pi/

session_picker.rs

//! Session picker TUI for selecting from available sessions.
//!
//! Provides an interactive list for choosing which session to resume.

use std::cmp::Reverse;
use std::collections::HashMap;
use std::fmt::Write;
use std::fs::{self, File};
use std::io::{BufRead, BufReader};
use std::path::{Path, PathBuf};
use std::time::{SystemTime, UNIX_EPOCH};

use bubbletea::{Cmd, KeyMsg, KeyType, Message, Program, quit};
use serde::Deserialize;

use crate::config::Config;
use crate::error::{Error, Result};
use crate::session::{Session, SessionHeader, encode_cwd};
use crate::session_index::{SessionIndex, SessionMeta};
use crate::theme::{Theme, TuiStyles};

/// Format a timestamp for display.
pub fn format_time(timestamp: &str) -> String {
    chrono::DateTime::parse_from_rfc3339(timestamp).map_or_else(
        |_| timestamp.to_string(),
        |dt| dt.format("%Y-%m-%d %H:%M").to_string(),
    )
}

/// Truncate a session id by character count for display.
#[must_use]
pub fn truncate_session_id(session_id: &str, max_chars: usize) -> &str {
    if max_chars == 0 {
        return "";
    }
    let end = session_id
        .char_indices()
        .nth(max_chars)
        .map_or(session_id.len(), |(idx, _)| idx);
    &session_id[..end]
}

/// The session picker TUI model.
#[derive(bubbletea::Model)]
pub struct SessionPicker {
    sessions: Vec<SessionMeta>,
    selected: usize,
    chosen: Option<usize>,
    cancelled: bool,
    confirm_delete: Option<usize>,
    status_message: Option<String>,
    sessions_root: Option<PathBuf>,
    styles: TuiStyles,
}

impl SessionPicker {
    /// Create a new session picker.
    #[allow(clippy::missing_const_for_fn)] // sessions: Vec cannot be const
    #[must_use]
    pub fn new(sessions: Vec<SessionMeta>) -> Self {
        let theme = Theme::dark();
        let styles = theme.tui_styles();
        Self {
            sessions,
            selected: 0,
            chosen: None,
            cancelled: false,
            confirm_delete: None,
            status_message: None,
            sessions_root: None,
            styles,
        }
    }

    #[must_use]
    pub fn with_theme(sessions: Vec<SessionMeta>, theme: &Theme) -> Self {
        let styles = theme.tui_styles();
        Self {
            sessions,
            selected: 0,
            chosen: None,
            cancelled: false,
            confirm_delete: None,
            status_message: None,
            sessions_root: None,
            styles,
        }
    }

    #[must_use]
    pub fn with_theme_and_root(
        sessions: Vec<SessionMeta>,
        theme: &Theme,
        sessions_root: PathBuf,
    ) -> Self {
        let styles = theme.tui_styles();
        Self {
            sessions,
            selected: 0,
            chosen: None,
            cancelled: false,
            confirm_delete: None,
            status_message: None,
            sessions_root: Some(sessions_root),
            styles,
        }
    }

    /// Get the selected session path after the picker completes.
    pub fn selected_path(&self) -> Option<&str> {
        self.chosen
            .and_then(|i| self.sessions.get(i))
            .map(|s| s.path.as_str())
    }

    /// Check if the picker was cancelled.
    pub const fn was_cancelled(&self) -> bool {
        self.cancelled
    }

    #[allow(clippy::unused_self, clippy::missing_const_for_fn)]
    fn init(&self) -> Option<Cmd> {
        None
    }

    #[allow(clippy::needless_pass_by_value)] // Required by Model trait
    pub fn update(&mut self, msg: Message) -> Option<Cmd> {
        if let Some(key) = msg.downcast_ref::<KeyMsg>() {
            if self.confirm_delete.is_some() {
                return self.handle_delete_prompt(key);
            }
            match key.key_type {
                KeyType::Up => {
                    if self.selected > 0 {
                        self.selected -= 1;
                    }
                }
                KeyType::Down => {
                    if self.selected < self.sessions.len().saturating_sub(1) {
                        self.selected += 1;
                    }
                }
                KeyType::Runes if key.runes == ['k'] => {
                    if self.selected > 0 {
                        self.selected -= 1;
                    }
                }
                KeyType::Runes if key.runes == ['j'] => {
                    if self.selected < self.sessions.len().saturating_sub(1) {
                        self.selected += 1;
                    }
                }
                KeyType::Enter => {
                    if !self.sessions.is_empty() {
                        self.chosen = Some(self.selected);
                    }
                    return Some(quit());
                }
                KeyType::Esc | KeyType::CtrlC => {
                    self.cancelled = true;
                    return Some(quit());
                }
                KeyType::Runes if key.runes == ['q'] => {
                    self.cancelled = true;
                    return Some(quit());
                }
                KeyType::CtrlD => {
                    if !self.sessions.is_empty() {
                        self.confirm_delete = Some(self.selected);
                        self.status_message =
                            Some("Delete session? Press y/n to confirm.".to_string());
                    }
                }
                _ => {}
            }
        }
        None
    }

