autom8-cli 0.3.0

//! Git worktree operations for autom8.
//!
//! This module provides functions for managing git worktrees, enabling
//! parallel execution of autom8 sessions on the same project.

use crate::error::{Autom8Error, Result};
use sha2::{Digest, Sha256};
use std::path::{Path, PathBuf};
use std::process::Command;

/// Information about a git worktree.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct WorktreeInfo {
    /// Absolute path to the worktree directory
    pub path: PathBuf,
    /// The branch checked out in this worktree (None for detached HEAD)
    pub branch: Option<String>,
    /// The current commit hash
    pub commit: String,
    /// Whether this is the main worktree (the original repo)
    pub is_main: bool,
    /// Whether this worktree is bare (no working directory)
    pub is_bare: bool,
    /// Whether the worktree is currently locked
    pub is_locked: bool,
    /// Whether the worktree is prunable (missing directory)
    pub is_prunable: bool,
}

impl WorktreeInfo {
    /// Parse a single worktree from porcelain output lines.
    ///
    /// The porcelain format outputs one attribute per line, with worktrees
    /// separated by blank lines.
    fn from_porcelain_lines(lines: &[&str]) -> Option<Self> {
        let mut path: Option<PathBuf> = None;
        let mut branch: Option<String> = None;
        let mut commit: Option<String> = None;
        let mut is_bare = false;
        let mut is_locked = false;
        let mut is_prunable = false;

        for line in lines {
            if let Some(rest) = line.strip_prefix("worktree ") {
                path = Some(PathBuf::from(rest));
            } else if let Some(rest) = line.strip_prefix("HEAD ") {
                commit = Some(rest.to_string());
            } else if let Some(rest) = line.strip_prefix("branch ") {
                // Branch is in format "refs/heads/branch-name"
                let branch_name = rest.strip_prefix("refs/heads/").unwrap_or(rest).to_string();
                branch = Some(branch_name);
            } else if *line == "bare" {
                is_bare = true;
            } else if *line == "detached" {
                // Detached HEAD - branch remains None
            } else if line.starts_with("locked") {
                is_locked = true;
            } else if line.starts_with("prunable") {
                is_prunable = true;
            }
        }

        let path = path?;
        let commit = commit?;

        // The first worktree listed is always the main worktree
        // We'll set this properly in list_worktrees()
        Some(WorktreeInfo {
            path,
            branch,
            commit,
            is_main: false,
            is_bare,
            is_locked,
            is_prunable,
        })
    }
}

/// List all worktrees for the current repository.
///
/// Returns information about each worktree including path, branch, and commit.
/// The main repository is always included in the list with `is_main: true`.
///
/// # Returns
/// * `Ok(Vec<WorktreeInfo>)` - List of worktrees (always has at least one - the main repo)
/// * `Err` - If not in a git repository or git command fails
pub fn list_worktrees() -> Result<Vec<WorktreeInfo>> {
    let output = Command::new("git")
        .args(["worktree", "list", "--porcelain"])
        .output()?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to list worktrees: {}",
            stderr.trim()
        )));
    }

    let stdout = String::from_utf8_lossy(&output.stdout);
    let worktrees = parse_worktree_list_porcelain(&stdout)?;

    Ok(worktrees)
}

/// Parse the output of `git worktree list --porcelain`.
///
/// The porcelain format is machine-readable with one attribute per line,
/// and worktrees separated by blank lines.
fn parse_worktree_list_porcelain(output: &str) -> Result<Vec<WorktreeInfo>> {
    let mut worktrees = Vec::new();
    let mut current_lines: Vec<&str> = Vec::new();
    let mut is_first = true;

    for line in output.lines() {
        if line.is_empty() {
            // End of a worktree block
            if !current_lines.is_empty() {
                if let Some(mut wt) = WorktreeInfo::from_porcelain_lines(&current_lines) {
                    // First worktree in the list is always the main worktree
                    wt.is_main = is_first;
                    is_first = false;
                    worktrees.push(wt);
                }
                current_lines.clear();
            }
        } else {
            current_lines.push(line);
        }
    }

