML entity encoding to prevent switching
-/// into any execution context, such as script, style, or event handlers. Using
-/// hex entities is recommended in the spec. In addition to the 5 characters
-/// significant in XML (&, <, >, ", '), the forward slash is included as it helps
-/// to end an HTML entity.
-///
-/// ```text
-/// & --> &amp;
-/// < --> &lt;
-/// > --> &gt;
-/// " --> &quot;
-/// ' --> &#x27;     &apos; is not recommended
-/// / --> &#x2F;     forward slash is included as it helps end an HTML entity
-/// ```
-#[inline]
-pub fn escape_html(input: &str) -> String {
-    let mut output = String::with_capacity(input.len() * 2);
-    for c in input.chars() {
-        match c {
-            '&' => output.push_str("&amp;"),
-            '<' => output.push_str("&lt;"),
-            '>' => output.push_str("&gt;"),
-            '"' => output.push_str("&quot;"),
-            '\'' => output.push_str("&#x27;"),
-            '/' => output.push_str("&#x2F;"),
-            _ => output.push(c),
-        }
-    }
-
-    // Not using shrink_to_fit() on purpose
-    output
-}
diff --git a/pkgs/by-name/ba/back/src/web/issue/mod.rs b/pkgs/by-name/ba/back/src/web/issue/mod.rs
deleted file mode 100644
index 79ef70f..0000000
--- a/pkgs/by-name/ba/back/src/web/issue/mod.rs
+++ /dev/null
@@ -1,337 +0,0 @@
-// Back - An extremely simple git issue tracking system. Inspired by tvix's
-// panettone
-//
-// Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This file is part of Back.
-//
-// You should have received a copy of the License along with this program.
-// If not, see <https://www.gnu.org/licenses/agpl.txt>.
-
-use std::fmt::Display;
-
-use chrono::DateTime;
-use gix::{bstr::ByteSlice, Commit, Id, ObjectId, Repository};
-use raw::{Operation, RawIssue};
-use rocket::response::content::RawHtml;
-
-use crate::config::BackConfig;
-
-use super::format::{BackString, Markdown};
-
-mod raw;
-
-#[derive(Debug, Default)]
-pub struct TimeStamp {
-    value: u64,
-}
-impl TimeStamp {
-    pub fn new(val: u64) -> Self {
-        Self { value: val }
-    }
-}
-impl Display for TimeStamp {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let date =
-            DateTime::from_timestamp(self.value as i64, 0).expect("This timestamp should be vaild");
-
-        let newdate = date.format("%Y-%m-%d %H:%M:%S");
-        f.write_str(newdate.to_string().as_str())
-    }
-}
-
-#[derive(Debug)]
-pub struct Comment<'a> {
-    pub id: Id<'a>,
-    pub author: Author,
-    pub message: Markdown,
-    pub timestamp: TimeStamp,
-}
-
-#[derive(Debug, Default)]
-pub struct Author {
-    name: BackString,
-    email: BackString,
-}
-
-#[derive(Debug)]
-pub struct IssueId<'a> {
-    value: Id<'a>,
-}
-impl<'a> IssueId<'a> {
-    pub fn new(id: Id<'a>) -> Self {
-        Self { value: id }
-    }
-}
-impl Display for IssueId<'_> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let shortend = self.value.shorten().expect("This should work.");
-        f.write_str(shortend.to_string().as_str())
-    }
-}
-
-#[derive(Default, Debug, PartialEq, Eq, PartialOrd, Ord, Copy, Clone)]
-pub enum Status {
-    #[default]
-    Open,
-    Closed,
-}
-impl Display for Status {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Status::Open => f.write_str("Open"),
-            Status::Closed => f.write_str("Closed"),
-        }
-    }
-}
-
-#[derive(Debug)]
-pub struct Issue<'a> {
-    pub id: IssueId<'a>,
-    pub author: Author,
-    pub timestamp: TimeStamp,
-    pub title: Markdown,
-    pub message: Markdown,
-    pub comments: Vec<Comment<'a>>,
-    pub status: Status,
-    pub last_status_change: Option<TimeStamp>,
-}
-impl<'a> Issue<'a> {
-    pub fn default_with_id(id: Id<'a>) -> Self {
-        Self {
-            id: IssueId::new(id),
-            author: Author::default(),
-            timestamp: TimeStamp::default(),
-            title: Markdown::default(),
-            message: Markdown::default(),
-            comments: <Vec<Comment>>::default(),
-            status: Status::default(),
-            last_status_change: <Option<TimeStamp>>::default(),
-        }
-    }
-
-    pub fn from_commit_id(repo: &'a Repository, commit_id: ObjectId) -> Self {
-        fn unwrap_id<'b>(repo: &Repository, id: &Commit<'b>) -> (RawIssue, Id<'b>) {
-            let tree_obj = repo
-                .find_object(
-                    id.tree_id()
-                        .expect("All of git-bug's commits should have trees attached to them'"),
-                )
-                .expect("The object with this id should exist.")
