purple_ssh/

containers.rs

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::time::{SystemTime, UNIX_EPOCH};

use serde::{Deserialize, Serialize};

// ---------------------------------------------------------------------------
// ContainerInfo model
// ---------------------------------------------------------------------------

/// Metadata for a single container (from `docker ps -a` / `podman ps -a`).
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct ContainerInfo {
    #[serde(rename = "ID")]
    pub id: String,
    #[serde(rename = "Names")]
    pub names: String,
    #[serde(rename = "Image")]
    pub image: String,
    #[serde(rename = "State")]
    pub state: String,
    #[serde(rename = "Status")]
    pub status: String,
    #[serde(rename = "Ports")]
    pub ports: String,
}

/// Parse NDJSON output from `docker ps --format '{{json .}}'`.
/// Invalid lines are silently ignored (MOTD lines, blank lines, etc.).
pub fn parse_container_ps(output: &str) -> Vec<ContainerInfo> {
    output
        .lines()
        .filter_map(|line| {
            let trimmed = line.trim();
            if trimmed.is_empty() {
                return None;
            }
            serde_json::from_str(trimmed).ok()
        })
        .collect()
}

// ---------------------------------------------------------------------------
// ContainerRuntime
// ---------------------------------------------------------------------------

/// Supported container runtimes.
#[derive(Copy, Clone, Debug, PartialEq, Serialize, Deserialize)]
pub enum ContainerRuntime {
    Docker,
    Podman,
}

impl ContainerRuntime {
    /// Returns the CLI binary name.
    pub fn as_str(&self) -> &'static str {
        match self {
            ContainerRuntime::Docker => "docker",
            ContainerRuntime::Podman => "podman",
        }
    }
}

/// Detect runtime from command output by matching the LAST non-empty trimmed
/// line. Only "docker" or "podman" are accepted. MOTD-resilient.
/// Currently unused (sentinel-based detection handles this inline) but kept
/// as a public utility for potential future two-step detection paths.
#[allow(dead_code)]
pub fn parse_runtime(output: &str) -> Option<ContainerRuntime> {
    let last = output
        .lines()
        .rev()
        .map(|l| l.trim())
        .find(|l| !l.is_empty())?;
    match last {
        "docker" => Some(ContainerRuntime::Docker),
        "podman" => Some(ContainerRuntime::Podman),
        _ => None,
    }
}

// ---------------------------------------------------------------------------
// ContainerAction
// ---------------------------------------------------------------------------

/// Actions that can be performed on a container.
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum ContainerAction {
    Start,
    Stop,
    Restart,
}

impl ContainerAction {
    /// Returns the CLI sub-command string.
    pub fn as_str(&self) -> &'static str {
        match self {
            ContainerAction::Start => "start",
            ContainerAction::Stop => "stop",
            ContainerAction::Restart => "restart",
        }
    }
}

/// Build the shell command to perform an action on a container.
pub fn container_action_command(
    runtime: ContainerRuntime,
    action: ContainerAction,
    container_id: &str,
) -> String {
    format!("{} {} {}", runtime.as_str(), action.as_str(), container_id)
}

// ---------------------------------------------------------------------------
// Container ID validation
// ---------------------------------------------------------------------------

/// Validate a container ID or name.
/// Accepts ASCII alphanumeric, hyphen, underscore, dot.
/// Rejects empty, non-ASCII, shell metacharacters, colon.
pub fn validate_container_id(id: &str) -> Result<(), String> {
    if id.is_empty() {
        return Err("Container ID must not be empty.".to_string());
    }
    for c in id.chars() {
        if !c.is_ascii_alphanumeric() && c != '-' && c != '_' && c != '.' {
            return Err(format!("Container ID contains invalid character: '{c}'"));
        }
    }
    Ok(())
}

// ---------------------------------------------------------------------------
// Combined SSH command + output parsing
// ---------------------------------------------------------------------------

/// Build the SSH command string for listing containers.
///
/// - `Some(Docker)` / `Some(Podman)`: direct listing for the known runtime.
/// - `None`: combined detection + listing with sentinel markers in one SSH call.
pub fn container_list_command(runtime: Option<ContainerRuntime>) -> String {
    match runtime {
        Some(ContainerRuntime::Docker) => "docker ps -a --format '{{json .}}'".to_string(),
        Some(ContainerRuntime::Podman) => "podman ps -a --format '{{json .}}'".to_string(),
        None => concat!(
            "if command -v docker >/dev/null 2>&1; then ",
            "echo '##purple:docker##' && docker ps -a --format '{{json .}}'; ",
            "elif command -v podman >/dev/null 2>&1; then ",
            "echo '##purple:podman##' && podman ps -a --format '{{json .}}'; ",
            "else echo '##purple:none##'; fi"
        )
        .to_string(),
    }
}

