dotm/

scanner.rs

use anyhow::{Context, Result};
use std::collections::HashMap;
use std::path::{Path, PathBuf};

/// What kind of entry a file action represents, determining how it gets deployed.
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum EntryKind {
    /// Plain base file -- symlink (user-mode) or copy (system-mode)
    Base,
    /// Host or role override -- symlink (user-mode) or copy (system-mode)
    Override,
    /// Tera template — rendered and written as a file
    Template,
}

/// Describes what to do with a single file during deployment.
#[derive(Debug)]
pub struct FileAction {
    /// The source file in the dotfiles repo
    pub source: PathBuf,
    /// The relative path where this file should be deployed (relative to target dir)
    pub target_rel_path: PathBuf,
    /// What kind of entry this is (base, override, or template)
    pub kind: EntryKind,
}

/// Scan a package directory and resolve overrides for the given host and roles.
///
/// Returns a list of FileActions describing what to deploy.
pub fn scan_package(pkg_dir: &Path, hostname: &str, roles: &[&str]) -> Result<Vec<FileAction>> {
    let mut files: HashMap<PathBuf, Vec<PathBuf>> = HashMap::new();

    collect_files(pkg_dir, pkg_dir, &mut files)
        .with_context(|| format!("failed to scan package directory: {}", pkg_dir.display()))?;

    let mut actions = Vec::new();

    for (target_path, variants) in &files {
        if let Some(action) = resolve_variant(target_path, variants, hostname, roles) {
            actions.push(action);
        }
    }

    actions.sort_by(|a, b| a.target_rel_path.cmp(&b.target_rel_path));
    Ok(actions)
}

/// Recursively collect files, grouping override variants by their canonical path.
fn collect_files(
    base: &Path,
    dir: &Path,
    files: &mut HashMap<PathBuf, Vec<PathBuf>>,
) -> Result<()> {
    for entry in std::fs::read_dir(dir)
        .with_context(|| format!("failed to read directory: {}", dir.display()))?
    {
        let entry = entry?;
        let path = entry.path();

        if path.is_dir() {
            if path.is_symlink() {
                eprintln!(
                    "warning: skipping symlink to directory: {}",
                    path.strip_prefix(base).unwrap_or(&path).display()
                );
                continue;
            }
            collect_files(base, &path, files)?;
        } else {
            let rel_path = path
                .strip_prefix(base)
                .expect("collected path must be under base directory")
                .to_path_buf();
            if rel_path.file_name().and_then(|n| n.to_str()).is_none() {
                eprintln!(
                    "warning: skipping non-UTF-8 filename: {}",
                    rel_path.display()
                );
                continue;
            }
            let canonical = canonical_target_path(&rel_path);
            files.entry(canonical).or_default().push(path);
        }
    }
    Ok(())
}

/// Extract filename as a UTF-8 string, panicking with a descriptive message on non-UTF-8 paths.
fn file_name_str(path: &Path) -> &str {
    path.file_name()
        .expect("path has no filename")
        .to_str()
        .expect("filename is not valid UTF-8")
}

/// Strip `##` suffix and `.tera` extension to get the canonical target path.
fn canonical_target_path(rel_path: &Path) -> PathBuf {
    let file_name = file_name_str(rel_path);

    // Strip ## suffix first
    let base_name = if let Some(idx) = file_name.find("##") {
        &file_name[..idx]
    } else {
        file_name
    };

    // Strip .tera extension
    let base_name = base_name.strip_suffix(".tera").unwrap_or(base_name);

    if let Some(parent) = rel_path.parent() {
        if parent == Path::new("") {
            PathBuf::from(base_name)
        } else {
            parent.join(base_name)
        }
    } else {
        PathBuf::from(base_name)
    }
}

/// Given all variants of a file, pick the best one for this host/roles.
/// Returns None if no variant matches the current host/roles and no base file exists.
fn resolve_variant(
    target_path: &Path,
    variants: &[PathBuf],
    hostname: &str,
    roles: &[&str],
) -> Option<FileAction> {
    let host_suffix = format!("##host.{hostname}");
    let host_suffix_tera = format!("{host_suffix}.tera");

    // Priority 1: host override
    if let Some(source) = variants.iter().find(|v| {
        let name = file_name_str(v);
        name.ends_with(&host_suffix) || name.ends_with(&host_suffix_tera)
    }) {
        let kind = if file_name_str(source).ends_with(".tera") {
            EntryKind::Template
        } else {
            EntryKind::Override
        };
        return Some(FileAction {
            source: source.clone(),
            target_rel_path: target_path.to_path_buf(),
            kind,
        });
    }

    // Priority 2: role override (last matching role wins)
    for role in roles.iter().rev() {
        let role_suffix = format!("##role.{role}");
        let role_suffix_tera = format!("{role_suffix}.tera");
        if let Some(source) = variants.iter().find(|v| {
            let name = file_name_str(v);
            name.ends_with(&role_suffix) || name.ends_with(&role_suffix_tera)
        }) {
            let kind = if file_name_str(source).ends_with(".tera") {
                EntryKind::Template
            } else {
                EntryKind::Override
            };
            return Some(FileAction {
                source: source.clone(),
                target_rel_path: target_path.to_path_buf(),
                kind,
            });
        }
    }

    // Priority 3: template (base file with .tera extension)
    if let Some(source) = variants.iter().find(|v| {
        let name = file_name_str(v);
        name.ends_with(".tera") && !name.contains("##")
    }) {
        return Some(FileAction {
            source: source.clone(),
            target_rel_path: target_path.to_path_buf(),
            kind: EntryKind::Template,
        });
    }

    // Priority 4: plain base file
    variants
        .iter()
        .find(|v| {
            let name = file_name_str(v);
            !name.contains("##") && !name.ends_with(".tera")
        })
        .map(|source| FileAction {
            source: source.clone(),
            target_rel_path: target_path.to_path_buf(),
            kind: EntryKind::Base,
        })
}