    fn handle_delete_prompt(&mut self, key: &KeyMsg) -> Option<Cmd> {
        match key.key_type {
            KeyType::Runes if key.runes == ['y'] || key.runes == ['Y'] => {
                if let Some(index) = self.confirm_delete.take() {
                    if let Err(err) = self.delete_session_at(index) {
                        self.status_message = Some(err.to_string());
                    } else {
                        self.status_message = Some("Session deleted.".to_string());
                        if self.sessions.is_empty() {
                            self.cancelled = true;
                            return Some(quit());
                        }
                    }
                }
            }
            KeyType::Runes if key.runes == ['n'] || key.runes == ['N'] => {
                self.confirm_delete = None;
                self.status_message = None;
            }
            KeyType::Esc | KeyType::CtrlC => {
                self.confirm_delete = None;
                self.status_message = None;
            }
            _ => {}
        }
        None
    }

    fn delete_session_at(&mut self, index: usize) -> Result<()> {
        let Some(meta) = self.sessions.get(index) else {
            return Ok(());
        };
        let path = PathBuf::from(&meta.path);
        delete_session_file(&path)?;
        if let Some(root) = self.sessions_root.as_ref() {
            let index = SessionIndex::for_sessions_root(root);
            let _ = index.delete_session_path(&path);
        }
        self.sessions.remove(index);
        if self.selected >= self.sessions.len() {
            self.selected = self.sessions.len().saturating_sub(1);
        }
        Ok(())
    }

    pub fn view(&self) -> String {
        let mut output = String::new();

        // Header
        let _ = writeln!(
            output,
            "\n  {}\n",
            self.styles.title.render("Select a session to resume")
        );

        if self.sessions.is_empty() {
            let _ = writeln!(
                output,
                "  {}",
                self.styles
                    .muted
                    .render("No sessions found for this project.")
            );
        } else {
            // Column headers
            let _ = writeln!(
                output,
                "  {:<20}  {:<30}  {:<8}  {}",
                self.styles.muted_bold.render("Time"),
                self.styles.muted_bold.render("Name"),
                self.styles.muted_bold.render("Messages"),
                self.styles.muted_bold.render("Session ID")
            );
            output.push_str("  ");
            output.push_str(&"-".repeat(78));
            output.push('\n');

            // Session rows
            for (i, session) in self.sessions.iter().enumerate() {
                let is_selected = i == self.selected;

                let prefix = if is_selected { ">" } else { " " };
                let time = format_time(&session.timestamp);
                let name = session
                    .name
                    .as_deref()
                    .unwrap_or("-")
                    .chars()
                    .take(28)
                    .collect::<String>();
                let messages = session.message_count.to_string();
                let id = truncate_session_id(&session.id, 8);

                let _ = writeln!(
                    output,
                    "{prefix} {}",
                    if is_selected {
                        self.styles
                            .selection
                            .render(&format!(" {time:<20}  {name:<30}  {messages:<8}  {id}"))
                    } else {
                        format!(" {time:<20}  {name:<30}  {messages:<8}  {id}")
                    }
                );
            }
        }

        // Help text
        output.push('\n');
        let _ = writeln!(
            output,
            "  {}",
            self.styles
                .muted
                .render("↑/↓/j/k: navigate  Enter: select  Ctrl+D: delete  Esc/q: cancel")
        );
        if let Some(message) = &self.status_message {
            let _ = writeln!(output, "  {}", self.styles.warning_bold.render(message));
        }

        output
    }
}

/// List sessions for the current working directory using the session index.
pub fn list_sessions_for_cwd() -> Vec<SessionMeta> {
    let Ok(cwd) = std::env::current_dir() else {
        return Vec::new();
    };
    list_sessions_for_project(&cwd, None)
}

/// Run the session picker and return the selected session.
pub async fn pick_session(override_dir: Option<&Path>) -> Option<Session> {
    let cwd = std::env::current_dir().ok()?;
    let base_dir = override_dir.map_or_else(Config::sessions_dir, PathBuf::from);
    let sessions = list_sessions_for_project(&cwd, override_dir);

    if sessions.is_empty() {
        return None;
    }

    if sessions.len() == 1 {
        // Only one session, just open it
        let mut session = Session::open(&sessions[0].path).await.ok()?;
        session.session_dir = Some(base_dir);
        return Some(session);
    }

    let config = Config::load().unwrap_or_default();
    let theme = Theme::resolve(&config, &cwd);
    let picker = SessionPicker::with_theme_and_root(sessions, &theme, base_dir.clone());

