//! Status-line and terminal-title rendering helpers for `ChatWidget`.
//!
//! Keeping this logic in a focused submodule makes the additive title/status
//! behavior easier to review without paging through the rest of `chatwidget.rs`.

use super::*;

pub(super) const DEFAULT_TERMINAL_TITLE_ITEMS: [&str; 2] = ["spinner", "project"];
pub(super) const TERMINAL_TITLE_SPINNER_FRAMES: [&str; 10] =
    ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
pub(super) const TERMINAL_TITLE_SPINNER_INTERVAL: Duration = Duration::from_millis(100);

#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
/// Compact runtime states that can be rendered into the terminal title.
///
/// This is intentionally smaller than the full status-header vocabulary. The
/// title needs short, stable labels, so callers map richer lifecycle events
/// onto one of these buckets before rendering.
pub(super) enum TerminalTitleStatusKind {
    Working,
    WaitingForBackgroundTerminal,
    Undoing,
    #[default]
    Thinking,
}

#[derive(Debug)]
/// Parsed status-surface configuration for one refresh pass.
///
/// The status line and terminal title share some expensive or stateful inputs
/// (notably git branch lookup and invalid-item warnings). This snapshot lets one
/// refresh pass compute those shared concerns once, then render both surfaces
/// from the same selection set.
struct StatusSurfaceSelections {
    status_line_items: Vec<StatusLineItem>,
    invalid_status_line_items: Vec<String>,
    terminal_title_items: Vec<TerminalTitleItem>,
    invalid_terminal_title_items: Vec<String>,
}

impl StatusSurfaceSelections {
    fn uses_git_branch(&self) -> bool {
        self.status_line_items.contains(&StatusLineItem::GitBranch)
            || self
                .terminal_title_items
                .contains(&TerminalTitleItem::GitBranch)
    }
}

#[derive(Clone, Debug)]
/// Cached project-root display name keyed by the cwd used for the last lookup.
///
/// Terminal-title refreshes can happen very frequently, so the title path avoids
/// repeatedly walking up the filesystem to rediscover the same project root name
/// while the working directory is unchanged.
pub(super) struct CachedProjectRootName {
    pub(super) cwd: PathBuf,
    pub(super) root_name: Option<String>,
}

impl ChatWidget {
    fn status_surface_selections(&self) -> StatusSurfaceSelections {
        let (status_line_items, invalid_status_line_items) = self.status_line_items_with_invalids();
        let (terminal_title_items, invalid_terminal_title_items) =
            self.terminal_title_items_with_invalids();
        StatusSurfaceSelections {
            status_line_items,
            invalid_status_line_items,
            terminal_title_items,
            invalid_terminal_title_items,
        }
    }

    fn warn_invalid_status_line_items_once(&mut self, invalid_items: &[String]) {
        if self.thread_id.is_some()
            && !invalid_items.is_empty()
            && self
                .status_line_invalid_items_warned
                .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
                .is_ok()
        {
            let label = if invalid_items.len() == 1 {
                "item"
            } else {
                "items"
            };
            let message = format!(
                "Ignored invalid status line {label}: {}.",
                proper_join(invalid_items)
            );
            self.on_warning(message);
        }
    }

    fn warn_invalid_terminal_title_items_once(&mut self, invalid_items: &[String]) {
        if self.thread_id.is_some()
            && !invalid_items.is_empty()
            && self
                .terminal_title_invalid_items_warned
                .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
                .is_ok()
        {
            let label = if invalid_items.len() == 1 {
                "item"
            } else {
                "items"
            };
            let message = format!(
                "Ignored invalid terminal title {label}: {}.",
                proper_join(invalid_items)
            );
            self.on_warning(message);
        }
    }

    fn sync_status_surface_shared_state(&mut self, selections: &StatusSurfaceSelections) {
        if !selections.uses_git_branch() {
            self.status_line_branch = None;
            self.status_line_branch_pending = false;
            self.status_line_branch_lookup_complete = false;
            return;
        }

