vdev 0.3.9

use std::fs;
use std::process::Command;

use anyhow::{Context, Result, bail};
use indoc::formatdoc;

use crate::utils::paths;

const CHANGELOG_DIR: &str = "changelog.d";
const FRAGMENT_TYPES: &[&str] = &["breaking", "security", "feature", "enhancement", "fix"];

/// Placeholder written for the author line when no handle can be detected.
/// The checker rejects fragments still containing this sentinel.
pub(crate) const TODO_HANDLE: &str = "TODO_your_gh_handle";

/// Scaffold a new changelog fragment.
#[derive(clap::Args, Debug)]
#[command()]
pub struct Cli {
    /// Fragment type.
    #[arg(value_parser = clap::builder::PossibleValuesParser::new(FRAGMENT_TYPES))]
    fragment_type: String,
    /// Unique slug (used as the filename prefix, e.g. `env_var_interpolation`).
    slug: String,
}

impl Cli {
    pub fn exec(self) -> Result<()> {
        validate_slug(&self.slug)?;

        let repo_root = paths::find_repo_root()?;
        let dir = repo_root.join(CHANGELOG_DIR);
        if !dir.is_dir() {
            bail!("{} does not exist", dir.display());
        }
        let file = dir.join(format!("{}.{}.md", self.slug, self.fragment_type));
        if file.exists() {
            bail!("{} already exists", file.display());
        }

        let author = detect_gh_handle().unwrap_or_else(|| TODO_HANDLE.to_string());
        let content = render_template(&self.fragment_type, &author);
        fs::write(&file, content)?;

        // `git add` the new fragment so the checker (which scans `git diff --diff-filter=A`)
        // picks it up immediately without a manual staging step. Report the failure if it
        // happens — the file is on disk, but the checker won't see it until it's staged.
        let status = Command::new("git")
            .args(["add", "--"])
            .arg(&file)
            .status()
            .with_context(|| format!("failed to run `git add {}`", file.display()))?;
        if !status.success() {
            bail!(
                "wrote {} but `git add` failed — stage it manually before running `vdev check changelog-fragments`.",
                file.display()
            );
        }

        info!("Created {}", relative(&repo_root, &file).display());
        info!("Edit the file, then run `vdev check changelog-fragments` to validate.");
        Ok(())
    }
}

/// A slug must be one filename component: ASCII alnum, `_`, or `-` only.
/// Rejects path separators, `..`, absolute paths, and anything with punctuation.
fn validate_slug(slug: &str) -> Result<()> {
    if slug.is_empty() {
        bail!("slug must not be empty");
    }
    if !slug
        .chars()
        .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
    {
        bail!(
            "invalid slug '{slug}': only ASCII letters, digits, '_', and '-' are allowed (got a path separator or punctuation?)"
        );
    }
    Ok(())
}

fn render_template(fragment_type: &str, author: &str) -> String {
    match fragment_type {
        "breaking" => formatdoc! {"
            # TODO one-line title

            ## Summary

            TODO one-paragraph summary that lands in the release changelog list.

            ## Migration

            TODO how to migrate. Use `N/A` for informational-only breakers.

            For config changes, show a before/after with fenced code blocks:

            #### Old

            ```yaml
            sinks:
              my_sink:
                option: old_value
            ```

            #### New

            ```yaml
            sinks:
              my_sink:
                option: new_value
            ```

            authors: {author}
        "},
        _ => formatdoc! {"
            TODO one-item description of the change.

            authors: {author}
        "},
    }
}

/// Best-effort GitHub handle detection:
/// 1. `git config --get github.user` (explicit override)
/// 2. `gh api user --jq .login` (uses the authenticated `gh` CLI if installed)
/// 3. `git config user.email` when it matches `<id>+<handle>@users.noreply.github.com`
///    or `<handle>@users.noreply.github.com`
fn detect_gh_handle() -> Option<String> {
    if let Some(h) = git_config("github.user") {
        return Some(h);
    }
    if let Some(h) = gh_authenticated_login() {
        return Some(h);
    }
    let email = git_config("user.email")?;
    handle_from_noreply(&email)
}

fn git_config(key: &str) -> Option<String> {
    let out = Command::new("git")
        .args(["config", "--get", key])
        .output()
        .ok()?;
    if !out.status.success() {
        return None;
    }
    let v = String::from_utf8(out.stdout).ok()?.trim().to_string();
    (!v.is_empty()).then_some(v)
}

fn gh_authenticated_login() -> Option<String> {
    let out = Command::new("gh")
        .args(["api", "user", "--jq", ".login"])
        .output()
        .ok()?;
    if !out.status.success() {
        return None;
    }
    let v = String::from_utf8(out.stdout).ok()?.trim().to_string();
    (!v.is_empty()).then_some(v)
}

fn handle_from_noreply(email: &str) -> Option<String> {
    let local = email
        .split_once('@')
        .filter(|(_, d)| *d == "users.noreply.github.com")?
        .0;
    let handle = local.split_once('+').map_or(local, |(_, h)| h);
    (!handle.is_empty()).then(|| handle.to_string())
}

fn relative<'a>(base: &std::path::Path, path: &'a std::path::Path) -> &'a std::path::Path {
    path.strip_prefix(base).unwrap_or(path)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn accepts_normal_slugs() {
        validate_slug("env_var_interpolation").unwrap();
        validate_slug("12345_kafka_ack").unwrap();
        validate_slug("Foo-Bar-1").unwrap();
    }

    #[test]
    fn rejects_traversal() {
        assert!(validate_slug("../outside").is_err());
        assert!(validate_slug("foo/bar").is_err());
        assert!(validate_slug("/etc/passwd").is_err());
    }

    #[test]
    fn rejects_empty_and_punctuation() {
        assert!(validate_slug("").is_err());
        assert!(validate_slug("foo.bar").is_err());
        assert!(validate_slug("foo bar").is_err());
    }
}