    // Don't forget the last worktree (output may not end with blank line)
    if !current_lines.is_empty() {
        if let Some(mut wt) = WorktreeInfo::from_porcelain_lines(&current_lines) {
            wt.is_main = is_first;
            worktrees.push(wt);
        }
    }

    Ok(worktrees)
}

/// Create a new worktree at the specified path for the given branch.
///
/// If the branch already exists, it will be checked out in the new worktree.
/// If the branch doesn't exist, it will be created from the current HEAD.
///
/// # Arguments
/// * `path` - The path where the worktree should be created
/// * `branch` - The branch name to checkout or create
///
/// # Returns
/// * `Ok(())` - Worktree created successfully
/// * `Err` - If creation fails (e.g., branch already checked out elsewhere)
pub fn create_worktree<P: AsRef<Path>>(path: P, branch: &str) -> Result<()> {
    let path = path.as_ref();

    // First, check if branch exists
    let branch_exists = Command::new("git")
        .args([
            "show-ref",
            "--verify",
            "--quiet",
            &format!("refs/heads/{}", branch),
        ])
        .output()?
        .status
        .success();

    let output = if branch_exists {
        // Branch exists, just add worktree
        Command::new("git")
            .args(["worktree", "add", path.to_string_lossy().as_ref(), branch])
            .output()?
    } else {
        // Create new branch with -b flag
        Command::new("git")
            .args([
                "worktree",
                "add",
                "-b",
                branch,
                path.to_string_lossy().as_ref(),
            ])
            .output()?
    };

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to create worktree at '{}' for branch '{}': {}",
            path.display(),
            branch,
            stderr.trim()
        )));
    }

    Ok(())
}

/// Remove a worktree at the specified path.
///
/// By default, this will fail if the worktree has uncommitted changes.
/// Use `force: true` to remove even with uncommitted changes.
///
/// # Arguments
/// * `path` - The path of the worktree to remove
/// * `force` - If true, remove even if the worktree has uncommitted changes
///
/// # Returns
/// * `Ok(())` - Worktree removed successfully
/// * `Err` - If removal fails
pub fn remove_worktree<P: AsRef<Path>>(path: P, force: bool) -> Result<()> {
    let path = path.as_ref();
    let path_str = path.to_string_lossy();

    let mut args = vec!["worktree", "remove"];
    if force {
        args.push("--force");
    }
    args.push(path_str.as_ref());

    let output = Command::new("git").args(&args).output()?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to remove worktree at '{}': {}",
            path.display(),
            stderr.trim()
        )));
    }

    Ok(())
}

/// Get the worktree root for the current directory.
///
/// If the current directory is inside a linked worktree (not the main repo),
/// returns the root path of that worktree. Returns None if in the main repo.
///
/// # Returns
/// * `Ok(Some(path))` - The worktree root if in a linked worktree
/// * `Ok(None)` - If in the main repository (not a linked worktree)
/// * `Err` - If not in a git repository
pub fn get_worktree_root() -> Result<Option<PathBuf>> {
    // git rev-parse --git-common-dir returns the .git dir of the main repo
    // git rev-parse --git-dir returns the .git dir of the current worktree
    // If they're different, we're in a linked worktree

    let git_dir_output = Command::new("git")
        .args(["rev-parse", "--git-dir"])
        .output()?;

    if !git_dir_output.status.success() {
        let stderr = String::from_utf8_lossy(&git_dir_output.stderr);
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to get git directory: {}",
            stderr.trim()
        )));
    }

    let git_dir = String::from_utf8_lossy(&git_dir_output.stdout)
        .trim()
        .to_string();

    // In a linked worktree, git-dir points to .git/worktrees/<name>
    // The gitdir file inside contains the path we need to check
    if git_dir.contains("/worktrees/") || git_dir.contains("\\worktrees\\") {
        // We're in a worktree - get the toplevel
        let toplevel_output = Command::new("git")
            .args(["rev-parse", "--show-toplevel"])
            .output()?;

        if !toplevel_output.status.success() {
            let stderr = String::from_utf8_lossy(&toplevel_output.stderr);
            return Err(Autom8Error::WorktreeError(format!(
                "Failed to get worktree root: {}",
                stderr.trim()
            )));
        }

        let toplevel = String::from_utf8_lossy(&toplevel_output.stdout)
            .trim()
            .to_string();
        return Ok(Some(PathBuf::from(toplevel)));
    }

