Add file browser, tests, and bin entrypoint

src/file-browser.js

@@ -0,0 +1,141 @@
+'use strict';
+
+/**
+ * File-browser helpers for prompt file mentions.
+ *
+ * Pure, terminal-free helpers used by the in-prompt file browser in
+ * `autocomplete-input.js`. Keeping them here means the listing, mention
+ * formatting and range math can be unit-tested without a TTY.
+ *
+ * Everything path-related stays relative to `ROOT_DIR` and uses forward
+ * slashes, matching the rest of the system (`list_files`, `read_file`,
+ * `ripgrep`). File reads are constrained to the workspace via `resolveSafe`.
+ */
+
+import fs from 'fs';
+import path from 'path';
+
+import { ROOT_DIR } from './config.js';
+import { listDir } from './dir-listing.js';
+import { resolveSafe } from './sandbox.js';
+
+/** Normalize a workspace-relative path to forward slashes, no trailing slash. */
+function normalizeRel(rel) {
+    return String(rel || '').replace(/\\/g, '/').replace(/\/+$/, '');
+}
+
+/** Return the parent of a workspace-relative directory path ('' at the root). */
+export function parentOf(cwd) {
+    const rel = normalizeRel(cwd);
+    if (!rel) return '';
+    const idx = rel.lastIndexOf('/');
+    return idx === -1 ? '' : rel.slice(0, idx);
+}
+
+/** Basename of a workspace-relative path. */
+export function baseOf(rel) {
+    const clean = normalizeRel(rel);
+    const idx = clean.lastIndexOf('/');
+    return idx === -1 ? clean : clean.slice(idx + 1);
+}
+
+/**
+ * List the entries of a workspace-relative directory for the browser.
+ *
+ * Directories come first (then files), each alphabetically. A synthetic
+ * `..` entry is prepended unless we are already at the workspace root.
+ * Respects `.gitignore` and hides dot-directories by delegating to `listDir`.
+ *
+ * Returns an array of `{ name, rel, type }` where `type` is one of
+ * `'parent' | 'd' | 'f'` and `rel` is relative to `ROOT_DIR` (no trailing
+ * slash; '' for the parent entry at depth 1).
+ */
+export function listEntries(cwd = '') {
+    const rel = normalizeRel(cwd);
+    const dir = rel ? path.join(ROOT_DIR, rel) : ROOT_DIR;
+    const { entries } = listDir(dir, { seek: 0, limit: Number.MAX_SAFE_INTEGER });
+
+    const dirs = entries.filter((e) => e.type === 'd');
+    const files = entries.filter((e) => e.type === 'f');
+    const byName = (a, b) => a.path.localeCompare(b.path);
+    dirs.sort(byName);
+    files.sort(byName);
+
+    const out = [];
+    if (rel) out.push({ name: '..', rel: parentOf(rel), type: 'parent' });
+    for (const e of dirs) {
+        const childRel = normalizeRel(e.path);
+        out.push({ name: baseOf(childRel), rel: childRel, type: 'd' });
+    }
+    for (const e of files) {
+        const childRel = normalizeRel(e.path);
+        out.push({ name: baseOf(childRel), rel: childRel, type: 'f' });
+    }
+    return out;
+}
+
+/**
+ * Read a workspace-relative file as an array of lines (split on `\n`).
+ *
+ * Returns `{ lines, binary }`. An empty file yields `[]`. A file containing a
+ * NUL byte in its first 8000 bytes is reported as binary with no lines, so the
+ * line selector can fall back to a whole-file mention without garbling output.
+ * Read/permission errors yield `{ lines: [], binary: false, error: true }`
+ * rather than throwing, so the browser can refresh and keep going.
+ */
+export function readLines(relPath) {
+    let abs;
+    try {
+        abs = resolveSafe(relPath);
+    } catch {
+        return { lines: [], binary: false, error: true };
+    }
+    let buf;
+    try {
+        buf = fs.readFileSync(abs);
+    } catch {
+        return { lines: [], binary: false, error: true };
+    }
+    if (buf.subarray(0, 8000).includes(0)) {
+        return { lines: [], binary: true };
+    }
+    const text = buf.toString('utf8');
+    const lines = text.length === 0 ? [] : text.split('\n');
+    return { lines, binary: false };
+}
+
+/**
+ * Format a mention for insertion into the prompt.
+ *
+ *   formatMention('a/b.js')          -> '@a/b.js'
+ *   formatMention('a/b.js', 10, 10)  -> '@a/b.js:10'
+ *   formatMention('a/b.js', 10, 20)  -> '@a/b.js:10-20'
+ */
+export function formatMention(relPath, start, end) {
+    const p = normalizeRel(relPath);
+    if (start === undefined || start === null) return `@${p}`;
+    if (end === undefined || end === null || end === start) return `@${p}:${start}`;
+    return `@${p}:${start}-${end}`;
+}
+
+/**
+ * Normalize a marked range from two 0-based line indices to the 1-based
+ * `{ start, end }` shown to the user (start <= end).
+ */
+export function normalizeRange(anchor, cursor) {
+    const a = Math.min(anchor, cursor);
+    const b = Math.max(anchor, cursor);
+    return { start: a + 1, end: b + 1 };
+}
+
+/**
+ * Top index of the visible window of `size` rows that keeps `cursor` in view.
+ * Returns 0 when everything fits.
+ */
+export function windowStart(cursor, total, size) {
+    if (total <= size) return 0;
+    let start = cursor - Math.floor(size / 2);
+    if (start < 0) start = 0;
+    if (start + size > total) start = total - size;
+    return start;
+}