minor changes

src/backend/mock.rs

@@ -0,0 +1,312 @@
+//! In-memory stub data mimicking a lore.kernel.org archive.
+//!
+//! Nothing here performs I/O. The real backend will fetch from
+//! <https://lore.kernel.org/git/> or shell out to `b4`/`lei`.
+
+use std::collections::HashMap;
+
+use crate::models::{Author, MailingList, Message, MessageId, Thread, ThreadId};
+
+use super::Backend;
+
+/// Static "mailing list content" the mock rotates through.
+struct ThreadSeed {
+    /// Series prefix, e.g. `PATCH v4`; empty for plain discussions.
+    prefix: &'static str,
+    subject: &'static str,
+    author_name: &'static str,
+    author_email: &'static str,
+    /// Total message count, including the cover letter when > 1.
+    message_count: usize,
+    /// Short display date for the thread list.
+    date: &'static str,
+}
+
+const THREAD_SEEDS: [ThreadSeed; 10] = [
+    ThreadSeed {
+        prefix: "PATCH v4",
+        subject: "refs: introduce a reftable backend for packed refs",
+        author_name: "Patrick Steinhardt",
+        author_email: "[email protected]",
+        message_count: 6,
+        date: "Sep 10",
+    },
+    ThreadSeed {
+        prefix: "PATCH v2",
+        subject: "t/perf: add benchmarks for ref operations",
+        author_name: "Victoria Dye",
+        author_email: "[email protected]",
+        message_count: 3,
+        date: "Sep 10",
+    },
+    ThreadSeed {
+        prefix: "RFC PATCH",
+        subject: "log --format: add a reftable dump backend",
+        author_name: "Karthik Nayak",
+        author_email: "[email protected]",
+        message_count: 2,
+        date: "Sep 09",
+    },
+    ThreadSeed {
+        prefix: "PATCH",
+        subject: "tests: convert remaining scripts to test-tool helpers",
+        author_name: "Ævar Arnfjörð Bjarmason",
+        author_email: "[email protected]",
+        message_count: 4,
+        date: "Sep 09",
+    },
+    ThreadSeed {
+        prefix: "",
+        subject: "git maintenance: schedule tasks on macOS via launchd",
+        author_name: "Derrick Stolee",
+        author_email: "[email protected]",
+        message_count: 1,
+        date: "Sep 08",
+    },
+    ThreadSeed {
+        prefix: "PATCH v3",
+        subject: "bundle-uri: support sparse filters in clones",
+        author_name: "Junio C Hamano",
+        author_email: "[email protected]",
+        message_count: 5,
+        date: "Sep 08",
+    },
+    ThreadSeed {
+        prefix: "PATCH",
+        subject: "rebase --update-refs: silence reflog message noise",
+        author_name: "Phillip Wood",
+        author_email: "[email protected]",
+        message_count: 2,
+        date: "Sep 07",
+    },
+    ThreadSeed {
+        prefix: "",
+        subject: "Git v2.48.0 released",
+        author_name: "Junio C Hamano",
+        author_email: "[email protected]",
+        message_count: 1,
+        date: "Sep 07",
+    },
+    ThreadSeed {
+        prefix: "PATCH v6",
+        subject: "worktree list: add --porcelain output",
+        author_name: "Elijah Newren",
+        author_email: "[email protected]",
+        message_count: 7,
+        date: "Sep 06",
+    },
+    ThreadSeed {
+        prefix: "PATCH",
+        subject: "submodule: parallelize fetch with --jobs",
+        author_name: "Taylor Blau",
+        author_email: "[email protected]",
+        message_count: 3,
+        date: "Sep 06",
+    },
+];
+
+/// Fixed pool of reviewers assigned as `Cc:` on mock messages.
+const REVIEWERS: [(&str, &str); 6] = [
+    ("Junio C Hamano", "[email protected]"),
+    ("Taylor Blau", "[email protected]"),
+    ("Ævar Arnfjörð Bjarmason", "[email protected]"),
+    ("Victoria Dye", "[email protected]"),
+    ("Elijah Newren", "[email protected]"),
+    ("Phillip Wood", "[email protected]"),
+];
+
+/// In-memory data source. [`Backend::refresh`] rotates the visible window
+/// over [`THREAD_SEEDS`] so `r` visibly changes the data.
+#[derive(Debug)]
+pub struct MockBackend {
+    list: MailingList,
+    /// Refresh counter: each refresh rotates the thread window.
+    generation: usize,
+    threads: Vec<Thread>,
+    messages: HashMap<ThreadId, Vec<Message>>,
+}
+
+impl MockBackend {
+    /// Build a backend for `list` with an initial snapshot.
+    ///
+    /// The starting generation is derived from the list name so different
+    /// lists show different (but deterministic) thread windows.
+    #[must_use]
+    pub fn new(list: &MailingList) -> Self {
+        let mut backend = Self {
+            list: list.clone(),
+            generation: fnv1a(list.name.as_bytes()) % THREAD_SEEDS.len(),
+            threads: Vec::new(),
+            messages: HashMap::new(),
+        };
+        backend.rebuild();
+        backend
+    }
+
+    /// Visible thread count varies with the generation so refreshes differ.
+    const fn visible_thread_count(generation: usize) -> usize {
+        THREAD_SEEDS.len().saturating_sub(2) + generation % 3
+    }
+
+    /// Regenerate the snapshot from the seed pool, rotated by `generation`.