-                .try_into_tree()
-                .expect("The git-bug's data model enforces this.");
-
-            let ops_ref = tree_obj
-                .find_entry("ops")
-                .expect("All of git-bug's trees should contain a 'ops' json file");
-
-            let issue_data = repo
-                .find_object(ops_ref.object_id())
-                .expect("The object with this id should exist.")
-                .try_into_blob()
-                .expect("The git-bug's data model enforces this.")
-                .data
-                .clone();
-
-            let raw_issue = serde_json::from_str(
-                issue_data
-                    .to_str()
-                    .expect("git-bug's ensures, that this is valid json."),
-            )
-            .expect("The returned json should be valid");
-
-            (raw_issue, id.id())
-        }
-
-        let commit_obj = repo
-            .find_object(commit_id)
-            .expect("The object with this id should exist.")
-            .try_into_commit()
-            .expect("The git-bug's data model enforces this.");
-
-        let mut issues = vec![unwrap_id(repo, &commit_obj)];
-
-        let mut current_commit_obj = commit_obj;
-        while current_commit_obj.parent_ids().count() != 0 {
-            assert_eq!(
-                current_commit_obj.parent_ids().count(),
-                1,
-                "There should be only one parent"
-            );
-            let parent = current_commit_obj
-                .parent_ids()
-                .last()
-                .expect("One does exist");
-
-            let parent_id = parent.object().expect("The object exists").id;
-            let parent_commit = repo
-                .find_object(parent_id)
-                .expect("This is a valid id")
-                .try_into_commit()
-                .expect("This should be a commit");
-
-            issues.push(unwrap_id(repo, &parent_commit));
-            current_commit_obj = parent_commit;
-        }
-
-        let mut final_issue = Self::default_with_id(current_commit_obj.id());
-        for (issue, id) in issues {
-            for op in issue.operations {
-                match op {
-                    Operation::AddComment { timestamp, message } => {
-                        final_issue.comments.push(Comment {
-                            id,
-                            author: issue.author.load_identity(repo),
-                            message: Markdown::from(message),
-                            timestamp: TimeStamp::new(timestamp),
-                        })
-                    }
-                    Operation::Create {
-                        timestamp,
-                        title,
-                        message,
-                    } => {
-                        final_issue.author = issue.author.load_identity(repo);
-                        final_issue.title = Markdown::from(title);
-                        final_issue.message = Markdown::from(message);
-                        final_issue.timestamp = TimeStamp::new(timestamp);
-                    }
-                    Operation::SetStatus { timestamp, status } => {
-                        final_issue.status = status;
-                        final_issue.last_status_change = Some(TimeStamp::new(timestamp));
-                    }
-                }
-            }
-        }
-        final_issue
-    }
-
-    pub fn to_list_entry(&self) -> RawHtml<String> {
-        let comment_list = if self.comments.is_empty() {
-            String::new()
-        } else {
-            format!(
-                r#"
-                <span class="comment-count"> - {} comments</span>
-            "#,
-                self.comments.len()
-            )
-        };
-        let Issue {
-            id,
-            title,
-            message: _,
-            author,
-            timestamp,
-            comments: _,
-            status: _,