    Ok(None)
}

/// Get the main repository root (works from any worktree).
///
/// Returns the path to the main repository, regardless of whether
/// the current directory is in the main repo or a linked worktree.
///
/// # Returns
/// * `Ok(path)` - The main repository root path
/// * `Err` - If not in a git repository
pub fn get_main_repo_root() -> Result<PathBuf> {
    // git rev-parse --git-common-dir gives us the path to the main .git directory
    let output = Command::new("git")
        .args(["rev-parse", "--git-common-dir"])
        .output()?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to get main repo root: {}",
            stderr.trim()
        )));
    }

    let git_common_dir = String::from_utf8_lossy(&output.stdout).trim().to_string();

    // The common dir is the .git directory - we want its parent
    let git_path = PathBuf::from(&git_common_dir);

    // Handle both .git file (in worktrees) and .git directory cases
    // Also handle absolute vs relative paths
    let main_repo_path = if git_path.is_absolute() {
        git_path.parent().map(|p| p.to_path_buf())
    } else {
        // Relative path - resolve it
        let current_dir = std::env::current_dir()?;
        let absolute_git = current_dir.join(&git_path);
        absolute_git
            .canonicalize()
            .ok()
            .and_then(|p| p.parent().map(|p| p.to_path_buf()))
    };

    main_repo_path.ok_or_else(|| {
        Autom8Error::WorktreeError("Failed to determine main repository root".to_string())
    })
}

/// Check if the current working directory is inside a linked worktree.
///
/// Returns true if the CWD is inside a linked worktree (not the main repository).
///
/// # Returns
/// * `Ok(true)` - CWD is inside a linked worktree
/// * `Ok(false)` - CWD is inside the main repository
/// * `Err` - If not in a git repository
pub fn is_in_worktree() -> Result<bool> {
    Ok(get_worktree_root()?.is_some())
}

/// Get the git repository name (basename of the main repo root).
///
/// This function returns the name of the git repository, which is the
/// basename of the main repository root directory. This ensures consistent
/// project identification regardless of whether you're in the main repo
/// or a linked worktree.
///
/// # Returns
/// * `Ok(Some(name))` - The repository name if in a git repository
/// * `Ok(None)` - If not in a git repository
/// * `Err` - If there's an error determining the repo name
///
/// # Example
/// ```no_run
/// use autom8::worktree::get_git_repo_name;
///
/// if let Some(name) = get_git_repo_name().expect("git error") {
///     println!("Repository: {}", name);
/// }
/// ```
pub fn get_git_repo_name() -> Result<Option<String>> {
    // First check if we're in a git repo
    let output = Command::new("git")
        .args(["rev-parse", "--git-common-dir"])
        .output()?;

    if !output.status.success() {
        // Not in a git repository - this is not an error, just means no git
        let stderr = String::from_utf8_lossy(&output.stderr);
        if stderr.contains("not a git repository") {
            return Ok(None);
        }
        return Err(Autom8Error::WorktreeError(format!(
            "Failed to check git repository: {}",
            stderr.trim()
        )));
    }

    // Get the main repo root (works from both main repo and worktrees)
    let main_root = get_main_repo_root()?;

    // Extract the basename
    main_root
        .file_name()
        .and_then(|n| n.to_str())
        .map(|s| Some(s.to_string()))
        .ok_or_else(|| {
            Autom8Error::WorktreeError("Could not determine repository name from path".to_string())
        })
}

// ============================================================================
// Session Identity System (US-002)
// ============================================================================

/// Well-known session ID for the main repository.
pub const MAIN_SESSION_ID: &str = "main";