    // Run the TUI
    let result = Program::new(picker).with_alt_screen().run();

    match result {
        Ok(picker) => {
            if picker.was_cancelled() {
                return None;
            }

            if let Some(path) = picker.selected_path() {
                let mut session = Session::open(path).await.ok()?;
                session.session_dir = Some(base_dir);
                Some(session)
            } else {
                None
            }
        }
        Err(_) => None,
    }
}

pub fn list_sessions_for_project(cwd: &Path, override_dir: Option<&Path>) -> Vec<SessionMeta> {
    let base_dir = override_dir.map_or_else(Config::sessions_dir, PathBuf::from);
    let project_session_dir = base_dir.join(encode_cwd(cwd));
    if !project_session_dir.exists() {
        return Vec::new();
    }

    let cwd_key = cwd.display().to_string();
    let index = SessionIndex::for_sessions_root(&base_dir);
    let mut sessions = index.list_sessions(Some(&cwd_key)).unwrap_or_default();

    if sessions.is_empty() && index.reindex_all().is_ok() {
        sessions = index.list_sessions(Some(&cwd_key)).unwrap_or_default();
    }

    sessions.retain(|meta| Path::new(&meta.path).exists());

    let scanned = scan_sessions_on_disk(&project_session_dir);
    if !scanned.is_empty() {
        let mut by_path: HashMap<String, SessionMeta> = sessions
            .into_iter()
            .map(|meta| (meta.path.clone(), meta))
            .collect();

        for meta in scanned {
            let should_replace = by_path
                .get(&meta.path)
                .is_some_and(|existing| meta.last_modified_ms > existing.last_modified_ms);
            if should_replace || !by_path.contains_key(&meta.path) {
                by_path.insert(meta.path.clone(), meta);
            }
        }

        sessions = by_path.into_values().collect();
    }

    sessions.sort_by_key(|m| Reverse(m.last_modified_ms));
    sessions.truncate(50);
    sessions
}

fn scan_sessions_on_disk(project_session_dir: &Path) -> Vec<SessionMeta> {
    let mut out = Vec::new();
    let Ok(entries) = fs::read_dir(project_session_dir) else {
        return out;
    };

    for entry in entries.flatten() {
        let path = entry.path();
        if is_session_file_path(&path) {
            if let Ok(meta) = build_meta_from_file(&path) {
                out.push(meta);
            }
        }
    }

    out
}

fn build_meta_from_file(path: &Path) -> crate::error::Result<SessionMeta> {
    match path.extension().and_then(|ext| ext.to_str()) {
        Some("jsonl") => build_meta_from_jsonl(path),
        #[cfg(feature = "sqlite-sessions")]
        Some("sqlite") => build_meta_from_sqlite(path),
        _ => Err(Error::session(format!(
            "Unsupported session file extension: {}",
            path.display()
        ))),
    }
}

#[derive(Deserialize)]
struct PartialEntry {
    #[serde(default)]
    r#type: String,
    #[serde(default)]
    name: Option<String>,
}

fn build_meta_from_jsonl(path: &Path) -> crate::error::Result<SessionMeta> {
    let file = File::open(path)?;
    let reader = BufReader::new(file);
    let mut lines = reader.lines();

    let header_line = lines
        .next()
        .transpose()?
        .ok_or_else(|| crate::error::Error::session("Empty session file"))?;

    let header: SessionHeader = serde_json::from_str(&header_line)
        .map_err(|e| crate::error::Error::session(format!("Parse session header: {e}")))?;

    let mut message_count = 0u64;
    let mut name = None;

    for line_res in lines {
        let line = line_res?;
        if let Ok(entry) = serde_json::from_str::<PartialEntry>(&line) {
            match entry.r#type.as_str() {
                "message" => message_count += 1,
                "session_info" => {
                    if entry.name.is_some() {
                        name = entry.name;
                    }
                }
                _ => {}
            }
        }
    }

    let meta = fs::metadata(path)?;
    let size_bytes = meta.len();
    let modified = meta.modified().unwrap_or(SystemTime::UNIX_EPOCH);
    let millis = modified
        .duration_since(UNIX_EPOCH)
        .unwrap_or_default()
        .as_millis();
    let last_modified_ms = i64::try_from(millis).unwrap_or(i64::MAX);

    Ok(SessionMeta {
        path: path.display().to_string(),
        id: header.id,
        cwd: header.cwd,
        timestamp: header.timestamp,
        message_count,
        last_modified_ms,
        size_bytes,
        name,
    })
}

#[cfg(feature = "sqlite-sessions")]
fn build_meta_from_sqlite(path: &Path) -> crate::error::Result<SessionMeta> {
    let meta = futures::executor::block_on(async {
        crate::session_sqlite::load_session_meta(path).await
    })?;
    let header = meta.header;

    let sqlite_meta = fs::metadata(path)?;
    let size_bytes = sqlite_meta.len();
    let modified = sqlite_meta.modified().unwrap_or(SystemTime::UNIX_EPOCH);
    let millis = modified
        .duration_since(UNIX_EPOCH)
        .unwrap_or_default()
        .as_millis();
    let last_modified_ms = i64::try_from(millis).unwrap_or(i64::MAX);