        let cwd = self.status_line_cwd().to_path_buf();
        self.sync_status_line_branch_state(&cwd);
        if !self.status_line_branch_lookup_complete {
            self.request_status_line_branch(cwd);
        }
    }

    fn refresh_status_line_from_selections(&mut self, selections: &StatusSurfaceSelections) {
        let enabled = !selections.status_line_items.is_empty();
        self.bottom_pane.set_status_line_enabled(enabled);
        if !enabled {
            self.set_status_line(/*status_line*/ None);
            return;
        }

        let mut parts = Vec::new();
        for item in &selections.status_line_items {
            if let Some(value) = self.status_line_value_for_item(item) {
                parts.push(value);
            }
        }

        let line = if parts.is_empty() {
            None
        } else {
            Some(Line::from(parts.join(" · ")))
        };
        self.set_status_line(line);
    }

    /// Clears the terminal title Codex most recently wrote, if any.
    ///
    /// This does not attempt to restore the shell or terminal's previous title;
    /// it only clears the managed title and updates the cache after a successful
    /// OSC write.
    pub(crate) fn clear_managed_terminal_title(&mut self) -> std::io::Result<()> {
        if self.last_terminal_title.is_some() {
            clear_terminal_title()?;
            self.last_terminal_title = None;
        }

        Ok(())
    }

    /// Renders and applies the terminal title for one parsed selection snapshot.
    ///
    /// Empty selections clear the managed title. Non-empty selections render the
    /// current values in configured order, skip unavailable segments, and cache
    /// the last successfully written title so redundant OSC writes are avoided.
    /// When the `spinner` item is present in an animated running state, this also
    /// schedules the next frame so the spinner keeps advancing.
    fn refresh_terminal_title_from_selections(&mut self, selections: &StatusSurfaceSelections) {
        if selections.terminal_title_items.is_empty() {
            if let Err(err) = self.clear_managed_terminal_title() {
                tracing::debug!(error = %err, "failed to clear terminal title");
            }
            return;
        }

        let now = Instant::now();
        let mut previous = None;
        let title = selections
            .terminal_title_items
            .iter()
            .copied()
            .filter_map(|item| {
                self.terminal_title_value_for_item(item, now)
                    .map(|value| (item, value))
            })
            .fold(String::new(), |mut title, (item, value)| {
                title.push_str(item.separator_from_previous(previous));
                title.push_str(&value);
                previous = Some(item);
                title
            });
        let title = (!title.is_empty()).then_some(title);
        let should_animate_spinner =
            self.should_animate_terminal_title_spinner_with_selections(selections);
        if self.last_terminal_title == title {
            if should_animate_spinner {
                self.frame_requester
                    .schedule_frame_in(TERMINAL_TITLE_SPINNER_INTERVAL);
            }
            return;
        }
        match title {
            Some(title) => match set_terminal_title(&title) {
                Ok(SetTerminalTitleResult::Applied) => {
                    self.last_terminal_title = Some(title);
                }
                Ok(SetTerminalTitleResult::NoVisibleContent) => {
                    if let Err(err) = self.clear_managed_terminal_title() {
                        tracing::debug!(error = %err, "failed to clear terminal title");
                    }
                }
                Err(err) => {
                    tracing::debug!(error = %err, "failed to set terminal title");
                }
            },
            None => {
                if let Err(err) = self.clear_managed_terminal_title() {
                    tracing::debug!(error = %err, "failed to clear terminal title");
                }
            }
        }

        if should_animate_spinner {
            self.frame_requester
                .schedule_frame_in(TERMINAL_TITLE_SPINNER_INTERVAL);
        }
    }