/// Generate a deterministic session ID from a worktree path.
///
/// The session ID is derived from the SHA-256 hash of the absolute path,
/// taking the first 8 characters. This ensures:
/// - Determinism: same path always produces the same ID
/// - Uniqueness: different paths produce different IDs (with high probability)
/// - Filesystem safety: only alphanumeric characters (hex digits)
/// - Readability: 8 characters is short but sufficient
///
/// # Arguments
/// * `worktree_path` - The absolute path to the worktree directory
///
/// # Returns
/// An 8-character hexadecimal string that uniquely identifies the worktree.
///
/// # Example
/// ```
/// use autom8::worktree::generate_session_id;
/// use std::path::Path;
///
/// let id = generate_session_id(Path::new("/home/user/project-feature"));
/// assert_eq!(id.len(), 8);
/// assert!(id.chars().all(|c| c.is_ascii_hexdigit()));
/// ```
pub fn generate_session_id(worktree_path: &Path) -> String {
    let path_str = worktree_path.to_string_lossy();
    let mut hasher = Sha256::new();
    hasher.update(path_str.as_bytes());
    let result = hasher.finalize();
    // Take first 8 characters of hex representation (4 bytes = 8 hex chars)
    hex::encode(&result[..4])
}

/// Get the session ID for the current working directory.
///
/// This function determines the appropriate session ID based on the current
/// location:
/// - If in the main repository: returns the well-known "main" session ID
/// - If in a linked worktree: returns a hash-based ID from the worktree path
///
/// # Returns
/// * `Ok(String)` - The session ID for the current directory
/// * `Err` - If not in a git repository
///
/// # Example
/// ```no_run
/// use autom8::worktree::get_current_session_id;
///
/// let session_id = get_current_session_id().expect("Not in a git repo");
/// println!("Session ID: {}", session_id);
/// ```
pub fn get_current_session_id() -> Result<String> {
    // Check if we're in a linked worktree
    if let Some(worktree_root) = get_worktree_root()? {
        // In a linked worktree - generate ID from path
        Ok(generate_session_id(&worktree_root))
    } else {
        // In main repository - use well-known ID
        Ok(MAIN_SESSION_ID.to_string())
    }
}

/// Get the session ID for the main repository.
///
/// This function returns the session ID that would be used when running
/// from the main repository (not a linked worktree). This is useful for
/// operations that need to reference the main session regardless of
/// the current working directory.
///
/// # Returns
/// The well-known "main" session ID.
pub fn get_main_session_id() -> String {
    MAIN_SESSION_ID.to_string()
}

/// Get the session ID for a specific worktree path.
///
/// This is a convenience function that combines path resolution with
/// session ID generation. For the main repository path, it returns "main".
/// For linked worktree paths, it generates a hash-based ID.
///
/// # Arguments
/// * `path` - The path to resolve a session ID for
///
/// # Returns
/// * `Ok(String)` - The session ID for the given path
/// * `Err` - If the path is not in a git repository or cannot be resolved
pub fn get_session_id_for_path(path: &Path) -> Result<String> {
    // Get the absolute path
    let abs_path = if path.is_absolute() {
        path.to_path_buf()
    } else {
        std::env::current_dir()?.join(path)
    };

    // Get the main repo root to compare
    let main_root = get_main_repo_root()?;

    // Canonicalize both paths for reliable comparison
    let abs_canonical = abs_path.canonicalize().unwrap_or(abs_path);
    let main_canonical = main_root.canonicalize().unwrap_or(main_root);

    // Check if this is the main repo
    if abs_canonical == main_canonical {
        Ok(MAIN_SESSION_ID.to_string())
    } else {
        Ok(generate_session_id(&abs_canonical))
    }
}

// ============================================================================
// Worktree Path Generation (US-007)
// ============================================================================