/// Parse the stdout of a container listing command.
///
/// When sentinels are present (combined detection run): extract runtime from
/// the sentinel line, parse remaining lines as NDJSON. When `caller_runtime`
/// is provided (subsequent run with known runtime): parse all lines as NDJSON.
pub fn parse_container_output(
    output: &str,
    caller_runtime: Option<ContainerRuntime>,
) -> Result<(ContainerRuntime, Vec<ContainerInfo>), String> {
    if let Some(sentinel_line) = output.lines().find(|l| l.trim().starts_with("##purple:")) {
        let sentinel = sentinel_line.trim();
        if sentinel == "##purple:none##" {
            return Err("No container runtime found. Install Docker or Podman.".to_string());
        }
        let runtime = if sentinel == "##purple:docker##" {
            ContainerRuntime::Docker
        } else if sentinel == "##purple:podman##" {
            ContainerRuntime::Podman
        } else {
            return Err(format!("Unknown sentinel: {sentinel}"));
        };
        let containers: Vec<ContainerInfo> = output
            .lines()
            .filter(|l| !l.trim().starts_with("##purple:"))
            .filter_map(|line| {
                let t = line.trim();
                if t.is_empty() {
                    return None;
                }
                serde_json::from_str(t).ok()
            })
            .collect();
        return Ok((runtime, containers));
    }

    match caller_runtime {
        Some(rt) => Ok((rt, parse_container_ps(output))),
        None => Err("No sentinel found and no runtime provided.".to_string()),
    }
}

// ---------------------------------------------------------------------------
// SSH fetch functions
// ---------------------------------------------------------------------------

/// Error from a container listing operation. Preserves the detected runtime
/// even when the `ps` command fails so it can be cached for future calls.
#[derive(Debug)]
pub struct ContainerError {
    pub runtime: Option<ContainerRuntime>,
    pub message: String,
}

impl std::fmt::Display for ContainerError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.message)
    }
}

/// Translate SSH stderr into a user-friendly error message.
fn friendly_container_error(stderr: &str, code: Option<i32>) -> String {
    let lower = stderr.to_lowercase();
    if lower.contains("command not found") {
        "Docker or Podman not found on remote host.".to_string()
    } else if lower.contains("permission denied") || lower.contains("got permission denied") {
        "Permission denied. Is your user in the docker group?".to_string()
    } else if lower.contains("cannot connect to the docker daemon")
        || lower.contains("cannot connect to podman")
    {
        "Container daemon is not running.".to_string()
    } else if lower.contains("connection refused") {
        "Connection refused.".to_string()
    } else if lower.contains("no route to host") || lower.contains("network is unreachable") {
        "Host unreachable.".to_string()
    } else {
        format!("Command failed with code {}.", code.unwrap_or(1))
    }
}

/// Fetch container list synchronously via SSH.
/// Follows the `fetch_remote_listing` pattern.
#[allow(clippy::too_many_arguments)]
pub fn fetch_containers(
    alias: &str,
    config_path: &Path,
    askpass: Option<&str>,
    bw_session: Option<&str>,
    has_tunnel: bool,
    cached_runtime: Option<ContainerRuntime>,
) -> Result<(ContainerRuntime, Vec<ContainerInfo>), ContainerError> {
    let command = container_list_command(cached_runtime);
    let result = crate::snippet::run_snippet(
        alias,
        config_path,
        &command,
        askpass,
        bw_session,
        true,
        has_tunnel,
    );
    match result {
        Ok(r) if r.status.success() => {
            parse_container_output(&r.stdout, cached_runtime).map_err(|e| ContainerError {
                runtime: cached_runtime,
                message: e,
            })
        }
        Ok(r) => {
            let stderr = r.stderr.trim().to_string();
            let msg = friendly_container_error(&stderr, r.status.code());
            Err(ContainerError {
                runtime: cached_runtime,
                message: msg,
            })
        }
        Err(e) => Err(ContainerError {
            runtime: cached_runtime,
            message: e.to_string(),
        }),
    }
}

/// Spawn a background thread to fetch container listings.
/// Follows the `spawn_remote_listing` pattern.
#[allow(clippy::too_many_arguments)]
pub fn spawn_container_listing<F>(
    alias: String,
    config_path: PathBuf,
    askpass: Option<String>,
    bw_session: Option<String>,
    has_tunnel: bool,
    cached_runtime: Option<ContainerRuntime>,
    send: F,
) where
    F: FnOnce(String, Result<(ContainerRuntime, Vec<ContainerInfo>), ContainerError>)
        + Send
        + 'static,
{
    std::thread::spawn(move || {
        let result = fetch_containers(
            &alias,
            &config_path,
            askpass.as_deref(),
            bw_session.as_deref(),
            has_tunnel,
            cached_runtime,
        );
        send(alias, result);
    });
}

/// Spawn a background thread to perform a container action (start/stop/restart).
/// Validates the container ID before executing.
#[allow(clippy::too_many_arguments)]
pub fn spawn_container_action<F>(
    alias: String,
    config_path: PathBuf,
    runtime: ContainerRuntime,
    action: ContainerAction,
    container_id: String,
    askpass: Option<String>,
    bw_session: Option<String>,
    has_tunnel: bool,
    send: F,
) where
    F: FnOnce(String, ContainerAction, Result<(), String>) + Send + 'static,
{
    std::thread::spawn(move || {
        if let Err(e) = validate_container_id(&container_id) {
            send(alias, action, Err(e));
            return;
        }
        let command = container_action_command(runtime, action, &container_id);
        let result = crate::snippet::run_snippet(
            &alias,
            &config_path,
            &command,
            askpass.as_deref(),
            bw_session.as_deref(),
            true,
            has_tunnel,
        );
        match result {
            Ok(r) if r.status.success() => send(alias, action, Ok(())),
            Ok(r) => {
                let msg = friendly_container_error(r.stderr.trim(), r.status.code());
                send(alias, action, Err(msg));
            }
            Err(e) => send(alias, action, Err(e.to_string())),
        }
    });
}

