use chrono::Local;
use git2::{Oid, Repository, Sort};
use regex::Regex;
use std::fs::File;
use std::io::{Read, Write};
use std::path::Path;

/// Outcome of a successful [`generate_entry`] call: everything the CLI
/// renders for the user, and everything a library consumer needs to chain
/// further steps.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GeneratedEntry {
    /// Source package name from the previous changelog entry.
    pub package: String,
    /// Version the changelog carried before the new entry was prepended.
    pub previous_version: String,
    /// Version of the freshly added entry.
    pub new_version: String,
    /// Distribution series the new entry targets.
    pub series: String,
    /// The changelog file that was updated.
    pub path: std::path::PathBuf,
}

/// The kind of upload a generated changelog entry describes: it selects how
/// the new entry's version is derived from the previous one. Ignored when an
/// explicit version is given.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub enum EntryKind {
    /// A regular upload: the version numbering follows the vendor of the
    /// target series — the Debian convention (`1.0-1` becomes `1.0-2`) for
    /// Debian series, the Ubuntu one for Ubuntu series (`1.0-1` becomes
    /// `1.0-1ubuntu1`, an already-Ubuntu `1.0-1ubuntu1` becomes
    /// `1.0-1ubuntu2`). Unresolvable series (UNRELEASED, unknown) number
    /// the Debian way.
    #[default]
    Normal,
    /// A non-maintainer upload: `1.0-1` becomes `1.0-1.1` (native `1.0`
    /// becomes `1.0+nmu1`)
    Nmu,
    /// A no-change rebuild: `1.0-1` becomes `1.0-1build1`
    Rebuild,
    /// An Ubuntu upload regardless of the target series: `1.0-1` becomes
    /// `1.0-1ubuntu1`. Library-only: the CLI has no flag selecting it,
    /// and targeting an Ubuntu series already picks this numbering.
    Ubuntu,
    /// A backport: numbered after the vendor of the target series —
    /// Debian's backports scheme (`1.0-1` becomes `1.0-1~bpo12+1`) or
    /// Ubuntu's per-release SRU scheme (`3.1-1ubuntu2` becomes
    /// `3.1-1ubuntu2~24.04.1`). The release number is derived from the
    /// target series, which must therefore be a numbered release (e.g.
    /// not sid).
    Backport,
}

/// Automatically generate a changelog entry from a commit history and previous changelog
pub async fn generate_entry(
    changelog_file: &str,
    cwd: Option<&Path>,
    user_version: Option<&str>,
    target_series: Option<&str>,
    kind: EntryKind,
) -> Result<GeneratedEntry, Box<dyn std::error::Error>> {
    let changelog_path = if let Some(path) = cwd {
        path.join(changelog_file)
    } else {
        Path::new(changelog_file).to_path_buf()
    };

    // Parse existing changelog to get current (old) version
    let (package, old_version, current_series) = parse_changelog_header(&changelog_path)?;

    // Open git repo, and find commits since last version tag
    let repo_path = if let Some(path) = cwd {
        path.to_path_buf()
    } else {
        std::env::current_dir()?
    };
    let commits = match Repository::open(&repo_path) {
        Ok(repo) => {
            let repo_changelog = changelog_in_repo(&repo, &changelog_path);
            get_commits_since_version(&repo, &old_version, repo_changelog.as_deref())?
        }
        // If there is no git repo (e.g. package downloaded from archive),
        // we just generate an empty list of changes
        Err(_e) => Vec::new(),
    };

    // The series the new entry targets: needed before the version is
    // computed, because a backport version carries the target release number
    let series = target_series.unwrap_or(&current_series).to_string();

    // Compute new version if needed, or use user-supplied one
    let new_version = if let Some(version) = user_version {
        version.to_string()
    } else {
        match kind {
            EntryKind::Normal => {
                let bump = normal_bump_for_series(&series).await;
                compute_new_version(&old_version, bump)?
            }
            EntryKind::Nmu => compute_new_version(&old_version, Bump::Nmu)?,
            EntryKind::Rebuild => compute_new_version(&old_version, Bump::Rebuild)?,
            EntryKind::Ubuntu => compute_new_version(&old_version, Bump::Ubuntu)?,
            EntryKind::Backport => {
                let suffix = backport_suffix_for_series(&series).await?;
                compute_new_version(&old_version, Bump::Backport(suffix))?
            }
        }
    };

    let (maintainer_name, maintainer_email) = get_maintainer_info()?;
    let new_entry = format_entry(
        &package,
        &new_version,
        &series,
        &commits,
        &maintainer_name,
        &maintainer_email,
    );

    prepend_to_file(&changelog_path, &new_entry)?;

    Ok(GeneratedEntry {
        package,
        previous_version: old_version,
        new_version,
        series,
        path: changelog_path,
    })
}

/// How the new version is derived from the previous one: the conditions
/// [`compute_new_version`] acts on. The suffixes follow the usual
/// Debian/Ubuntu numbering conventions.
#[derive(Debug, Clone, PartialEq, Eq)]
enum Bump {
    /// Regular upload: increment the trailing number
    Normal,
    /// Ubuntu upload: `1.0-9` becomes `1.0-9ubuntu1`; a trailing
    /// no-change-rebuild marker is dropped first (`1.0-9build1` becomes
    /// `1.0-9ubuntu1`)
    Ubuntu,
    /// Non-maintainer upload: `1.0-1` becomes `1.0-1.1`, native `1.0`
    /// becomes `1.0+nmu1`
    Nmu,
    /// No-change rebuild: `1.0-1` becomes `1.0-1build1`
    Rebuild,
    /// Backport to the release whose version suffix is carried
    /// (`"~bpo12+"` for Debian bookworm, `"~24.04."` for Ubuntu noble):
    /// `1.0-1` becomes `1.0-1~bpo12+1`, `3.1-1ubuntu2` becomes
    /// `3.1-1ubuntu2~24.04.1`
    Backport(String),
}