-            last_status_change: _,
-        } = self;
-        let Author { name, email } = author;
-        RawHtml(format!(
-            r#"
-               <li>
-                  <a href="/issue/{id}">
-                     <p>
-                        <span class="issue-subject">{title}</span>
-                     </p>
-                     <span class="issue-number">{id}</span> - <span class="created-by-at">Opened by <span class="user-name">{name}</span> <span class="user-email">&lt;{email}&gt;</span> at <span class="timestamp">{timestamp}</span></span>{comment_list}                  </a>
-               </li>
-"#,
-        ))
-    }
-
-    pub fn to_html(&self, config: &BackConfig) -> RawHtml<String> {
-        let fmt_comments: String = self
-            .comments
-            .iter()
-            .map(|val| {
-                let Comment {
-                    id,
-                    author,
-                    message,
-                    timestamp,
-                } = val;
-                let Author { name, email: _ } = author;
-
-                format!(
-                    r#"
-               <li class="comment" id="{id}">
-                  {message}
-                  <p class="comment-info"><span class="user-name">{name} at {timestamp}</span></p>
-               </li>
-                "#,
-                )
-            })
-            .collect::<Vec<String>>()
-            .join("\n");
-
-        let maybe_comments = if fmt_comments.is_empty() {
-            String::new()
-        } else {
-            format!(
-                r#"
-            <ol class="issue-history">
-            {fmt_comments}
-            </ol>
-            "#
-            )
-        };
-
-        {
-            let Issue {
-                id,
-                title,
-                message,
-                author,
-                timestamp,
-                comments: _,
-                status: _,
-                last_status_change: _,
-            } = self;
-            let Author { name, email } = author;
-            let html_title = BackString::from(title.clone());
-
-            RawHtml(format!(
-                r#"
-<!DOCTYPE html>
-<html lang="en">
-   <head>
-      <title>{html_title} | Back</title>
-      <link href="/style.css" rel="stylesheet" type="text/css">
-      <meta content="width=device-width,initial-scale=1" name="viewport">
-   </head>
-   <body>
-      <div class="content">
-         <nav>
-         <a href="/issues/open">Open Issues</a>
-         <a href="/issues/closed">Closed Issues</a>
-         </nav>
-         <header>
-            <h1>{title}</h1>
-            <div class="issue-number">{id}</div>
-         </header>
-         <main>
-            <div class="issue-info">
-                <span class="created-by-at">Opened by <span class="user-name">{name}</span> <span class="user-email">&lt;{email}&gt;</span> at <span class="timestamp">{timestamp}</span></span>
-            </div>
-            {message}
-            {maybe_comments}
-         </main>
-         <footer>
-            <nav>
-            <a href="/issues/open">Open Issues</a>
-            <a href="{}">Source code</a>
-            <a href="/issues/closed">Closed Issues</a>
-            </nav>
-         </footer>
-      </div>
-   </body>
-</html>
-"#,
-                config.source_code_repository_url
-            ))
-        }
-    }
-}
diff --git a/pkgs/by-name/ba/back/src/web/issue/raw.rs b/pkgs/by-name/ba/back/src/web/issue/raw.rs
deleted file mode 100644
index bb447ec..0000000
--- a/pkgs/by-name/ba/back/src/web/issue/raw.rs
+++ /dev/null
@@ -1,145 +0,0 @@
-// Back - An extremely simple git issue tracking system. Inspired by tvix's
-// panettone
-//
-// Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This file is part of Back.
-//
-// You should have received a copy of the License along with this program.
-// If not, see <https://www.gnu.org/licenses/agpl.txt>.