// ---------------------------------------------------------------------------
// JSON lines cache
// ---------------------------------------------------------------------------

/// A cached container listing for a single host.
#[derive(Debug, Clone)]
pub struct ContainerCacheEntry {
    pub timestamp: u64,
    pub runtime: ContainerRuntime,
    pub containers: Vec<ContainerInfo>,
}

/// Serde helper for a single JSON line in the cache file.
#[derive(Serialize, Deserialize)]
struct CacheLine {
    alias: String,
    timestamp: u64,
    runtime: ContainerRuntime,
    containers: Vec<ContainerInfo>,
}

/// Load container cache from `~/.purple/container_cache.jsonl`.
/// Malformed lines are silently ignored. Duplicate aliases: last-write-wins.
pub fn load_container_cache() -> HashMap<String, ContainerCacheEntry> {
    let mut map = HashMap::new();
    let Some(home) = dirs::home_dir() else {
        return map;
    };
    let path = home.join(".purple").join("container_cache.jsonl");
    let Ok(content) = std::fs::read_to_string(&path) else {
        return map;
    };
    for line in content.lines() {
        let trimmed = line.trim();
        if trimmed.is_empty() {
            continue;
        }
        if let Ok(entry) = serde_json::from_str::<CacheLine>(trimmed) {
            map.insert(
                entry.alias,
                ContainerCacheEntry {
                    timestamp: entry.timestamp,
                    runtime: entry.runtime,
                    containers: entry.containers,
                },
            );
        }
    }
    map
}

/// Save container cache to `~/.purple/container_cache.jsonl` via atomic write.
pub fn save_container_cache(cache: &HashMap<String, ContainerCacheEntry>) {
    let Some(home) = dirs::home_dir() else {
        return;
    };
    let path = home.join(".purple").join("container_cache.jsonl");
    let mut lines = Vec::with_capacity(cache.len());
    for (alias, entry) in cache {
        let line = CacheLine {
            alias: alias.clone(),
            timestamp: entry.timestamp,
            runtime: entry.runtime,
            containers: entry.containers.clone(),
        };
        if let Ok(s) = serde_json::to_string(&line) {
            lines.push(s);
        }
    }
    let content = lines.join("\n");
    let _ = crate::fs_util::atomic_write(&path, content.as_bytes());
}

// ---------------------------------------------------------------------------
// String truncation
// ---------------------------------------------------------------------------

/// Truncate a string to at most `max` characters. Appends ".." if truncated.
pub fn truncate_str(s: &str, max: usize) -> String {
    let count = s.chars().count();
    if count <= max {
        s.to_string()
    } else {
        let cut = max.saturating_sub(2);
        let end = s.char_indices().nth(cut).map(|(i, _)| i).unwrap_or(s.len());
        format!("{}..", &s[..end])
    }
}

// ---------------------------------------------------------------------------
// Relative time
// ---------------------------------------------------------------------------

/// Format a Unix timestamp as a human-readable relative time string.
pub fn format_relative_time(timestamp: u64) -> String {
    let now = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap_or_default()
        .as_secs();
    let diff = now.saturating_sub(timestamp);
    if diff < 60 {
        "just now".to_string()
    } else if diff < 3600 {
        format!("{}m ago", diff / 60)
    } else if diff < 86400 {
        format!("{}h ago", diff / 3600)
    } else {
        format!("{}d ago", diff / 86400)
    }
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

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

    fn make_json(
        id: &str,
        names: &str,
        image: &str,
        state: &str,
        status: &str,
        ports: &str,
    ) -> String {
        serde_json::json!({
            "ID": id,
            "Names": names,
            "Image": image,
            "State": state,
            "Status": status,
            "Ports": ports,
        })
        .to_string()
    }

    // -- parse_container_ps --------------------------------------------------

    #[test]
    fn parse_ps_empty() {
        assert!(parse_container_ps("").is_empty());
        assert!(parse_container_ps("   \n  \n").is_empty());
    }

    #[test]
    fn parse_ps_single() {
        let line = make_json("abc", "web", "nginx:latest", "running", "Up 2h", "80/tcp");
        let r = parse_container_ps(&line);
        assert_eq!(r.len(), 1);
        assert_eq!(r[0].id, "abc");
        assert_eq!(r[0].names, "web");
        assert_eq!(r[0].image, "nginx:latest");
        assert_eq!(r[0].state, "running");
    }

    #[test]
    fn parse_ps_multiple() {
        let lines = [
            make_json("a", "web", "nginx", "running", "Up", "80/tcp"),
            make_json("b", "db", "postgres", "exited", "Exited (0)", ""),
        ];
        let r = parse_container_ps(&lines.join("\n"));
        assert_eq!(r.len(), 2);
    }

    #[test]
    fn parse_ps_invalid_lines_ignored() {
        let valid = make_json("x", "c", "i", "running", "Up", "");
        let input = format!("garbage\n{valid}\nalso bad");
        assert_eq!(parse_container_ps(&input).len(), 1);
    }