/// Compute the next (most probable) version number of a package, from the
/// old version and the kind of upload the entry describes
fn compute_new_version(
    old_version: &str,
    bump: Bump,
) -> Result<String, Box<dyn std::error::Error>> {
    match bump {
        Bump::Ubuntu => increment_suffix(strip_build_suffix(old_version), "ubuntu"),
        Bump::Rebuild => increment_suffix(old_version, "build"),
        Bump::Nmu => {
            if old_version.contains('-') {
                increment_suffix(old_version, ".")
            } else {
                increment_suffix(old_version, "+nmu")
            }
        }
        // A re-backport of the same release reuses its suffix counter,
        // incrementing the trailing number: increment_suffix appends the
        // suffix with a fresh 1 when the version carries no such suffix
        // yet (including when it is a backport of another release, whose
        // counter is left untouched)
        Bump::Backport(suffix) => increment_suffix(old_version, &suffix),
        Bump::Normal => increment_suffix(old_version, ""),
    }
}

/// The version an Ubuntu upload is numbered from: a trailing
/// no-change-rebuild marker is dropped, because a real change on top of a
/// rebuild replaces the marker rather than appending to it — `X-2build1`
/// becomes `X-2ubuntu1`, where an appended `X-2build1ubuntu1` would
/// misrepresent the lineage and sort below `X-2ubuntu1`
fn strip_build_suffix(version: &str) -> &str {
    let stem = version.trim_end_matches(|c: char| c.is_ascii_digit());
    match stem.strip_suffix("build") {
        Some(base) if stem.len() < version.len() => &version[..base.len()],
        _ => version,
    }
}

/// The version bump a regular ([`EntryKind::Normal`]) upload gets, derived
/// from the vendor of the target series: Ubuntu series number their uploads
/// the Ubuntu way (`1.0-1` becomes `1.0-1ubuntu1`), everything else —
/// Debian series, but also UNRELEASED and series no distro-info data knows —
/// numbers the Debian way (`1.0-1` becomes `1.0-2`).
async fn normal_bump_for_series(series: &str) -> Bump {
    match crate::distro_info::get_dist_from_series(series).await {
        Ok(dist) if dist == "ubuntu" => Bump::Ubuntu,
        _ => Bump::Normal,
    }
}

/// The version suffix that backport versions are numbered with, derived
/// from the vendor of the target series: Debian backports follow the
/// backports.debian.org scheme (`~bpo12+1`), Ubuntu backports the
/// per-release SRU scheme of the Ubuntu version-strings documentation
/// (`3.1-1ubuntu2~22.04.1` for a development version backported to 22.04).
/// A backport suite name (`bookworm-backports`) is accepted too. Errors
/// when the series has no usable release number (Debian sid or
/// experimental, unknown series): the numbering cannot be derived for it.
async fn backport_suffix_for_series(series: &str) -> Result<String, Box<dyn std::error::Error>> {
    let base = series
        .strip_suffix("-backports-sloppy")
        .or_else(|| series.strip_suffix("-backports"))
        .unwrap_or(series);
    let unnumbered = || {
        format!(
            "Could not determine the release number of series '{series}', \
             needed to number the backport version (Debian ~bpo12+1, \
             Ubuntu ~24.04.1). Target a released Debian or Ubuntu series \
             or pass the version explicitly with --version."
        )
    };
    let Some((dist, number)) = crate::distro_info::get_series_release_number(base).await? else {
        return Err(unnumbered().into());
    };
    match dist.as_str() {
        // backports.debian.org numbers with the plain integer release number
        "debian" if !number.is_empty() && number.chars().all(|c| c.is_ascii_digit()) => {
            Ok(format!("~bpo{}+", number))
        }
        // Ubuntu numbers per release as YY.MM; the trailing `.N` counts
        // the per-release SRU uploads
        "ubuntu"
            if number.split('.').count() == 2
                && number
                    .split('.')
                    .all(|part| !part.is_empty() && part.chars().all(|c| c.is_ascii_digit())) =>
        {
            Ok(format!("~{}.", number))
        }
        _ => Err(unnumbered().into()),
    }
}

/// Increment a version number by 1, for a given suffix
fn increment_suffix(version: &str, suffix: &str) -> Result<String, Box<dyn std::error::Error>> {
    // If suffix is empty, we just look for trailing digits
    // If suffix is not empty, we look for suffix followed by digits

    let pattern = if suffix.is_empty() {
        r"(\d+)$".to_string()
    } else {
        format!(r"{}(\d+)$", regex::escape(suffix))
    };

    let re = Regex::new(&pattern).unwrap();

    if let Some(caps) = re.captures(version) {
        let num_str = caps.get(1).unwrap().as_str();
        // Parse as u64 so that large trailing numbers (e.g. date-based
        // versions like '1.0-20250123123456', which do not fit in a u32)
        // still increment normally
        let num: u64 = num_str.parse().map_err(|_| {
            format!(
                "Cannot increment version '{version}': trailing number '{num_str}' \
                 is too large to be incremented. Specify a version explicitly instead."
            )
        })?;
        let range = caps.get(1).unwrap().range();
        let new_num = num.checked_add(1).ok_or_else(|| {
            format!(
                "Cannot increment version '{version}': trailing number {num} \
                 is too large to be incremented. Specify a version explicitly instead."
            )
        })?;
        let mut new_ver = version.to_string();
        new_ver.replace_range(range, &new_num.to_string());
        return Ok(new_ver);
    }

    // If pattern not found, append suffix + "1"
    // But if suffix is empty, we default to appending "-1" (standard Debian revision start)
    if suffix.is_empty() {
        Ok(format!("{}-1", version))
    } else {
        Ok(format!("{}{}{}", version, suffix, 1))
    }
}

/// Parse a changelog file first entry header
/// Returns (package, version, series) tuple from the last modification entry
pub fn parse_changelog_header(
    path: &Path,
) -> Result<(String, String, String), Box<dyn std::error::Error>> {
    let entry = crate::debian::parse_changelog_entry(path)?;
    Ok((entry.source, entry.version.full(), entry.distribution))
}