    /// Recomputes both status surfaces from one shared config snapshot.
    ///
    /// This is the common refresh entrypoint for the footer status line and the
    /// terminal title. It parses both configurations once, emits invalid-item
    /// warnings once, synchronizes shared cached state (such as git-branch
    /// lookup), then renders each surface from that shared snapshot.
    pub(crate) fn refresh_status_surfaces(&mut self) {
        let selections = self.status_surface_selections();
        self.warn_invalid_status_line_items_once(&selections.invalid_status_line_items);
        self.warn_invalid_terminal_title_items_once(&selections.invalid_terminal_title_items);
        self.sync_status_surface_shared_state(&selections);
        self.refresh_status_line_from_selections(&selections);
        self.refresh_terminal_title_from_selections(&selections);
    }

    /// Recomputes and emits the terminal title from config and runtime state.
    pub(crate) fn refresh_terminal_title(&mut self) {
        let selections = self.status_surface_selections();
        self.warn_invalid_terminal_title_items_once(&selections.invalid_terminal_title_items);
        self.sync_status_surface_shared_state(&selections);
        self.refresh_terminal_title_from_selections(&selections);
    }

    pub(super) fn request_status_line_branch_refresh(&mut self) {
        let selections = self.status_surface_selections();
        if !selections.uses_git_branch() {
            return;
        }
        let cwd = self.status_line_cwd().to_path_buf();
        self.sync_status_line_branch_state(&cwd);
        self.request_status_line_branch(cwd);
    }

    /// Parses configured status-line ids into known items and collects unknown ids.
    ///
    /// Unknown ids are deduplicated in insertion order for warning messages.
    fn status_line_items_with_invalids(&self) -> (Vec<StatusLineItem>, Vec<String>) {
        let mut invalid = Vec::new();
        let mut invalid_seen = HashSet::new();
        let mut items = Vec::new();
        for id in self.configured_status_line_items() {
            match id.parse::<StatusLineItem>() {
                Ok(item) => items.push(item),
                Err(_) => {
                    if invalid_seen.insert(id.clone()) {
                        invalid.push(format!(r#""{id}""#));
                    }
                }
            }
        }
        (items, invalid)
    }

    pub(super) fn configured_status_line_items(&self) -> Vec<String> {
        self.config.tui_status_line.clone().unwrap_or_else(|| {
            DEFAULT_STATUS_LINE_ITEMS
                .iter()
                .map(ToString::to_string)
                .collect()
        })
    }

    /// Parses configured terminal-title ids into known items and collects unknown ids.
    ///
    /// Unknown ids are deduplicated in insertion order for warning messages.
    fn terminal_title_items_with_invalids(&self) -> (Vec<TerminalTitleItem>, Vec<String>) {
        let mut invalid = Vec::new();
        let mut invalid_seen = HashSet::new();
        let mut items = Vec::new();
        for id in self.configured_terminal_title_items() {
            match id.parse::<TerminalTitleItem>() {
                Ok(item) => items.push(item),
                Err(_) => {
                    if invalid_seen.insert(id.clone()) {
                        invalid.push(format!(r#""{id}""#));
                    }
                }
            }
        }
        (items, invalid)
    }

    /// Returns the configured terminal-title ids, or the default ordering when unset.
    pub(super) fn configured_terminal_title_items(&self) -> Vec<String> {
        self.config.tui_terminal_title.clone().unwrap_or_else(|| {
            DEFAULT_TERMINAL_TITLE_ITEMS
                .iter()
                .map(ToString::to_string)
                .collect()
        })
    }

    fn status_line_cwd(&self) -> &Path {
        self.current_cwd.as_ref().unwrap_or(&self.config.cwd)
    }