/// Convert a branch name to a filesystem-safe slug.
///
/// Replaces slashes with dashes, removes unsafe characters, and normalizes
/// to produce a valid directory name component.
///
/// # Arguments
/// * `branch_name` - The git branch name to slugify
///
/// # Returns
/// A filesystem-safe version of the branch name.
///
/// # Example
/// ```
/// use autom8::worktree::slugify_branch_name;
///
/// assert_eq!(slugify_branch_name("feature/login"), "feature-login");
/// assert_eq!(slugify_branch_name("feat/add-user-auth"), "feat-add-user-auth");
/// ```
pub fn slugify_branch_name(branch_name: &str) -> String {
    branch_name
        .chars()
        .map(|c| {
            if c == '/' || c == '\\' {
                '-'
            } else if c.is_ascii_alphanumeric() || c == '-' || c == '_' || c == '.' {
                c
            } else {
                '-'
            }
        })
        .collect::<String>()
        // Collapse multiple dashes into one
        .split('-')
        .filter(|s| !s.is_empty())
        .collect::<Vec<_>>()
        .join("-")
}

/// Generate the worktree path from a pattern and parameters.
///
/// Replaces placeholders in the pattern:
/// - `{repo}` - The repository name
/// - `{branch}` - The branch name (slugified)
///
/// The worktree is created as a sibling directory of the main repository.
///
/// # Arguments
/// * `pattern` - The path pattern (e.g., "{repo}-wt-{branch}")
/// * `repo_name` - The repository name
/// * `branch_name` - The branch name (will be slugified)
///
/// # Returns
/// The generated worktree directory name.
///
/// # Example
/// ```
/// use autom8::worktree::generate_worktree_name;
///
/// let name = generate_worktree_name("{repo}-wt-{branch}", "myproject", "feature/login");
/// assert_eq!(name, "myproject-wt-feature-login");
/// ```
pub fn generate_worktree_name(pattern: &str, repo_name: &str, branch_name: &str) -> String {
    let slugified_branch = slugify_branch_name(branch_name);
    pattern
        .replace("{repo}", repo_name)
        .replace("{branch}", &slugified_branch)
}

/// Generate the full path for a worktree.
///
/// Creates the worktree as a sibling directory of the main repository.
///
/// # Arguments
/// * `pattern` - The path pattern (e.g., "{repo}-wt-{branch}")
/// * `branch_name` - The branch name (will be slugified)
///
/// # Returns
/// * `Ok(PathBuf)` - The full path where the worktree should be created
/// * `Err` - If not in a git repository
///
/// # Example
/// ```no_run
/// use autom8::worktree::generate_worktree_path;
///
/// // If main repo is at /home/user/myproject, returns:
/// // /home/user/myproject-wt-feature-login
/// let path = generate_worktree_path("{repo}-wt-{branch}", "feature/login").unwrap();
/// ```
pub fn generate_worktree_path(pattern: &str, branch_name: &str) -> Result<PathBuf> {
    let main_repo = get_main_repo_root()?;
    let repo_name = main_repo
        .file_name()
        .and_then(|n| n.to_str())
        .ok_or_else(|| {
            Autom8Error::WorktreeError("Could not determine repository name".to_string())
        })?;

    let worktree_name = generate_worktree_name(pattern, repo_name, branch_name);

    // Place worktree as sibling of main repo
    let parent = main_repo.parent().ok_or_else(|| {
        Autom8Error::WorktreeError("Could not determine repository parent directory".to_string())
    })?;

    Ok(parent.join(worktree_name))
}

/// Result of ensuring a worktree exists.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum WorktreeResult {
    /// A new worktree was created at this path
    Created(PathBuf),
    /// An existing worktree was found and reused at this path
    Reused(PathBuf),
}

impl WorktreeResult {
    /// Get the path regardless of whether it was created or reused.
    pub fn path(&self) -> &Path {
        match self {
            WorktreeResult::Created(p) | WorktreeResult::Reused(p) => p,
        }
    }

    /// Returns true if the worktree was newly created.
    pub fn was_created(&self) -> bool {
        matches!(self, WorktreeResult::Created(_))
    }
}