/// What a new changelog entry may target as series, derived from the
/// current changelog ([`series_candidates`]).
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SeriesCandidates {
    /// Offer `options` with `default` preselected; when the selection
    /// cannot be made (cancelled, no interactive user) `fallback` — the
    /// changelog's current series — is used instead.
    Choose {
        /// Selector labels: each series name, or `<suite> (<series>)`
        /// for a series aliased by a changelog suite name (Debian's
        /// 'unstable (sid)').
        options: Vec<String>,
        /// Changelog distribution each label of `options` maps to,
        /// parallel to it: an aliased label selects its suite name —
        /// what a changelog distribution field expects — while every
        /// other label selects itself.
        values: Vec<String>,
        /// Preselected label.
        default: String,
        /// Series to fall back to when nothing can be selected.
        fallback: String,
    },
    /// Nothing to choose: the series list was unavailable, keep the
    /// current series.
    Keep(String),
}

/// Derive the candidate series for a new changelog entry from the changelog
/// at `changelog_path`.
///
/// An UNRELEASED entry offers itself as a pinned first option (selecting it
/// keeps the changelog unreleased) on top of the current vendor's series
/// list, defaulting to the development series; any other series resolves
/// through the series list of its own distribution. A changelog suite name
/// (Debian's 'unstable') identifies the same series as its alias's codename
/// ('sid') and resolves to that dist's list. `None` when the changelog
/// cannot be parsed (no default to derive at all).
pub async fn series_candidates(changelog_path: &Path) -> Option<SeriesCandidates> {
    let (_package, _version, current) = parse_changelog_header(changelog_path).ok()?;

    if crate::distro_info::is_unreleased(&current) {
        // Vendors keep original casing ("Ubuntu"), while the series data
        // keys are lowercase
        let dist = crate::build::env::current_vendor().to_lowercase();
        match crate::distro_info::get_ordered_series_name(&dist).await {
            Ok(series_list) => {
                let (labels, series_values, _) = selector_options(&dist, &series_list, "");
                let mut options = vec![crate::distro_info::UNRELEASED.to_string()];
                let mut values = vec![crate::distro_info::UNRELEASED.to_string()];
                options.extend(labels);
                values.extend(series_values);
                // Default to the development series (the first real entry),
                // not to the pinned UNRELEASED entry itself
                let default = if options.len() > 1 {
                    options[1].clone()
                } else {
                    current.clone()
                };
                Some(SeriesCandidates::Choose {
                    options,
                    values,
                    default,
                    fallback: current,
                })
            }
            Err(_) => Some(SeriesCandidates::Keep(current)),
        }
    } else {
        // The changelog may target a suite name instead of a series
        // codename: Debian conventionally writes 'unstable' where the
        // series data carries 'sid'. The two identify the same series:
        // the alias resolves to its codename's dist for the lookup.
        let resolved = match crate::distro_info::get_dist_from_series(&current).await {
            Ok(dist) => Some((dist, current.clone())),
            Err(_) => crate::distro_info::resolve_suite_alias(&current),
        };
        match resolved {
            Some((dist, canonical)) => {
                match crate::distro_info::get_ordered_series_name(&dist).await {
                    // Even an empty list goes through the selector: its
                    // fallback prints and takes the default, like it always has
                    Ok(series_list) => {
                        let (options, values, default) =
                            selector_options(&dist, &series_list, &canonical);
                        Some(SeriesCandidates::Choose {
                            options,
                            values,
                            // A stale alias whose codename left the series
                            // list offers the raw name instead
                            default: default.unwrap_or_else(|| canonical.clone()),
                            fallback: current,
                        })
                    }
                    Err(_) => Some(SeriesCandidates::Keep(current)),
                }
            }
            None => Some(SeriesCandidates::Keep(current)),
        }
    }
}

/// The selector entries for a dist's series list: (labels, changelog
/// targets, label of `current`'s entry). A series aliased by a
/// changelog suite name (Debian's 'unstable' for 'sid') is offered as
/// `<suite> (<series>)` but targets the suite name — what a changelog
/// distribution field expects — while every other series is offered,
/// and targeted, under its own name. `current` may be a name that is
/// not in the list at all (e.g. UNRELEASED), in which case no default
/// is returned.
fn selector_options(
    dist: &str,
    series: &[String],
    current: &str,
) -> (Vec<String>, Vec<String>, Option<String>) {
    let mut labels = Vec::with_capacity(series.len());
    let mut values = Vec::with_capacity(series.len());
    let mut default = None;
    for s in series {
        let (label, value) = match crate::distro_info::series_suite_alias(dist, s) {
            Some(suite) => (format!("{suite} ({s})"), suite),
            None => (s.clone(), s.clone()),
        };
        if s == current {
            default = Some(label.clone());
        }
        labels.push(label);
        values.push(value);
    }
    (labels, values, default)
}

/// The changelog distribution a selected series-selector label maps to
/// ([`SeriesCandidates::Choose`]): an aliased entry ('unstable (sid)')
/// targets its suite name, any other label targets itself, and a
/// free-typed series the selector does not offer is its own target.
pub fn selected_series(options: &[String], values: &[String], selected: String) -> String {
    options
        .iter()
        .position(|o| *o == selected)
        .and_then(|idx| values.get(idx).cloned())
        .unwrap_or(selected)
}

/// Parse a changelog file footer to extract maintainer information
/// Returns (name, email) tuple from the last modification entry
pub fn parse_changelog_footer(path: &Path) -> Result<(String, String), Box<dyn std::error::Error>> {
    let entry = crate::debian::parse_changelog_entry(path)?;
    Ok((entry.maintainer_name, entry.maintainer_email))
}

/*
* Obtain all commit messages as a list since the previous release, to
* format into a changelog entry
*/
fn get_commits_since_version(
    repo: &Repository,
    version: &str,
    changelog_path: Option<&Path>,
) -> Result<Vec<String>, Box<dyn std::error::Error>> {
    // Preferred boundary: the tag of the current (previous) version
    if let Some(tag_id) = find_version_tag(repo, version) {
        return commit_summaries_since(repo, tag_id);
    }