    Ok(SessionMeta {
        path: path.display().to_string(),
        id: header.id,
        cwd: header.cwd,
        timestamp: header.timestamp,
        message_count: meta.message_count,
        last_modified_ms,
        size_bytes,
        name: meta.name,
    })
}

fn is_session_file_path(path: &Path) -> bool {
    match path.extension().and_then(|ext| ext.to_str()) {
        Some("jsonl") => true,
        #[cfg(feature = "sqlite-sessions")]
        Some("sqlite") => true,
        _ => false,
    }
}

pub(crate) fn delete_session_file(path: &Path) -> Result<()> {
    delete_session_file_with_trash_cmd(path, "trash")
}

fn delete_session_file_with_trash_cmd(path: &Path, trash_cmd: &str) -> Result<()> {
    if try_trash_with_cmd(path, trash_cmd) {
        return Ok(());
    }
    match fs::remove_file(path) {
        Ok(()) => Ok(()),
        Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(()),
        Err(err) => Err(Error::session(format!(
            "Failed to delete session {}: {err}",
            path.display()
        ))),
    }
}

fn try_trash_with_cmd(path: &Path, trash_cmd: &str) -> bool {
    match std::process::Command::new(trash_cmd).arg(path).status() {
        Ok(status) if status.success() => true,
        Ok(status) => {
            tracing::warn!(
                path = %path.display(),
                exit = status.code().unwrap_or(-1),
                "trash command failed; falling back to direct file removal"
            );
            false
        }
        Err(err) if err.kind() == std::io::ErrorKind::NotFound => false,
        Err(err) => {
            tracing::warn!(
                path = %path.display(),
                error = %err,
                "trash command invocation failed; falling back to direct file removal"
            );
            false
        }
    }
}

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

    fn make_meta(path: &Path) -> SessionMeta {
        SessionMeta {
            path: path.display().to_string(),
            id: "sess".to_string(),
            cwd: "/tmp".to_string(),
            timestamp: "2025-01-15T10:00:00.000Z".to_string(),
            message_count: 1,
            last_modified_ms: 1000,
            size_bytes: 100,
            name: None,
        }
    }

    fn key_msg(key_type: KeyType, runes: Vec<char>) -> Message {
        Message::new(KeyMsg {
            key_type,
            runes,
            alt: false,
            paste: false,
        })
    }

    #[test]
    fn test_format_time() {
        let ts = "2025-01-15T10:30:00.000Z";
        let formatted = format_time(ts);
        assert!(formatted.contains("2025-01-15"));
        assert!(formatted.contains("10:30"));
    }

    #[test]
    fn test_format_time_invalid_returns_input() {
        let ts = "not-a-timestamp";
        assert_eq!(format_time(ts), ts);
    }

    #[test]
    fn truncate_session_id_handles_unicode_boundaries() {
        assert_eq!(truncate_session_id("abcdefghijk", 8), "abcdefgh");
        assert_eq!(truncate_session_id("αβγδεζηθικ", 8), "αβγδεζηθ");
    }

    #[test]
    fn test_is_session_file_path() {
        assert!(is_session_file_path(Path::new("/tmp/sess.jsonl")));
        assert!(!is_session_file_path(Path::new("/tmp/sess.txt")));
        assert!(!is_session_file_path(Path::new("/tmp/noext")));
        #[cfg(feature = "sqlite-sessions")]
        assert!(is_session_file_path(Path::new("/tmp/sess.sqlite")));
    }

    #[test]
    fn test_session_picker_navigation() {
        let sessions = vec![
            SessionMeta {
                path: "/test/a.jsonl".to_string(),
                id: "aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T10:00:00.000Z".to_string(),
                message_count: 1,
                last_modified_ms: 1000,
                size_bytes: 100,
                name: None,
            },
            SessionMeta {
                path: "/test/b.jsonl".to_string(),
                id: "bbbbbbbb-cccc-dddd-eeee-ffffffffffff".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T11:00:00.000Z".to_string(),
                message_count: 2,
                last_modified_ms: 2000,
                size_bytes: 200,
                name: Some("Test session".to_string()),
            },
        ];

        let mut picker = SessionPicker::new(sessions);
        assert_eq!(picker.selected, 0);

        // Navigate down
        picker.update(key_msg(KeyType::Down, vec![]));
        assert_eq!(picker.selected, 1);

        // Navigate up
        picker.update(key_msg(KeyType::Up, vec![]));
        assert_eq!(picker.selected, 0);
    }

    #[test]
    fn test_session_picker_vim_keys() {
        let sessions = vec![
            SessionMeta {
                path: "/test/a.jsonl".to_string(),
                id: "aaaaaaaa".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T10:00:00.000Z".to_string(),
                message_count: 1,
                last_modified_ms: 1000,
                size_bytes: 100,
                name: None,
            },
            SessionMeta {
                path: "/test/b.jsonl".to_string(),
                id: "bbbbbbbb".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T11:00:00.000Z".to_string(),
                message_count: 2,
                last_modified_ms: 2000,
                size_bytes: 200,
                name: None,
            },
        ];

        let mut picker = SessionPicker::new(sessions);
        assert_eq!(picker.selected, 0);