/// Ensure a worktree exists for the specified branch.
///
/// If a worktree already exists for this branch, it is reused.
/// Otherwise, a new worktree is created.
///
/// # Arguments
/// * `pattern` - The path pattern for the worktree name
/// * `branch_name` - The branch to use for the worktree
///
/// # Returns
/// * `Ok(WorktreeResult::Created(path))` - A new worktree was created
/// * `Ok(WorktreeResult::Reused(path))` - An existing worktree was found
/// * `Err` - If worktree creation fails
pub fn ensure_worktree(pattern: &str, branch_name: &str) -> Result<WorktreeResult> {
    let target_path = generate_worktree_path(pattern, branch_name)?;

    // Check if a worktree already exists at this path or for this branch
    let worktrees = list_worktrees()?;
    for wt in &worktrees {
        // Check if there's a worktree at our target path
        if wt.path == target_path {
            // Verify it has the right branch
            if let Some(ref wt_branch) = wt.branch {
                if wt_branch == branch_name {
                    return Ok(WorktreeResult::Reused(target_path));
                }
            }
            // Path exists but with wrong branch - this is a conflict
            return Err(Autom8Error::WorktreeError(format!(
                "Worktree at '{}' exists but uses branch '{}', not '{}'",
                target_path.display(),
                wt.branch.as_deref().unwrap_or("(detached)"),
                branch_name
            )));
        }

        // Check if there's already a worktree for this branch at a different path
        if let Some(ref wt_branch) = wt.branch {
            if wt_branch == branch_name && !wt.is_main {
                // Branch is already checked out in a worktree - reuse it
                return Ok(WorktreeResult::Reused(wt.path.clone()));
            }
        }
    }

    // No existing worktree found - create a new one
    create_worktree(&target_path, branch_name)?;
    Ok(WorktreeResult::Created(target_path))
}

/// Get detailed information about worktree creation failure.
///
/// Provides suggestions for how to resolve common worktree creation issues.
/// Error messages follow the pattern: what happened → why → how to fix.
///
/// # Arguments
/// * `error` - The error message from the failed git command
/// * `branch_name` - The branch that was being created
/// * `worktree_path` - The path where the worktree was being created
///
/// # Returns
/// A user-friendly error message with suggestions.
pub fn format_worktree_error(error: &str, branch_name: &str, worktree_path: &Path) -> String {
    let mut message = format!(
        "Failed to create worktree for branch '{}' at '{}'.\n\n",
        branch_name,
        worktree_path.display()
    );

    // Analyze the error and provide specific suggestions
    if error.contains("already checked out") {
        message.push_str("Reason: Branch is already checked out in another worktree.\n\n");
        message.push_str("To resolve this, try one of the following:\n");
        message.push_str("  1. Use a different branch name in your spec\n");
        message.push_str("  2. Run `git worktree list` to see existing worktrees\n");
        message
            .push_str("  3. Remove the conflicting worktree with `git worktree remove <path>`\n");
        message.push_str("\nManual worktree creation steps:\n");
        message.push_str(&format!(
            "  git worktree add -b {} '{}'\n",
            branch_name,
            worktree_path.display()
        ));
    } else if error.contains("already exists") {
        message.push_str("Reason: A directory or worktree already exists at this path.\n\n");
        message.push_str("To resolve this, try one of the following:\n");
        message.push_str(&format!(
            "  1. Remove the existing directory: rm -rf '{}'\n",
            worktree_path.display()
        ));
        message.push_str("  2. Use a different branch name in your spec\n");
        message.push_str("  3. Configure a different worktree_path_pattern in config\n");
        message.push_str("\nManual worktree creation steps (after removing existing):\n");
        message.push_str(&format!(
            "  git worktree add '{}' {}\n",
            worktree_path.display(),
            branch_name
        ));
    } else if error.contains("permission denied") || error.contains("Permission denied") {
        message.push_str("Reason: Insufficient permissions to create the worktree directory.\n\n");
        message.push_str("To resolve this, try one of the following:\n");
        message.push_str(&format!(
            "  1. Check write permissions on: {}\n",
            worktree_path
                .parent()
                .map(|p| p.display().to_string())
                .unwrap_or_else(|| "parent directory".to_string())
        ));
        message.push_str("  2. Run with appropriate permissions (e.g., sudo if needed)\n");
        message
            .push_str("  3. Choose a different location in your config's worktree_path_pattern\n");
    } else {
        message.push_str(&format!("Error: {}\n\n", error));
        message.push_str("To resolve this, try one of the following:\n");
        message.push_str("  1. Ensure you're in a git repository\n");
        message.push_str("  2. Run `git worktree list` to check current worktrees\n");
        message.push_str("  3. Check git configuration and permissions\n");
        message.push_str("\nManual worktree creation steps:\n");
        message.push_str(&format!(
            "  git worktree add '{}' {}\n",
            worktree_path.display(),
            branch_name
        ));
    }

