import { type ExecFileException, execFile, spawnSync } from "child_process";
import { existsSync, type FSWatcher, readFileSync, unwatchFile, watchFile } from "fs";
import { dirname, join } from "path";
import { closeWatcher, FS_WATCH_RETRY_DELAY_MS, watchWithErrorHandler } from "../utils/fs-watch.js";
import { findGitPaths, type GitPaths } from "../utils/git.js";
/** Ask git for the current branch. Returns null on detached HEAD or if git is unavailable. */
function resolveBranchWithGitSync(repoDir: string): string | null {
const result = spawnSync("git", ["--no-optional-locks", "symbolic-ref", "--quiet", "--short", "HEAD"], {
cwd: repoDir,
encoding: "utf8",
stdio: ["ignore", "pipe", "ignore"],
});
const branch = result.status === 0 ? result.stdout.trim() : "";
return branch || null;
}
/** Ask git for the current branch asynchronously. Returns null on detached HEAD or if git is unavailable. */
function resolveBranchWithGitAsync(repoDir: string): Promise<string | null> {
return new Promise((resolvePromise) => {
execFile(
"git",
["--no-optional-locks", "symbolic-ref", "--quiet", "--short", "HEAD"],
{
cwd: repoDir,
encoding: "utf8",
},
(error: ExecFileException | null, stdout: string) => {
if (error) {
resolvePromise(null);
return;
}
const branch = stdout.trim();
resolvePromise(branch || null);
},
);
});
}
/**
* Provides git branch and extension statuses - data not otherwise accessible to extensions.
* Token stats, model info available via ctx.sessionManager and ctx.model.
*/
export class FooterDataProvider {
private cwd: string;
private static readonly WATCH_DEBOUNCE_MS = 500;
private extensionStatuses = new Map<string, string>();
private cachedBranch: string | null | undefined = undefined;
private gitPaths: GitPaths | null | undefined = undefined;
private headWatcher: FSWatcher | null = null;
private reftableWatcher: FSWatcher | null = null;
private reftableTablesListWatcher: FSWatcher | null = null;
private reftableTablesListPath: string | null = null;
private branchChangeCallbacks = new Set<() => void>();
private availableProviderCount = 0;
private refreshTimer: ReturnType<typeof setTimeout> | null = null;
private gitWatcherRetryTimer: ReturnType<typeof setTimeout> | null = null;
private refreshInFlight = false;
private refreshPending = false;
private disposed = false;
constructor(cwd: string) {
this.cwd = cwd;
this.gitPaths = findGitPaths(cwd);
this.setupGitWatcher();
}
/** Current git branch, null if not in repo, "detached" if detached HEAD */
getGitBranch(): string | null {
if (this.cachedBranch === undefined) {
this.cachedBranch = this.resolveGitBranchSync();
}
return this.cachedBranch;
}
/** Extension status texts set via ctx.ui.setStatus() */
getExtensionStatuses(): ReadonlyMap<string, string> {
return this.extensionStatuses;
}
/** Subscribe to git branch changes. Returns unsubscribe function. */
onBranchChange(callback: () => void): () => void {
this.branchChangeCallbacks.add(callback);
return () => this.branchChangeCallbacks.delete(callback);
}
/** Internal: set extension status */
setExtensionStatus(key: string, text: string | undefined): void {
if (text === undefined) {
this.extensionStatuses.delete(key);
} else {
this.extensionStatuses.set(key, text);
}
}
/** Internal: clear extension statuses */
clearExtensionStatuses(): void {
this.extensionStatuses.clear();
}
/** Number of unique providers with available models (for footer display) */
getAvailableProviderCount(): number {
return this.availableProviderCount;
}
/** Internal: update available provider count */
setAvailableProviderCount(count: number): void {
this.availableProviderCount = count;
}
setCwd(cwd: string): void {
if (this.cwd === cwd) {
return;
}
this.cwd = cwd;
if (this.refreshTimer) {
clearTimeout(this.refreshTimer);
this.refreshTimer = null;
}
this.clearGitWatchers();
this.cachedBranch = undefined;
this.gitPaths = findGitPaths(cwd);
this.setupGitWatcher();
this.notifyBranchChange();
}
/** Internal: cleanup */
dispose(): void {
this.disposed = true;
if (this.refreshTimer) {
clearTimeout(this.refreshTimer);
this.refreshTimer = null;
}
this.clearGitWatchers();
this.branchChangeCallbacks.clear();
}
private notifyBranchChange(): void {
for (const cb of this.branchChangeCallbacks) cb();
}