        // Navigate down with 'j'
        picker.update(key_msg(KeyType::Runes, vec!['j']));
        assert_eq!(picker.selected, 1);

        // Navigate up with 'k'
        picker.update(key_msg(KeyType::Runes, vec!['k']));
        assert_eq!(picker.selected, 0);
    }

    #[test]
    fn session_picker_delete_prompt_and_cancel() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("sess.jsonl");
        fs::write(&session_path, "test").expect("write session");

        let sessions = vec![make_meta(&session_path)];
        let mut picker = SessionPicker::new(sessions);

        picker.update(key_msg(KeyType::CtrlD, vec![]));
        assert!(picker.confirm_delete.is_some());

        picker.update(key_msg(KeyType::Runes, vec!['n']));
        assert!(picker.confirm_delete.is_none());
        assert!(session_path.exists());
    }

    #[test]
    fn session_picker_delete_confirm_removes_file() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("sess.jsonl");
        fs::write(&session_path, "test").expect("write session");

        let sessions = vec![make_meta(&session_path)];
        let mut picker = SessionPicker::new(sessions);

        picker.update(key_msg(KeyType::CtrlD, vec![]));

        picker.update(key_msg(KeyType::Runes, vec!['y']));

        assert!(!session_path.exists());
        assert!(picker.sessions.is_empty());
    }

    #[test]
    fn session_picker_navigation_bounds() {
        let sessions = vec![
            SessionMeta {
                path: "/test/a.jsonl".to_string(),
                id: "aaaaaaaa".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T10:00:00.000Z".to_string(),
                message_count: 1,
                last_modified_ms: 1000,
                size_bytes: 100,
                name: None,
            },
            SessionMeta {
                path: "/test/b.jsonl".to_string(),
                id: "bbbbbbbb".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T11:00:00.000Z".to_string(),
                message_count: 2,
                last_modified_ms: 2000,
                size_bytes: 200,
                name: None,
            },
        ];

        let mut picker = SessionPicker::new(sessions);
        picker.update(key_msg(KeyType::Up, vec![]));
        assert_eq!(picker.selected, 0);

        picker.update(key_msg(KeyType::Down, vec![]));
        picker.update(key_msg(KeyType::Down, vec![]));
        assert_eq!(picker.selected, 1);
    }

    #[test]
    fn session_picker_enter_selects_current_session() {
        let sessions = vec![
            SessionMeta {
                path: "/test/a.jsonl".to_string(),
                id: "aaaaaaaa".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T10:00:00.000Z".to_string(),
                message_count: 1,
                last_modified_ms: 1000,
                size_bytes: 100,
                name: None,
            },
            SessionMeta {
                path: "/test/b.jsonl".to_string(),
                id: "bbbbbbbb".to_string(),
                cwd: "/test".to_string(),
                timestamp: "2025-01-15T11:00:00.000Z".to_string(),
                message_count: 2,
                last_modified_ms: 2000,
                size_bytes: 200,
                name: Some("chosen".to_string()),
            },
        ];

        let mut picker = SessionPicker::new(sessions);
        picker.update(key_msg(KeyType::Down, vec![]));
        picker.update(key_msg(KeyType::Enter, vec![]));
        assert_eq!(picker.selected_path(), Some("/test/b.jsonl"));
        assert!(!picker.was_cancelled());
    }

    #[test]
    fn session_picker_cancel_keys_mark_cancelled() {
        let sessions = vec![SessionMeta {
            path: "/test/a.jsonl".to_string(),
            id: "aaaaaaaa".to_string(),
            cwd: "/test".to_string(),
            timestamp: "2025-01-15T10:00:00.000Z".to_string(),
            message_count: 1,
            last_modified_ms: 1000,
            size_bytes: 100,
            name: None,
        }];

        let mut esc_picker = SessionPicker::new(sessions.clone());
        esc_picker.update(key_msg(KeyType::Esc, vec![]));
        assert!(esc_picker.was_cancelled());

        let mut q_picker = SessionPicker::new(sessions.clone());
        q_picker.update(key_msg(KeyType::Runes, vec!['q']));
        assert!(q_picker.was_cancelled());

        let mut ctrl_c_picker = SessionPicker::new(sessions);
        ctrl_c_picker.update(key_msg(KeyType::CtrlC, vec![]));
        assert!(ctrl_c_picker.was_cancelled());
    }

