// Per-project count of files containing non-erasable syntax (what downlevel mode has to
// down-level): enum, instantiated namespace/module, parameter properties, `import =`,
// `export =`. AST-based (TypeScript's parser), not a grep, so decorators-only files and
// commented-out keywords don't miscount.
// Usage: node scripts/oss-oss-count-nonerasable.mjs
import ts from "typescript";
import { projects, ossRoot, walkFiles } from "./oss-corpus.mjs";
import path from "node:path";
import fs from "node:fs";

const SK = ts.SyntaxKind;

function hasNonErasable(sf) {
  const found = new Set();
  (function visit(n) {
    switch (n.kind) {
      case SK.EnumDeclaration:
        found.add("enum");
        break;
      case SK.ModuleDeclaration:
        // Instantiated namespace/module: has a body with real statements (not just a
        // declare-only ambient module, which is erased like any other declaration).
        if (n.body && !(n.modifiers?.some((m) => m.kind === SK.DeclareKeyword))) found.add("namespace");
        break;
      case SK.ImportEqualsDeclaration:
        found.add("import=");
        break;
      case SK.ExportAssignment:
        if (n.isExportEquals) found.add("export=");
        break;
      case SK.Parameter:
        if (n.modifiers?.some((m) => [SK.PublicKeyword, SK.PrivateKeyword, SK.ProtectedKeyword, SK.ReadonlyKeyword].includes(m.kind))) {
          found.add("param-property");
        }
        break;
    }
    ts.forEachChild(n, visit);
  })(sf);
  return found;
}

const rows = [];
for (const name of projects()) {
  const dir = path.join(ossRoot, name);
  let files = 0, withNonErasable = 0;
  const kindCounts = {};
  for (const f of walkFiles(dir)) {
    let src;
    try { src = fs.readFileSync(f, "utf8"); } catch { continue; }
    files++;
    const sf = ts.createSourceFile(path.basename(f), src, ts.ScriptTarget.ESNext, false, ts.ScriptKind.TS);
    const found = hasNonErasable(sf);
    if (found.size) {
      withNonErasable++;
      for (const k of found) kindCounts[k] = (kindCounts[k] ?? 0) + 1;
    }
  }
  rows.push({ name, files, withNonErasable, kindCounts });
  console.log(`${name.padEnd(18)} files=${files} non-erasable=${withNonErasable} ${JSON.stringify(kindCounts)}`);
}
fs.writeFileSync(path.join(import.meta.dirname, "../corpus/oss-nonerasable.json"), JSON.stringify(rows, null, 2) + "\n");
console.log("\nwritten corpus/oss-nonerasable.json");