    // No tag: fall back to the last commit that modified the changelog
    // itself, whose commit introduces the previous entry. Its changes
    // since then are the new entry's content — so entries stay correct in
    // repositories that commit their changelogs without tagging them.
    let Some(rel_path) = changelog_path else {
        return Ok(Vec::new());
    };
    let Some(boundary) = last_commit_touching(repo, rel_path)? else {
        // The changelog was never committed; nothing to walk from
        return Ok(Vec::new());
    };

    // Prefer a tag of the version the committed changelog carries: it may
    // point past the changelog commit itself (e.g. a later release commit)
    let boundary_id = version_at_commit(repo, &boundary, rel_path)
        .and_then(|committed_version| find_version_tag(repo, &committed_version))
        .unwrap_or_else(|| boundary.id());
    commit_summaries_since(repo, boundary_id)
}

/// The commit names a Debian version may be tagged under in a repository
fn version_tag_names(version: &str) -> Vec<String> {
    vec![
        format!("debian/{}", version),
        format!("debian/v{}", version),
        format!("v{}", version),
        version.to_string(),
    ]
}

/// Find the commit a version tag points at, probing the usual tag formats
fn find_version_tag(repo: &Repository, version: &str) -> Option<Oid> {
    for tag_name in version_tag_names(version) {
        if let Ok(r) = repo.revparse_single(&tag_name) {
            // A matching name resolves either to a commit (lightweight
            // tag) or to a tag object (annotated tag)
            if let Some(commit) = r.as_commit() {
                return Some(commit.id());
            } else if let Some(tag) = r.as_tag() {
                return Some(tag.target_id());
            }
        }
    }
    None
}

/// The commit summaries from HEAD down to (excluding) `boundary`
fn commit_summaries_since(
    repo: &Repository,
    boundary: Oid,
) -> Result<Vec<String>, Box<dyn std::error::Error>> {
    let mut revwalk = repo.revwalk()?;
    revwalk.set_sorting(Sort::TIME)?;
    revwalk.push_head()?;
    revwalk.hide(boundary)?;

    let mut commits = Vec::new();
    for id in revwalk {
        let id = id?;
        let commit = repo.find_commit(id)?;
        let message = commit.message().unwrap_or("").trim();
        let summary = message.lines().next().unwrap_or("").to_string();
        if !summary.is_empty() {
            commits.push(summary);
        }
    }

    Ok(commits)
}

/// The changelog path relative to the repository root, used to walk the
/// history of the file. `None` when the changelog lives outside the
/// repository working directory.
fn changelog_in_repo(repo: &Repository, changelog_path: &Path) -> Option<std::path::PathBuf> {
    let workdir = repo.workdir()?.canonicalize().ok()?;
    let absolute = if changelog_path.is_absolute() {
        changelog_path.to_path_buf()
    } else {
        std::env::current_dir().ok()?.join(changelog_path)
    };
    let absolute = absolute.canonicalize().ok()?;
    absolute
        .strip_prefix(&workdir)
        .ok()
        .map(|p| p.to_path_buf())
}

/// The last commit that modified the file at `rel_path`, newest first
fn last_commit_touching<'a>(
    repo: &'a Repository,
    rel_path: &Path,
) -> Result<Option<git2::Commit<'a>>, Box<dyn std::error::Error>> {
    let mut revwalk = repo.revwalk()?;
    revwalk.set_sorting(Sort::TIME)?;
    if repo.head().is_err() {
        // Unborn HEAD: the repository has no commits yet
        return Ok(None);
    }
    revwalk.push_head()?;

    for id in revwalk {
        let commit = repo.find_commit(id?)?;
        if commit_touches_path(repo, &commit, rel_path)? {
            return Ok(Some(commit));
        }
    }
    Ok(None)
}

/// Whether `commit` modified the file at `rel_path` relative to its first
/// parent (a root commit counts when it adds the file)
fn commit_touches_path(
    repo: &Repository,
    commit: &git2::Commit<'_>,
    rel_path: &Path,
) -> Result<bool, Box<dyn std::error::Error>> {
    let new_tree = commit.tree()?;
    let parent_tree = if commit.parent_count() > 0 {
        Some(commit.parent(0)?.tree()?)
    } else {
        None
    };
    let mut opts = git2::DiffOptions::new();
    opts.pathspec(rel_path.to_string_lossy().to_string());
    let diff = repo.diff_tree_to_tree(parent_tree.as_ref(), Some(&new_tree), Some(&mut opts))?;
    Ok(diff.deltas().len() > 0)
}

/// The version recorded by the changelog content as of `commit`
fn version_at_commit(
    repo: &Repository,
    commit: &git2::Commit<'_>,
    rel_path: &Path,
) -> Option<String> {
    let blob = commit
        .tree()
        .ok()?
        .get_path(rel_path)
        .ok()
        .and_then(|entry| repo.find_blob(entry.id()).ok())?;
    let content = std::str::from_utf8(blob.content()).ok()?;
    let entry = crate::debian::parse_changelog_entry_from_str(content).ok()?;
    Some(entry.version.full())
}

/*
* Create a changelog entry from information, i.e. format that information
* into a changelog entry
*/
fn format_entry(
    package: &str,
    version: &str,
    series: &str,
    changes: &[String],
    maintainer_name: &str,
    maintainer_email: &str,
) -> String {
    let mut entry = String::new();

    // Header: package, version and distribution series
    entry.push_str(&format!(
        "{} ({}) {}; urgency=medium\n\n",
        package, version, series
    ));

    // Changes
    for change in changes {
        entry.push_str(&format!("  * {}\n", change));
    }
    if changes.is_empty() {
        entry.push_str("  * \n");
    }

    // Footer: date, maintainer
    let date = Local::now().format("%a, %d %b %Y %H:%M:%S %z").to_string();
    entry.push_str(&format!(
        "\n -- {} <{}>  {}\n\n",
        maintainer_name, maintainer_email, date
    ));

    entry
}

/*
* Add content to the beginning of a file
*/
fn prepend_to_file(path: &Path, content: &str) -> Result<(), Box<dyn std::error::Error>> {
    let mut file = File::open(path)?;
    let mut existing_content = String::new();
    file.read_to_string(&mut existing_content)?;

    let mut file = File::create(path)?;
    file.write_all(content.as_bytes())?;
    file.write_all(existing_content.as_bytes())?;