    /// Resolves the project root associated with `cwd`.
    ///
    /// Git repository root wins when available. Otherwise we fall back to the
    /// nearest project config layer so non-git projects can still surface a
    /// stable project label.
    fn status_line_project_root_for_cwd(&self, cwd: &Path) -> Option<PathBuf> {
        if let Some(repo_root) = get_git_repo_root(cwd) {
            return Some(repo_root);
        }

        self.config
            .config_layer_stack
            .get_layers(
                ConfigLayerStackOrdering::LowestPrecedenceFirst,
                /*include_disabled*/ true,
            )
            .iter()
            .find_map(|layer| match &layer.name {
                ConfigLayerSource::Project { dot_codex_folder } => {
                    dot_codex_folder.as_path().parent().map(Path::to_path_buf)
                }
                _ => None,
            })
    }

    fn status_line_project_root_name_for_cwd(&self, cwd: &Path) -> Option<String> {
        self.status_line_project_root_for_cwd(cwd).map(|root| {
            root.file_name()
                .map(|name| name.to_string_lossy().to_string())
                .unwrap_or_else(|| format_directory_display(&root, /*max_width*/ None))
        })
    }

    /// Returns a cached project-root display name for the active cwd.
    fn status_line_project_root_name(&mut self) -> Option<String> {
        let cwd = self.status_line_cwd().to_path_buf();
        if let Some(cache) = &self.status_line_project_root_name_cache
            && cache.cwd == cwd
        {
            return cache.root_name.clone();
        }

        let root_name = self.status_line_project_root_name_for_cwd(&cwd);
        self.status_line_project_root_name_cache = Some(CachedProjectRootName {
            cwd,
            root_name: root_name.clone(),
        });
        root_name
    }

    /// Produces the terminal-title `project` value.
    ///
    /// This prefers the cached project-root name and falls back to the current
    /// directory name when no project root can be inferred.
    fn terminal_title_project_name(&mut self) -> Option<String> {
        let project = self.status_line_project_root_name().or_else(|| {
            let cwd = self.status_line_cwd();
            Some(
                cwd.file_name()
                    .map(|name| name.to_string_lossy().to_string())
                    .unwrap_or_else(|| format_directory_display(cwd, /*max_width*/ None)),
            )
        })?;
        Some(Self::truncate_terminal_title_part(
            project, /*max_chars*/ 24,
        ))
    }

    /// Resets git-branch cache state when the status-line cwd changes.
    ///
    /// The branch cache is keyed by cwd because branch lookup is performed relative to that path.
    /// Keeping stale branch values across cwd changes would surface incorrect repository context.
    fn sync_status_line_branch_state(&mut self, cwd: &Path) {
        if self
            .status_line_branch_cwd
            .as_ref()
            .is_some_and(|path| path == cwd)
        {
            return;
        }
        self.status_line_branch_cwd = Some(cwd.to_path_buf());
        self.status_line_branch = None;
        self.status_line_branch_pending = false;
        self.status_line_branch_lookup_complete = false;
    }

    /// Starts an async git-branch lookup unless one is already running.
    ///
    /// The resulting `StatusLineBranchUpdated` event carries the lookup cwd so callers can reject
    /// stale completions after directory changes.
    fn request_status_line_branch(&mut self, cwd: PathBuf) {
        if self.status_line_branch_pending {
            return;
        }
        self.status_line_branch_pending = true;
        let tx = self.app_event_tx.clone();
        tokio::spawn(async move {
            let branch = current_branch_name(&cwd).await;
            tx.send(AppEvent::StatusLineBranchUpdated { cwd, branch });
        });
    }