    #[test]
    fn session_picker_view_empty_and_populated_states() {
        let empty_picker = SessionPicker::new(Vec::new());
        let empty_view = empty_picker.view();
        assert!(empty_view.contains("Select a session to resume"));
        assert!(empty_view.contains("No sessions found for this project."));

        let sessions = vec![SessionMeta {
            path: "/test/a.jsonl".to_string(),
            id: "aaaaaaaa-bbbb".to_string(),
            cwd: "/test".to_string(),
            timestamp: "2025-01-15T10:00:00.000Z".to_string(),
            message_count: 3,
            last_modified_ms: 1000,
            size_bytes: 100,
            name: Some("demo".to_string()),
        }];
        let mut populated = SessionPicker::new(sessions);
        populated.update(key_msg(KeyType::CtrlD, vec![]));
        let view = populated.view();
        assert!(view.contains("Messages"));
        assert!(view.contains("Session ID"));
        assert!(view.contains("Delete session? Press y/n to confirm."));
    }

    #[test]
    fn session_picker_view_handles_non_ascii_session_ids() {
        let sessions = vec![SessionMeta {
            path: "/test/u.jsonl".to_string(),
            id: "αβγδεζηθι".to_string(),
            cwd: "/test".to_string(),
            timestamp: "2025-01-15T10:00:00.000Z".to_string(),
            message_count: 1,
            last_modified_ms: 1000,
            size_bytes: 100,
            name: Some("unicode".to_string()),
        }];

        let view = SessionPicker::new(sessions).view();
        assert!(view.contains("αβγδεζηθ"));
    }

    // ── selected_path when nothing chosen ──────────────────────────────

    #[test]
    fn selected_path_returns_none_when_no_selection() {
        let picker = SessionPicker::new(vec![make_meta(Path::new("/tmp/a.jsonl"))]);
        assert!(picker.selected_path().is_none());
        assert!(!picker.was_cancelled());
    }

    // ── with_theme constructor ─────────────────────────────────────────

    #[test]
    fn with_theme_constructor_sets_initial_state() {
        let theme = Theme::dark();
        let sessions = vec![make_meta(Path::new("/tmp/a.jsonl"))];
        let picker = SessionPicker::with_theme(sessions, &theme);
        assert_eq!(picker.selected, 0);
        assert!(!picker.was_cancelled());
        assert!(picker.selected_path().is_none());
    }

    // ── delete last session causes quit ────────────────────────────────

    #[test]
    fn delete_last_session_sets_cancelled_true() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("only.jsonl");
        fs::write(&session_path, "test").expect("write");

        let mut picker = SessionPicker::new(vec![make_meta(&session_path)]);

        picker.update(key_msg(KeyType::CtrlD, vec![]));
        let cmd = picker.update(key_msg(KeyType::Runes, vec!['y']));
        assert!(picker.was_cancelled());
        assert!(cmd.is_some()); // quit command issued
    }

    // ── Esc during delete prompt cancels prompt ────────────────────────

    #[test]
    fn esc_cancels_delete_prompt() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("sess.jsonl");
        fs::write(&session_path, "test").expect("write");

        let mut picker = SessionPicker::new(vec![make_meta(&session_path)]);
        picker.update(key_msg(KeyType::CtrlD, vec![]));
        assert!(picker.confirm_delete.is_some());

        picker.update(key_msg(KeyType::Esc, vec![]));
        assert!(picker.confirm_delete.is_none());
        assert!(picker.status_message.is_none());
    }

    // ── enter on empty list still returns quit ─────────────────────────

    #[test]
    fn enter_on_empty_list_returns_quit() {
        let mut picker = SessionPicker::new(Vec::new());
        let cmd = picker.update(key_msg(KeyType::Enter, vec![]));
        assert!(cmd.is_some()); // quit
        assert!(picker.selected_path().is_none());
    }

    // ── ctrl-d on empty list is a noop ─────────────────────────────────

    #[test]
    fn ctrl_d_on_empty_list_is_noop() {
        let mut picker = SessionPicker::new(Vec::new());
        picker.update(key_msg(KeyType::CtrlD, vec![]));
        assert!(picker.confirm_delete.is_none());
    }

    // ── build_meta_from_jsonl ──────────────────────────────────────────

    #[test]
    fn build_meta_from_jsonl_parses_session_file() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("test.jsonl");
        let header = serde_json::json!({
            "type": "header",
            "id": "abc123",
            "cwd": "/work",
            "timestamp": "2025-06-01T12:00:00.000Z"
        });
        let msg1 = serde_json::json!({
            "type": "message",
            "timestamp": "2025-06-01T12:00:01.000Z",
            "message": {"role": "user", "content": "hi"}
        });
        let msg2 = serde_json::json!({
            "type": "message",
            "timestamp": "2025-06-01T12:00:02.000Z",
            "message": {"role": "user", "content": "hello again"}
        });
        let info = serde_json::json!({
            "type": "session_info",
            "timestamp": "2025-06-01T12:00:03.000Z",
            "name": "My Session"
        });
        let content = format!(
            "{}\n{}\n{}\n{}",
            serde_json::to_string(&header).unwrap(),
            serde_json::to_string(&msg1).unwrap(),
            serde_json::to_string(&msg2).unwrap(),
            serde_json::to_string(&info).unwrap(),
        );
        fs::write(&session_path, content).expect("write");

        let meta = build_meta_from_jsonl(&session_path).expect("parse meta");
        assert_eq!(meta.id, "abc123");
        assert_eq!(meta.cwd, "/work");
        assert_eq!(meta.message_count, 2);
        assert_eq!(meta.name.as_deref(), Some("My Session"));
        assert!(meta.size_bytes > 0);
    }