-
-use gix::{bstr::ByteSlice, Repository};
-use serde::Deserialize;
-use serde_json::Value;
-
-use crate::web::format::BackString;
-
-use super::{Author, Status};
-
-macro_rules! get {
-    ($value:expr, $name:expr, $type_fun:ident) => {
-        $value
-            .get($name)
-            .expect(concat!(
-                "Expected field ",
-                stringify!($name),
-                "to exists, but was missing."
-            ))
-            .$type_fun()
-            .expect(concat!(
-                "Failed to interpret field ",
-                stringify!($name),
-                " as ",
-                stringify!($type),
-                "!"
-            ))
-    };
-}
-
-#[derive(Deserialize)]
-pub(super) struct RawIssue {
-    pub(super) author: RawAuthor,
-
-    #[serde(alias = "ops")]
-    pub(super) operations: Vec<Operation>,
-}
-
-#[derive(Deserialize, Clone, Default, Debug)]
-pub(super) struct RawAuthor {
-    id: String,
-}
-
-impl RawAuthor {
-    pub fn load_identity(&self, repo: &Repository) -> Author {
-        let commit_obj = repo
-            .find_reference(&format!("refs/identities/{}", self.id))
-            .expect("All authors should also have identities")
-            .peel_to_commit()
-            .expect("All identities should be commits");
-        let tree_obj = repo
-            .find_tree(
-                commit_obj
-                    .tree()
-                    .expect("The commit should have an tree associated with it")
-                    .id,
-            )
-            .expect("This should be a tree");
-        let data = repo
-            .find_blob(
-                tree_obj
-                    .find_entry("version")
-                    .expect("This entry should exist")
-                    .object()
-                    .expect("This should point to a blob entry")
-                    .id,
-            )
-            .expect("This blob should exist")
-            .data
-            .clone();
-
-        let json: Value = serde_json::from_str(data.to_str().expect("This is encoded json"))
-            .expect("This is valid json");
-
-        Author {
-            name: BackString::from(get! {json, "name", as_str}.to_owned()),
-            email: BackString::from(get! {json, "email", as_str}.to_owned()),
-        }
-    }
-}
-
-#[derive(Deserialize)]
-#[serde(from = "Value")]
-pub(super) enum Operation {
-    AddComment {
-        timestamp: u64,
-        message: String,
-        // files: Option<String>, TODO
-    },
-    SetStatus {
-        timestamp: u64,
-        status: Status,
-    },
-    Create {
-        timestamp: u64,
-        title: String,
-        message: String,
-        // files: Option<String>, TODO
-    },
-}
-
-impl From<u64> for Status {
-    fn from(value: u64) -> Self {
-        match value {
-            1 => Status::Open,
-            2 => Status::Closed,
-            other => todo!("The status ({other}) is not yet implemented."),
-        }
-    }
-}
-
-impl From<Value> for Operation {
-    fn from(value: Value) -> Self {
-        match value
-            .get("type")
-            .expect("Should exist")
-            .as_u64()
-            .expect("This should work")
-        {
-            1 => Self::Create {
-                title: get! {value, "title", as_str}.to_owned(),
-                message: get! {value, "message", as_str}.to_owned(),
-                timestamp: get! {value, "timestamp", as_u64},
-            },
-            3 => Self::AddComment {
-                message: get! {value, "message", as_str}.to_owned(),
-                timestamp: get! {value, "timestamp", as_u64},
-            },
-            4 => Self::SetStatus {
-                status: Status::from(get! {value, "status", as_u64}),
-                timestamp: get! {value, "timestamp", as_u64},
-            },
-            other => todo!("The type ({other}) is not yet added as a a valid operation. It's value is: '{value}''"),
-        }
-    }
-}
diff --git a/pkgs/by-name/ba/back/src/web/issue_html.rs b/pkgs/by-name/ba/back/src/web/issue_html.rs
new file mode 100644
index 0000000..45c0281
--- /dev/null
+++ b/pkgs/by-name/ba/back/src/web/issue_html.rs
@@ -0,0 +1,166 @@
+// Back - An extremely simple git issue tracking system. Inspired by tvix's
+// panettone
+//
+// Copyright (C) 2024 Benedikt Peetz <benedikt.peetz@b-peetz.de>
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This file is part of Back.