    #[test]
    fn parse_ps_all_docker_states() {
        for state in [
            "created",
            "restarting",
            "running",
            "removing",
            "paused",
            "exited",
            "dead",
        ] {
            let line = make_json("id", "c", "img", state, "s", "");
            let r = parse_container_ps(&line);
            assert_eq!(r[0].state, state, "failed for {state}");
        }
    }

    #[test]
    fn parse_ps_compose_names() {
        let line = make_json("a", "myproject-redis-1", "redis:7", "running", "Up", "");
        assert_eq!(parse_container_ps(&line)[0].names, "myproject-redis-1");
    }

    #[test]
    fn parse_ps_sha256_image() {
        let line = make_json("a", "app", "sha256:abcdef123456", "running", "Up", "");
        assert!(parse_container_ps(&line)[0].image.starts_with("sha256:"));
    }

    #[test]
    fn parse_ps_long_ports() {
        let ports = "0.0.0.0:80->80/tcp, 0.0.0.0:443->443/tcp, :::80->80/tcp";
        let line = make_json("a", "proxy", "nginx", "running", "Up", ports);
        assert_eq!(parse_container_ps(&line)[0].ports, ports);
    }

    // -- parse_runtime -------------------------------------------------------

    #[test]
    fn runtime_docker() {
        assert_eq!(parse_runtime("docker"), Some(ContainerRuntime::Docker));
    }

    #[test]
    fn runtime_podman() {
        assert_eq!(parse_runtime("podman"), Some(ContainerRuntime::Podman));
    }

    #[test]
    fn runtime_none() {
        assert_eq!(parse_runtime(""), None);
        assert_eq!(parse_runtime("   "), None);
        assert_eq!(parse_runtime("unknown"), None);
        assert_eq!(parse_runtime("Docker"), None); // case sensitive
    }

    #[test]
    fn runtime_motd_prepended() {
        let input = "Welcome to Ubuntu 22.04\nSystem info\ndocker";
        assert_eq!(parse_runtime(input), Some(ContainerRuntime::Docker));
    }

    #[test]
    fn runtime_trailing_whitespace() {
        assert_eq!(parse_runtime("docker  "), Some(ContainerRuntime::Docker));
        assert_eq!(parse_runtime("podman\t"), Some(ContainerRuntime::Podman));
    }

    #[test]
    fn runtime_motd_after_output() {
        let input = "docker\nSystem update available.";
        // Last non-empty line is "System update available." which is not a runtime
        assert_eq!(parse_runtime(input), None);
    }

    // -- ContainerAction x ContainerRuntime ----------------------------------

    #[test]
    fn action_command_all_combinations() {
        let cases = [
            (
                ContainerRuntime::Docker,
                ContainerAction::Start,
                "docker start c1",
            ),
            (
                ContainerRuntime::Docker,
                ContainerAction::Stop,
                "docker stop c1",
            ),
            (
                ContainerRuntime::Docker,
                ContainerAction::Restart,
                "docker restart c1",
            ),
            (
                ContainerRuntime::Podman,
                ContainerAction::Start,
                "podman start c1",
            ),
            (
                ContainerRuntime::Podman,
                ContainerAction::Stop,
                "podman stop c1",
            ),
            (
                ContainerRuntime::Podman,
                ContainerAction::Restart,
                "podman restart c1",
            ),
        ];
        for (rt, action, expected) in cases {
            assert_eq!(container_action_command(rt, action, "c1"), expected);
        }
    }

    #[test]
    fn action_as_str() {
        assert_eq!(ContainerAction::Start.as_str(), "start");
        assert_eq!(ContainerAction::Stop.as_str(), "stop");
        assert_eq!(ContainerAction::Restart.as_str(), "restart");
    }

    #[test]
    fn runtime_as_str() {
        assert_eq!(ContainerRuntime::Docker.as_str(), "docker");
        assert_eq!(ContainerRuntime::Podman.as_str(), "podman");
    }

    // -- validate_container_id -----------------------------------------------

    #[test]
    fn id_valid_hex() {
        assert!(validate_container_id("a1b2c3d4e5f6").is_ok());
    }

    #[test]
    fn id_valid_names() {
        assert!(validate_container_id("myapp").is_ok());
        assert!(validate_container_id("my-app").is_ok());
        assert!(validate_container_id("my_app").is_ok());
        assert!(validate_container_id("my.app").is_ok());
        assert!(validate_container_id("myproject-web-1").is_ok());
    }

    #[test]
    fn id_empty() {
        assert!(validate_container_id("").is_err());
    }

    #[test]
    fn id_space() {
        assert!(validate_container_id("my app").is_err());
    }

    #[test]
    fn id_newline() {
        assert!(validate_container_id("app\n").is_err());
    }

    #[test]
    fn id_injection_semicolon() {
        assert!(validate_container_id("app;rm -rf /").is_err());
    }

    #[test]
    fn id_injection_pipe() {
        assert!(validate_container_id("app|cat /etc/passwd").is_err());
    }

    #[test]
    fn id_injection_dollar() {
        assert!(validate_container_id("app$HOME").is_err());
    }

    #[test]
    fn id_injection_backtick() {
        assert!(validate_container_id("app`whoami`").is_err());
    }

    #[test]
    fn id_unicode_rejected() {
        assert!(validate_container_id("app\u{00e9}").is_err());
        assert!(validate_container_id("\u{0430}pp").is_err()); // Cyrillic а
    }