private scheduleRefresh(): void {
if (this.disposed || this.refreshTimer) return;
if (this.refreshInFlight) {
this.refreshPending = true;
return;
}
this.refreshTimer = setTimeout(() => {
this.refreshTimer = null;
void this.refreshGitBranchAsync();
}, FooterDataProvider.WATCH_DEBOUNCE_MS);
}
private async refreshGitBranchAsync(): Promise<void> {
if (this.disposed) return;
if (this.refreshInFlight) {
this.refreshPending = true;
return;
}
this.refreshInFlight = true;
try {
const nextBranch = await this.resolveGitBranchAsync();
if (this.disposed) return;
if (this.cachedBranch !== undefined && this.cachedBranch !== nextBranch) {
this.cachedBranch = nextBranch;
this.notifyBranchChange();
return;
}
this.cachedBranch = nextBranch;
} finally {
this.refreshInFlight = false;
if (this.refreshPending && !this.disposed) {
this.refreshPending = false;
this.scheduleRefresh();
}
}
}
private resolveGitBranchSync(): string | null {
try {
if (!this.gitPaths) return null;
const content = readFileSync(this.gitPaths.headPath, "utf8").trim();
if (content.startsWith("ref: refs/heads/")) {
const branch = content.slice(16);
return branch === ".invalid" ? (resolveBranchWithGitSync(this.gitPaths.repoDir) ?? "detached") : branch;
}
return "detached";
} catch {
return null;
}
}
private async resolveGitBranchAsync(): Promise<string | null> {
try {
if (!this.gitPaths) return null;
const content = readFileSync(this.gitPaths.headPath, "utf8").trim();
if (content.startsWith("ref: refs/heads/")) {
const branch = content.slice(16);
return branch === ".invalid"
? ((await resolveBranchWithGitAsync(this.gitPaths.repoDir)) ?? "detached")
: branch;
}
return "detached";
} catch {
return null;
}
}
private clearGitWatchers(): void {
closeWatcher(this.headWatcher);
this.headWatcher = null;
closeWatcher(this.reftableWatcher);
this.reftableWatcher = null;
closeWatcher(this.reftableTablesListWatcher);
this.reftableTablesListWatcher = null;
if (this.reftableTablesListPath) {
unwatchFile(this.reftableTablesListPath);
this.reftableTablesListPath = null;
}
if (this.gitWatcherRetryTimer) {
clearTimeout(this.gitWatcherRetryTimer);
this.gitWatcherRetryTimer = null;
}
}
private scheduleGitWatcherRetry(): void {
if (this.disposed || this.gitWatcherRetryTimer) {
return;
}
this.gitWatcherRetryTimer = setTimeout(() => {
this.gitWatcherRetryTimer = null;
this.setupGitWatcher();
}, FS_WATCH_RETRY_DELAY_MS);
}
private handleGitWatcherError(): void {
this.clearGitWatchers();
this.scheduleGitWatcherRetry();
}
private setupGitWatcher(): void {
this.clearGitWatchers();
if (!this.gitPaths) return;
// Watch the directory containing HEAD, not HEAD itself.
// Git uses atomic writes (write temp, rename over HEAD), which changes the inode.
// fs.watch on a file stops working after the inode changes.
this.headWatcher = watchWithErrorHandler(
dirname(this.gitPaths.headPath),
(_eventType, filename) => {
if (!filename || filename === "HEAD") {
this.scheduleRefresh();
}
},
() => this.handleGitWatcherError(),
);
if (!this.headWatcher) {
return;
}
// In reftable repos, branch switches update files in the reftable directory
// instead of HEAD. Watch it separately so the footer picks up those changes.
const reftableDir = join(this.gitPaths.commonGitDir, "reftable");
if (existsSync(reftableDir)) {
this.reftableWatcher = watchWithErrorHandler(
reftableDir,
() => {
this.scheduleRefresh();
},
() => this.handleGitWatcherError(),
);
if (!this.reftableWatcher) {
return;
}
const tablesListPath = join(reftableDir, "tables.list");
if (existsSync(tablesListPath)) {
this.reftableTablesListPath = tablesListPath;
this.reftableTablesListWatcher = watchWithErrorHandler(
tablesListPath,
() => {
this.scheduleRefresh();
},
() => this.handleGitWatcherError(),
);
if (!this.reftableTablesListWatcher) {
return;
}
watchFile(tablesListPath, { interval: 250 }, (current, previous) => {
if (
current.mtimeMs !== previous.mtimeMs ||
current.ctimeMs !== previous.ctimeMs ||
current.size !== previous.size
) {
this.scheduleRefresh();
}
});
}
}
}
}
/** Read-only view for extensions - excludes setExtensionStatus, setAvailableProviderCount and dispose */
export type ReadonlyFooterDataProvider = Pick<
FooterDataProvider,
"getGitBranch" | "getExtensionStatuses" | "getAvailableProviderCount" | "onBranchChange"
>;