+//
+// You should have received a copy of the License along with this program.
+// If not, see <https://www.gnu.org/licenses/agpl.txt>.
+
+use rocket::response::content::RawHtml;
+
+use crate::{
+    config::BackConfig,
+    git_bug::{
+        format::HtmlString,
+        issue::{identity::Author, CollapsedIssue, Comment},
+    },
+};
+
+impl CollapsedIssue {
+    pub fn to_list_entry(&self) -> RawHtml<String> {
+        let comment_list = if self.comments.is_empty() {
+            String::new()
+        } else {
+            let comments_string = if self.comments.len() > 1 {
+                "comments"
+            } else {
+                "comment"
+            };
+
+            format!(
+                r#"
+                <span class="comment-count"> - {} {}</span>
+            "#,
+                self.comments.len(),
+                comments_string
+            )
+        };
+
+        let CollapsedIssue {
+            id,
+            title,
+            message: _,
+            author,
+            timestamp,
+            comments: _,
+            status: _,
+            last_status_change: _,
+            labels: _,
+        } = self;
+
+        let Author { name, email, id: _ } = author;
+
+        RawHtml(format!(
+            r#"
+               <li>
+                  <a href="/issue/{id}">
+                     <p>
+                        <span class="issue-subject">{title}</span>
+                     </p>
+                     <span class="issue-number">{id}</span> - <span class="created-by-at">Opened by <span class="user-name">{name}</span> <span class="user-email">&lt;{email}&gt;</span> at <span class="timestamp">{timestamp}</span></span>{comment_list}                  </a>
+               </li>
+"#,
+        ))
+    }
+
+    pub fn to_html(&self, config: &BackConfig) -> RawHtml<String> {
+        let comments = if self.comments.is_empty() {
+            String::new()
+        } else {
+            let fmt_comments: String = self
+                .comments
+                .iter()
+                .map(|val| {
+                    let Comment {
+                        id,
+                        author,
+                        message,
+                        timestamp,
+                    } = val;
+                    let Author {
+                        name,
+                        email: _,
+                        id: _,
+                    } = author;
+
+                    format!(
+                        r#"
+               <li class="comment" id="{id}">
+                  {message}
+                  <p class="comment-info"><span class="user-name">{name} at {timestamp}</span></p>
+               </li>
+                "#,
+                    )
+                })
+                .collect::<Vec<String>>()
+                .join("\n");
+
+            format!(
+                r#"
+            <ol class="issue-history">
+            {fmt_comments}
+            </ol>
+            "#
+            )
+        };
+
+        {
+            let CollapsedIssue {
+                id,
+                title,
+                message,
+                author,
+                timestamp,
+                comments: _,
+                status: _,
+                last_status_change: _,
+                labels: _,
+            } = self;
+            let Author { name, email, id: _ } = author;
+            let html_title = HtmlString::from(title.clone());
+
+            RawHtml(format!(
+                r#"
+<!DOCTYPE html>
+<html lang="en">
+   <head>
+      <title>{html_title} | Back</title>
+      <link href="/style.css" rel="stylesheet" type="text/css">
+      <meta content="width=device-width,initial-scale=1" name="viewport">
+   </head>
+   <body>
+      <div class="content">
+         <nav>
+         <a href="/issues/open">Open Issues</a>
+         <a href="/issues/closed">Closed Issues</a>
+         </nav>
+         <header>
+            <h1>{title}</h1>
+            <div class="issue-number">{id}</div>
+         </header>
+         <main>
+            <div class="issue-info">
+                <span class="created-by-at">Opened by <span class="user-name">{name}</span> <span class="user-email">&lt;{email}&gt;</span> at <span class="timestamp">{timestamp}</span></span>
+            </div>
+            {message}
+            {comments}
+         </main>
+         <footer>
+            <nav>
+            <a href="/issues/open">Open Issues</a>
+            <a href="{}">Source code</a>
+            <a href="/issues/closed">Closed Issues</a>
+            </nav>
+         </footer>
+      </div>
+   </body>
+</html>
+"#,
+                config.source_code_repository_url
+            ))
+        }
+    }
+}
diff --git a/pkgs/by-name/ba/back/src/web/mod.rs b/pkgs/by-name/ba/back/src/web/mod.rs
index ed91e7e..1e6a5af 100644
--- a/pkgs/by-name/ba/back/src/web/mod.rs
+++ b/pkgs/by-name/ba/back/src/web/mod.rs
@@ -9,125 +9,121 @@
 // You should have received a copy of the License along with this program.