    #[test]
    fn id_colon_rejected() {
        assert!(validate_container_id("app:latest").is_err());
    }

    // -- container_list_command ----------------------------------------------

    #[test]
    fn list_cmd_docker() {
        assert_eq!(
            container_list_command(Some(ContainerRuntime::Docker)),
            "docker ps -a --format '{{json .}}'"
        );
    }

    #[test]
    fn list_cmd_podman() {
        assert_eq!(
            container_list_command(Some(ContainerRuntime::Podman)),
            "podman ps -a --format '{{json .}}'"
        );
    }

    #[test]
    fn list_cmd_none_has_sentinels() {
        let cmd = container_list_command(None);
        assert!(cmd.contains("##purple:docker##"));
        assert!(cmd.contains("##purple:podman##"));
        assert!(cmd.contains("##purple:none##"));
    }

    #[test]
    fn list_cmd_none_docker_first() {
        let cmd = container_list_command(None);
        let d = cmd.find("##purple:docker##").unwrap();
        let p = cmd.find("##purple:podman##").unwrap();
        assert!(d < p);
    }

    // -- parse_container_output ----------------------------------------------

    #[test]
    fn output_docker_sentinel() {
        let c = make_json("abc", "web", "nginx", "running", "Up", "80/tcp");
        let out = format!("##purple:docker##\n{c}");
        let (rt, cs) = parse_container_output(&out, None).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert_eq!(cs.len(), 1);
    }

    #[test]
    fn output_podman_sentinel() {
        let c = make_json("xyz", "db", "pg", "exited", "Exited", "");
        let out = format!("##purple:podman##\n{c}");
        let (rt, _) = parse_container_output(&out, None).unwrap();
        assert_eq!(rt, ContainerRuntime::Podman);
    }

    #[test]
    fn output_none_sentinel() {
        let r = parse_container_output("##purple:none##", None);
        assert!(r.is_err());
        assert!(r.unwrap_err().contains("No container runtime"));
    }

    #[test]
    fn output_no_sentinel_with_caller() {
        let c = make_json("a", "app", "img", "running", "Up", "");
        let (rt, cs) = parse_container_output(&c, Some(ContainerRuntime::Docker)).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert_eq!(cs.len(), 1);
    }

    #[test]
    fn output_no_sentinel_no_caller() {
        let c = make_json("a", "app", "img", "running", "Up", "");
        assert!(parse_container_output(&c, None).is_err());
    }

    #[test]
    fn output_motd_before_sentinel() {
        let c = make_json("a", "app", "img", "running", "Up", "");
        let out = format!("Welcome to server\nInfo line\n##purple:docker##\n{c}");
        let (rt, cs) = parse_container_output(&out, None).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert_eq!(cs.len(), 1);
    }

    #[test]
    fn output_empty_container_list() {
        let (rt, cs) = parse_container_output("##purple:docker##\n", None).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert!(cs.is_empty());
    }

    #[test]
    fn output_multiple_containers() {
        let c1 = make_json("a", "web", "nginx", "running", "Up", "80/tcp");
        let c2 = make_json("b", "db", "pg", "exited", "Exited", "");
        let c3 = make_json("c", "cache", "redis", "running", "Up", "6379/tcp");
        let out = format!("##purple:podman##\n{c1}\n{c2}\n{c3}");
        let (_, cs) = parse_container_output(&out, None).unwrap();
        assert_eq!(cs.len(), 3);
    }

    // -- friendly_container_error --------------------------------------------

    #[test]
    fn friendly_error_command_not_found() {
        let msg = friendly_container_error("bash: docker: command not found", Some(127));
        assert_eq!(msg, "Docker or Podman not found on remote host.");
    }

    #[test]
    fn friendly_error_permission_denied() {
        let msg = friendly_container_error(
            "Got permission denied while trying to connect to the Docker daemon socket",
            Some(1),
        );
        assert_eq!(msg, "Permission denied. Is your user in the docker group?");
    }

    #[test]
    fn friendly_error_daemon_not_running() {
        let msg = friendly_container_error(
            "Cannot connect to the Docker daemon at unix:///var/run/docker.sock",
            Some(1),
        );
        assert_eq!(msg, "Container daemon is not running.");
    }

    #[test]
    fn friendly_error_connection_refused() {
        let msg = friendly_container_error("ssh: connect to host: Connection refused", Some(255));
        assert_eq!(msg, "Connection refused.");
    }

    #[test]
    fn friendly_error_empty_stderr() {
        let msg = friendly_container_error("", Some(1));
        assert_eq!(msg, "Command failed with code 1.");
    }

    #[test]
    fn friendly_error_unknown_stderr_uses_generic_message() {
        let msg = friendly_container_error("some unknown error", Some(1));
        assert_eq!(msg, "Command failed with code 1.");
    }