    message
}

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

    // ========================================================================
    // Porcelain parsing tests - these test actual parsing logic
    // ========================================================================

    #[test]
    fn test_parse_porcelain_single_worktree() {
        let output = "worktree /home/user/project\nHEAD abc1234567890abcdef1234567890abcdef12345678\nbranch refs/heads/main\n\n";

        let worktrees = parse_worktree_list_porcelain(output).unwrap();
        assert_eq!(worktrees.len(), 1);

        let wt = &worktrees[0];
        assert_eq!(wt.path, PathBuf::from("/home/user/project"));
        assert_eq!(wt.branch, Some("main".to_string()));
        assert_eq!(wt.commit, "abc1234567890abcdef1234567890abcdef12345678");
        assert!(wt.is_main);
        assert!(!wt.is_bare);
    }

    #[test]
    fn test_parse_porcelain_multiple_worktrees() {
        let output = concat!(
            "worktree /home/user/project\n",
            "HEAD abc1234567890abcdef1234567890abcdef12345678\n",
            "branch refs/heads/main\n",
            "\n",
            "worktree /home/user/project-feature\n",
            "HEAD def5678901234abcdef5678901234abcdef56789012\n",
            "branch refs/heads/feature/test\n",
            "\n"
        );

        let worktrees = parse_worktree_list_porcelain(output).unwrap();
        assert_eq!(worktrees.len(), 2);

        assert!(worktrees[0].is_main);
        assert_eq!(worktrees[0].branch, Some("main".to_string()));
        assert!(!worktrees[1].is_main);
        assert_eq!(worktrees[1].branch, Some("feature/test".to_string()));
    }

    #[test]
    fn test_parse_porcelain_special_states() {
        // Detached HEAD
        let output = "worktree /path\nHEAD abc123\ndetached\n\n";
        let wt = &parse_worktree_list_porcelain(output).unwrap()[0];
        assert!(wt.branch.is_none());

        // Bare repo
        let output = "worktree /path.git\nHEAD abc123\nbare\n\n";
        let wt = &parse_worktree_list_porcelain(output).unwrap()[0];
        assert!(wt.is_bare);

        // Locked
        let output = "worktree /path\nHEAD abc123\nbranch refs/heads/main\nlocked\n\n";
        let wt = &parse_worktree_list_porcelain(output).unwrap()[0];
        assert!(wt.is_locked);

        // Prunable
        let output = "worktree /path\nHEAD abc123\nbranch refs/heads/main\nprunable\n\n";
        let wt = &parse_worktree_list_porcelain(output).unwrap()[0];
        assert!(wt.is_prunable);
    }

    #[test]
    fn test_parse_porcelain_edge_cases() {
        // No trailing newline
        let output = "worktree /path\nHEAD abc123\nbranch refs/heads/main";
        assert_eq!(parse_worktree_list_porcelain(output).unwrap().len(), 1);

        // Empty output
        assert!(parse_worktree_list_porcelain("").unwrap().is_empty());

        // Path with spaces
        let output = "worktree /home/user/my project/repo\nHEAD abc123\nbranch refs/heads/main\n\n";
        assert_eq!(
            parse_worktree_list_porcelain(output).unwrap()[0].path,
            PathBuf::from("/home/user/my project/repo")
        );
    }