    Ok(())
}

/// Discover the maintainer identity for changelog entries and package
/// scaffolding: `$DEBFULLNAME`/`$DEBEMAIL` when both are set, else the git
/// configuration (`user.name`/`user.email`).
///
/// Returns `(name, email)`, with a pointed error telling the user how to
/// configure the missing piece.
pub fn get_maintainer_info() -> Result<(String, String), Box<dyn std::error::Error>> {
    // From environment variables
    if let (Ok(name), Ok(email)) = (std::env::var("DEBFULLNAME"), std::env::var("DEBEMAIL")) {
        return Ok((name, email));
    }

    // From git config
    let config = git2::Config::open_default().map_err(|e| {
        format!(
            "Could not determine maintainer information. \
             Neither $DEBFULLNAME/$DEBEMAIL nor git configuration is available: {}. \
             Set the DEBFULLNAME and DEBEMAIL environment variables, \
             or configure git with `git config --global user.name` and `git config --global user.email`.",
            e
        )
    })?;
    let name = config.get_string("user.name").map_err(|e| {
        format!(
            "Could not find git 'user.name' configuration: {}. \
             Set it with `git config --global user.name \"Your Name\"` \
             or define the DEBFULLNAME environment variable.",
            e
        )
    })?;
    let email = config.get_string("user.email").map_err(|e| {
        format!(
            "Could not find git 'user.email' configuration: {}. \
             Set it with `git config --global user.email \"you@example.com\"` \
             or define the DEBEMAIL environment variable.",
            e
        )
    })?;
    Ok((name, email))
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::process::Command;
    use tempfile::TempDir;

    /// An UNRELEASED changelog offers UNRELEASED pinned first, the
    /// development series as the default, and itself as the fallback.
    #[tokio::test]
    async fn series_candidates_unreleased_pins_entry_and_defaults_to_dev() {
        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("changelog");
        std::fs::write(
            &path,
            "hello (1.0-1) UNRELEASED; urgency=medium\n\n  * Something.\n\n \
             -- A B <a@b.c>  Mon, 01 Jan 2024 00:00:00 +0000\n",
        )
        .unwrap();

        match series_candidates(&path).await {
            Some(SeriesCandidates::Choose {
                options,
                values,
                default,
                fallback,
            }) => {
                assert_eq!(options[0], "UNRELEASED");
                assert_eq!(values[0], "UNRELEASED");
                assert!(options.len() > 1, "the vendor series list is offered");
                assert_eq!(default, options[1]);
                assert_eq!(
                    selected_series(&options, &values, default.clone()),
                    values[1]
                );
                assert_eq!(fallback, "UNRELEASED");
            }
            other => panic!("expected Choose, got {other:?}"),
        }
    }

    /// A released changelog offers its distribution's series with the
    /// current one preselected. Uses a series of the host vendor so the
    /// test only relies on the local distro-info data.
    #[tokio::test]
    async fn series_candidates_released_defaults_to_current_series() {
        let dist = crate::build::env::current_vendor().to_lowercase();
        let vendor_series = crate::distro_info::get_ordered_series_name(&dist)
            .await
            .expect("the host vendor's series data resolves");
        // Any released series of the vendor works; the changelog names it.
        let current = vendor_series.last().expect("non-empty series list");

        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("changelog");
        std::fs::write(
            &path,
            format!(
                "hello (1.0-1) {current}; urgency=medium\n\n  * Something.\n\n \
                 -- A B <a@b.c>  Mon, 01 Jan 2024 00:00:00 +0000\n"
            ),
        )
        .unwrap();

        match series_candidates(&path).await {
            Some(SeriesCandidates::Choose {
                options,
                values,
                default,
                fallback,
            }) => {
                // The current series is preselected through its label, and
                // selecting it targets the name the changelog already carries
                let idx = values
                    .iter()
                    .position(|v| v == current)
                    .expect("the current series is offered");
                assert_eq!(default, options[idx]);
                assert_eq!(
                    selected_series(&options, &values, options[idx].clone()),
                    *current
                );
                assert_eq!(fallback, *current);
            }
            other => panic!("expected Choose, got {other:?}"),
        }
    }

    /// A changelog targeting Debian's 'unstable' suite — the conventional
    /// Debian development distribution, which the series data knows as the
    /// codename 'sid' — resolves to the Debian series list: the selector
    /// offers the aliased entry as 'unstable (sid)', preselected, and
    /// selecting it targets 'unstable' itself.
    #[tokio::test]
    async fn series_candidates_suite_alias_matches_unstable_and_sid() {
        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("changelog");
        std::fs::write(
            &path,
            "hello (1.0-1) unstable; urgency=medium\n\n  * Something.\n\n \
             -- A B <a@b.c>  Mon, 01 Jan 2024 00:00:00 +0000\n",
        )
        .unwrap();

        match series_candidates(&path).await {
            Some(SeriesCandidates::Choose {
                options,
                values,
                default,
                fallback,
            }) => {
                let idx = options
                    .iter()
                    .position(|o| o == "unstable (sid)")
                    .expect("sid is offered as its suite alias");
                assert_eq!(values[idx], "unstable");
                assert_eq!(default, "unstable (sid)");
                assert_eq!(fallback, "unstable");
                // Selecting the aliased entry targets the suite name
                assert_eq!(
                    selected_series(&options, &values, options[idx].clone()),
                    "unstable"
                );
                // A free-typed series the selector does not offer is its own
                // target
                assert_eq!(
                    selected_series(&options, &values, "trixie".to_string()),
                    "trixie"
                );
            }
            other => panic!("expected Choose, got {other:?}"),
        }
    }