+    fn rebuild(&mut self) {
+        self.threads.clear();
+        self.messages.clear();
+        let visible = Self::visible_thread_count(self.generation);
+        let start = self.generation % THREAD_SEEDS.len();
+        for offset in 0..visible {
+            let seed = &THREAD_SEEDS[(start + offset) % THREAD_SEEDS.len()];
+            let thread_id = ThreadId(offset);
+            self.threads.push(Thread {
+                id: thread_id,
+                subject: series_subject(seed),
+                author: seed_author(seed),
+                date: seed.date.to_owned(),
+                message_count: seed.message_count,
+            });
+            let list = (0..seed.message_count)
+                .map(|index| message_from_seed(seed, &self.list, offset, index))
+                .collect();
+            self.messages.insert(thread_id, list);
+        }
+    }
+}
+
+impl Backend for MockBackend {
+    fn list_name(&self) -> &str {
+        &self.list.name
+    }
+
+    fn threads(&self) -> &[Thread] {
+        &self.threads
+    }
+
+    fn messages(&self, thread_id: ThreadId) -> &[Message] {
+        self.messages.get(&thread_id).map_or(&[], Vec::as_slice)
+    }
+
+    fn refresh(&mut self) -> anyhow::Result<()> {
+        self.generation += 1;
+        self.rebuild();
+        Ok(())
+    }
+}
+
+/// Deterministic FNV-1a hash used to vary mock data per list.
+fn fnv1a(bytes: &[u8]) -> usize {
+    let mut hash: usize = 0x811c_9dc5;
+    let mut index = 0;
+    while index < bytes.len() {
+        hash ^= usize::from(bytes[index]);
+        hash = hash.wrapping_mul(0x0100_0193);
+        index += 1;
+    }
+    hash
+}
+
+fn seed_author(seed: &ThreadSeed) -> Author {
+    Author {
+        name: seed.author_name.to_owned(),
+        email: seed.author_email.to_owned(),
+    }
+}
+
+/// Thread subject: `[<prefix> 0/<n>] <subject>` for series, plain otherwise.
+fn series_subject(seed: &ThreadSeed) -> String {
+    if seed.prefix.is_empty() || seed.message_count <= 1 {
+        seed.subject.to_owned()
+    } else {
+        format!(
+            "[{} 0/{}] {}",
+            seed.prefix,
+            seed.message_count - 1,
+            seed.subject
+        )
+    }
+}
+
+fn message_from_seed(
+    seed: &ThreadSeed,
+    list: &MailingList,
+    thread_offset: usize,
+    index: usize,
+) -> Message {
+    let subject = if seed.prefix.is_empty() || seed.message_count <= 1 {
+        seed.subject.to_owned()
+    } else {
+        format!(
+            "[{} {}/{}] {}",
+            seed.prefix,
+            index,
+            seed.message_count - 1,
+            seed.subject
+        )
+    };
+    let to = vec![Author {
+        name: list.name.clone(),
+        email: list.address.clone(),
+    }];
+    let count = 1 + (thread_offset + index) % 2;
+    let start = (thread_offset * 7 + index) % REVIEWERS.len();
+    let cc = (0..count)
+        .map(|i| {
+            let (name, email) = REVIEWERS[(start + i) % REVIEWERS.len()];
+            Author {
+                name: name.to_owned(),
+                email: email.to_owned(),
+            }
+        })
+        .collect();
+    Message {
+        id: MessageId(index),
+        subject,
+        author: seed_author(seed),
+        to,
+        cc,
+        date: message_date(thread_offset, index),
+        body: message_body(seed, index),
+    }
+}
+
+fn message_date(thread_offset: usize, index: usize) -> String {
+    format!(
+        "Fri, 11 Sep 2026 {:02}:{:02}:{:02} +0200",
+        8 + thread_offset % 9,
+        index * 7 % 60,
+        (index * 13 + thread_offset) % 60
+    )
+}
+
+fn message_body(seed: &ThreadSeed, index: usize) -> String {
+    let total = seed.message_count.saturating_sub(1);
+    let intro = if seed.message_count <= 1 {
+        format!(
+            "This is a standalone message about {}.\n\nDetails and rationale follow; review and\nfeedback are welcome.",
+            seed.subject
+        )
+    } else if index == 0 {
+        format!(
+            "Cover letter for the {} series: {}.\n\nThe full series follows. See the individual\npatches for the actual changes.",
+            seed.prefix, seed.subject
+        )
+    } else {
+        format!(
+            "Patch {index}/{total} of the {} series.\n\nOne focused change:\n- {} (summary stub)\n- tests updated accordingly",
+            seed.prefix, seed.subject
+        )
+    };
+    if index == 0 && seed.message_count > 1 {
+        // Cover letters carry no diff.
+        return intro;
+    }
+    let diff = format!(
+        "---\n diff --git a/refs/reftable/backend.c b/refs/reftable/backend.c\n\
+         index abcdef0..fedcba1 100644\n\
+         --- a/refs/reftable/backend.c\n\
+         +++ b/refs/reftable/backend.c\n\
+         @@ -1{index},3 +1{index},3 @@\n\
+         -// old behavior (removed)\n\
+         +// new behavior (lazymail placeholder diff)"
+    );
+    format!("{intro}\n\n{diff}")
+}