    #[test]
    fn build_meta_from_jsonl_empty_file_returns_error() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("empty.jsonl");
        fs::write(&session_path, "").expect("write");

        assert!(build_meta_from_jsonl(&session_path).is_err());
    }

    // ── is_session_file_path additional cases ──────────────────────────

    #[test]
    fn is_session_file_path_rejects_common_non_session_extensions() {
        assert!(!is_session_file_path(Path::new("/tmp/file.json")));
        assert!(!is_session_file_path(Path::new("/tmp/file.md")));
        assert!(!is_session_file_path(Path::new("/tmp/file.rs")));
    }

    // ── scan_sessions_on_disk ──────────────────────────────────────────

    #[test]
    fn scan_sessions_on_disk_finds_valid_session_files() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("session.jsonl");
        let header = serde_json::json!({
            "type": "header",
            "id": "scan-test",
            "cwd": "/work",
            "timestamp": "2025-06-01T12:00:00.000Z"
        });
        fs::write(&session_path, serde_json::to_string(&header).unwrap()).expect("write");

        // Also create a non-session file that should be ignored
        fs::write(tmp.path().join("notes.txt"), "not a session").expect("write");

        let found = scan_sessions_on_disk(tmp.path());
        assert_eq!(found.len(), 1);
        assert_eq!(found[0].id, "scan-test");
    }

    #[test]
    fn scan_sessions_on_disk_nonexistent_dir_returns_empty() {
        let found = scan_sessions_on_disk(Path::new("/nonexistent/dir"));
        assert!(found.is_empty());
    }

    // ── with_theme_and_root constructor ────────────────────────────────

    #[test]
    fn with_theme_and_root_stores_sessions_root() {
        let theme = Theme::dark();
        let root = PathBuf::from("/sessions");
        let picker = SessionPicker::with_theme_and_root(Vec::new(), &theme, root);
        assert!(picker.sessions_root.is_some());
    }

    // ── delete adjusts selection when at end ───────────────────────────

    #[test]
    fn delete_adjusts_selection_when_at_end() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let path_a = tmp.path().join("a.jsonl");
        let path_b = tmp.path().join("b.jsonl");
        fs::write(&path_a, "test").expect("write a");
        fs::write(&path_b, "test").expect("write b");

        let mut picker = SessionPicker::new(vec![make_meta(&path_a), make_meta(&path_b)]);

        // Navigate to second item
        picker.update(key_msg(KeyType::Down, vec![]));
        assert_eq!(picker.selected, 1);

        // Delete it
        picker.update(key_msg(KeyType::CtrlD, vec![]));
        picker.update(key_msg(KeyType::Runes, vec!['y']));

        // Selection should clamp back to 0
        assert_eq!(picker.selected, 0);
        assert_eq!(picker.sessions.len(), 1);
    }

    #[test]
    fn delete_session_file_falls_back_when_trash_command_missing() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("missing-trash-fallback.jsonl");
        fs::write(&session_path, "test").expect("write");

        let result = delete_session_file_with_trash_cmd(
            &session_path,
            "__pi_agent_rust_nonexistent_trash_command__",
        );
        assert!(result.is_ok(), "delete should fall back to remove_file");
        assert!(!session_path.exists(), "session file should be deleted");
    }

    #[cfg(unix)]
    #[test]
    fn delete_session_file_falls_back_when_trash_exits_non_zero() {
        use std::os::unix::fs::PermissionsExt as _;

        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("failing-trash-fallback.jsonl");
        fs::write(&session_path, "test").expect("write");

        let trash_script = tmp.path().join("fake-trash.sh");
        fs::write(&trash_script, "#!/bin/sh\nexit 2\n").expect("write script");
        let mut perms = fs::metadata(&trash_script).expect("metadata").permissions();
        perms.set_mode(0o755);
        fs::set_permissions(&trash_script, perms).expect("chmod");

        let trash_cmd = trash_script.to_string_lossy();
        let result = delete_session_file_with_trash_cmd(&session_path, &trash_cmd);
        assert!(result.is_ok(), "delete should fall back to remove_file");
        assert!(!session_path.exists(), "session file should be deleted");
    }