 // If not, see <https://www.gnu.org/licenses/agpl.txt>.
 
-use std::path::Path;
-
 use crate::{
     config::BackConfig,
-    web::issue::{Issue, Status},
+    error::{self, Error},
+    git_bug::{
+        dag::issues_from_repository,
+        issue::{CollapsedIssue, Status},
+    },
 };
-use gix::{refs::Target, Repository};
-use issue_show::BackPrefix;
+use prefix::BackPrefix;
 use rocket::{
     get,
     response::content::{RawCss, RawHtml},
     State,
 };
 
-mod format;
-mod issue;
-mod issue_show;
+mod issue_html;
+pub mod prefix;
 
 #[get("/style.css")]
 pub fn styles() -> RawCss<String> {
     RawCss(include_str!("../../assets/style.css").to_owned())
 }
 
-fn list_all_issues(repo: &'_ Repository) -> Vec<Issue<'_>> {
-    repo.refs
-        .iter()
-        .expect("We should be able to iterate over references")
-        .prefixed(Path::new("refs/bugs/"))
-        .expect("The 'refs/bugs/' namespace should exist")
-        .map(|val| {
-            let reference = val.expect("'val' should be an object?");
-            if let Target::Object(commit_id) = reference.target {
-                Issue::from_commit_id(repo, commit_id)
-            } else {
-                unreachable!("All 'refs/bugs/' should contain a clear target.");
-            }
-        })
-        .collect()
-}
-
 pub fn issue_list_boilerplate(
     config: &State<BackConfig>,
     wanted_status: Status,
     counter_status: Status,
-) -> RawHtml<String> {
+) -> error::Result<RawHtml<String>> {
     let repository = &config.repository;
 
-    let issue_list = list_all_issues(&repository.to_thread_local())
-        .iter()
+    let issue_list = issues_from_repository(&repository.to_thread_local())?
+        .into_iter()
         .fold(String::new(), |acc, val| {
-            format!("{}{}", acc, &issue_to_string(val, wanted_status).0)
+            let issue = val.collaps();
+
+            format!("{}{}", acc, {
+                if issue.status == wanted_status {
+                    let issue_entry = issue.to_list_entry();
+                    issue_entry.0
+                } else {
+                    String::new()
+                }
+            })
         });
 
     let counter_status_lower = counter_status.to_string().to_lowercase();
-    RawHtml(format!(
+    Ok(RawHtml(format!(
         r#"
-<!DOCTYPE html>
-<html lang="en">
-   <head>
-      <title>Back</title>
-      <link href="/style.css" rel="stylesheet" type="text/css">
-      <meta content="width=device-width,initial-scale=1" name="viewport">
-   </head>
-   <body>
-      <div class="content">
-         <header>
-            <h1>{wanted_status} Issues</h1>
-         </header>
-         <main>
-            <div class="issue-links">
-               <a href="/issues/{counter_status_lower}/">View {counter_status} issues</a>
-               <a href="{}">Source code</a>
-               <!--
-               <form class="issue-search" method="get">
-                   <input name="search" title="Issue search query" type="search">
-                   <input class="sr-only" type="submit" value="Search Issues">
-               </form>
-               -->
-            </div>
-            <ol class="issue-list">
-            {issue_list}
-            </ol>
-         </main>
-      </div>
-   </body>
-</html>
-"#,
+    <!DOCTYPE html>
+    <html lang="en">
+       <head>
+          <title>Back</title>
