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`.

1 files changed, 185 insertions, 0 deletions

diff --git a/pkgs/by-name/ba/back/src/git_bug/issue/mod.rs b/pkgs/by-name/ba/back/src/git_bug/issue/mod.rs
new file mode 100644
index 0000000..f27bfec
--- /dev/null
+++ b/pkgs/by-name/ba/back/src/git_bug/issue/mod.rs
@@ -0,0 +1,185 @@
+// 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 entity::{Entity, Id};
+use identity::Author;
+use label::Label;
+use operation::Operation;
+use serde_json::Value;
+
+use super::format::{MarkDown, TimeStamp};
+
+pub mod entity;
+pub mod identity;
+pub mod label;
+pub mod operation;
+
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+pub enum Status {
+    Open,
+    Closed,
+}
+impl From<&Value> for Status {
+    fn from(value: &Value) -> Self {
+        match value.as_u64().expect("This should be a integer") {
+            1 => Self::Open,
+            2 => Self::Closed,
+            other => unimplemented!("Invalid status string: '{other}'"),
+        }
+    }
+}
+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 CollapsedIssue {
+    pub id: Id,
+    pub author: Author,
+    pub timestamp: TimeStamp,
+    pub title: MarkDown,
+    pub message: MarkDown,
+    pub comments: Vec<Comment>,
+    pub status: Status,
+    pub last_status_change: TimeStamp,
+    pub labels: Vec<Label>,
+}
+impl From<RawCollapsedIssue> for CollapsedIssue {
+    fn from(r: RawCollapsedIssue) -> Self {
+        macro_rules! get {
+            ($name:ident) => {
+                r.$name.expect(concat!(
+                    "'",
+                    stringify!($name),
+                    "' is unset, when trying to collapes an issue! (This is likely a bug)"
+                ))
+            };
+        }
+
+        Self {
+            id: get! {id},
+            author: get! {author},
+            timestamp: get! {timestamp},
+            title: get! {title},
+            message: get! {message},
+            comments: r.comments,
+            status: get! {status},
+            last_status_change: get! {last_status_change},
+            labels: r.labels,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Comment {
+    pub id: Id,
+    pub author: Author,
+    pub timestamp: TimeStamp,
+    pub message: MarkDown,
+}
+
+#[derive(Debug, Default)]
+pub struct RawCollapsedIssue {
+    pub id: Option<Id>,
+    pub author: Option<Author>,
+    pub timestamp: Option<TimeStamp>,
+    pub title: Option<MarkDown>,
+    pub message: Option<MarkDown>,
+    pub status: Option<Status>,
+    pub last_status_change: Option<TimeStamp>,
+
+    // NOTE(@bpeetz): These values set here already, because an issue without these
+    // would be perfectly valid. <2024-12-26>
+    pub labels: Vec<Label>,
+    pub comments: Vec<Comment>,
+}
+
+impl RawCollapsedIssue {
+    pub fn append_entity(&mut self, entity: Entity) {
+        for op in entity.operations {
+            match op {
+                Operation::AddComment { timestamp, message } => {
+                    self.comments.push(Comment {
+                        id: entity.id.clone(),
+                        author: entity.author.clone(),
+                        timestamp,
+                        message,
+                    });
+                }
+                Operation::Create {
+                    timestamp,
+                    title,
+                    message,
+                } => {
+                    self.id = Some(entity.id.clone());
+                    self.author = Some(entity.author.clone());
+                    self.timestamp = Some(timestamp.clone());
+                    self.title = Some(title);
+                    self.message = Some(message);
+                    self.status = Some(Status::Open); // This is the default in git_bug
+                    self.last_status_change = Some(timestamp);
+                }
+                Operation::EditComment {
+                    timestamp,
+                    target,
+                    message,
+                } => {
+                    let comments = &mut self.comments;
+
+                    let target_comment = comments
+                        .iter_mut()
+                        .find(|comment| comment.id == target)
+                        .expect("The target must be a valid comment");
+
+                    // TODO(@bpeetz): We should probably set a `edited = true` flag here. <2024-12-26>
+                    // TODO(@bpeetz): Should we also change the author? <2024-12-26>
+
+                    target_comment.timestamp = timestamp;
+                    target_comment.message = message;
+                }
+                Operation::LabelChange {
+                    timestamp: _,
+                    added,
+                    removed,
+                } => {
+                    let labels = self.labels.clone();
+
+                    self.labels = labels
+                        .into_iter()
+                        .filter(|val| !removed.contains(val))
+                        .chain(added.into_iter())
+                        .collect();
+                }
+                Operation::SetStatus { timestamp, status } => {
+                    self.status = Some(status);
+                    self.last_status_change = Some(timestamp);
+                }
+                Operation::SetTitle {
+                    timestamp: _,
+                    title,
+                    was: _,
+                } => {
+                    self.title = Some(title);
+                }
+
+                Operation::NoOp {} => unimplemented!(),
+                Operation::SetMetadata {} => unimplemented!(),
+            }
+        }
+    }
+}