    /// A changelog naming the codename ('sid') resolves to the same
    /// selector entry as the suite alias ('unstable'): the two identify
    /// the same series.
    #[tokio::test]
    async fn series_candidates_sid_defaults_to_the_suite_alias_label() {
        let dir = tempfile::tempdir().unwrap();
        let path = dir.path().join("changelog");
        std::fs::write(
            &path,
            "hello (1.0-1) sid; urgency=medium\n\n  * Something.\n\n \
             -- A B <a@b.c>  Mon, 01 Jan 2024 00:00:00 +0000\n",
        )
        .unwrap();

        match series_candidates(&path).await {
            Some(SeriesCandidates::Choose {
                options,
                values,
                default,
                fallback,
            }) => {
                assert_eq!(default, "unstable (sid)");
                assert_eq!(
                    selected_series(&options, &values, default.clone()),
                    "unstable"
                );
                assert_eq!(fallback, "sid");
            }
            other => panic!("expected Choose, got {other:?}"),
        }
    }

    /// Without a parsable changelog there is no candidate at all.
    #[tokio::test]
    async fn series_candidates_none_without_changelog() {
        let dir = tempfile::tempdir().unwrap();
        assert!(
            series_candidates(&dir.path().join("changelog"))
                .await
                .is_none()
        );
    }

    /// Serializes the tests that mutate the process-global DEBFULLNAME /
    /// DEBEMAIL variables: run in parallel, they otherwise race each
    /// other's identity reads and assertions.
    static IDENTITY_LOCK: std::sync::LazyLock<tokio::sync::Mutex<()>> =
        std::sync::LazyLock::new(|| tokio::sync::Mutex::new(()));

    fn setup_repo(dir: &Path) {
        Command::new("git")
            .arg("init")
            .current_dir(dir)
            .output()
            .unwrap();
        Command::new("git")
            .arg("config")
            .arg("user.email")
            .arg("you@example.com")
            .current_dir(dir)
            .output()
            .unwrap();
        Command::new("git")
            .arg("config")
            .arg("user.name")
            .arg("Your Name")
            .current_dir(dir)
            .output()
            .unwrap();
    }

    fn commit(dir: &Path, message: &str) {
        Command::new("git")
            .arg("commit")
            .arg("--allow-empty")
            .arg("-m")
            .arg(message)
            .current_dir(dir)
            .output()
            .unwrap();
    }

    fn tag(dir: &Path, name: &str) {
        Command::new("git")
            .arg("tag")
            .arg(name)
            .current_dir(dir)
            .output()
            .unwrap();
    }

    #[tokio::test]
    async fn test_generate_entry() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);

        // Create initial changelog
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        let initial_content = "mypackage (0.1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n";
        std::fs::write(&changelog_path, initial_content).unwrap();

        // Commit and tag
        Command::new("git")
            .arg("add")
            .arg(".")
            .current_dir(repo_dir)
            .output()
            .unwrap();
        commit(repo_dir, "Initial commit");
        tag(repo_dir, "debian/0.1.0-1");

        // New commits
        commit(repo_dir, "Fix bug A");
        commit(repo_dir, "Add feature B");

        // Generate entry
        let _identity = IDENTITY_LOCK.lock().await;
        unsafe {
            std::env::set_var("DEBFULLNAME", "Maintainer Maintainer");
            std::env::set_var("DEBEMAIL", "maintainer@maintainer.com");
        }
        generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            None,
            EntryKind::Normal,
        )
        .await
        .unwrap();
        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }

        // Verify content
        let content = std::fs::read_to_string(&changelog_path).unwrap();
        println!("{}", content);

        assert!(content.contains("mypackage (0.1.0-2) unstable; urgency=medium"));
        assert!(content.contains("* Fix bug A"));
        assert!(content.contains("* Add feature B"));
        assert!(content.contains(" -- Maintainer Maintainer <maintainer@maintainer.com> "));
        // Should still contain old content
        assert!(content.contains("mypackage (0.1.0-1) unstable; urgency=medium"));
    }

    /// Without any version tag, the history of the changelog itself
    /// delimits the entry: the commits since the changelog was last
    /// committed are the changes, and the changelog commit is not one.
    #[tokio::test]
    async fn test_generate_entry_without_tags() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);

        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        let initial_content = "mypackage (0.1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n";
        std::fs::write(&changelog_path, initial_content).unwrap();

        // Commit the changelog, but do not tag it
        Command::new("git")
            .arg("add")
            .arg(".")
            .current_dir(repo_dir)
            .output()
            .unwrap();
        commit(repo_dir, "Initial commit");

        commit(repo_dir, "Fix bug A");
        commit(repo_dir, "Add feature B");

        let _identity = IDENTITY_LOCK.lock().await;
        unsafe {
            std::env::set_var("DEBFULLNAME", "Maintainer Maintainer");
            std::env::set_var("DEBEMAIL", "maintainer@maintainer.com");
        }
        generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            None,
            EntryKind::Normal,
        )
        .await
        .unwrap();
        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }

        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.contains("mypackage (0.1.0-2) unstable; urgency=medium"));
        assert!(content.contains("* Fix bug A"));
        assert!(content.contains("* Add feature B"));
        assert!(!content.contains("* Initial commit"));
    }

    /// A changelog that was never committed has no revision to walk the
    /// history from: the entry is generated without commit summaries.
    #[tokio::test]
    async fn test_generate_entry_uncommitted_changelog() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);

        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(&changelog_path, "mypackage (0.1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n").unwrap();
        commit(repo_dir, "Some change");

        let _identity = IDENTITY_LOCK.lock().await;
        unsafe {
            std::env::set_var("DEBFULLNAME", "Maintainer Maintainer");
            std::env::set_var("DEBEMAIL", "maintainer@maintainer.com");
        }
        generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            None,
            EntryKind::Normal,
        )
        .await
        .unwrap();
        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }

        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.contains("mypackage (0.1.0-2) unstable; urgency=medium"));
        assert!(!content.contains("* Some change"));
    }

    /// An uncommitted newer entry on top of the changelog (e.g. UNRELEASED
    /// from a previous run) does not hide the previous version: the tag of
    /// the last *committed* version is still used as the boundary.
    #[tokio::test]
    async fn test_generate_entry_tag_from_committed_version() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);

