extension.js

const vscode = require("vscode");

// Heavy / noisy paths an AI agent almost never needs to read. We only write the ones that exist.
const CANDIDATES = [
  "node_modules", "dist", "build", ".next", "out", "coverage", ".turbo", ".cache",
  ".venv", "venv", "__pycache__", ".pytest_cache", ".mypy_cache",
  "target", "vendor", ".gradle", "bin", "obj",
  ".git", ".idea", ".vscode", ".DS_Store"
];
// Glob patterns that are noise regardless of folder presence.
const GLOBS = [
  "*.lock", "package-lock.json", "pnpm-lock.yaml", "yarn.lock", "bun.lockb",
  "*.min.js", "*.map", "*.log",
  "*.png", "*.jpg", "*.jpeg", "*.gif", "*.webp", "*.ico", "*.pdf",
  "*.zip", "*.tar", "*.gz", "*.mp4", "*.mov", "*.woff", "*.woff2", "*.ttf"
];

function uriOf(rootUri, rel) {
  let u = rootUri;
  for (const p of rel.split("/")) u = vscode.Uri.joinPath(u, p);
  return u;
}

async function exists(rootUri, rel) {
  try { await vscode.workspace.fs.stat(uriOf(rootUri, rel)); return true; } catch { return false; }
}

async function listTopLevel(rootUri) {
  try {
    const entries = await vscode.workspace.fs.readDirectory(rootUri);
    return entries
      .filter(([name]) => !name.startsWith(".") && name !== "node_modules")
      .map(([name, type]) => ({ name, dir: type === vscode.FileType.Directory }))
      .sort((a, b) => (a.dir === b.dir ? a.name.localeCompare(b.name) : a.dir ? -1 : 1));
  } catch { return []; }
}

async function detectEntryPoints(rootUri) {
  const candidates = [
    "src/index.ts", "src/index.js", "src/main.ts", "src/main.tsx", "src/app.tsx",
    "app/page.tsx", "pages/index.tsx", "index.js", "index.ts", "main.py", "app.py",
    "src/main.rs", "main.go", "cmd/main.go"
  ];
  const found = [];
  for (const c of candidates) if (await exists(rootUri, c)) found.push(c);
  return found;
}

function buildIgnore(presentDirs) {
  const lines = [
    "# Generated by Context Saver — files your AI agent should skip to save tokens.",
    "# Works with Cursor (.cursorignore). Tune to taste.",
    ""
  ];
  if (presentDirs.length) {
    lines.push("# Heavy folders");
    for (const d of presentDirs) lines.push(`${d}/`);
    lines.push("");
  }
  lines.push("# Noise files");
  lines.push(...GLOBS);
  lines.push("");
  return lines.join("\n");
}

async function buildRepoMap(rootUri) {
  const top = await listTopLevel(rootUri);
  const entries = await detectEntryPoints(rootUri);
  const lines = [
    "# Repo map",
    "",
    "A compact orientation for AI agents — read this instead of crawling the whole tree.",
    "",
    "## Top-level layout"
  ];
  for (const e of top.slice(0, 40)) lines.push(`- ${e.dir ? "📁 " : "📄 "}${e.name}${e.dir ? "/" : ""}`);
  if (entries.length) {
    lines.push("", "## Likely entry points");
    for (const e of entries) lines.push(`- \`${e}\``);
  }
  lines.push(
    "",
    "## How to navigate",
    "- Start from the entry points above; follow imports rather than reading every file.",
    "- Folders listed in the ignore file are build output / deps — don't read them.",
    ""
  );
  return lines.join("\n");
}

async function writeFile(rootUri, rel, content) {
  const target = uriOf(rootUri, rel);
  try {
    await vscode.workspace.fs.stat(target);
    const choice = await vscode.window.showWarningMessage(`${rel} already exists. Overwrite it?`, "Overwrite", "Skip");
    if (choice !== "Overwrite") return false;
  } catch { /* not present */ }
  await vscode.workspace.fs.writeFile(target, Buffer.from(content, "utf8"));
  return true;
}

async function generate() {
  const folders = vscode.workspace.workspaceFolders;
  if (!folders || folders.length === 0) {
    vscode.window.showErrorMessage("Open a folder/workspace first.");
    return;
  }
  const rootUri = folders[0].uri;

  const presentDirs = [];
  for (const d of CANDIDATES) if (await exists(rootUri, d)) presentDirs.push(d);

  const written = [];
  if (await writeFile(rootUri, ".cursorignore", buildIgnore(presentDirs))) written.push(".cursorignore");
  if (await writeFile(rootUri, ".agent/repo-map.md", await buildRepoMap(rootUri))) written.push(".agent/repo-map.md");

  if (!written.length) { vscode.window.showInformationMessage("Context Saver: nothing written."); return; }
  const action = await vscode.window.showInformationMessage(
    `Context Saver: wrote ${written.join(", ")}. Your agent will skip ${presentDirs.length} heavy folder(s).`,
    "Open repo map",
    "Get the Pro config pack"
  );
  if (action === "Open repo map") {
    const doc = await vscode.workspace.openTextDocument(uriOf(rootUri, ".agent/repo-map.md"));
    vscode.window.showTextDocument(doc);
  } else if (action === "Get the Pro config pack") {
    vscode.env.openExternal(vscode.Uri.parse("https://alphaletgo.gumroad.com/l/agentic-coding-kit"));
  }
}

function activate(context) {
  context.subscriptions.push(vscode.commands.registerCommand("contextSaver.generate", generate));
}
function deactivate() {}
module.exports = { activate, deactivate };