    #[test]
    fn test_from_porcelain_lines_missing_required_fields() {
        // Missing path
        assert!(
            WorktreeInfo::from_porcelain_lines(&["HEAD abc123", "branch refs/heads/main"])
                .is_none()
        );
        // Missing commit
        assert!(
            WorktreeInfo::from_porcelain_lines(&["worktree /path", "branch refs/heads/main"])
                .is_none()
        );
    }

    // ========================================================================
    // Session ID tests - test determinism and uniqueness
    // ========================================================================

    #[test]
    fn test_generate_session_id_properties() {
        let path = Path::new("/home/user/project-feature");
        let id = generate_session_id(path);

        // 8 hex characters
        assert_eq!(id.len(), 8);
        assert!(id.chars().all(|c| c.is_ascii_hexdigit()));

        // Deterministic
        assert_eq!(id, generate_session_id(path));

        // Different paths produce different IDs
        let id2 = generate_session_id(Path::new("/home/user/other-project"));
        assert_ne!(id, id2);
    }

    #[test]
    fn test_generate_session_id_uniqueness() {
        let paths = [
            "/home/user/project1",
            "/home/user/project2",
            "/tmp/worktree-a",
            "/tmp/worktree-b",
        ];

        let ids: Vec<String> = paths
            .iter()
            .map(|p| generate_session_id(Path::new(p)))
            .collect();

        let unique_ids: std::collections::HashSet<_> = ids.iter().collect();
        assert_eq!(ids.len(), unique_ids.len());
    }

    #[test]
    fn test_main_session_id() {
        assert_eq!(MAIN_SESSION_ID, "main");
        assert_eq!(get_main_session_id(), "main");
    }

    // ========================================================================
    // Branch name slugification tests
    // ========================================================================

    #[test]
    fn test_slugify_branch_name() {
        assert_eq!(slugify_branch_name("feature/login"), "feature-login");
        assert_eq!(
            slugify_branch_name("feature/user/auth"),
            "feature-user-auth"
        );
        assert_eq!(slugify_branch_name("main"), "main");
        assert_eq!(slugify_branch_name("v1.0.0"), "v1.0.0");
        assert_eq!(slugify_branch_name("feature//login"), "feature-login"); // collapses multiple
        assert_eq!(slugify_branch_name("feature@login"), "feature-login"); // removes special chars
    }

    #[test]
    fn test_generate_worktree_name() {
        assert_eq!(
            generate_worktree_name("{repo}-wt-{branch}", "myproject", "feature/login"),
            "myproject-wt-feature-login"
        );
        assert_eq!(
            generate_worktree_name("{repo}_worktree_{branch}", "myproject", "main"),
            "myproject_worktree_main"
        );
    }

    // ========================================================================
    // WorktreeResult tests
    // ========================================================================

    #[test]
    fn test_worktree_result() {
        let path = PathBuf::from("/test/path");
        let created = WorktreeResult::Created(path.clone());
        let reused = WorktreeResult::Reused(path.clone());

        assert_eq!(created.path(), &path);
        assert_eq!(reused.path(), &path);
        assert!(created.was_created());
        assert!(!reused.was_created());
    }

    // ========================================================================
    // Error formatting tests
    // ========================================================================

    #[test]
    fn test_format_worktree_error_messages() {
        // Already checked out
        let msg = format_worktree_error(
            "fatal: branch 'main' is already checked out",
            "main",
            Path::new("/new/worktree"),
        );
        assert!(msg.contains("already checked out"));
        assert!(msg.contains("To resolve"));
        assert!(msg.contains("git worktree"));

        // Already exists
        let msg = format_worktree_error(
            "fatal: already exists",
            "feature",
            Path::new("/new/worktree"),
        );
        assert!(msg.contains("already exists"));
        assert!(msg.contains("after removing existing"));

        // Permission denied
        let msg = format_worktree_error(
            "error: permission denied",
            "feature",
            Path::new("/restricted"),
        );
        assert!(msg.contains("permissions"));

        // Generic error includes manual steps
        let msg = format_worktree_error("unknown error", "feature/login", Path::new("/path/to/wt"));
        assert!(msg.contains("Manual worktree creation"));
        assert!(msg.contains("feature/login"));
    }
}