        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        let initial_content = "mypackage (0.1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n";
        std::fs::write(&changelog_path, initial_content).unwrap();

        Command::new("git")
            .arg("add")
            .arg(".")
            .current_dir(repo_dir)
            .output()
            .unwrap();
        commit(repo_dir, "Initial commit");
        tag(repo_dir, "debian/0.1.0-1");

        commit(repo_dir, "Fix bug A");
        commit(repo_dir, "Add feature B");

        // Leave an uncommitted newer entry on top
        let mut unreleased = String::from(
            "mypackage (0.1.0-2) UNRELEASED; urgency=medium\n\n  * WIP.\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        );
        unreleased.push_str(initial_content);
        std::fs::write(&changelog_path, unreleased).unwrap();

        let _identity = IDENTITY_LOCK.lock().await;
        unsafe {
            std::env::set_var("DEBFULLNAME", "Maintainer Maintainer");
            std::env::set_var("DEBEMAIL", "maintainer@maintainer.com");
        }
        generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            None,
            EntryKind::Normal,
        )
        .await
        .unwrap();
        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }

        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.contains("mypackage (0.1.0-3) UNRELEASED; urgency=medium"));
        assert!(content.contains("* Fix bug A"));
        assert!(content.contains("* Add feature B"));
    }

    #[test]
    fn test_compute_new_version() {
        // Debian upload
        assert_eq!(
            compute_new_version("15.2.0-8", Bump::Normal).unwrap(),
            "15.2.0-9"
        );
        assert_eq!(
            compute_new_version("15.2.0-9", Bump::Normal).unwrap(),
            "15.2.0-10"
        );

        // Ubuntu upload
        assert_eq!(
            compute_new_version("15.2.0-9", Bump::Ubuntu).unwrap(),
            "15.2.0-9ubuntu1"
        );
        assert_eq!(
            compute_new_version("15.2.0-9ubuntu1", Bump::Ubuntu).unwrap(),
            "15.2.0-9ubuntu2"
        );
        // Ubuntu upload on top of a rebuild drops the buildN marker:
        // appending would give 15.2.0-9build1ubuntu1, which sorts below
        // the proper 15.2.0-9ubuntu1
        assert_eq!(
            compute_new_version("15.2.0-9build1", Bump::Ubuntu).unwrap(),
            "15.2.0-9ubuntu1"
        );
        assert_eq!(
            compute_new_version("15.2.0-9ubuntu1build1", Bump::Ubuntu).unwrap(),
            "15.2.0-9ubuntu2"
        );
        // Native packages
        assert_eq!(
            compute_new_version("15.2.0build1", Bump::Ubuntu).unwrap(),
            "15.2.0ubuntu1"
        );

        // No change rebuild
        assert_eq!(
            compute_new_version("15.2.0-9", Bump::Rebuild).unwrap(),
            "15.2.0-9build1"
        );
        assert_eq!(
            compute_new_version("15.2.0-9build1", Bump::Rebuild).unwrap(),
            "15.2.0-9build2"
        );

        // Rebuild of Ubuntu version
        assert_eq!(
            compute_new_version("15.2.0-9ubuntu1", Bump::Rebuild).unwrap(),
            "15.2.0-9ubuntu1build1"
        );

        // NMU
        // Native
        assert_eq!(compute_new_version("1.0", Bump::Nmu).unwrap(), "1.0+nmu1");
        assert_eq!(
            compute_new_version("1.0+nmu1", Bump::Nmu).unwrap(),
            "1.0+nmu2"
        );

        // Non-native
        assert_eq!(compute_new_version("1.0-1", Bump::Nmu).unwrap(), "1.0-1.1");
        assert_eq!(
            compute_new_version("1.0-1.1", Bump::Nmu).unwrap(),
            "1.0-1.2"
        );

        // NMU of NMU?
        assert_eq!(
            compute_new_version("1.0-1.2", Bump::Nmu).unwrap(),
            "1.0-1.3"
        );

        // Backport, Debian scheme
        assert_eq!(
            compute_new_version("1.0-1", Bump::Backport("~bpo12+".to_string())).unwrap(),
            "1.0-1~bpo12+1"
        );
        // Re-backporting the same source reuses the counter
        assert_eq!(
            compute_new_version("1.0-1~bpo12+1", Bump::Backport("~bpo12+".to_string())).unwrap(),
            "1.0-1~bpo12+2"
        );
        // Native packages backport too
        assert_eq!(
            compute_new_version("1.0", Bump::Backport("~bpo12+".to_string())).unwrap(),
            "1.0~bpo12+1"
        );
        // A version carrying another release's counter gains a fresh one
        assert_eq!(
            compute_new_version("1.0-1~bpo11+1", Bump::Backport("~bpo12+".to_string())).unwrap(),
            "1.0-1~bpo11+1~bpo12+1"
        );

        // Backport, Ubuntu scheme (Ubuntu version-strings documentation)
        assert_eq!(
            compute_new_version("3.1-1ubuntu2", Bump::Backport("~22.04.".to_string())).unwrap(),
            "3.1-1ubuntu2~22.04.1"
        );
        // Subsequent per-release SRU uploads increment the counter
        assert_eq!(
            compute_new_version(
                "3.1-1ubuntu2~22.04.1",
                Bump::Backport("~22.04.".to_string())
            )
            .unwrap(),
            "3.1-1ubuntu2~22.04.2"
        );
        // Native packages
        assert_eq!(
            compute_new_version("3.1", Bump::Backport("~22.04.".to_string())).unwrap(),
            "3.1~22.04.1"
        );

        // Native package uploads
        assert_eq!(compute_new_version("1.0", Bump::Normal).unwrap(), "1.1");
        assert_eq!(compute_new_version("1.0.5", Bump::Normal).unwrap(), "1.0.6");
        assert_eq!(
            compute_new_version("20241126", Bump::Normal).unwrap(),
            "20241127"
        );
    }