    /// Resolves a display string for one configured status-line item.
    ///
    /// Returning `None` means "omit this item for now", not "configuration error". Callers rely on
    /// this to keep partially available status lines readable while waiting for session, token, or
    /// git metadata.
    pub(super) fn status_line_value_for_item(&mut self, item: &StatusLineItem) -> Option<String> {
        match item {
            StatusLineItem::ModelName => Some(self.model_display_name().to_string()),
            StatusLineItem::ModelWithReasoning => {
                let label =
                    Self::status_line_reasoning_effort_label(self.effective_reasoning_effort());
                let fast_label = if self
                    .should_show_fast_status(self.current_model(), self.config.service_tier)
                {
                    " fast"
                } else {
                    ""
                };
                Some(format!("{} {label}{fast_label}", self.model_display_name()))
            }
            StatusLineItem::CurrentDir => {
                Some(format_directory_display(
                    self.status_line_cwd(),
                    /*max_width*/ None,
                ))
            }
            StatusLineItem::ProjectRoot => self.status_line_project_root_name(),
            StatusLineItem::GitBranch => self.status_line_branch.clone(),
            StatusLineItem::UsedTokens => {
                let usage = self.status_line_total_usage();
                let total = usage.tokens_in_context_window();
                if total <= 0 {
                    None
                } else {
                    Some(format!("{} used", format_tokens_compact(total)))
                }
            }
            StatusLineItem::ContextRemaining => self
                .status_line_context_remaining_percent()
                .map(|remaining| format!("{remaining}% left")),
            StatusLineItem::ContextUsed => self
                .status_line_context_used_percent()
                .map(|used| format!("{used}% used")),
            StatusLineItem::FiveHourLimit => {
                let window = self
                    .rate_limit_snapshots_by_limit_id
                    .get("codex")
                    .and_then(|s| s.primary.as_ref());
                let label = window
                    .and_then(|window| window.window_minutes)
                    .map(get_limits_duration)
                    .unwrap_or_else(|| "5h".to_string());
                self.status_line_limit_display(window, &label)
            }
            StatusLineItem::WeeklyLimit => {
                let window = self
                    .rate_limit_snapshots_by_limit_id
                    .get("codex")
                    .and_then(|s| s.secondary.as_ref());
                let label = window
                    .and_then(|window| window.window_minutes)
                    .map(get_limits_duration)
                    .unwrap_or_else(|| "weekly".to_string());
                self.status_line_limit_display(window, &label)
            }
            StatusLineItem::CodexVersion => Some(CODEX_CLI_VERSION.to_string()),
            StatusLineItem::ContextWindowSize => self
                .status_line_context_window_size()
                .map(|cws| format!("{} window", format_tokens_compact(cws))),
            StatusLineItem::TotalInputTokens => Some(format!(
                "{} in",
                format_tokens_compact(self.status_line_total_usage().input_tokens)
            )),
            StatusLineItem::TotalOutputTokens => Some(format!(
                "{} out",
                format_tokens_compact(self.status_line_total_usage().output_tokens)
            )),
            StatusLineItem::SessionId => self.thread_id.map(|id| id.to_string()),
            StatusLineItem::FastMode => Some(
                if matches!(self.config.service_tier, Some(ServiceTier::Fast)) {
                    "Fast on".to_string()
                } else {
                    "Fast off".to_string()
                },
            ),
        }
    }

    /// Resolves one configured terminal-title item into a displayable segment.
    ///
    /// Returning `None` means "omit this segment for now" so callers can keep
    /// the configured order while hiding values that are not yet available.
    fn terminal_title_value_for_item(
        &mut self,
        item: TerminalTitleItem,
        now: Instant,
    ) -> Option<String> {
        match item {
            TerminalTitleItem::AppName => Some("codex".to_string()),
            TerminalTitleItem::Project => self.terminal_title_project_name(),
            TerminalTitleItem::Spinner => self.terminal_title_spinner_text_at(now),
            TerminalTitleItem::Status => Some(self.terminal_title_status_text()),
            TerminalTitleItem::Thread => self.thread_name.as_ref().and_then(|name| {
                let trimmed = name.trim();
                if trimmed.is_empty() {
                    None
                } else {
                    Some(Self::truncate_terminal_title_part(
                        trimmed.to_string(),
                        /*max_chars*/ 48,
                    ))
                }
            }),
            TerminalTitleItem::GitBranch => self.status_line_branch.as_ref().map(|branch| {
                Self::truncate_terminal_title_part(branch.clone(), /*max_chars*/ 32)
            }),
            TerminalTitleItem::Model => Some(Self::truncate_terminal_title_part(
                self.model_display_name().to_string(),
                /*max_chars*/ 32,
            )),
            TerminalTitleItem::TaskProgress => self.terminal_title_task_progress(),
        }
    }