+          <link href="/style.css" rel="stylesheet" type="text/css">
+          <meta content="width=device-width,initial-scale=1" name="viewport">
+       </head>
+       <body>
+          <div class="content">
+             <header>
+                <h1>{wanted_status} Issues</h1>
+             </header>
+             <main>
+                <div class="issue-links">
+                   <a href="/issues/{counter_status_lower}/">View {counter_status} issues</a>
+                   <a href="{}">Source code</a>
+                   <!--
+                   <form class="issue-search" method="get">
+                       <input name="search" title="Issue search query" type="search">
+                       <input class="sr-only" type="submit" value="Search Issues">
+                   </form>
+                   -->
+                </div>
+                <ol class="issue-list">
+                {issue_list}
+                </ol>
+             </main>
+          </div>
+       </body>
+    </html>
+    "#,
         config.source_code_repository_url
-    ))
+    )))
 }
 
 #[get("/issues/open")]
-pub fn open(config: &State<BackConfig>) -> RawHtml<String> {
+pub fn open(config: &State<BackConfig>) -> error::Result<RawHtml<String>> {
     issue_list_boilerplate(config, Status::Open, Status::Closed)
 }
 #[get("/issues/closed")]
-pub fn closed(config: &State<BackConfig>) -> RawHtml<String> {
+pub fn closed(config: &State<BackConfig>) -> error::Result<RawHtml<String>> {
     issue_list_boilerplate(config, Status::Closed, Status::Open)
 }
 
 #[get("/issue/<prefix>")]
-pub fn show_issue(config: &State<BackConfig>, prefix: BackPrefix) -> RawHtml<String> {
+pub fn show_issue(
+    config: &State<BackConfig>,
+    prefix: Result<BackPrefix, gix::hash::prefix::from_hex::Error>,
+) -> error::Result<RawHtml<String>> {
+    // NOTE(@bpeetz): Explicitly unwrap the `prefix` here (instead of taking the unwrapped value as
+    // argument), to avoid triggering rockets "errors forward to the next route" feature.
+    // This ensures, that our error message actually reaches the user. <2024-12-26>
+    let prefix = prefix?;
+
     let repository = config.repository.to_thread_local();
 
-    let all_issues = list_all_issues(&repository);
+    let all_issues: Vec<CollapsedIssue> = issues_from_repository(&repository)?
+        .into_iter()
+        .map(|val| val.collapse())
+        .collect();
+
     let maybe_issue = all_issues
         .iter()
         .find(|issue| issue.id.to_string().starts_with(&prefix.to_string()));
 
     match maybe_issue {
-        Some(issue) => issue.to_html(config),
-        None => RawHtml(format!("Issue with id '{prefix}' not found!")),
-    }
-}
-
-fn issue_to_string(issue: &Issue<'_>, status: Status) -> RawHtml<String> {
-    if issue.status == status {
-        issue.to_list_entry()
-    } else {
-        RawHtml(String::default())
+        Some(issue) => Ok(issue.to_html(config)),
+        None => Err(Error::IssuesPrefixMissing { prefix }),
     }
 }
diff --git a/pkgs/by-name/ba/back/src/web/issue_show.rs b/pkgs/by-name/ba/back/src/web/prefix.rs
index 638840e..5143799 100644
--- a/pkgs/by-name/ba/back/src/web/issue_show.rs
+++ b/pkgs/by-name/ba/back/src/web/prefix.rs
@@ -14,6 +14,7 @@ use std::fmt::Display;
 use gix::hash::Prefix;
 use rocket::request::FromParam;
 
+#[derive(Debug)]
 pub struct BackPrefix {
     prefix: Prefix,
 }