    // -- cache serialization -------------------------------------------------

    #[test]
    fn cache_round_trip() {
        let line = CacheLine {
            alias: "web1".to_string(),
            timestamp: 1_700_000_000,
            runtime: ContainerRuntime::Docker,
            containers: vec![ContainerInfo {
                id: "abc".to_string(),
                names: "nginx".to_string(),
                image: "nginx:latest".to_string(),
                state: "running".to_string(),
                status: "Up 2h".to_string(),
                ports: "80/tcp".to_string(),
            }],
        };
        let s = serde_json::to_string(&line).unwrap();
        let d: CacheLine = serde_json::from_str(&s).unwrap();
        assert_eq!(d.alias, "web1");
        assert_eq!(d.runtime, ContainerRuntime::Docker);
        assert_eq!(d.containers.len(), 1);
        assert_eq!(d.containers[0].id, "abc");
    }

    #[test]
    fn cache_round_trip_podman() {
        let line = CacheLine {
            alias: "host2".to_string(),
            timestamp: 200,
            runtime: ContainerRuntime::Podman,
            containers: vec![],
        };
        let s = serde_json::to_string(&line).unwrap();
        let d: CacheLine = serde_json::from_str(&s).unwrap();
        assert_eq!(d.runtime, ContainerRuntime::Podman);
    }

    #[test]
    fn cache_parse_empty() {
        let map: HashMap<String, ContainerCacheEntry> =
            "".lines().filter_map(parse_cache_line).collect();
        assert!(map.is_empty());
    }

    #[test]
    fn cache_parse_malformed_ignored() {
        let valid = serde_json::to_string(&CacheLine {
            alias: "good".to_string(),
            timestamp: 1,
            runtime: ContainerRuntime::Docker,
            containers: vec![],
        })
        .unwrap();
        let content = format!("garbage\n{valid}\nalso bad");
        let map: HashMap<String, ContainerCacheEntry> =
            content.lines().filter_map(parse_cache_line).collect();
        assert_eq!(map.len(), 1);
        assert!(map.contains_key("good"));
    }

    #[test]
    fn cache_parse_multiple_hosts() {
        let lines: Vec<String> = ["h1", "h2", "h3"]
            .iter()
            .enumerate()
            .map(|(i, alias)| {
                serde_json::to_string(&CacheLine {
                    alias: alias.to_string(),
                    timestamp: i as u64,
                    runtime: ContainerRuntime::Docker,
                    containers: vec![],
                })
                .unwrap()
            })
            .collect();
        let content = lines.join("\n");
        let map: HashMap<String, ContainerCacheEntry> =
            content.lines().filter_map(parse_cache_line).collect();
        assert_eq!(map.len(), 3);
    }

    /// Helper: parse a single cache line (mirrors load_container_cache logic).
    fn parse_cache_line(line: &str) -> Option<(String, ContainerCacheEntry)> {
        let t = line.trim();
        if t.is_empty() {
            return None;
        }
        let entry: CacheLine = serde_json::from_str(t).ok()?;
        Some((
            entry.alias,
            ContainerCacheEntry {
                timestamp: entry.timestamp,
                runtime: entry.runtime,
                containers: entry.containers,
            },
        ))
    }

    // -- truncate_str --------------------------------------------------------

    #[test]
    fn truncate_short() {
        assert_eq!(truncate_str("hi", 10), "hi");
    }

    #[test]
    fn truncate_exact() {
        assert_eq!(truncate_str("hello", 5), "hello");
    }

    #[test]
    fn truncate_long() {
        assert_eq!(truncate_str("hello world", 7), "hello..");
    }

    #[test]
    fn truncate_empty() {
        assert_eq!(truncate_str("", 5), "");
    }

    #[test]
    fn truncate_max_two() {
        assert_eq!(truncate_str("hello", 2), "..");
    }

    #[test]
    fn truncate_multibyte() {
        assert_eq!(truncate_str("café-app", 6), "café..");
    }

    #[test]
    fn truncate_emoji() {
        assert_eq!(truncate_str("🐳nginx", 5), "🐳ng..");
    }

    // -- format_relative_time ------------------------------------------------

    fn now_secs() -> u64 {
        SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_secs()
    }

    #[test]
    fn relative_just_now() {
        assert_eq!(format_relative_time(now_secs()), "just now");
        assert_eq!(format_relative_time(now_secs() - 30), "just now");
        assert_eq!(format_relative_time(now_secs() - 59), "just now");
    }

    #[test]
    fn relative_minutes() {
        assert_eq!(format_relative_time(now_secs() - 60), "1m ago");
        assert_eq!(format_relative_time(now_secs() - 300), "5m ago");
        assert_eq!(format_relative_time(now_secs() - 3599), "59m ago");
    }

    #[test]
    fn relative_hours() {
        assert_eq!(format_relative_time(now_secs() - 3600), "1h ago");
        assert_eq!(format_relative_time(now_secs() - 7200), "2h ago");
    }

    #[test]
    fn relative_days() {
        assert_eq!(format_relative_time(now_secs() - 86400), "1d ago");
        assert_eq!(format_relative_time(now_secs() - 7 * 86400), "7d ago");
    }

    #[test]
    fn relative_future_saturates() {
        assert_eq!(format_relative_time(now_secs() + 10000), "just now");
    }

    // -- Additional edge-case tests -------------------------------------------

    #[test]
    fn parse_ps_whitespace_only_lines_between_json() {
        let c1 = make_json("a", "web", "nginx", "running", "Up", "");
        let c2 = make_json("b", "db", "pg", "exited", "Exited", "");
        let input = format!("{c1}\n   \n\t\n{c2}");
        let r = parse_container_ps(&input);
        assert_eq!(r.len(), 2);
        assert_eq!(r[0].id, "a");
        assert_eq!(r[1].id, "b");
    }