    #[test]
    fn test_compute_new_version_large_trailing_number() {
        // Date-based versions with a trailing number larger than u32::MAX
        // must increment normally (they fit in a u64)
        assert_eq!(
            compute_new_version("1.0-20250123123456", Bump::Normal).unwrap(),
            "1.0-20250123123457"
        );

        // A number that does not even fit in a u64 yields a clear error
        // instead of panicking
        let err = compute_new_version("1.0-99999999999999999999999999", Bump::Normal);
        assert!(err.is_err());

        // u64::MAX itself cannot be incremented
        let err = compute_new_version("1.0-18446744073709551615", Bump::Normal);
        assert!(err.is_err());
    }

    /// A backport entry is numbered after the Debian release number of the
    /// target series (`~bpo12+1` for bookworm). Relies on the host
    /// distro-info data mapping bookworm to 12 (see distro_info tests).
    #[tokio::test]
    async fn test_generate_entry_backport_numbering() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(
            &changelog_path,
            "mypackage (1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        )
        .unwrap();

        let _identity = IDENTITY_LOCK.lock().await;
        unsafe {
            std::env::set_var("DEBFULLNAME", "Maintainer Maintainer");
            std::env::set_var("DEBEMAIL", "maintainer@maintainer.com");
        }
        let entry = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("bookworm"),
            EntryKind::Backport,
        )
        .await
        .unwrap();
        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }

        assert_eq!(entry.new_version, "1.0-1~bpo12+1");
        assert_eq!(entry.series, "bookworm");
        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.contains("mypackage (1.0-1~bpo12+1) bookworm; urgency=medium"));
    }

    /// Backport numbering needs a usable release number: Debian's rolling
    /// series (sid) carry none and are rejected before anything is written,
    /// pointing at --series/--version instead.
    #[tokio::test]
    async fn test_generate_entry_backport_requires_numbered_series() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(
            &changelog_path,
            "mypackage (1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        )
        .unwrap();

        let result = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("sid"),
            EntryKind::Backport,
        )
        .await;
        assert!(result.is_err());

        // Nothing was written: the changelog is untouched
        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.starts_with("mypackage (1.0-1) unstable"));
    }

    /// Ubuntu backports follow the per-release SRU scheme of the Ubuntu
    /// version-strings documentation: the development release's version
    /// with ~YY.MM.1 appended, independently of what the target release
    /// carries. Relies on the host distro-info data mapping noble to
    /// 24.04 (see the distro_info tests).
    #[tokio::test]
    async fn test_generate_entry_backport_ubuntu_numbering() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(
            &changelog_path,
            "mypackage (3.1-1ubuntu2) questing; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        )
        .unwrap();

        let entry = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("noble"),
            EntryKind::Backport,
        )
        .await
        .unwrap();

        assert_eq!(entry.new_version, "3.1-1ubuntu2~24.04.1");
        assert_eq!(entry.series, "noble");
        let content = std::fs::read_to_string(&changelog_path).unwrap();
        assert!(content.contains("mypackage (3.1-1ubuntu2~24.04.1) noble; urgency=medium"));
    }

    /// A regular upload is numbered after the vendor of its target series:
    /// a Debian-style version uploaded to an Ubuntu series gains the
    /// ubuntu1 suffix, and re-bumping the now-Ubuntu changelog increments
    /// that counter instead of the revision. Relies on the host distro-info
    /// data listing noble (see the distro_info tests). The git repo
    /// provides the maintainer identity: DEBFULLNAME/DEBEMAIL are
    /// process-global and other tests mutate them in parallel.
    #[tokio::test]
    async fn test_generate_entry_ubuntu_series_numbering() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(
            &changelog_path,
            "mypackage (1.0-1) unstable; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        )
        .unwrap();

        let entry = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("noble"),
            EntryKind::Normal,
        )
        .await
        .unwrap();
        assert_eq!(entry.new_version, "1.0-1ubuntu1");
        assert_eq!(entry.series, "noble");

        // Re-bumping the now-Ubuntu changelog increments the counter
        let entry = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("noble"),
            EntryKind::Normal,
        )
        .await
        .unwrap();
        assert_eq!(entry.new_version, "1.0-1ubuntu2");
    }

    /// An Ubuntu upload of a package whose changelog carries a rebuild
    /// version drops the buildN marker: 1.0-1build1 numbers the next entry
    /// 1.0-1ubuntu1 (1.0-1build1ubuntu1 would sort below 1.0-1ubuntu1).
    /// Relies on the host distro-info data listing noble (see the
    /// distro_info tests). The git repo provides the maintainer identity:
    /// DEBFULLNAME/DEBEMAIL are process-global and other tests mutate them
    /// in parallel.
    #[tokio::test]
    async fn test_generate_entry_ubuntu_series_numbering_after_rebuild() {
        let temp_dir = TempDir::new().unwrap();
        let repo_dir = temp_dir.path();
        setup_repo(repo_dir);
        let changelog_path = repo_dir.join("debian/changelog");
        std::fs::create_dir_all(repo_dir.join("debian")).unwrap();
        std::fs::write(
            &changelog_path,
            "mypackage (1.0-1build1) noble; urgency=medium\n\n  * Initial release\n\n -- Maintainer <m@e.com>  Wed, 01 Jan 2020 00:00:00 +0000\n",
        )
        .unwrap();

        let entry = generate_entry(
            "debian/changelog",
            Some(repo_dir),
            None,
            Some("noble"),
            EntryKind::Normal,
        )
        .await
        .unwrap();
        assert_eq!(entry.new_version, "1.0-1ubuntu1");
    }

    #[test]
    fn test_get_maintainer_info() {
        let _identity = IDENTITY_LOCK.blocking_lock();
        // Test with env vars
        unsafe {
            std::env::set_var("DEBFULLNAME", "Env Name");
            std::env::set_var("DEBEMAIL", "env@example.com");
        }

        let (name, email) = get_maintainer_info().unwrap();
        assert_eq!(name, "Env Name");
        assert_eq!(email, "env@example.com");

        unsafe {
            std::env::remove_var("DEBFULLNAME");
            std::env::remove_var("DEBEMAIL");
        }
    }
}