    /// Computes the compact runtime status label used by the terminal title.
    ///
    /// Startup takes precedence over normal task states, and idle state renders
    /// as `Ready` regardless of the last active status bucket.
    pub(super) fn terminal_title_status_text(&self) -> String {
        if self.mcp_startup_status.is_some() {
            return "Starting".to_string();
        }

        match self.terminal_title_status_kind {
            TerminalTitleStatusKind::Working if !self.bottom_pane.is_task_running() => {
                "Ready".to_string()
            }
            TerminalTitleStatusKind::WaitingForBackgroundTerminal
                if !self.bottom_pane.is_task_running() =>
            {
                "Ready".to_string()
            }
            TerminalTitleStatusKind::Thinking if !self.bottom_pane.is_task_running() => {
                "Ready".to_string()
            }
            TerminalTitleStatusKind::Working => "Working".to_string(),
            TerminalTitleStatusKind::WaitingForBackgroundTerminal => "Waiting".to_string(),
            TerminalTitleStatusKind::Undoing => "Undoing".to_string(),
            TerminalTitleStatusKind::Thinking => "Thinking".to_string(),
        }
    }

    pub(super) fn terminal_title_spinner_text_at(&self, now: Instant) -> Option<String> {
        if !self.config.animations {
            return None;
        }

        if !self.terminal_title_has_active_progress() {
            return None;
        }

        Some(self.terminal_title_spinner_frame_at(now).to_string())
    }

    fn terminal_title_spinner_frame_at(&self, now: Instant) -> &'static str {
        let elapsed = now.saturating_duration_since(self.terminal_title_animation_origin);
        let frame_index =
            (elapsed.as_millis() / TERMINAL_TITLE_SPINNER_INTERVAL.as_millis()) as usize;
        TERMINAL_TITLE_SPINNER_FRAMES[frame_index % TERMINAL_TITLE_SPINNER_FRAMES.len()]
    }

    fn terminal_title_uses_spinner(&self) -> bool {
        self.config
            .tui_terminal_title
            .as_ref()
            .is_none_or(|items| items.iter().any(|item| item == "spinner"))
    }

    fn terminal_title_has_active_progress(&self) -> bool {
        self.mcp_startup_status.is_some()
            || self.bottom_pane.is_task_running()
            || self.terminal_title_status_kind == TerminalTitleStatusKind::Undoing
    }

    pub(super) fn should_animate_terminal_title_spinner(&self) -> bool {
        self.config.animations
            && self.terminal_title_uses_spinner()
            && self.terminal_title_has_active_progress()
    }

    fn should_animate_terminal_title_spinner_with_selections(
        &self,
        selections: &StatusSurfaceSelections,
    ) -> bool {
        self.config.animations
            && selections
                .terminal_title_items
                .contains(&TerminalTitleItem::Spinner)
            && self.terminal_title_has_active_progress()
    }

    /// Formats the last `update_plan` progress snapshot for terminal-title display.
    pub(super) fn terminal_title_task_progress(&self) -> Option<String> {
        let (completed, total) = self.last_plan_progress?;
        if total == 0 {
            return None;
        }
        Some(format!("Tasks {completed}/{total}"))
    }

    /// Truncates a title segment by grapheme cluster and appends `...` when needed.
    pub(super) fn truncate_terminal_title_part(value: String, max_chars: usize) -> String {
        if max_chars == 0 {
            return String::new();
        }

        let mut graphemes = value.graphemes(true);
        let head: String = graphemes.by_ref().take(max_chars).collect();
        if graphemes.next().is_none() || max_chars <= 3 {
            return head;
        }

        let mut truncated = head.graphemes(true).take(max_chars - 3).collect::<String>();
        truncated.push_str("...");
        truncated
    }
}