    #[test]
    fn id_just_dot() {
        assert!(validate_container_id(".").is_ok());
    }

    #[test]
    fn id_just_dash() {
        assert!(validate_container_id("-").is_ok());
    }

    #[test]
    fn id_slash_rejected() {
        assert!(validate_container_id("my/container").is_err());
    }

    #[test]
    fn list_cmd_none_valid_shell_syntax() {
        let cmd = container_list_command(None);
        assert!(cmd.contains("if "), "should start with if");
        assert!(cmd.contains("fi"), "should end with fi");
        assert!(cmd.contains("elif "), "should have elif fallback");
        assert!(cmd.contains("else "), "should have else branch");
    }

    #[test]
    fn output_sentinel_on_last_line() {
        let r = parse_container_output("some MOTD\n##purple:docker##", None);
        let (rt, cs) = r.unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert!(cs.is_empty());
    }

    #[test]
    fn output_sentinel_none_on_last_line() {
        let r = parse_container_output("MOTD line\n##purple:none##", None);
        assert!(r.is_err());
        assert!(r.unwrap_err().contains("No container runtime"));
    }

    #[test]
    fn relative_time_unix_epoch() {
        // Timestamp 0 is decades ago, should show many days
        let result = format_relative_time(0);
        assert!(
            result.contains("d ago"),
            "epoch should be days ago: {result}"
        );
    }

    #[test]
    fn truncate_unicode_within_limit() {
        // 3-byte chars but total byte len 9 > max 5, yet char count is 3
        // truncate_str uses byte length so this string of 3 chars (9 bytes) > max 5
        assert_eq!(truncate_str("abc", 5), "abc"); // ASCII fits
    }

    #[test]
    fn truncate_ascii_boundary() {
        // Ensure max=0 does not panic
        assert_eq!(truncate_str("hello", 0), "..");
    }

    #[test]
    fn truncate_max_one() {
        assert_eq!(truncate_str("hello", 1), "..");
    }

    #[test]
    fn cache_serde_unknown_runtime_rejected() {
        let json = r#"{"alias":"h","timestamp":1,"runtime":"Containerd","containers":[]}"#;
        let result = serde_json::from_str::<CacheLine>(json);
        assert!(result.is_err(), "unknown runtime should be rejected");
    }

    #[test]
    fn cache_duplicate_alias_last_wins() {
        let line1 = serde_json::to_string(&CacheLine {
            alias: "dup".to_string(),
            timestamp: 1,
            runtime: ContainerRuntime::Docker,
            containers: vec![],
        })
        .unwrap();
        let line2 = serde_json::to_string(&CacheLine {
            alias: "dup".to_string(),
            timestamp: 99,
            runtime: ContainerRuntime::Podman,
            containers: vec![],
        })
        .unwrap();
        let content = format!("{line1}\n{line2}");
        let map: HashMap<String, ContainerCacheEntry> =
            content.lines().filter_map(parse_cache_line).collect();
        assert_eq!(map.len(), 1);
        // HashMap::from_iter keeps last for duplicate keys
        assert_eq!(map["dup"].runtime, ContainerRuntime::Podman);
        assert_eq!(map["dup"].timestamp, 99);
    }

    #[test]
    fn friendly_error_no_route() {
        let msg = friendly_container_error("ssh: No route to host", Some(255));
        assert_eq!(msg, "Host unreachable.");
    }

    #[test]
    fn friendly_error_network_unreachable() {
        let msg = friendly_container_error("connect: Network is unreachable", Some(255));
        assert_eq!(msg, "Host unreachable.");
    }

    #[test]
    fn friendly_error_none_exit_code() {
        let msg = friendly_container_error("", None);
        assert_eq!(msg, "Command failed with code 1.");
    }

    #[test]
    fn container_error_display() {
        let err = ContainerError {
            runtime: Some(ContainerRuntime::Docker),
            message: "test error".to_string(),
        };
        assert_eq!(format!("{err}"), "test error");
    }

    #[test]
    fn container_error_display_no_runtime() {
        let err = ContainerError {
            runtime: None,
            message: "no runtime".to_string(),
        };
        assert_eq!(format!("{err}"), "no runtime");
    }

    // -- Additional tests: parse_container_ps edge cases ----------------------

    #[test]
    fn parse_ps_crlf_line_endings() {
        let c1 = make_json("a", "web", "nginx", "running", "Up", "");
        let c2 = make_json("b", "db", "pg", "exited", "Exited", "");
        let input = format!("{c1}\r\n{c2}\r\n");
        let r = parse_container_ps(&input);
        assert_eq!(r.len(), 2);
        assert_eq!(r[0].id, "a");
        assert_eq!(r[1].id, "b");
    }

    #[test]
    fn parse_ps_trailing_newline() {
        let c = make_json("a", "web", "nginx", "running", "Up", "");
        let input = format!("{c}\n");
        let r = parse_container_ps(&input);
        assert_eq!(
            r.len(),
            1,
            "trailing newline should not create phantom entry"
        );
    }

    #[test]
    fn parse_ps_leading_whitespace_json() {
        let c = make_json("a", "web", "nginx", "running", "Up", "");
        let input = format!("  {c}");
        let r = parse_container_ps(&input);
        assert_eq!(
            r.len(),
            1,
            "leading whitespace before JSON should be trimmed"
        );
        assert_eq!(r[0].id, "a");
    }