    #[cfg(unix)]
    #[test]
    fn delete_session_file_succeeds_when_trash_deleted_file_then_failed() {
        use std::os::unix::fs::PermissionsExt as _;

        let tmp = tempfile::tempdir().expect("tempdir");
        let session_path = tmp.path().join("trash-deleted-then-failed.jsonl");
        fs::write(&session_path, "test").expect("write");

        let trash_script = tmp.path().join("fake-trash-delete-then-fail.sh");
        fs::write(
            &trash_script,
            format!("#!/bin/sh\nrm -f \"{}\"\nexit 2\n", session_path.display()),
        )
        .expect("write script");
        let mut perms = fs::metadata(&trash_script).expect("metadata").permissions();
        perms.set_mode(0o755);
        fs::set_permissions(&trash_script, perms).expect("chmod");

        let trash_cmd = trash_script.to_string_lossy();
        let result = delete_session_file_with_trash_cmd(&session_path, &trash_cmd);
        assert!(
            result.is_ok(),
            "delete should be idempotent when file is already gone"
        );
        assert!(!session_path.exists(), "session file should remain deleted");
    }

    mod proptest_session_picker {
        use super::*;
        use proptest::prelude::*;

        proptest! {
            /// `truncate_session_id` never returns more chars than requested.
            #[test]
            fn truncate_respects_limit(s in "[a-z0-9\\-]{1,40}", max in 0..50usize) {
                let result = truncate_session_id(&s, max);
                assert!(result.chars().count() <= max);
            }

            /// `truncate_session_id` is a prefix of the original.
            #[test]
            fn truncate_is_prefix(s in "[a-z0-9\\-]{1,40}", max in 1..50usize) {
                let result = truncate_session_id(&s, max);
                assert!(s.starts_with(result));
            }

            /// `truncate_session_id` with max >= len returns the whole string.
            #[test]
            fn truncate_large_limit_identity(s in "[a-z0-9\\-]{1,20}") {
                let len = s.chars().count();
                let result = truncate_session_id(&s, len + 10);
                assert_eq!(result, s.as_str());
            }

            /// `truncate_session_id` with max=0 returns empty.
            #[test]
            fn truncate_zero_is_empty(s in "\\PC{1,20}") {
                assert_eq!(truncate_session_id(&s, 0), "");
            }

            /// `format_time` never panics on arbitrary strings.
            #[test]
            fn format_time_never_panics(ts in "\\PC{0,40}") {
                let _ = format_time(&ts);
            }

            /// Valid RFC3339 timestamps format to YYYY-MM-DD HH:MM.
            #[test]
            fn format_time_valid_rfc3339(
                year in 2020..2030u32,
                month in 1..12u32,
                day in 1..28u32,
                hour in 0..23u32,
                min in 0..59u32
            ) {
                let ts = format!("{year}-{month:02}-{day:02}T{hour:02}:{min:02}:00Z");
                let result = format_time(&ts);
                assert!(result.contains(&format!("{year}-{month:02}-{day:02}")));
                assert!(result.contains(&format!("{hour:02}:{min:02}")));
            }

            /// Invalid timestamps are returned as-is.
            #[test]
            fn format_time_invalid_passthrough(s in "[a-z]{5,15}") {
                assert_eq!(format_time(&s), s);
            }

            /// `is_session_file_path` accepts .jsonl files.
            #[test]
            fn is_session_file_path_accepts_jsonl(name in "[a-z]{1,10}") {
                let path = format!("/tmp/{name}.jsonl");
                assert!(is_session_file_path(Path::new(&path)));
            }

            /// `is_session_file_path` rejects random extensions.
            #[test]
            fn is_session_file_path_rejects_other(
                name in "[a-z]{1,10}",
                ext in "[a-z]{1,5}"
            ) {
                prop_assume!(ext != "jsonl" && ext != "sqlite");
                let path = format!("/tmp/{name}.{ext}");
                assert!(!is_session_file_path(Path::new(&path)));
            }

            /// `is_session_file_path` rejects files without extensions.
            #[test]
            fn is_session_file_path_rejects_no_ext(name in "[a-z]{1,10}") {
                assert!(!is_session_file_path(Path::new(&format!("/tmp/{name}"))));
            }

            /// `truncate_session_id` handles multi-byte unicode.
            #[test]
            fn truncate_unicode(max in 0..10usize) {
                let s = "\u{1F600}\u{1F601}\u{1F602}\u{1F603}\u{1F604}"; // 5 emoji
                let result = truncate_session_id(s, max);
                assert!(result.chars().count() <= max);
                assert!(s.starts_with(result));
            }

            /// Truncation is idempotent for a fixed limit.
            #[test]
            fn truncate_idempotent(s in "\\PC{1,40}", max in 0..40usize) {
                let once = truncate_session_id(&s, max);
                let twice = truncate_session_id(once, max);
                assert_eq!(once, twice);
            }

            /// Valid RFC3339 formatting is fixed-width (`YYYY-MM-DD HH:MM`).
            #[test]
            fn format_time_valid_rfc3339_fixed_width(
                year in 2020..2030u32,
                month in 1..12u32,
                day in 1..28u32,
                hour in 0..23u32,
                min in 0..59u32
            ) {
                let ts = format!("{year}-{month:02}-{day:02}T{hour:02}:{min:02}:00Z");
                let result = format_time(&ts);
                assert_eq!(result.len(), 16);
            }
        }
    }
}