    // -- Additional tests: parse_runtime edge cases ---------------------------

    #[test]
    fn parse_runtime_empty_lines_between_motd() {
        let input = "Welcome\n\n\n\ndocker";
        assert_eq!(parse_runtime(input), Some(ContainerRuntime::Docker));
    }

    #[test]
    fn parse_runtime_crlf() {
        let input = "MOTD\r\npodman\r\n";
        assert_eq!(parse_runtime(input), Some(ContainerRuntime::Podman));
    }

    // -- Additional tests: parse_container_output edge cases ------------------

    #[test]
    fn output_unknown_sentinel() {
        let r = parse_container_output("##purple:unknown##", None);
        assert!(r.is_err());
        let msg = r.unwrap_err();
        assert!(msg.contains("Unknown sentinel"), "got: {msg}");
    }

    #[test]
    fn output_sentinel_with_crlf() {
        let c = make_json("a", "web", "nginx", "running", "Up", "");
        let input = format!("##purple:docker##\r\n{c}\r\n");
        let (rt, cs) = parse_container_output(&input, None).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert_eq!(cs.len(), 1);
    }

    #[test]
    fn output_sentinel_indented() {
        let c = make_json("a", "web", "nginx", "running", "Up", "");
        let input = format!("  ##purple:docker##\n{c}");
        let (rt, cs) = parse_container_output(&input, None).unwrap();
        assert_eq!(rt, ContainerRuntime::Docker);
        assert_eq!(cs.len(), 1);
    }

    #[test]
    fn output_caller_runtime_podman() {
        let c = make_json("a", "app", "img", "running", "Up", "");
        let (rt, cs) = parse_container_output(&c, Some(ContainerRuntime::Podman)).unwrap();
        assert_eq!(rt, ContainerRuntime::Podman);
        assert_eq!(cs.len(), 1);
    }

    // -- Additional tests: container_action_command ---------------------------

    #[test]
    fn action_command_long_id() {
        let long_id = "a".repeat(64);
        let cmd =
            container_action_command(ContainerRuntime::Docker, ContainerAction::Start, &long_id);
        assert_eq!(cmd, format!("docker start {long_id}"));
    }

    // -- Additional tests: validate_container_id ------------------------------

    #[test]
    fn id_full_sha256() {
        let id = "a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2";
        assert_eq!(id.len(), 64);
        assert!(validate_container_id(id).is_ok());
    }

    #[test]
    fn id_ampersand_rejected() {
        assert!(validate_container_id("app&rm").is_err());
    }

    #[test]
    fn id_parentheses_rejected() {
        assert!(validate_container_id("app(1)").is_err());
        assert!(validate_container_id("app)").is_err());
    }

    #[test]
    fn id_angle_brackets_rejected() {
        assert!(validate_container_id("app<1>").is_err());
        assert!(validate_container_id("app>").is_err());
    }

    // -- Additional tests: friendly_container_error ---------------------------

    #[test]
    fn friendly_error_podman_daemon() {
        let msg = friendly_container_error("cannot connect to podman", Some(125));
        assert_eq!(msg, "Container daemon is not running.");
    }

    #[test]
    fn friendly_error_case_insensitive() {
        let msg = friendly_container_error("PERMISSION DENIED", Some(1));
        assert_eq!(msg, "Permission denied. Is your user in the docker group?");
    }

    // -- Additional tests: Copy traits ----------------------------------------

    #[test]
    fn container_runtime_copy() {
        let a = ContainerRuntime::Docker;
        let b = a; // Copy
        assert_eq!(a, b); // both still usable
    }

    #[test]
    fn container_action_copy() {
        let a = ContainerAction::Start;
        let b = a; // Copy
        assert_eq!(a, b); // both still usable
    }

    // -- Additional tests: truncate_str edge cases ----------------------------

    #[test]
    fn truncate_multibyte_utf8() {
        // "caf\u{00e9}-app" is 8 chars; truncating to 6 keeps "caf\u{00e9}" + ".."
        assert_eq!(truncate_str("caf\u{00e9}-app", 6), "caf\u{00e9}..");
    }

    // -- Additional tests: format_relative_time boundaries --------------------

    #[test]
    fn format_relative_time_boundary_60s() {
        let ts = now_secs() - 60;
        assert_eq!(format_relative_time(ts), "1m ago");
    }

    #[test]
    fn format_relative_time_boundary_3600s() {
        let ts = now_secs() - 3600;
        assert_eq!(format_relative_time(ts), "1h ago");
    }

    #[test]
    fn format_relative_time_boundary_86400s() {
        let ts = now_secs() - 86400;
        assert_eq!(format_relative_time(ts), "1d ago");
    }

    // -- Additional tests: ContainerError Debug -------------------------------

    #[test]
    fn container_error_debug() {
        let err = ContainerError {
            runtime: Some(ContainerRuntime::Docker),
            message: "test".to_string(),
        };
        let dbg = format!("{err:?}");
        assert!(
            dbg.contains("Docker"),
            "Debug should include runtime: {dbg}"
        );
        assert!(dbg.contains("test"), "Debug should include message: {dbg}");
    }
}